Discussion:
[libvirt] [PATCH v5 6/6] block: Enable qemu_open/close to work with fd sets
Corey Bryant
2012-07-23 13:08:05 UTC
Permalink
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.

Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.

Signed-off-by: Corey Bryant <***@linux.vnet.ibm.com>

v2:
-Get rid of file_open and move dup code to qemu_open
(***@redhat.com)
-Use strtol wrapper instead of atoi (***@redhat.com)

v3:
-Add note about fd leakage (***@redhat.com)

v4
-Moved patch to be later in series (***@redhat.com)
-Update qemu_open to check access mode flags and set flags that
can be set (***@redhat.com, ***@redhat.com)

v5:
-This patch was overhauled quite a bit in this version, with
the addition of fd set and refcount support.
-Use qemu_set_cloexec() on dup'd fd (***@redhat.com)
-Modify flags set by fcntl on dup'd fd (***@redhat.com)
-Reduce syscalls when setting flags for dup'd fd (***@redhat.com)
-Fix O_RDWR, O_RDONLY, O_WRONLY checks (***@redhat.com)
---
block/raw-posix.c | 24 +++++-----
block/raw-win32.c | 2 +-
block/vmdk.c | 4 +-
block/vpc.c | 2 +-
block/vvfat.c | 12 ++---
cutils.c | 5 ++
monitor.c | 85 +++++++++++++++++++++++++++++++++
monitor.h | 4 ++
osdep.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
qemu-common.h | 3 +-
qemu-tool.c | 12 +++++
11 files changed, 267 insertions(+), 24 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index a172de3..5d0a801 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
out_free_buf:
qemu_vfree(s->aligned_buf);
out_close:
- qemu_close(fd);
+ qemu_close(fd, filename);
return -errno;
}

@@ -376,7 +376,7 @@ static void raw_close(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
if (s->fd >= 0) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
if (s->aligned_buf != NULL)
qemu_vfree(s->aligned_buf);
@@ -580,7 +580,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
result = -errno;
}
- if (qemu_close(fd) != 0) {
+ if (qemu_close(fd, filename) != 0) {
result = -errno;
}
}
@@ -850,7 +850,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
if (fd < 0) {
bsdPath[strlen(bsdPath)-1] = '1';
} else {
- qemu_close(fd);
+ qemu_close(fd, bsdPath);
}
filename = bsdPath;
}
@@ -889,7 +889,7 @@ static int fd_open(BlockDriverState *bs)
last_media_present = (s->fd >= 0);
if (s->fd >= 0 &&
(get_clock() - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
#ifdef DEBUG_FLOPPY
printf("Floppy closed\n");
@@ -988,7 +988,7 @@ static int hdev_create(const char *filename, QEMUOptionParameter *options)
else if (lseek(fd, 0, SEEK_END) < total_size * BDRV_SECTOR_SIZE)
ret = -ENOSPC;

- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}

@@ -1038,7 +1038,7 @@ static int floppy_open(BlockDriverState *bs, const char *filename, int flags)
return ret;

/* close fd so that we can reopen it as needed */
- qemu_close(s->fd);
+ qemu_close(s->fd, filename);
s->fd = -1;
s->fd_media_changed = 1;

@@ -1070,7 +1070,7 @@ static int floppy_probe_device(const char *filename)
prio = 100;

outc:
- qemu_close(fd);
+ qemu_close(fd, filename);
out:
return prio;
}
@@ -1105,14 +1105,14 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
int fd;

if (s->fd >= 0) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
}
fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
if (fd >= 0) {
if (ioctl(fd, FDEJECT, 0) < 0)
perror("FDEJECT");
- qemu_close(fd);
+ qemu_close(fd, bs->filename);
}
}

@@ -1173,7 +1173,7 @@ static int cdrom_probe_device(const char *filename)
prio = 100;

outc:
- qemu_close(fd);
+ qemu_close(fd, filename);
out:
return prio;
}
@@ -1281,7 +1281,7 @@ static int cdrom_reopen(BlockDriverState *bs)
* FreeBSD seems to not notice sometimes...
*/
if (s->fd >= 0)
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
fd = qemu_open(bs->filename, s->open_flags, 0644);
if (fd < 0) {
s->fd = -1;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index c56bf83..b795871 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -261,7 +261,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
return -EIO;
set_sparse(fd);
ftruncate(fd, total_size * 512);
- qemu_close(fd);
+ qemu_close(fd, filename);
return 0;
}

diff --git a/block/vmdk.c b/block/vmdk.c
index daee426..7f1206b 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1258,7 +1258,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,

ret = 0;
exit:
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}

@@ -1506,7 +1506,7 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options)
}
ret = 0;
exit:
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}

diff --git a/block/vpc.c b/block/vpc.c
index c0b82c4..20f648a 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -744,7 +744,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
}

fail:
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}

diff --git a/block/vvfat.c b/block/vvfat.c
index 59d3c5b..cbc7543 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1105,7 +1105,7 @@ static inline void vvfat_close_current_file(BDRVVVFATState *s)
if(s->current_mapping) {
s->current_mapping = NULL;
if (s->current_fd) {
- qemu_close(s->current_fd);
+ qemu_close(s->current_fd, s->current_mapping->path);
s->current_fd = 0;
}
}
@@ -2230,7 +2230,7 @@ static int commit_one_file(BDRVVVFATState* s,
}
if (offset > 0) {
if (lseek(fd, offset, SEEK_SET) != offset) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -3;
}
@@ -2251,13 +2251,13 @@ static int commit_one_file(BDRVVVFATState* s,
(uint8_t*)cluster, (rest_size + 0x1ff) / 0x200);

if (ret < 0) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return ret;
}

if (write(fd, cluster, rest_size) < 0) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -2;
}
@@ -2268,11 +2268,11 @@ static int commit_one_file(BDRVVVFATState* s,

if (ftruncate(fd, size)) {
perror("ftruncate()");
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -4;
}
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);

return commit_mappings(s, first_cluster, dir_index);
diff --git a/cutils.c b/cutils.c
index e2bc1b8..4e6bfdc 100644
--- a/cutils.c
+++ b/cutils.c
@@ -375,3 +375,8 @@ int qemu_parse_fd(const char *param)
}
return fd;
}
+
+int qemu_parse_fdset(const char *param)
+{
+ return qemu_parse_fd(param);
+}
diff --git a/monitor.c b/monitor.c
index 30b085f..fddd2b5 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}

+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount++;
+ break;
+ }
+ }
+}
+
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount--;
+ if (mon_fdset->refcount == 0) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ break;
+ }
+ }
+}
+
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
+ }
+
+ switch (flags & O_ACCMODE) {
+ case O_RDWR:
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ case O_RDONLY:
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ case O_WRONLY:
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ }
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
diff --git a/monitor.h b/monitor.h
index 5f4de1b..1efed38 100644
--- a/monitor.h
+++ b/monitor.h
@@ -86,4 +86,8 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret);

int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);

+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags);
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id);
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id);
+
#endif /* !MONITOR_H */
diff --git a/osdep.c b/osdep.c
index 7b09dff..0303cdd 100644
--- a/osdep.c
+++ b/osdep.c
@@ -47,6 +47,7 @@ extern int madvise(caddr_t, size_t, int);
#include "qemu-common.h"
#include "trace.h"
#include "qemu_socket.h"
+#include "monitor.h"

static const char *qemu_version = QEMU_VERSION;

@@ -75,6 +76,79 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}

+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
+
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
+
+ qemu_set_cloexec(ret);
+
+ return ret;
+
+fail:
+ serrno = errno;
+ if (ret != -1) {
+ close(ret);
+ }
+ errno = serrno;
+ return -1;
+}

/*
* Opens a file with FD_CLOEXEC set
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;

+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
+ if (fd == -1) {
+ return -1;
+ }
+
+ dupfd = qemu_dup(fd, flags);
+ if (fd == -1) {
+ return -1;
+ }
+
+ monitor_fdset_increment_refcount(default_mon, fdset_id);
+
+ return dupfd;
+ }
+#endif
+
if (flags & O_CREAT) {
va_list ap;

@@ -104,8 +208,40 @@ int qemu_open(const char *name, int flags, ...)
return ret;
}

-int qemu_close(int fd)
+int qemu_close(int fd, const char *name)
{
+ const char *fdset_id_str;
+
+ /* Close fd that was dup'd from an fdset */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int ret;
+ int64_t fdset_id;
+ int fdset_fd;
+ int flags;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ return -1;
+ }
+
+ flags = fcntl(fd, F_GETFL);
+ if (flags == -1) {
+ return -1;
+ }
+
+ fdset_fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
+ if (fdset_fd == -1) {
+ return -1;
+ }
+
+ ret = close(fd);
+ if (ret == 0) {
+ monitor_fdset_decrement_refcount(default_mon, fdset_id);
+ }
+
+ return ret;
+ }
+
return close(fd);
}

diff --git a/qemu-common.h b/qemu-common.h
index c8ddf2f..6b4123c 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -147,6 +147,7 @@ int qemu_fls(int i);
int qemu_fdatasync(int fd);
int fcntl_setfl(int fd, int flag);
int qemu_parse_fd(const char *param);
+int qemu_parse_fdset(const char *param);

/*
* strtosz() suffixes used to specify the default treatment of an
@@ -188,7 +189,7 @@ const char *path(const char *pathname);
void *qemu_oom_check(void *ptr);

int qemu_open(const char *name, int flags, ...);
-int qemu_close(int fd);
+int qemu_close(int fd, const char *name);
ssize_t qemu_write_full(int fd, const void *buf, size_t count)
QEMU_WARN_UNUSED_RESULT;
ssize_t qemu_send_full(int fd, const void *buf, size_t count, int flags)
diff --git a/qemu-tool.c b/qemu-tool.c
index 318c5fc..f4db9db 100644
--- a/qemu-tool.c
+++ b/qemu-tool.c
@@ -31,6 +31,7 @@ struct QEMUBH
};

Monitor *cur_mon;
+Monitor *default_mon;

int monitor_cur_is_qmp(void)
{
@@ -57,6 +58,17 @@ void monitor_protocol_event(MonitorEvent event, QObject *data)
{
}

+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ return -1;
+}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+}
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+}
+
int64_t cpu_get_clock(void)
{
return qemu_get_clock_ns(rt_clock);
--
1.7.10.4
Corey Bryant
2012-07-23 13:08:01 UTC
Permalink
This patch adds support that enables passing of file descriptors
to the QEMU monitor where they will be stored in specified file
descriptor sets.

A file descriptor set can be used by a client like libvirt to
store file descriptors for the same file. This allows the
client to open a file with different access modes (O_RDWR,
O_WRONLY, O_RDONLY) and add/remove the passed fds to/from an fd
set as needed. This will allow QEMU to (in a later patch in this
series) "open" and "reopen" the same file by dup()ing the fd in
the fd set that corresponds to the file, where the fd has the
matching access mode flag that QEMU requests.

The new QMP commands are:
add-fd: Add a file descriptor to an fd set
remove-fd: Remove a file descriptor from an fd set
query-fdsets: Return information describing all fd sets

Note: These commands are not compatible with the existing getfd
and closefd QMP commands.

v5:
-This patch is new in v5 and replaces the pass-fd QMP command
from v4.
-By grouping fds in fd sets, we ease managability with an fd
set per file, addressing concerns raised in v4 about handling
"reopens" and preventing fd leakage. (***@redhat.com,
***@redhat.com, ***@redhat.com)

Signed-off-by: Corey Bryant <***@linux.vnet.ibm.com>
---
monitor.c | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
qapi-schema.json | 97 ++++++++++++++++++++++++++++++++++++
qmp-commands.hx | 121 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 361 insertions(+), 1 deletion(-)

diff --git a/monitor.c b/monitor.c
index 09aa3cd..e27dbbe 100644
--- a/monitor.c
+++ b/monitor.c
@@ -140,6 +140,24 @@ struct mon_fd_t {
QLIST_ENTRY(mon_fd_t) next;
};

+/* file descriptor associated with a file descriptor set */
+typedef struct mon_fdset_fd_t mon_fdset_fd_t;
+struct mon_fdset_fd_t {
+ int fd;
+ bool removed;
+ QLIST_ENTRY(mon_fdset_fd_t) next;
+};
+
+/* file descriptor set containing fds passed via SCM_RIGHTS */
+typedef struct mon_fdset_t mon_fdset_t;
+struct mon_fdset_t {
+ int64_t id;
+ int refcount;
+ bool in_use;
+ QLIST_HEAD(, mon_fdset_fd_t) fds;
+ QLIST_ENTRY(mon_fdset_t) next;
+};
+
typedef struct MonitorControl {
QObject *id;
JSONMessageParser parser;
@@ -176,7 +194,8 @@ struct Monitor {
int print_calls_nr;
#endif
QError *error;
- QLIST_HEAD(,mon_fd_t) fds;
+ QLIST_HEAD(, mon_fd_t) fds;
+ QLIST_HEAD(, mon_fdset_t) fdsets;
QLIST_ENTRY(Monitor) entry;
};

@@ -2396,6 +2415,129 @@ int monitor_get_fd(Monitor *mon, const char *fdname)
return -1;
}

+static void monitor_fdset_cleanup(mon_fdset_t *mon_fdset)
+{
+ mon_fdset_fd_t *mon_fdset_fd;
+ mon_fdset_fd_t *mon_fdset_fd_next;
+
+ if (mon_fdset->refcount != 0) {
+ return;
+ }
+
+ QLIST_FOREACH_SAFE(mon_fdset_fd, &mon_fdset->fds, next, mon_fdset_fd_next) {
+ if (!mon_fdset->in_use || mon_fdset_fd->removed) {
+ close(mon_fdset_fd->fd);
+ QLIST_REMOVE(mon_fdset_fd, next);
+ g_free(mon_fdset_fd);
+ }
+ }
+
+ if (QLIST_EMPTY(&mon_fdset->fds)) {
+ QLIST_REMOVE(mon_fdset, next);
+ g_free(mon_fdset);
+ }
+}
+
+AddfdInfo *qmp_add_fd(int64_t fdset_id, Error **errp)
+{
+ int fd;
+ Monitor *mon = cur_mon;
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ AddfdInfo *fdinfo;
+
+ fd = qemu_chr_fe_get_msgfd(mon->chr);
+ if (fd == -1) {
+ qerror_report(QERR_FD_NOT_SUPPLIED);
+ return NULL;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ break;
+ }
+ }
+
+ if (!mon_fdset) {
+ mon_fdset = g_malloc0(sizeof(*mon_fdset));
+ mon_fdset->id = fdset_id;
+ mon_fdset->refcount = 0;
+ mon_fdset->in_use = true;
+ QLIST_INSERT_HEAD(&mon->fdsets, mon_fdset, next);
+ }
+
+ mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd));
+ mon_fdset_fd->fd = fd;
+ mon_fdset_fd->removed = false;
+ QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next);
+
+ fdinfo = g_malloc0(sizeof(*fdinfo));
+ fdinfo->fdset_id = fdset_id;
+ fdinfo->fd = fd;
+
+ return fdinfo;
+}
+
+void qmp_remove_fd(int64_t fdset_id, int64_t fd, Error **errp)
+{
+ Monitor *mon = cur_mon;
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ char fd_str[20];
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->fd != fd) {
+ continue;
+ }
+ mon_fdset_fd->removed = true;
+ monitor_fdset_cleanup(mon_fdset);
+ return;
+ }
+ }
+ snprintf(fd_str, sizeof(fd_str), "%ld", fd);
+ qerror_report(QERR_FD_NOT_FOUND, fd_str);
+}
+
+FdsetInfoList *qmp_query_fdsets(Error **errp)
+{
+ Monitor *mon = cur_mon;
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ FdsetInfoList *fdset_list = NULL;
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info));
+ FdsetFdInfoList *fdsetfd_list = NULL;
+
+ fdset_info->value = g_malloc0(sizeof(*fdset_info->value));
+ fdset_info->value->fdset_id = mon_fdset->id;
+ fdset_info->value->refcount = mon_fdset->refcount;
+ fdset_info->value->in_use = mon_fdset->in_use;
+
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ FdsetFdInfoList *fdsetfd_info = g_malloc0(sizeof(*fdsetfd_info));
+
+ fdsetfd_info->value = g_malloc0(sizeof(*fdsetfd_info->value));
+ fdsetfd_info->value->fd = mon_fdset_fd->fd;
+ fdsetfd_info->value->removed = mon_fdset_fd->removed;
+
+ fdsetfd_info->next = fdsetfd_list;
+ fdsetfd_list = fdsetfd_info;
+ }
+
+ fdset_info->value->fds = fdsetfd_list;
+
+ fdset_info->next = fdset_list;
+ fdset_list = fdset_info;
+ }
+
+ return fdset_list;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
diff --git a/qapi-schema.json b/qapi-schema.json
index a92adb1..c07ff07 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1905,3 +1905,100 @@
# Since: 0.14.0
##
{ 'command': 'closefd', 'data': {'fdname': 'str'} }
+
+# @AddfdInfo:
+#
+# Information about a file descriptor that was added to an fd set.
+#
+# @fdset_id: The ID of the fd set that @fd was added to.
+#
+# @fd: The file descriptor that was received via SCM rights and
+# added to the fd set.
+#
+# Since: 1.2.0
+##
+{ 'type': 'AddfdInfo', 'data': {'fdset_id': 'int', 'fd': 'int'} }
+
+##
+# @add-fd:
+#
+# Add a file descriptor, that was passed via SCM rights, to an fd set.
+#
+# @fdset_id: The ID of the fd set to add the file descriptor to.
+#
+# Returns: @AddfdInfo on success
+# If file descriptor was not received, FdNotSupplied
+#
+# Since: 1.2.0
+##
+{ 'command': 'add-fd', 'data': {'fdset_id': 'int'},
+ 'returns': 'AddfdInfo' }
+
+##
+# @remove-fd:
+#
+# Remove a file descriptor from an fd set.
+#
+# @fdset_id: The ID of the fd set that the file descriptor belongs to.
+#
+# @fd: The file descriptor that is to be removed.
+#
+# Returns: Nothing on success
+# If @fdset_id or @fd is not found, FdNotFound
+#
+# Since: 1.2.0
+#
+# Notes: File descriptors that are removed:
+# o will not be closed until the reference count corresponding
+# to @fdset_id reaches zero.
+# o will not be available for use after successful completion
+# of the remove-fd command.
+##
+{ 'command': 'remove-fd', 'data': {'fdset_id': 'int', 'fd': 'int'} }
+
+##
+# @FdsetFdInfo:
+#
+# Information about a file descriptor that belongs to an fd set.
+#
+# @fd: The file descriptor value.
+#
+# @removed: If true, the remove-fd command has been issued for this fd.
+#
+# Since: 1.2.0
+##
+{ 'type': 'FdsetFdInfo', 'data': {'fd': 'int', 'removed': 'bool'} }
+
+##
+# @FdsetInfo:
+#
+# Information about an fd set.
+#
+# @fdset_id: The ID of the fd set.
+#
+# @refcount: A count of the number of outstanding dup() references to
+# this fd set.
+#
+# @in_use: If true, this fd set is in use by a connected QMP monitor.
+#
+# @fds: A list of file descriptors that belong to this fd set.
+#
+# Since: 1.2.0
+##
+{ 'type': 'FdsetInfo',
+ 'data': {'fdset_id': 'int', 'refcount': 'int', 'in_use': 'bool',
+ 'fds': ['FdsetFdInfo']} }
+
+##
+# @query-fdsets:
+#
+# Return information describing all fd sets.
+#
+# Returns: A list of @FdsetInfo
+#
+# Since: 1.2.0
+#
+# Notes: File descriptors are not closed until @refcount is zero,
+# and either @in_use is false or @removed is true.
+##
+{ 'command': 'query-fdsets', 'returns': ['FdsetInfo'] }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index e3cf3c5..d485df4 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -926,6 +926,127 @@ Example:

EQMP

+ {
+ .name = "add-fd",
+ .args_type = "fdset_id:i",
+ .params = "add-fd fdset_id",
+ .help = "Add a file descriptor, that was passed via SCM rights, to an fd set",
+ .mhandler.cmd_new = qmp_marshal_input_add_fd,
+ },
+
+SQMP
+add-fd
+-------
+
+Add a file descriptor, that was passed via SCM rights, to an fd set.
+
+Arguments:
+
+- "fdset_id": The ID of the fd set to add the file descriptor to. (json-int)
+
+Return a json-object with the following information:
+
+- "fdset_id": The ID of the fd set that the fd was added to. (json-int)
+- "fd": The file descriptor that was received via SCM rights and added to the
+ fd set. (json-int)
+
+Example:
+
+-> { "execute": "add-fd", "arguments": { "fdset_id": 1 } }
+<- { "return": { "fdset_id": 1, "fd": 3 } }
+
+EQMP
+
+ {
+ .name = "remove-fd",
+ .args_type = "fdset_id:i,fd:i",
+ .params = "remove-fd fdset_id fd",
+ .help = "Remove a file descriptor from an fd set",
+ .mhandler.cmd_new = qmp_marshal_input_remove_fd,
+ },
+
+SQMP
+remove-fd
+---------
+
+Remove a file descriptor from an fd set.
+
+Arguments:
+
+- "fdset_id": The ID of the fd set that the file descriptor belongs to.
+ (json-int)
+- "fd": The file descriptor that is to be removed. (json-int)
+
+Example:
+
+-> { "execute": "remove-fd", "arguments": { "fdset_id": 1, "fd": 3 } }
+<- { "return": {} }
+
+Notes:
+
+(1) File descriptors that are removed:
+ (a) will not be closed until the reference count corresponding to fdset_id
+ reaches zero.
+ (b) will not be available for use after successful completion of the
+ remove-fd command.
+
+EQMP
+
+ {
+ .name = "query-fdsets",
+ .args_type = "",
+ .help = "Return information describing all fd sets",
+ .mhandler.cmd_new = qmp_marshal_input_query_fdsets,
+ },
+
+SQMP
+query-fdsets
+-------------
+
+Return information describing all fd sets.
+
+Arguments: None
+
+Example:
+
+-> { "execute": "query-fdsets" }
+<- { "return": [
+ {
+ "fdset_id": 1
+ "refcount": 0,
+ "in_use": true,
+ "fds": [
+ {
+ "fd": 21,
+ "removed": false
+ },
+ {
+ "fd": 23,
+ "removed": false
+ }
+ ],
+ },
+ {
+ "fdset_id": 2
+ "refcount": 0,
+ "in_use": true,
+ "fds": [
+ {
+ "fd": 22,
+ "removed": false
+ }
+ ],
+ }
+ ]
+ }
+
+Notes:
+
+(1) File descriptors are not closed until refcount is zero, and
+ either in_use is false or removed is true.
+
+EQMP
+
{
.name = "block_passwd",
.args_type = "device:B,password:s",
--
1.7.10.4
Eric Blake
2012-07-25 18:16:53 UTC
Permalink
Post by Corey Bryant
This patch adds support that enables passing of file descriptors
to the QEMU monitor where they will be stored in specified file
descriptor sets.
+##
+#
+# Add a file descriptor, that was passed via SCM rights, to an fd set.
+#
Should this parameter be optional, in which case qemu generates the set
number as the next available? The return information would include the
set number whether or not this parameter was present from the caller,
and allowing it to be optional makes it slightly easier for callers to
generate a new set without having to make the caller track which set ids
are in use.
Post by Corey Bryant
+##
+#
+# Remove a file descriptor from an fd set.
+#
+#
Should 'fd' be optional, as a shorthand for saying that _all_ fds
belonging to the set be marked as removed at once?
Post by Corey Bryant
+++ b/qmp-commands.hx
EQMP
+ {
+ .name = "add-fd",
+ .args_type = "fdset_id:i",
+ .params = "add-fd fdset_id",
+ .help = "Add a file descriptor, that was passed via SCM rights, to an fd set",
+ .mhandler.cmd_new = qmp_marshal_input_add_fd,
+ },
+
+SQMP
+add-fd
+-------
+
+Add a file descriptor, that was passed via SCM rights, to an fd set.
+
+
+- "fdset_id": The ID of the fd set to add the file descriptor to. (json-int)
May need tweaking, based on the answers to the above questions.
--
Eric Blake ***@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Corey Bryant
2012-07-26 02:55:24 UTC
Permalink
Post by Eric Blake
Post by Corey Bryant
This patch adds support that enables passing of file descriptors
to the QEMU monitor where they will be stored in specified file
descriptor sets.
+##
+#
+# Add a file descriptor, that was passed via SCM rights, to an fd set.
+#
Should this parameter be optional, in which case qemu generates the set
number as the next available? The return information would include the
set number whether or not this parameter was present from the caller,
and allowing it to be optional makes it slightly easier for callers to
generate a new set without having to make the caller track which set ids
are in use.
Post by Corey Bryant
+##
+#
+# Remove a file descriptor from an fd set.
+#
+#
Should 'fd' be optional, as a shorthand for saying that _all_ fds
belonging to the set be marked as removed at once?
Yes, this makes sense.
Post by Eric Blake
Post by Corey Bryant
+++ b/qmp-commands.hx
EQMP
+ {
+ .name = "add-fd",
+ .args_type = "fdset_id:i",
+ .params = "add-fd fdset_id",
+ .help = "Add a file descriptor, that was passed via SCM rights, to an fd set",
+ .mhandler.cmd_new = qmp_marshal_input_add_fd,
+ },
+
+SQMP
+add-fd
+-------
+
+Add a file descriptor, that was passed via SCM rights, to an fd set.
+
+
+- "fdset_id": The ID of the fd set to add the file descriptor to. (json-int)
May need tweaking, based on the answers to the above questions.
Ok.
--
Regards,
Corey
Corey Bryant
2012-07-23 13:08:03 UTC
Permalink
This patch converts all block layer open calls to qemu_open.

Note that this adds the O_CLOEXEC flag to the changed open paths
when the O_CLOEXEC macro is defined.

Signed-off-by: Corey Bryant <***@linux.vnet.ibm.com>
---
v2:
-Convert calls to qemu_open instead of file_open (***@redhat.com)
-Mention introduction of O_CLOEXEC (***@redhat.com)

v3-v5:
-No changes
---
block/raw-posix.c | 18 +++++++++---------
block/raw-win32.c | 4 ++--
block/vdi.c | 5 +++--
block/vmdk.c | 21 +++++++++------------
block/vpc.c | 2 +-
block/vvfat.c | 4 ++--
6 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 0dce089..7408a42 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -572,8 +572,8 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
options++;
}

- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
- 0644);
+ fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+ 0644);
if (fd < 0) {
result = -errno;
} else {
@@ -846,7 +846,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
if ( bsdPath[ 0 ] != '\0' ) {
strcat(bsdPath,"s0");
/* some CDs don't have a partition 0 */
- fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+ fd = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
if (fd < 0) {
bsdPath[strlen(bsdPath)-1] = '1';
} else {
@@ -903,7 +903,7 @@ static int fd_open(BlockDriverState *bs)
#endif
return -EIO;
}
- s->fd = open(bs->filename, s->open_flags & ~O_NONBLOCK);
+ s->fd = qemu_open(bs->filename, s->open_flags & ~O_NONBLOCK);
if (s->fd < 0) {
s->fd_error_time = get_clock();
s->fd_got_error = 1;
@@ -977,7 +977,7 @@ static int hdev_create(const char *filename, QEMUOptionParameter *options)
options++;
}

- fd = open(filename, O_WRONLY | O_BINARY);
+ fd = qemu_open(filename, O_WRONLY | O_BINARY);
if (fd < 0)
return -errno;

@@ -1055,7 +1055,7 @@ static int floppy_probe_device(const char *filename)
if (strstart(filename, "/dev/fd", NULL))
prio = 50;

- fd = open(filename, O_RDONLY | O_NONBLOCK);
+ fd = qemu_open(filename, O_RDONLY | O_NONBLOCK);
if (fd < 0) {
goto out;
}
@@ -1108,7 +1108,7 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
close(s->fd);
s->fd = -1;
}
- fd = open(bs->filename, s->open_flags | O_NONBLOCK);
+ fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
if (fd >= 0) {
if (ioctl(fd, FDEJECT, 0) < 0)
perror("FDEJECT");
@@ -1158,7 +1158,7 @@ static int cdrom_probe_device(const char *filename)
int prio = 0;
struct stat st;

- fd = open(filename, O_RDONLY | O_NONBLOCK);
+ fd = qemu_open(filename, O_RDONLY | O_NONBLOCK);
if (fd < 0) {
goto out;
}
@@ -1282,7 +1282,7 @@ static int cdrom_reopen(BlockDriverState *bs)
*/
if (s->fd >= 0)
close(s->fd);
- fd = open(bs->filename, s->open_flags, 0644);
+ fd = qemu_open(bs->filename, s->open_flags, 0644);
if (fd < 0) {
s->fd = -1;
return -EIO;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index e4b0b75..8d7838d 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -255,8 +255,8 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
options++;
}

- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
- 0644);
+ fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+ 0644);
if (fd < 0)
return -EIO;
set_sparse(fd);
diff --git a/block/vdi.c b/block/vdi.c
index 57325d6..c4f1529 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -653,8 +653,9 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options)
options++;
}

- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
- 0644);
+ fd = qemu_open(filename,
+ O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+ 0644);
if (fd < 0) {
return -errno;
}
diff --git a/block/vmdk.c b/block/vmdk.c
index 18e9b4c..557dc1b 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1161,10 +1161,9 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
VMDK4Header header;
uint32_t tmp, magic, grains, gd_size, gt_size, gt_count;

- fd = open(
- filename,
- O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
- 0644);
+ fd = qemu_open(filename,
+ O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+ 0644);
if (fd < 0) {
return -errno;
}
@@ -1484,15 +1483,13 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options)
(flags & BLOCK_FLAG_COMPAT6 ? 6 : 4),
total_size / (int64_t)(63 * 16 * 512));
if (split || flat) {
- fd = open(
- filename,
- O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
- 0644);
+ fd = qemu_open(filename,
+ O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+ 0644);
} else {
- fd = open(
- filename,
- O_WRONLY | O_BINARY | O_LARGEFILE,
- 0644);
+ fd = qemu_open(filename,
+ O_WRONLY | O_BINARY | O_LARGEFILE,
+ 0644);
}
if (fd < 0) {
return -errno;
diff --git a/block/vpc.c b/block/vpc.c
index 5cd13d1..60ebf5a 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -678,7 +678,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
}

/* Create the file */
- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
+ fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
if (fd < 0) {
return -EIO;
}
diff --git a/block/vvfat.c b/block/vvfat.c
index 7b1dcee..22b586a 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1162,7 +1162,7 @@ static int open_file(BDRVVVFATState* s,mapping_t* mapping)
if(!s->current_mapping ||
strcmp(s->current_mapping->path,mapping->path)) {
/* open file */
- int fd = open(mapping->path, O_RDONLY | O_BINARY | O_LARGEFILE);
+ int fd = qemu_open(mapping->path, O_RDONLY | O_BINARY | O_LARGEFILE);
if(fd<0)
return -1;
vvfat_close_current_file(s);
@@ -2221,7 +2221,7 @@ static int commit_one_file(BDRVVVFATState* s,
for (i = s->cluster_size; i < offset; i += s->cluster_size)
c = modified_fat_get(s, c);

- fd = open(mapping->path, O_RDWR | O_CREAT | O_BINARY, 0666);
+ fd = qemu_open(mapping->path, O_RDWR | O_CREAT | O_BINARY, 0666);
if (fd < 0) {
fprintf(stderr, "Could not open %s... (%s, %d)\n", mapping->path,
strerror(errno), errno);
--
1.7.10.4
Eric Blake
2012-07-25 19:22:20 UTC
Permalink
Post by Corey Bryant
This patch converts all block layer open calls to qemu_open.
Note that this adds the O_CLOEXEC flag to the changed open paths
when the O_CLOEXEC macro is defined.
Is it actually adding O_CLOEXEC, or just the ability to use O_CLOEXEC?

Or is the actual change that the end result is that the fd now has
FD_CLOEXEC set unconditionally, whether by O_CLOEXEC (which the caller
need not pass) or by fcntl()?
Post by Corey Bryant
+++ b/block/raw-posix.c
@@ -572,8 +572,8 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
options++;
}
- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
- 0644);
+ fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+ 0644);
After all, I don't see O_CLOEXEC used here.
Post by Corey Bryant
if (fd < 0) {
result = -errno;
} else {
@@ -846,7 +846,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
if ( bsdPath[ 0 ] != '\0' ) {
strcat(bsdPath,"s0");
/* some CDs don't have a partition 0 */
- fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+ fd = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
Also, I still stand by my earlier claim that we don't need O_LARGEFILE
here (we should already be configuring for 64-bit off_t by default),
although cleaning that up is probably worth an independent commit.
Post by Corey Bryant
+++ b/block/vdi.c
@@ -653,8 +653,9 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options)
options++;
}
- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
- 0644);
+ fd = qemu_open(filename,
+ O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+ 0644);
Another pointless O_LARGEFILE, and so forth.
--
Eric Blake ***@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Corey Bryant
2012-07-26 03:11:18 UTC
Permalink
Post by Eric Blake
Post by Corey Bryant
This patch converts all block layer open calls to qemu_open.
Note that this adds the O_CLOEXEC flag to the changed open paths
when the O_CLOEXEC macro is defined.
Is it actually adding O_CLOEXEC, or just the ability to use O_CLOEXEC?
It is adding O_CLOEXEC in qemu_open() on the open() call (as long as it
is defined).
Post by Eric Blake
Or is the actual change that the end result is that the fd now has
FD_CLOEXEC set unconditionally, whether by O_CLOEXEC (which the caller
need not pass) or by fcntl()?
The statement in the commit message isn't referring to anything dealing
with qemu_dup(). The statement is specifically talking about the open()
call in qemu_open(), and the point is to alert folks that old open()
calls are now being routed through qemu_open() and likely are using the
O_CLOEXEC flag, which is new behavior.
Post by Eric Blake
Post by Corey Bryant
+++ b/block/raw-posix.c
@@ -572,8 +572,8 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
options++;
}
- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
- 0644);
+ fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+ 0644);
After all, I don't see O_CLOEXEC used here.
That's right. qemu_open() adds O_CLOEXEC on the open() call.
Post by Eric Blake
Post by Corey Bryant
if (fd < 0) {
result = -errno;
} else {
@@ -846,7 +846,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
if ( bsdPath[ 0 ] != '\0' ) {
strcat(bsdPath,"s0");
/* some CDs don't have a partition 0 */
- fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+ fd = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
Also, I still stand by my earlier claim that we don't need O_LARGEFILE
here (we should already be configuring for 64-bit off_t by default),
although cleaning that up is probably worth an independent commit.
I have a note to get rid of O_LARGEFILE as a separate follow-on patch.
Post by Eric Blake
Post by Corey Bryant
+++ b/block/vdi.c
@@ -653,8 +653,9 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options)
options++;
}
- fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
- 0644);
+ fd = qemu_open(filename,
+ O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+ 0644);
Another pointless O_LARGEFILE, and so forth.
Yep.
--
Regards,
Corey
Corey Bryant
2012-07-23 13:08:02 UTC
Permalink
Each fd set has a boolean that keeps track of whether or not the
fd set is in use by a monitor connection. When a monitor
disconnects, all fds that are members of an fd set with refcount
of zero are closed. This prevents any fd leakage associated with
a client disconnect prior to using a passed fd.

v5:
-This patch is new in v5.
-This support addresses concerns from v4 regarding fd leakage
if the client disconnects unexpectedly. (***@redhat.com,
***@redhat.com, ***@redhat.com)

Signed-off-by: Corey Bryant <***@linux.vnet.ibm.com>
---
monitor.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/monitor.c b/monitor.c
index e27dbbe..30b085f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2538,6 +2538,19 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
return fdset_list;
}

+static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_t *mon_fdset_next;
+
+ QLIST_FOREACH_SAFE(mon_fdset, &mon->fdsets, next, mon_fdset_next) {
+ mon_fdset->in_use = in_use;
+ if (!in_use) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ }
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
@@ -4751,9 +4764,11 @@ static void monitor_control_event(void *opaque, int event)
data = get_qmp_greeting();
monitor_json_emitter(mon, data);
qobject_decref(data);
+ monitor_fdsets_set_in_use(mon, true);
break;
case CHR_EVENT_CLOSED:
json_message_parser_destroy(&mon->mc->parser);
+ monitor_fdsets_set_in_use(mon, false);
break;
}
}
--
1.7.10.4
Corey Bryant
2012-07-23 13:08:04 UTC
Permalink
This patch converts all block layer close calls, that correspond
to qemu_open calls, to qemu_close.

v5:
-This patch is new in v5. (***@redhat.com, ***@redhat.com)

Signed-off-by: Corey Bryant <***@linux.vnet.ibm.com>
---
block/raw-posix.c | 24 ++++++++++++------------
block/raw-win32.c | 2 +-
block/vmdk.c | 4 ++--
block/vpc.c | 2 +-
block/vvfat.c | 12 ++++++------
osdep.c | 5 +++++
qemu-common.h | 1 +
savevm.c | 4 ++--
8 files changed, 30 insertions(+), 24 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 7408a42..a172de3 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
out_free_buf:
qemu_vfree(s->aligned_buf);
out_close:
- close(fd);
+ qemu_close(fd);
return -errno;
}

@@ -376,7 +376,7 @@ static void raw_close(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
if (s->fd >= 0) {
- close(s->fd);
+ qemu_close(s->fd);
s->fd = -1;
if (s->aligned_buf != NULL)
qemu_vfree(s->aligned_buf);
@@ -580,7 +580,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
result = -errno;
}
- if (close(fd) != 0) {
+ if (qemu_close(fd) != 0) {
result = -errno;
}
}
@@ -850,7 +850,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
if (fd < 0) {
bsdPath[strlen(bsdPath)-1] = '1';
} else {
- close(fd);
+ qemu_close(fd);
}
filename = bsdPath;
}
@@ -889,7 +889,7 @@ static int fd_open(BlockDriverState *bs)
last_media_present = (s->fd >= 0);
if (s->fd >= 0 &&
(get_clock() - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
- close(s->fd);
+ qemu_close(s->fd);
s->fd = -1;
#ifdef DEBUG_FLOPPY
printf("Floppy closed\n");
@@ -988,7 +988,7 @@ static int hdev_create(const char *filename, QEMUOptionParameter *options)
else if (lseek(fd, 0, SEEK_END) < total_size * BDRV_SECTOR_SIZE)
ret = -ENOSPC;

- close(fd);
+ qemu_close(fd);
return ret;
}

@@ -1038,7 +1038,7 @@ static int floppy_open(BlockDriverState *bs, const char *filename, int flags)
return ret;

/* close fd so that we can reopen it as needed */
- close(s->fd);
+ qemu_close(s->fd);
s->fd = -1;
s->fd_media_changed = 1;

@@ -1070,7 +1070,7 @@ static int floppy_probe_device(const char *filename)
prio = 100;

outc:
- close(fd);
+ qemu_close(fd);
out:
return prio;
}
@@ -1105,14 +1105,14 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
int fd;

if (s->fd >= 0) {
- close(s->fd);
+ qemu_close(s->fd);
s->fd = -1;
}
fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
if (fd >= 0) {
if (ioctl(fd, FDEJECT, 0) < 0)
perror("FDEJECT");
- close(fd);
+ qemu_close(fd);
}
}

@@ -1173,7 +1173,7 @@ static int cdrom_probe_device(const char *filename)
prio = 100;

outc:
- close(fd);
+ qemu_close(fd);
out:
return prio;
}
@@ -1281,7 +1281,7 @@ static int cdrom_reopen(BlockDriverState *bs)
* FreeBSD seems to not notice sometimes...
*/
if (s->fd >= 0)
- close(s->fd);
+ qemu_close(s->fd);
fd = qemu_open(bs->filename, s->open_flags, 0644);
if (fd < 0) {
s->fd = -1;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index 8d7838d..c56bf83 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -261,7 +261,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
return -EIO;
set_sparse(fd);
ftruncate(fd, total_size * 512);
- close(fd);
+ qemu_close(fd);
return 0;
}

diff --git a/block/vmdk.c b/block/vmdk.c
index 557dc1b..daee426 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1258,7 +1258,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,

ret = 0;
exit:
- close(fd);
+ qemu_close(fd);
return ret;
}

@@ -1506,7 +1506,7 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options)
}
ret = 0;
exit:
- close(fd);
+ qemu_close(fd);
return ret;
}

diff --git a/block/vpc.c b/block/vpc.c
index 60ebf5a..c0b82c4 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -744,7 +744,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
}

fail:
- close(fd);
+ qemu_close(fd);
return ret;
}

diff --git a/block/vvfat.c b/block/vvfat.c
index 22b586a..59d3c5b 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1105,7 +1105,7 @@ static inline void vvfat_close_current_file(BDRVVVFATState *s)
if(s->current_mapping) {
s->current_mapping = NULL;
if (s->current_fd) {
- close(s->current_fd);
+ qemu_close(s->current_fd);
s->current_fd = 0;
}
}
@@ -2230,7 +2230,7 @@ static int commit_one_file(BDRVVVFATState* s,
}
if (offset > 0) {
if (lseek(fd, offset, SEEK_SET) != offset) {
- close(fd);
+ qemu_close(fd);
g_free(cluster);
return -3;
}
@@ -2251,13 +2251,13 @@ static int commit_one_file(BDRVVVFATState* s,
(uint8_t*)cluster, (rest_size + 0x1ff) / 0x200);

if (ret < 0) {
- close(fd);
+ qemu_close(fd);
g_free(cluster);
return ret;
}

if (write(fd, cluster, rest_size) < 0) {
- close(fd);
+ qemu_close(fd);
g_free(cluster);
return -2;
}
@@ -2268,11 +2268,11 @@ static int commit_one_file(BDRVVVFATState* s,

if (ftruncate(fd, size)) {
perror("ftruncate()");
- close(fd);
+ qemu_close(fd);
g_free(cluster);
return -4;
}
- close(fd);
+ qemu_close(fd);
g_free(cluster);

return commit_mappings(s, first_cluster, dir_index);
diff --git a/osdep.c b/osdep.c
index 03817f0..7b09dff 100644
--- a/osdep.c
+++ b/osdep.c
@@ -104,6 +104,11 @@ int qemu_open(const char *name, int flags, ...)
return ret;
}

+int qemu_close(int fd)
+{
+ return close(fd);
+}
+
/*
* A variant of write(2) which handles partial write.
*
diff --git a/qemu-common.h b/qemu-common.h
index 09676f5..c8ddf2f 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -188,6 +188,7 @@ const char *path(const char *pathname);
void *qemu_oom_check(void *ptr);

int qemu_open(const char *name, int flags, ...);
+int qemu_close(int fd);
ssize_t qemu_write_full(int fd, const void *buf, size_t count)
QEMU_WARN_UNUSED_RESULT;
ssize_t qemu_send_full(int fd, const void *buf, size_t count, int flags)
diff --git a/savevm.c b/savevm.c
index a15c163..3269dd4 100644
--- a/savevm.c
+++ b/savevm.c
@@ -513,7 +513,7 @@ static void qemu_fill_buffer(QEMUFile *f)
*
* Returns f->close() return value, or 0 if close function is not set.
*/
-static int qemu_close(QEMUFile *f)
+static int _qemu_fclose(QEMUFile *f)
{
int ret = 0;
if (f->close) {
@@ -535,7 +535,7 @@ int qemu_fclose(QEMUFile *f)
{
int ret;
qemu_fflush(f);
- ret = qemu_close(f);
+ ret = _qemu_fclose(f);
/* If any error was spotted before closing, we should report it
* instead of the close() return value.
*/
--
1.7.10.4
Corey Bryant
2012-07-23 13:08:00 UTC
Permalink
Set the close-on-exec flag for the file descriptor received
via SCM_RIGHTS.

v4
-This patch is new in v4 (***@redhat.com)

v5
-Fallback to FD_CLOEXEC if MSG_CMSG_CLOEXEC is not available
(***@redhat.com, ***@linux.vnet.ibm.com)

Signed-off-by: Corey Bryant <***@linux.vnet.ibm.com>
---
qemu-char.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/qemu-char.c b/qemu-char.c
index c2aaaee..eedf66d 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2263,9 +2263,17 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf, size_t len)
msg.msg_control = &msg_control;
msg.msg_controllen = sizeof(msg_control);

+#ifdef MSG_CMSG_CLOEXEC
+ ret = recvmsg(s->fd, &msg, MSG_CMSG_CLOEXEC);
+#else
ret = recvmsg(s->fd, &msg, 0);
- if (ret > 0 && s->is_unix)
+ if (ret > 0) {
+ qemu_set_cloexec(s->fd);
+ }
+#endif
+ if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
+ }

return ret;
}
--
1.7.10.4
Eric Blake
2012-07-23 22:50:10 UTC
Permalink
Post by Corey Bryant
Set the close-on-exec flag for the file descriptor received
via SCM_RIGHTS.
+++ b/qemu-char.c
@@ -2263,9 +2263,17 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf, size_t len)
msg.msg_control = &msg_control;
msg.msg_controllen = sizeof(msg_control);
+#ifdef MSG_CMSG_CLOEXEC
+ ret = recvmsg(s->fd, &msg, MSG_CMSG_CLOEXEC);
+#else
ret = recvmsg(s->fd, &msg, 0);
- if (ret > 0 && s->is_unix)
+ if (ret > 0) {
+ qemu_set_cloexec(s->fd);
Wrong fd. You aren't changing cloexec on the socket (s->fd), but on the
fd that was received via msg (which you don't know at this point in time).
Post by Corey Bryant
+ }
+#endif
+ if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
Only here do you know what fd you received.

I would write it more like:

int flags = 0;
#ifdef MSG_CMSG_CLOEXEC
flags |= MSG_CMSG_CLOEXEC
#endif
ret = recvmsg(s->fd, &msg, flags);
if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
#ifndef MSG_CMSG_CLOEXEC
qemu_set_cloexec(/* fd determined from msg */)
#endif
}

which almost implies that unix_process_msgfd() should be the function
that sets cloexec, but without wasting the time doing so if recvmsg
already did the job.
--
Eric Blake ***@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Corey Bryant
2012-07-24 02:19:52 UTC
Permalink
Post by Eric Blake
Post by Corey Bryant
Set the close-on-exec flag for the file descriptor received
via SCM_RIGHTS.
+++ b/qemu-char.c
@@ -2263,9 +2263,17 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf, size_t len)
msg.msg_control = &msg_control;
msg.msg_controllen = sizeof(msg_control);
+#ifdef MSG_CMSG_CLOEXEC
+ ret = recvmsg(s->fd, &msg, MSG_CMSG_CLOEXEC);
+#else
ret = recvmsg(s->fd, &msg, 0);
- if (ret > 0 && s->is_unix)
+ if (ret > 0) {
+ qemu_set_cloexec(s->fd);
Wrong fd. You aren't changing cloexec on the socket (s->fd), but on the
fd that was received via msg (which you don't know at this point in time).
Ugh, that's bad.
Post by Eric Blake
Post by Corey Bryant
+ }
+#endif
+ if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
Only here do you know what fd you received.
int flags = 0;
#ifdef MSG_CMSG_CLOEXEC
flags |= MSG_CMSG_CLOEXEC
#endif
ret = recvmsg(s->fd, &msg, flags);
if (ret > 0 && s->is_unix) {
unix_process_msgfd(chr, &msg);
#ifndef MSG_CMSG_CLOEXEC
qemu_set_cloexec(/* fd determined from msg */)
#endif
}
which almost implies that unix_process_msgfd() should be the function
that sets cloexec, but without wasting the time doing so if recvmsg
already did the job.
Thanks for the suggestion and catching this. I'll take this into
account in the next version.
--
Regards,
Corey
Corey Bryant
2012-07-23 13:14:42 UTC
Permalink
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
-Get rid of file_open and move dup code to qemu_open
v4
-Update qemu_open to check access mode flags and set flags that
-This patch was overhauled quite a bit in this version, with
the addition of fd set and refcount support.
---
block/raw-posix.c | 24 +++++-----
block/raw-win32.c | 2 +-
block/vmdk.c | 4 +-
block/vpc.c | 2 +-
block/vvfat.c | 12 ++---
cutils.c | 5 ++
monitor.c | 85 +++++++++++++++++++++++++++++++++
monitor.h | 4 ++
osdep.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
qemu-common.h | 3 +-
qemu-tool.c | 12 +++++
11 files changed, 267 insertions(+), 24 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index a172de3..5d0a801 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
qemu_vfree(s->aligned_buf);
- qemu_close(fd);
+ qemu_close(fd, filename);
return -errno;
}
@@ -376,7 +376,7 @@ static void raw_close(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
if (s->fd >= 0) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
if (s->aligned_buf != NULL)
qemu_vfree(s->aligned_buf);
@@ -580,7 +580,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
result = -errno;
}
- if (qemu_close(fd) != 0) {
+ if (qemu_close(fd, filename) != 0) {
result = -errno;
}
}
@@ -850,7 +850,7 @@ static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
if (fd < 0) {
bsdPath[strlen(bsdPath)-1] = '1';
} else {
- qemu_close(fd);
+ qemu_close(fd, bsdPath);
}
filename = bsdPath;
}
@@ -889,7 +889,7 @@ static int fd_open(BlockDriverState *bs)
last_media_present = (s->fd >= 0);
if (s->fd >= 0 &&
(get_clock() - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
#ifdef DEBUG_FLOPPY
printf("Floppy closed\n");
@@ -988,7 +988,7 @@ static int hdev_create(const char *filename, QEMUOptionParameter *options)
else if (lseek(fd, 0, SEEK_END) < total_size * BDRV_SECTOR_SIZE)
ret = -ENOSPC;
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
@@ -1038,7 +1038,7 @@ static int floppy_open(BlockDriverState *bs, const char *filename, int flags)
return ret;
/* close fd so that we can reopen it as needed */
- qemu_close(s->fd);
+ qemu_close(s->fd, filename);
s->fd = -1;
s->fd_media_changed = 1;
@@ -1070,7 +1070,7 @@ static int floppy_probe_device(const char *filename)
prio = 100;
- qemu_close(fd);
+ qemu_close(fd, filename);
return prio;
}
@@ -1105,14 +1105,14 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
int fd;
if (s->fd >= 0) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
}
fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
if (fd >= 0) {
if (ioctl(fd, FDEJECT, 0) < 0)
perror("FDEJECT");
- qemu_close(fd);
+ qemu_close(fd, bs->filename);
}
}
@@ -1173,7 +1173,7 @@ static int cdrom_probe_device(const char *filename)
prio = 100;
- qemu_close(fd);
+ qemu_close(fd, filename);
return prio;
}
@@ -1281,7 +1281,7 @@ static int cdrom_reopen(BlockDriverState *bs)
* FreeBSD seems to not notice sometimes...
*/
if (s->fd >= 0)
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
fd = qemu_open(bs->filename, s->open_flags, 0644);
if (fd < 0) {
s->fd = -1;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index c56bf83..b795871 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -261,7 +261,7 @@ static int raw_create(const char *filename, QEMUOptionParameter *options)
return -EIO;
set_sparse(fd);
ftruncate(fd, total_size * 512);
- qemu_close(fd);
+ qemu_close(fd, filename);
return 0;
}
diff --git a/block/vmdk.c b/block/vmdk.c
index daee426..7f1206b 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1258,7 +1258,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
ret = 0;
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
@@ -1506,7 +1506,7 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options)
}
ret = 0;
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
diff --git a/block/vpc.c b/block/vpc.c
index c0b82c4..20f648a 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -744,7 +744,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
}
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
diff --git a/block/vvfat.c b/block/vvfat.c
index 59d3c5b..cbc7543 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1105,7 +1105,7 @@ static inline void vvfat_close_current_file(BDRVVVFATState *s)
if(s->current_mapping) {
s->current_mapping = NULL;
if (s->current_fd) {
- qemu_close(s->current_fd);
+ qemu_close(s->current_fd, s->current_mapping->path);
s->current_fd = 0;
}
}
@@ -2230,7 +2230,7 @@ static int commit_one_file(BDRVVVFATState* s,
}
if (offset > 0) {
if (lseek(fd, offset, SEEK_SET) != offset) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -3;
}
@@ -2251,13 +2251,13 @@ static int commit_one_file(BDRVVVFATState* s,
(uint8_t*)cluster, (rest_size + 0x1ff) / 0x200);
if (ret < 0) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return ret;
}
if (write(fd, cluster, rest_size) < 0) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -2;
}
@@ -2268,11 +2268,11 @@ static int commit_one_file(BDRVVVFATState* s,
if (ftruncate(fd, size)) {
perror("ftruncate()");
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -4;
}
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return commit_mappings(s, first_cluster, dir_index);
diff --git a/cutils.c b/cutils.c
index e2bc1b8..4e6bfdc 100644
--- a/cutils.c
+++ b/cutils.c
@@ -375,3 +375,8 @@ int qemu_parse_fd(const char *param)
}
return fd;
}
+
+int qemu_parse_fdset(const char *param)
+{
+ return qemu_parse_fd(param);
+}
diff --git a/monitor.c b/monitor.c
index 30b085f..fddd2b5 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount++;
+ break;
+ }
+ }
+}
+
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount--;
+ if (mon_fdset->refcount == 0) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ break;
+ }
+ }
+}
+
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ }
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
diff --git a/monitor.h b/monitor.h
index 5f4de1b..1efed38 100644
--- a/monitor.h
+++ b/monitor.h
@@ -86,4 +86,8 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret);
int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags);
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id);
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id);
+
#endif /* !MONITOR_H */
diff --git a/osdep.c b/osdep.c
index 7b09dff..0303cdd 100644
--- a/osdep.c
+++ b/osdep.c
@@ -47,6 +47,7 @@ extern int madvise(caddr_t, size_t, int);
#include "qemu-common.h"
#include "trace.h"
#include "qemu_socket.h"
+#include "monitor.h"
static const char *qemu_version = QEMU_VERSION;
@@ -75,6 +76,79 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
+
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
+
+ qemu_set_cloexec(ret);
+
+ return ret;
+
+ serrno = errno;
+ if (ret != -1) {
+ close(ret);
+ }
+ errno = serrno;
+ return -1;
+}
/*
* Opens a file with FD_CLOEXEC set
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Post by Corey Bryant
+ if (fd == -1) {
+ return -1;
+ }
+
+ dupfd = qemu_dup(fd, flags);
+ if (fd == -1) {
+ return -1;
+ }
+
+ monitor_fdset_increment_refcount(default_mon, fdset_id);
+
+ return dupfd;
+ }
+#endif
+
if (flags & O_CREAT) {
va_list ap;
@@ -104,8 +208,40 @@ int qemu_open(const char *name, int flags, ...)
return ret;
}
-int qemu_close(int fd)
+int qemu_close(int fd, const char *name)
{
+ const char *fdset_id_str;
+
+ /* Close fd that was dup'd from an fdset */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int ret;
+ int64_t fdset_id;
+ int fdset_fd;
+ int flags;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ return -1;
+ }
+
+ flags = fcntl(fd, F_GETFL);
+ if (flags == -1) {
+ return -1;
+ }
+
+ fdset_fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
+ if (fdset_fd == -1) {
+ return -1;
+ }
+
+ ret = close(fd);
+ if (ret == 0) {
+ monitor_fdset_decrement_refcount(default_mon, fdset_id);
+ }
+
+ return ret;
+ }
+
return close(fd);
}
diff --git a/qemu-common.h b/qemu-common.h
index c8ddf2f..6b4123c 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -147,6 +147,7 @@ int qemu_fls(int i);
int qemu_fdatasync(int fd);
int fcntl_setfl(int fd, int flag);
int qemu_parse_fd(const char *param);
+int qemu_parse_fdset(const char *param);
/*
* strtosz() suffixes used to specify the default treatment of an
@@ -188,7 +189,7 @@ const char *path(const char *pathname);
void *qemu_oom_check(void *ptr);
int qemu_open(const char *name, int flags, ...);
-int qemu_close(int fd);
+int qemu_close(int fd, const char *name);
ssize_t qemu_write_full(int fd, const void *buf, size_t count)
QEMU_WARN_UNUSED_RESULT;
ssize_t qemu_send_full(int fd, const void *buf, size_t count, int flags)
diff --git a/qemu-tool.c b/qemu-tool.c
index 318c5fc..f4db9db 100644
--- a/qemu-tool.c
+++ b/qemu-tool.c
@@ -31,6 +31,7 @@ struct QEMUBH
};
Monitor *cur_mon;
+Monitor *default_mon;
int monitor_cur_is_qmp(void)
{
@@ -57,6 +58,17 @@ void monitor_protocol_event(MonitorEvent event, QObject *data)
{
}
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ return -1;
+}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+}
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+}
+
int64_t cpu_get_clock(void)
{
return qemu_get_clock_ns(rt_clock);
--
Regards,
Corey
Corey Bryant
2012-08-02 22:21:28 UTC
Permalink
Post by Corey Bryant
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
-Get rid of file_open and move dup code to qemu_open
v4
-Update qemu_open to check access mode flags and set flags that
-This patch was overhauled quite a bit in this version, with
the addition of fd set and refcount support.
---
block/raw-posix.c | 24 +++++-----
block/raw-win32.c | 2 +-
block/vmdk.c | 4 +-
block/vpc.c | 2 +-
block/vvfat.c | 12 ++---
cutils.c | 5 ++
monitor.c | 85 +++++++++++++++++++++++++++++++++
monitor.h | 4 ++
osdep.c | 138
++++++++++++++++++++++++++++++++++++++++++++++++++++-
qemu-common.h | 3 +-
qemu-tool.c | 12 +++++
11 files changed, 267 insertions(+), 24 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index a172de3..5d0a801 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs,
const char *filename,
qemu_vfree(s->aligned_buf);
- qemu_close(fd);
+ qemu_close(fd, filename);
return -errno;
}
@@ -376,7 +376,7 @@ static void raw_close(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
if (s->fd >= 0) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
if (s->aligned_buf != NULL)
qemu_vfree(s->aligned_buf);
@@ -580,7 +580,7 @@ static int raw_create(const char *filename,
QEMUOptionParameter *options)
if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
result = -errno;
}
- if (qemu_close(fd) != 0) {
+ if (qemu_close(fd, filename) != 0) {
result = -errno;
}
}
@@ -850,7 +850,7 @@ static int hdev_open(BlockDriverState *bs, const
char *filename, int flags)
if (fd < 0) {
bsdPath[strlen(bsdPath)-1] = '1';
} else {
- qemu_close(fd);
+ qemu_close(fd, bsdPath);
}
filename = bsdPath;
}
@@ -889,7 +889,7 @@ static int fd_open(BlockDriverState *bs)
last_media_present = (s->fd >= 0);
if (s->fd >= 0 &&
(get_clock() - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
#ifdef DEBUG_FLOPPY
printf("Floppy closed\n");
@@ -988,7 +988,7 @@ static int hdev_create(const char *filename,
QEMUOptionParameter *options)
else if (lseek(fd, 0, SEEK_END) < total_size * BDRV_SECTOR_SIZE)
ret = -ENOSPC;
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
@@ -1038,7 +1038,7 @@ static int floppy_open(BlockDriverState *bs,
const char *filename, int flags)
return ret;
/* close fd so that we can reopen it as needed */
- qemu_close(s->fd);
+ qemu_close(s->fd, filename);
s->fd = -1;
s->fd_media_changed = 1;
@@ -1070,7 +1070,7 @@ static int floppy_probe_device(const char *filename)
prio = 100;
- qemu_close(fd);
+ qemu_close(fd, filename);
return prio;
}
@@ -1105,14 +1105,14 @@ static void floppy_eject(BlockDriverState *bs, bool eject_flag)
int fd;
if (s->fd >= 0) {
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
s->fd = -1;
}
fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
if (fd >= 0) {
if (ioctl(fd, FDEJECT, 0) < 0)
perror("FDEJECT");
- qemu_close(fd);
+ qemu_close(fd, bs->filename);
}
}
@@ -1173,7 +1173,7 @@ static int cdrom_probe_device(const char *filename)
prio = 100;
- qemu_close(fd);
+ qemu_close(fd, filename);
return prio;
}
@@ -1281,7 +1281,7 @@ static int cdrom_reopen(BlockDriverState *bs)
* FreeBSD seems to not notice sometimes...
*/
if (s->fd >= 0)
- qemu_close(s->fd);
+ qemu_close(s->fd, bs->filename);
fd = qemu_open(bs->filename, s->open_flags, 0644);
if (fd < 0) {
s->fd = -1;
diff --git a/block/raw-win32.c b/block/raw-win32.c
index c56bf83..b795871 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -261,7 +261,7 @@ static int raw_create(const char *filename,
QEMUOptionParameter *options)
return -EIO;
set_sparse(fd);
ftruncate(fd, total_size * 512);
- qemu_close(fd);
+ qemu_close(fd, filename);
return 0;
}
diff --git a/block/vmdk.c b/block/vmdk.c
index daee426..7f1206b 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1258,7 +1258,7 @@ static int vmdk_create_extent(const char
*filename, int64_t filesize,
ret = 0;
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
@@ -1506,7 +1506,7 @@ static int vmdk_create(const char *filename,
QEMUOptionParameter *options)
}
ret = 0;
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
diff --git a/block/vpc.c b/block/vpc.c
index c0b82c4..20f648a 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -744,7 +744,7 @@ static int vpc_create(const char *filename,
QEMUOptionParameter *options)
}
- qemu_close(fd);
+ qemu_close(fd, filename);
return ret;
}
diff --git a/block/vvfat.c b/block/vvfat.c
index 59d3c5b..cbc7543 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1105,7 +1105,7 @@ static inline void
vvfat_close_current_file(BDRVVVFATState *s)
if(s->current_mapping) {
s->current_mapping = NULL;
if (s->current_fd) {
- qemu_close(s->current_fd);
+ qemu_close(s->current_fd, s->current_mapping->path);
s->current_fd = 0;
}
}
@@ -2230,7 +2230,7 @@ static int commit_one_file(BDRVVVFATState* s,
}
if (offset > 0) {
if (lseek(fd, offset, SEEK_SET) != offset) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -3;
}
@@ -2251,13 +2251,13 @@ static int commit_one_file(BDRVVVFATState* s,
(uint8_t*)cluster, (rest_size + 0x1ff) / 0x200);
if (ret < 0) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return ret;
}
if (write(fd, cluster, rest_size) < 0) {
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -2;
}
@@ -2268,11 +2268,11 @@ static int commit_one_file(BDRVVVFATState* s,
if (ftruncate(fd, size)) {
perror("ftruncate()");
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return -4;
}
- qemu_close(fd);
+ qemu_close(fd, mapping->path);
g_free(cluster);
return commit_mappings(s, first_cluster, dir_index);
diff --git a/cutils.c b/cutils.c
index e2bc1b8..4e6bfdc 100644
--- a/cutils.c
+++ b/cutils.c
@@ -375,3 +375,8 @@ int qemu_parse_fd(const char *param)
}
return fd;
}
+
+int qemu_parse_fdset(const char *param)
+{
+ return qemu_parse_fd(param);
+}
diff --git a/monitor.c b/monitor.c
index 30b085f..fddd2b5 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount++;
+ break;
+ }
+ }
+}
+
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount--;
+ if (mon_fdset->refcount == 0) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ break;
+ }
+ }
+}
+
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ }
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
diff --git a/monitor.h b/monitor.h
index 5f4de1b..1efed38 100644
--- a/monitor.h
+++ b/monitor.h
@@ -86,4 +86,8 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret);
int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags);
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id);
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id);
+
#endif /* !MONITOR_H */
diff --git a/osdep.c b/osdep.c
index 7b09dff..0303cdd 100644
--- a/osdep.c
+++ b/osdep.c
@@ -47,6 +47,7 @@ extern int madvise(caddr_t, size_t, int);
#include "qemu-common.h"
#include "trace.h"
#include "qemu_socket.h"
+#include "monitor.h"
static const char *qemu_version = QEMU_VERSION;
@@ -75,6 +76,79 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
+
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
+
+ qemu_set_cloexec(ret);
+
+ return ret;
+
+ serrno = errno;
+ if (ret != -1) {
+ close(ret);
+ }
+ errno = serrno;
+ return -1;
+}
/*
* Opens a file with FD_CLOEXEC set
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Does it make sense to use default_mon here? After digging into this
some more, I'm thinking it makes sense, and I'll explain why.

It looks like cur_mon can't be used. cur_mon will point to the monitor
object for the duration of a command, and be reset to old_mon (NULL in
my case) after the command completes.

qemu_open() and qemu_close() are frequently called long after a monitor
command has come and gone, so cur_mon won't work. For example,
drive_add will cause qemu_open() to be called, but after the command has
completed, the file will keep getting opened/closed during normal QEMU
operation. I'm not sure why, I've just noticed this behavior.

Does anyone have any thoughts on this? It would require fd sets to be
added to the default monitor only.
--
Regards,
Corey
Kevin Wolf
2012-08-06 09:15:19 UTC
Permalink
Post by Corey Bryant
Post by Corey Bryant
Post by Corey Bryant
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Does it make sense to use default_mon here? After digging into this
some more, I'm thinking it makes sense, and I'll explain why.
It looks like cur_mon can't be used. cur_mon will point to the monitor
object for the duration of a command, and be reset to old_mon (NULL in
my case) after the command completes.
qemu_open() and qemu_close() are frequently called long after a monitor
command has come and gone, so cur_mon won't work. For example,
drive_add will cause qemu_open() to be called, but after the command has
completed, the file will keep getting opened/closed during normal QEMU
operation. I'm not sure why, I've just noticed this behavior.
Does anyone have any thoughts on this? It would require fd sets to be
added to the default monitor only.
I think we have two design options that would make sense:

1. Make the file descriptors global instead of per-monitor. Is there a
reason why each monitor has its own set of fds? (Also I'm wondering
if they survive a monitor disconnect this way?)

2. Save a monitor reference with the fdset information.

Allowing to send file descriptors on every monitor, but making only
those of the default monitor actually usable, sounds like a bad choice
to me.

Kevin
Corey Bryant
2012-08-06 13:32:37 UTC
Permalink
Post by Kevin Wolf
Post by Corey Bryant
Post by Corey Bryant
Post by Corey Bryant
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Does it make sense to use default_mon here? After digging into this
some more, I'm thinking it makes sense, and I'll explain why.
It looks like cur_mon can't be used. cur_mon will point to the monitor
object for the duration of a command, and be reset to old_mon (NULL in
my case) after the command completes.
qemu_open() and qemu_close() are frequently called long after a monitor
command has come and gone, so cur_mon won't work. For example,
drive_add will cause qemu_open() to be called, but after the command has
completed, the file will keep getting opened/closed during normal QEMU
operation. I'm not sure why, I've just noticed this behavior.
Does anyone have any thoughts on this? It would require fd sets to be
added to the default monitor only.
1. Make the file descriptors global instead of per-monitor. Is there a
reason why each monitor has its own set of fds? (Also I'm wondering
if they survive a monitor disconnect this way?)
I'd prefer to have them associated with a monitor object so that we can
more easily keep track of whether or not they're in use by a monitor
connection.
Post by Kevin Wolf
2. Save a monitor reference with the fdset information.
Are you saying that each monitor would have the same copy of fdset
information?
Post by Kevin Wolf
Allowing to send file descriptors on every monitor, but making only
those of the default monitor actually usable, sounds like a bad choice
to me.
What if we also allow them to be added only to the default monitor?
--
Regards,
Corey
Kevin Wolf
2012-08-06 13:51:33 UTC
Permalink
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
Post by Corey Bryant
Post by Corey Bryant
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Does it make sense to use default_mon here? After digging into this
some more, I'm thinking it makes sense, and I'll explain why.
It looks like cur_mon can't be used. cur_mon will point to the monitor
object for the duration of a command, and be reset to old_mon (NULL in
my case) after the command completes.
qemu_open() and qemu_close() are frequently called long after a monitor
command has come and gone, so cur_mon won't work. For example,
drive_add will cause qemu_open() to be called, but after the command has
completed, the file will keep getting opened/closed during normal QEMU
operation. I'm not sure why, I've just noticed this behavior.
Does anyone have any thoughts on this? It would require fd sets to be
added to the default monitor only.
1. Make the file descriptors global instead of per-monitor. Is there a
reason why each monitor has its own set of fds? (Also I'm wondering
if they survive a monitor disconnect this way?)
I'd prefer to have them associated with a monitor object so that we can
more easily keep track of whether or not they're in use by a monitor
connection.
Hm, I see.
Post by Corey Bryant
Post by Kevin Wolf
2. Save a monitor reference with the fdset information.
Are you saying that each monitor would have the same copy of fdset
information?
This one doesn't really make sense indeed...
Post by Corey Bryant
Post by Kevin Wolf
Allowing to send file descriptors on every monitor, but making only
those of the default monitor actually usable, sounds like a bad choice
to me.
What if we also allow them to be added only to the default monitor?
Would get you some kind of consistency at least, even though I don't
like that secondary monitors can't use the functionality.

Can't we make the fdset information global, so that a qemu_open/close()
searches all of them, but let it have a Monitor* owner for keeping track
whether it's in use?

Kevin
Corey Bryant
2012-08-06 14:15:17 UTC
Permalink
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
Post by Corey Bryant
Post by Corey Bryant
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Does it make sense to use default_mon here? After digging into this
some more, I'm thinking it makes sense, and I'll explain why.
It looks like cur_mon can't be used. cur_mon will point to the monitor
object for the duration of a command, and be reset to old_mon (NULL in
my case) after the command completes.
qemu_open() and qemu_close() are frequently called long after a monitor
command has come and gone, so cur_mon won't work. For example,
drive_add will cause qemu_open() to be called, but after the command has
completed, the file will keep getting opened/closed during normal QEMU
operation. I'm not sure why, I've just noticed this behavior.
Does anyone have any thoughts on this? It would require fd sets to be
added to the default monitor only.
1. Make the file descriptors global instead of per-monitor. Is there a
reason why each monitor has its own set of fds? (Also I'm wondering
if they survive a monitor disconnect this way?)
I'd prefer to have them associated with a monitor object so that we can
more easily keep track of whether or not they're in use by a monitor
connection.
Hm, I see.
Post by Corey Bryant
Post by Kevin Wolf
2. Save a monitor reference with the fdset information.
Are you saying that each monitor would have the same copy of fdset
information?
This one doesn't really make sense indeed...
Post by Corey Bryant
Post by Kevin Wolf
Allowing to send file descriptors on every monitor, but making only
those of the default monitor actually usable, sounds like a bad choice
to me.
What if we also allow them to be added only to the default monitor?
Would get you some kind of consistency at least, even though I don't
like that secondary monitors can't use the functionality.
Can't we make the fdset information global, so that a qemu_open/close()
searches all of them, but let it have a Monitor* owner for keeping track
whether it's in use?
I think global fdsets might work (sorry I didn't think it through enough
on my first reply). I think I'll need to drop the "in_use" flag and tie
monitor references into the refcount. (I know I know, you suggested
that a while back.. :). I'll give it a shot and see how it goes.
--
Regards,
Corey
Corey Bryant
2012-08-07 16:43:15 UTC
Permalink
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
Post by Corey Bryant
Post by Corey Bryant
@@ -84,6 +158,36 @@ int qemu_open(const char *name, int flags, ...)
int ret;
int mode = 0;
+#ifndef _WIN32
+ const char *fdset_id_str;
+
+ /* Attempt dup of fd from fd set */
+ if (strstart(name, "/dev/fdset/", &fdset_id_str)) {
+ int64_t fdset_id;
+ int fd, dupfd;
+
+ fdset_id = qemu_parse_fdset(fdset_id_str);
+ if (fdset_id == -1) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ fd = monitor_fdset_get_fd(default_mon, fdset_id, flags);
I know that use of default_mon in this patch is not correct, but I
wanted to get these patches out for review. I used default_mon for
testing because cur_mon wasn't pointing to the monitor I'd added fd sets
to. I need to figure out why.
Does it make sense to use default_mon here? After digging into this
some more, I'm thinking it makes sense, and I'll explain why.
It looks like cur_mon can't be used. cur_mon will point to the monitor
object for the duration of a command, and be reset to old_mon (NULL in
my case) after the command completes.
qemu_open() and qemu_close() are frequently called long after a monitor
command has come and gone, so cur_mon won't work. For example,
drive_add will cause qemu_open() to be called, but after the command has
completed, the file will keep getting opened/closed during normal QEMU
operation. I'm not sure why, I've just noticed this behavior.
Does anyone have any thoughts on this? It would require fd sets to be
added to the default monitor only.
1. Make the file descriptors global instead of per-monitor. Is there a
reason why each monitor has its own set of fds? (Also I'm wondering
if they survive a monitor disconnect this way?)
I'd prefer to have them associated with a monitor object so that we can
more easily keep track of whether or not they're in use by a monitor
connection.
Hm, I see.
Post by Corey Bryant
Post by Kevin Wolf
2. Save a monitor reference with the fdset information.
Are you saying that each monitor would have the same copy of fdset
information?
This one doesn't really make sense indeed...
Post by Corey Bryant
Post by Kevin Wolf
Allowing to send file descriptors on every monitor, but making only
those of the default monitor actually usable, sounds like a bad choice
to me.
What if we also allow them to be added only to the default monitor?
Would get you some kind of consistency at least, even though I don't
like that secondary monitors can't use the functionality.
Can't we make the fdset information global, so that a qemu_open/close()
searches all of them, but let it have a Monitor* owner for keeping track
whether it's in use?
I think global fdsets might work (sorry I didn't think it through enough
on my first reply). I think I'll need to drop the "in_use" flag and tie
monitor references into the refcount. (I know I know, you suggested
that a while back.. :). I'll give it a shot and see how it goes.
I just submitted the v7 patch series which makes fd sets global, rather
than each Monitor object having an fd set. This allows the list of fd
sets to be shared among all monitor connections.
--
Regards,
Corey
Kevin Wolf
2012-07-24 12:07:57 UTC
Permalink
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
-Get rid of file_open and move dup code to qemu_open
v4
-Update qemu_open to check access mode flags and set flags that
-This patch was overhauled quite a bit in this version, with
the addition of fd set and refcount support.
---
block/raw-posix.c | 24 +++++-----
block/raw-win32.c | 2 +-
block/vmdk.c | 4 +-
block/vpc.c | 2 +-
block/vvfat.c | 12 ++---
cutils.c | 5 ++
monitor.c | 85 +++++++++++++++++++++++++++++++++
monitor.h | 4 ++
osdep.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
qemu-common.h | 3 +-
qemu-tool.c | 12 +++++
11 files changed, 267 insertions(+), 24 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index a172de3..5d0a801 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
qemu_vfree(s->aligned_buf);
- qemu_close(fd);
+ qemu_close(fd, filename);
return -errno;
}
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?

But if we decided to keep it like this, please use the right interface
from the beginning in patch 5 instead of updating it here.
Post by Corey Bryant
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount++;
+ break;
+ }
+ }
+}
+
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount--;
+ if (mon_fdset->refcount == 0) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ break;
+ }
+ }
+}
These two functions are almost the same. Would a
monitor_fdset_update_refcount(mon, fdset_id, value) make sense? These
functions could then be kept as thin wrappers around it, or they could
even be dropped completely.
Post by Corey Bryant
+
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ }
I think you mean:

if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
return mon_fdset_fd->fd;
}

What about other flags that cannot be set with fcntl(), like O_SYNC on
older kernels or possibly non-Linux? (The block layer doesn't use it any
more, but I think we want to keep the function generally useful)
Post by Corey Bryant
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
@@ -75,6 +76,79 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
It's worth trying to set it before failing, newer kernels can do it. But
as I said above, if you can fail here, it makes sense to consider O_SYNC
when selecting the right file descriptor from the fdset.
Post by Corey Bryant
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
What about this instead of the loop:

int setfl_flags = O_APPEND | O_ASYNC | ... ;

dup_flags &= ~setfl_flags;
dup_flags |= (flags & setfl_flags);
Post by Corey Bryant
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
O_CREAT | O_EXCL kind of loses its meaning here, but okay, it's hard to
do better with file descriptors.
Post by Corey Bryant
+
+ qemu_set_cloexec(ret);
Wait... If O_CLOEXEC is set, you set the flag immediately and if it
isn't you set it at the end of the function? What's the intended use
case for not using O_CLOEXEC then?

Kevin
Corey Bryant
2012-07-25 03:41:56 UTC
Permalink
Post by Kevin Wolf
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
-Get rid of file_open and move dup code to qemu_open
v4
-Update qemu_open to check access mode flags and set flags that
-This patch was overhauled quite a bit in this version, with
the addition of fd set and refcount support.
---
block/raw-posix.c | 24 +++++-----
block/raw-win32.c | 2 +-
block/vmdk.c | 4 +-
block/vpc.c | 2 +-
block/vvfat.c | 12 ++---
cutils.c | 5 ++
monitor.c | 85 +++++++++++++++++++++++++++++++++
monitor.h | 4 ++
osdep.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
qemu-common.h | 3 +-
qemu-tool.c | 12 +++++
11 files changed, 267 insertions(+), 24 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index a172de3..5d0a801 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
qemu_vfree(s->aligned_buf);
- qemu_close(fd);
+ qemu_close(fd, filename);
return -errno;
}
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.

We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
Post by Kevin Wolf
But if we decided to keep it like this, please use the right interface
from the beginning in patch 5 instead of updating it here.
Ok
Post by Kevin Wolf
Post by Corey Bryant
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount++;
+ break;
+ }
+ }
+}
+
+void monitor_fdset_decrement_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id == fdset_id) {
+ mon_fdset->refcount--;
+ if (mon_fdset->refcount == 0) {
+ monitor_fdset_cleanup(mon_fdset);
+ }
+ break;
+ }
+ }
+}
These two functions are almost the same. Would a
monitor_fdset_update_refcount(mon, fdset_id, value) make sense? These
functions could then be kept as thin wrappers around it, or they could
even be dropped completely.
This makes sense and I'll try one of these approaches. I actually
started to do something along these lines in v5 but reverted back to the
two independent functions because it was easier to read the code.
Post by Kevin Wolf
Post by Corey Bryant
+
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ }
if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
return mon_fdset_fd->fd;
}
Yes, that would be a bit simpler wouldn't it. :)
Post by Kevin Wolf
What about other flags that cannot be set with fcntl(), like O_SYNC on
older kernels or possibly non-Linux? (The block layer doesn't use it any
more, but I think we want to keep the function generally useful)
I see what you're getting at here. Basically you could have 2 fds in an
fdset with the same access mode flags, but one has O_SYNC on and the
other has O_SYNC off. That seems like it would make sense to implement.
As a work-around, I think a user could just create a separate fdset
for the same file with different O_SYNC value. But from a client
perspective, it would be nicer to have this taken care of for you.
Post by Kevin Wolf
Post by Corey Bryant
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
@@ -75,6 +76,79 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
It's worth trying to set it before failing, newer kernels can do it. But
as I said above, if you can fail here, it makes sense to consider O_SYNC
when selecting the right file descriptor from the fdset.
I'm on a 3.4.4 Fedora kernel that doesn't appear to support
fcntl(O_SYNC), but perhaps I'm doing something wrong. Here's my test
code (shortened for simplicty):

int main() {
int fd;
int flags;

fd = open("/tmp/corey", O_RDWR | O_CREAT,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);

flags = fcntl(fd, F_GETFL);
printf("flags=%08x\n", flags); //A

fcntl(fd, F_SETFL, O_SYNC);
printf("O_SYNC=%08x\n", O_SYNC);

flags = fcntl(fd, F_GETFL);
printf("flags=%08x\n", flags); //B
}

fcntl doesn't fail, but the flags I print out at A are the same as the
flags printed out at B, so it appears that O_SYNC doesn't get set.
Post by Kevin Wolf
Post by Corey Bryant
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
int setfl_flags = O_APPEND | O_ASYNC | ... ;
dup_flags &= ~setfl_flags;
dup_flags |= (flags & setfl_flags);
I like your suggestion, it's much simpler.
Post by Kevin Wolf
Post by Corey Bryant
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
O_CREAT | O_EXCL kind of loses its meaning here, but okay, it's hard to
do better with file descriptors.
I agree and I don't know if we can do any better.
Post by Kevin Wolf
Post by Corey Bryant
+
+ qemu_set_cloexec(ret);
Wait... If O_CLOEXEC is set, you set the flag immediately and if it
isn't you set it at the end of the function? What's the intended use
case for not using O_CLOEXEC then?
This is a mistake. I think I just need to be using qemu_set_cloexec()
instead of fcntl_setfl() earlier in this function and get rid of this
latter call to qemu_set_cloexec().
--
Regards,
Corey
Kevin Wolf
2012-07-25 08:22:46 UTC
Permalink
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
diff --git a/block/raw-posix.c b/block/raw-posix.c
index a172de3..5d0a801 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -271,7 +271,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
qemu_vfree(s->aligned_buf);
- qemu_close(fd);
+ qemu_close(fd, filename);
return -errno;
}
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.
We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
I don't think so. qemu_close() is not a fast path and happens almost
never, and the list is short enough that searching it isn't a problem
anyway.
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ }
if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
return mon_fdset_fd->fd;
}
Yes, that would be a bit simpler wouldn't it. :)
Post by Kevin Wolf
What about other flags that cannot be set with fcntl(), like O_SYNC on
older kernels or possibly non-Linux? (The block layer doesn't use it any
more, but I think we want to keep the function generally useful)
I see what you're getting at here. Basically you could have 2 fds in an
fdset with the same access mode flags, but one has O_SYNC on and the
other has O_SYNC off. That seems like it would make sense to implement.
As a work-around, I think a user could just create a separate fdset
for the same file with different O_SYNC value. But from a client
perspective, it would be nicer to have this taken care of for you.
Now that the block layer doesn't use O_SYNC any more, it's more of a
theoretical point. I don't think there's any other place, where we'd
need to switch O_SYNC during runtime.

Taking it into consideration is complicated by the fact that some
kernels allow to fcntl() O_SYNC and others don't, so enforcing a match
here wouldn't feel completely right either.

Maybe just leave it as it is. :-)
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
+ }
+ errno = EACCES;
+ return -1;
+ }
+ errno = ENOENT;
+ return -1;
+}
+
/* mon_cmds and info_cmds would be sorted at runtime */
static mon_cmd_t mon_cmds[] = {
#include "hmp-commands.h"
@@ -75,6 +76,79 @@ int qemu_madvise(void *addr, size_t len, int advice)
#endif
}
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
It's worth trying to set it before failing, newer kernels can do it. But
as I said above, if you can fail here, it makes sense to consider O_SYNC
when selecting the right file descriptor from the fdset.
I'm on a 3.4.4 Fedora kernel that doesn't appear to support
fcntl(O_SYNC), but perhaps I'm doing something wrong. Here's my test
code (shortened for simplicty): [...]
Hm, true. So it seems that patch has never made it into the kernel, in
fact...
Post by Corey Bryant
Post by Kevin Wolf
Post by Corey Bryant
+
+ qemu_set_cloexec(ret);
Wait... If O_CLOEXEC is set, you set the flag immediately and if it
isn't you set it at the end of the function? What's the intended use
case for not using O_CLOEXEC then?
This is a mistake. I think I just need to be using qemu_set_cloexec()
instead of fcntl_setfl() earlier in this function and get rid of this
latter call to qemu_set_cloexec().
Yes, probably. And in fact, I think this shouldn't even be conditional
on flags & O_CLOEXEC. The whole reason qemu_open() was introduced
originally was to always set O_CLOEXEC.

Kevin
Eric Blake
2012-07-25 19:25:26 UTC
Permalink
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.
We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
I don't think so. qemu_close() is not a fast path and happens almost
never, and the list is short enough that searching it isn't a problem
anyway.
I agree - just do the loop to do the reverse lookup yourself, rather
than making qemu_close() have a different signature than close().
--
Eric Blake ***@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Corey Bryant
2012-07-26 03:21:55 UTC
Permalink
Post by Eric Blake
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.
We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
I don't think so. qemu_close() is not a fast path and happens almost
never, and the list is short enough that searching it isn't a problem
anyway.
I agree - just do the loop to do the reverse lookup yourself, rather
than making qemu_close() have a different signature than close().
Great, I'll do this then.
--
Regards,
Corey
Eric Blake
2012-07-26 13:13:02 UTC
Permalink
Post by Corey Bryant
Post by Eric Blake
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.
We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
I don't think so. qemu_close() is not a fast path and happens almost
never, and the list is short enough that searching it isn't a problem
anyway.
I agree - just do the loop to do the reverse lookup yourself, rather
than making qemu_close() have a different signature than close().
Great, I'll do this then.
You may want an optimization of using a bitset for tracking which fds
are tracked by fdset in the first place, so that the fast path of
qemu_close() will be a check against the bitset to see if you even have
to waste time on the reverse lookup in the first place. The bitset will
typically be small (bounded not only by the maximum possible fd, but
further by the fact that we don't usually open that many fds in the
first place), but I'm not sure if you can get away with static sizing.
--
Eric Blake ***@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Kevin Wolf
2012-07-26 13:16:35 UTC
Permalink
Post by Eric Blake
Post by Corey Bryant
Post by Eric Blake
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.
We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
I don't think so. qemu_close() is not a fast path and happens almost
never, and the list is short enough that searching it isn't a problem
anyway.
I agree - just do the loop to do the reverse lookup yourself, rather
than making qemu_close() have a different signature than close().
Great, I'll do this then.
You may want an optimization of using a bitset for tracking which fds
are tracked by fdset in the first place, so that the fast path of
qemu_close() will be a check against the bitset to see if you even have
to waste time on the reverse lookup in the first place. The bitset will
typically be small (bounded not only by the maximum possible fd, but
further by the fact that we don't usually open that many fds in the
first place), but I'm not sure if you can get away with static sizing.
Premature optimisation, in my opinion. The list is really small.

Kevin
Corey Bryant
2012-07-27 04:07:38 UTC
Permalink
Post by Kevin Wolf
Post by Eric Blake
Post by Corey Bryant
Post by Eric Blake
Post by Kevin Wolf
Post by Corey Bryant
Post by Kevin Wolf
Hm, not a nice interface where qemu_close() needs the filename and
(worse) could be given a wrong filename. Maybe it would be better to
maintain a list of fd -> fdset mappings in qemu_open/close?
I agree, I don't really like it either.
We already have a list of fd -> fdset mappings (mon_fdset_fd_t ->
mon_fdset_t). Would it be too costly to loop through all the fdsets/fds
at the beginning of every qemu_close()?
I don't think so. qemu_close() is not a fast path and happens almost
never, and the list is short enough that searching it isn't a problem
anyway.
I agree - just do the loop to do the reverse lookup yourself, rather
than making qemu_close() have a different signature than close().
Great, I'll do this then.
You may want an optimization of using a bitset for tracking which fds
are tracked by fdset in the first place, so that the fast path of
qemu_close() will be a check against the bitset to see if you even have
to waste time on the reverse lookup in the first place. The bitset will
typically be small (bounded not only by the maximum possible fd, but
further by the fact that we don't usually open that many fds in the
first place), but I'm not sure if you can get away with static sizing.
Premature optimisation, in my opinion. The list is really small.
Kevin
I'll probably hold off on any optimisation at this point, but I can
revisit it in the future if it's needed.
--
Regards,
Corey
Kevin Wolf
2012-07-24 12:09:19 UTC
Permalink
qemu-char: Add MSG_CMSG_CLOEXEC flag to recvmsg
qapi: Introduce add-fd, remove-fd, query-fdsets
monitor: Clean up fd sets on monitor disconnect
block: Convert open calls to qemu_open
block: Convert close calls to qemu_close
block: Enable qemu_open/close to work with fd sets
block/raw-posix.c | 42 ++++-----
block/raw-win32.c | 6 +-
block/vdi.c | 5 +-
block/vmdk.c | 25 +++---
block/vpc.c | 4 +-
block/vvfat.c | 16 ++--
cutils.c | 5 ++
monitor.c | 244 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
monitor.h | 4 +
osdep.c | 141 +++++++++++++++++++++++++++++++
qapi-schema.json | 97 +++++++++++++++++++++
qemu-char.c | 10 ++-
qemu-common.h | 2 +
qemu-tool.c | 12 +++
qmp-commands.hx | 121 ++++++++++++++++++++++++++
savevm.c | 4 +-
16 files changed, 684 insertions(+), 54 deletions(-)
Apart from the points I commented on in patch 6, and what Eric and you
found, this looks good to me.

Kevin
Corey Bryant
2012-07-25 03:42:51 UTC
Permalink
Post by Kevin Wolf
qemu-char: Add MSG_CMSG_CLOEXEC flag to recvmsg
qapi: Introduce add-fd, remove-fd, query-fdsets
monitor: Clean up fd sets on monitor disconnect
block: Convert open calls to qemu_open
block: Convert close calls to qemu_close
block: Enable qemu_open/close to work with fd sets
block/raw-posix.c | 42 ++++-----
block/raw-win32.c | 6 +-
block/vdi.c | 5 +-
block/vmdk.c | 25 +++---
block/vpc.c | 4 +-
block/vvfat.c | 16 ++--
cutils.c | 5 ++
monitor.c | 244 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
monitor.h | 4 +
osdep.c | 141 +++++++++++++++++++++++++++++++
qapi-schema.json | 97 +++++++++++++++++++++
qemu-char.c | 10 ++-
qemu-common.h | 2 +
qemu-tool.c | 12 +++
qmp-commands.hx | 121 ++++++++++++++++++++++++++
savevm.c | 4 +-
16 files changed, 684 insertions(+), 54 deletions(-)
Apart from the points I commented on in patch 6, and what Eric and you
found, this looks good to me.
Kevin
Great, thanks for the review!
--
Regards,
Corey
Eric Blake
2012-07-25 19:43:00 UTC
Permalink
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
+++ b/monitor.c
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
Am I reading this code right by stating that 'if there is no monitor, we
don't increment the refcount'? How does a monitor reattach affect
things? Or am I missing something fundamental about the cases when
'mon==NULL' will exist?
Post by Corey Bryant
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
This says we fail on the first fcntl() failure, instead of trying other
fds in the set. Granted, an fcntl() failure is probably the sign of a
bigger bug (such as closing an fd at the wrong point in time), so I
guess trying to go on doesn't make much sense once we already know we
are hosed.
Post by Corey Bryant
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
Do we want to allow the case where the caller asked for O_RDONLY, but
the set only has O_RDWR? After all, the caller is getting a compatible
subset of what the set offers.
Post by Corey Bryant
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
Likewise, should we allow a caller asking for O_WRONLY when the set
provides only O_RDWR?
Post by Corey Bryant
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
F_DUPFD_CLOEXEC is required by POSIX but not implemented on all modern
OS yet; you probably need some #ifdef and/or configure guards.
Post by Corey Bryant
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
You _can't_ call F_SETFL with O_CLOEXEC. O_CLOEXEC only causes open()
to set FD_CLOEXEC; thereafter, including in the case of this dup, what
you want to do is instead set FD_CLOEXEC via F_SETFD (aka call
qemu_set_cloexec, not fcntl_setfl).
Post by Corey Bryant
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
+
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
Rather than looping one bit at a time, you should do this as a mask
operation.
Post by Corey Bryant
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
+
+ qemu_set_cloexec(ret);
If we're going to blindly set FD_CLOEXEC at the end of the day, rather
than try to honor O_CLOEXEC, then why not simplify the beginning of this
function:

ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
if (ret == -1 && errno == EINVAL) {
ret = dup(fd);
if (ret != -1) {
qemu_set_cloexec(ret);
}
}
if (ret == -1) {
goto fail;
}
--
Eric Blake ***@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Kevin Wolf
2012-07-26 09:07:07 UTC
Permalink
Post by Eric Blake
Post by Corey Bryant
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
This says we fail on the first fcntl() failure, instead of trying other
fds in the set. Granted, an fcntl() failure is probably the sign of a
bigger bug (such as closing an fd at the wrong point in time), so I
guess trying to go on doesn't make much sense once we already know we
are hosed.
I think I'll stick with it the way it is. If fcntl() fails we might
have a tainted fd set so I think we should fail.
The alternative would be s/return 1/continue/, right? I think either way
is acceptable.
Post by Eric Blake
Post by Corey Bryant
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
Do we want to allow the case where the caller asked for O_RDONLY, but
the set only has O_RDWR? After all, the caller is getting a compatible
subset of what the set offers.
I don't see a problem with it.
I would require exact matches like you implemented, in order to prevent
damage if we ever had a bug that writes to a read-only file. I believe
it also makes the semantics clearer and the code simpler, while it
shouldn't make much of a difference for clients.

Kevin
Corey Bryant
2012-07-27 03:59:33 UTC
Permalink
Post by Kevin Wolf
Post by Eric Blake
Post by Corey Bryant
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
This says we fail on the first fcntl() failure, instead of trying other
fds in the set. Granted, an fcntl() failure is probably the sign of a
bigger bug (such as closing an fd at the wrong point in time), so I
guess trying to go on doesn't make much sense once we already know we
are hosed.
I think I'll stick with it the way it is. If fcntl() fails we might
have a tainted fd set so I think we should fail.
The alternative would be s/return 1/continue/, right? I think either way
is acceptable.
Post by Eric Blake
Post by Corey Bryant
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
Do we want to allow the case where the caller asked for O_RDONLY, but
the set only has O_RDWR? After all, the caller is getting a compatible
subset of what the set offers.
I don't see a problem with it.
I would require exact matches like you implemented, in order to prevent
damage if we ever had a bug that writes to a read-only file. I believe
it also makes the semantics clearer and the code simpler, while it
shouldn't make much of a difference for clients.
Kevin
Alright, then I'll plan on requiring exact matches of access mode flags.
--
Regards,
Corey
Corey Bryant
2012-07-27 04:03:49 UTC
Permalink
Post by Kevin Wolf
Post by Corey Bryant
Post by Eric Blake
Post by Corey Bryant
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
Post by Eric Blake
Post by Corey Bryant
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
This says we fail on the first fcntl() failure, instead of trying other
fds in the set. Granted, an fcntl() failure is probably the sign of a
bigger bug (such as closing an fd at the wrong point in time), so I
guess trying to go on doesn't make much sense once we already know we
are hosed.
I think I'll stick with it the way it is. If fcntl() fails we might
have a tainted fd set so I think we should fail.
The alternative would be s/return 1/continue/, right? I think either way
is acceptable.
Yes, we'd continue the loop instead of returning -1. I prefer to return
on the first failure, but if anyone feels strongly about continuing the
loop, please let me know.
--
Regards,
Corey
Corey Bryant
2012-07-26 03:57:37 UTC
Permalink
Post by Eric Blake
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
+++ b/monitor.c
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
Am I reading this code right by stating that 'if there is no monitor, we
don't increment the refcount'? How does a monitor reattach affect
things? Or am I missing something fundamental about the cases when
'mon==NULL' will exist?
Yes you're reading this correctly.

I'm pretty sure that mon will only be NULL if QEMU is started without a
monitor.

If QEMU has a monitor, and libvirt disconnects it's connection to the
qemu monitor, then I believe mon will remain non-NULL.

I'll plan on testing this out to verify though. (I'm out most of this
week and will be back full time starting next Tues.)
Post by Eric Blake
Post by Corey Bryant
+int monitor_fdset_get_fd(Monitor *mon, int64_t fdset_id, int flags)
+{
+ mon_fdset_t *mon_fdset;
+ mon_fdset_fd_t *mon_fdset_fd;
+ int mon_fd_flags;
+
+ if (!mon) {
+ errno = ENOENT;
+ return -1;
+ }
+
+ QLIST_FOREACH(mon_fdset, &mon->fdsets, next) {
+ if (mon_fdset->id != fdset_id) {
+ continue;
+ }
+ QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
+ if (mon_fdset_fd->removed) {
+ continue;
+ }
+
+ mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
+ if (mon_fd_flags == -1) {
+ return -1;
This says we fail on the first fcntl() failure, instead of trying other
fds in the set. Granted, an fcntl() failure is probably the sign of a
bigger bug (such as closing an fd at the wrong point in time), so I
guess trying to go on doesn't make much sense once we already know we
are hosed.
I think I'll stick with it the way it is. If fcntl() fails we might
have a tainted fd set so I think we should fail.
Post by Eric Blake
Post by Corey Bryant
+ }
+
+ switch (flags & O_ACCMODE) {
+ if ((mon_fd_flags & O_ACCMODE) == O_RDWR) {
+ return mon_fdset_fd->fd;
+ }
+ break;
+ if ((mon_fd_flags & O_ACCMODE) == O_RDONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
Do we want to allow the case where the caller asked for O_RDONLY, but
the set only has O_RDWR? After all, the caller is getting a compatible
subset of what the set offers.
I don't see a problem with it.
Post by Eric Blake
Post by Corey Bryant
+ if ((mon_fd_flags & O_ACCMODE) == O_WRONLY) {
+ return mon_fdset_fd->fd;
+ }
+ break;
Likewise, should we allow a caller asking for O_WRONLY when the set
provides only O_RDWR?
I don't see a problem with it.
Post by Eric Blake
Post by Corey Bryant
+/*
+ * Dups an fd and sets the flags
+ */
+static int qemu_dup(int fd, int flags)
+{
+ int i;
+ int ret;
+ int serrno;
+ int dup_flags;
+ int setfl_flags[] = { O_APPEND, O_ASYNC, O_DIRECT, O_NOATIME,
+ O_NONBLOCK, 0 };
+
+ if (flags & O_CLOEXEC) {
+ ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
F_DUPFD_CLOEXEC is required by POSIX but not implemented on all modern
OS yet; you probably need some #ifdef and/or configure guards.
Ok
Post by Eric Blake
Post by Corey Bryant
+ if (ret == -1 && errno == EINVAL) {
+ ret = dup(fd);
+ if (ret != -1 && fcntl_setfl(ret, O_CLOEXEC) == -1) {
You _can't_ call F_SETFL with O_CLOEXEC. O_CLOEXEC only causes open()
to set FD_CLOEXEC; thereafter, including in the case of this dup, what
you want to do is instead set FD_CLOEXEC via F_SETFD (aka call
qemu_set_cloexec, not fcntl_setfl).
I know, this is a mistake. I'm planning to replace fcntl_setfl() here
with qemu_set_cloexec().
Post by Eric Blake
Post by Corey Bryant
+ goto fail;
+ }
+ }
+ } else {
+ ret = dup(fd);
+ }
+
+ if (ret == -1) {
+ goto fail;
+ }
+
+ dup_flags = fcntl(ret, F_GETFL);
+ if (dup_flags == -1) {
+ goto fail;
+ }
+
+ if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {
+ errno = EINVAL;
+ goto fail;
+ }
+
+ /* Set/unset flags that we can with fcntl */
+ i = 0;
+ while (setfl_flags[i] != 0) {
+ if (flags & setfl_flags[i]) {
+ dup_flags = (dup_flags | setfl_flags[i]);
+ } else {
+ dup_flags = (dup_flags & ~setfl_flags[i]);
+ }
+ i++;
+ }
Rather than looping one bit at a time, you should do this as a mask
operation.
I agree.
Post by Eric Blake
Post by Corey Bryant
+
+ if (fcntl(ret, F_SETFL, dup_flags) == -1) {
+ goto fail;
+ }
+
+ /* Truncate the file in the cases that open() would truncate it */
+ if (flags & O_TRUNC ||
+ ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {
+ if (ftruncate(ret, 0) == -1) {
+ goto fail;
+ }
+ }
+
+ qemu_set_cloexec(ret);
If we're going to blindly set FD_CLOEXEC at the end of the day, rather
than try to honor O_CLOEXEC, then why not simplify the beginning of this
This call to qemu_set_cloexec() was a mistake. I'm planning on removing it.
Post by Eric Blake
ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);
if (ret == -1 && errno == EINVAL) {
ret = dup(fd);
if (ret != -1) {
qemu_set_cloexec(ret);
}
}
if (ret == -1) {
goto fail;
}
I'll plan on sticking with the existing code in the beginning of this
function with the modifications mentioned above.
--
Regards,
Corey
Corey Bryant
2012-08-02 15:08:24 UTC
Permalink
Post by Corey Bryant
Post by Eric Blake
Post by Corey Bryant
When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set. If the fd is found, a dup of the fd will be returned
from qemu_open.
Each fd set has a reference count. The purpose of the reference
count is to determine if an fd set contains file descriptors that
have open dup() references that have not yet been closed. It is
incremented on qemu_open and decremented on qemu_close. It is
not until the refcount is zero that file desriptors in an fd set
can be closed. If an fd set has dup() references open, then we
must keep the other fds in the fd set open in case a reopen
of the file occurs that requires an fd with a different access
mode.
+++ b/monitor.c
@@ -2551,6 +2551,91 @@ static void monitor_fdsets_set_in_use(Monitor *mon, bool in_use)
}
}
+void monitor_fdset_increment_refcount(Monitor *mon, int64_t fdset_id)
+{
+ mon_fdset_t *mon_fdset;
+
+ if (!mon) {
+ return;
+ }
Am I reading this code right by stating that 'if there is no monitor, we
don't increment the refcount'? How does a monitor reattach affect
things? Or am I missing something fundamental about the cases when
'mon==NULL' will exist?
Yes you're reading this correctly.
I'm pretty sure that mon will only be NULL if QEMU is started without a
monitor.
If QEMU has a monitor, and libvirt disconnects it's connection to the
qemu monitor, then I believe mon will remain non-NULL.
I've verified this to be true and everything is working as expected.

If libvirt's connection to the monitor fd is closed, mon will remain
non-NULL and the refcount will still be incremented/decremented on
qemu_open()/qemu_close(). When libvirt reconnects, any fdsets that
haven't been cleaned up will still be available. query-fdsets can be
used to determine what's available.
--
Regards,
Corey
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