[PATCH v2 1/4] virfile: Add virFileGetLockOwner function
The function is used to retrieve the PID of the process holding an
exclusive lock on the file.
Signed-off-by: Vasiliy Ulyanov <vulyanov(a)suse.de>
---
src/libvirt_private.syms | 1 +
src/util/virfile.c | 45 ++++++++++++++++++++++++++++++++++++++++
src/util/virfile.h | 2 ++
3 files changed, 48 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 5b76e66e61..214f375a91 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2224,6 +2224,7 @@ virFileFreeACLs;
virFileGetACLs;
virFileGetDefaultHugepage;
virFileGetHugepageSize;
+virFileGetLockOwner;
virFileGetMountReverseSubtree;
virFileGetMountSubtree;
virFileGetXAttr;
diff --git a/src/util/virfile.c b/src/util/virfile.c
index d6faf7e3d2..b9149fb0d7 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -460,6 +460,43 @@ int virFileUnlock(int fd, off_t start, off_t len)
}
+/**
+ * virFileGetLockOwner:
+ * @fd: file descriptor to get the lock from
+ * @start: byte offset for the lock
+ * @len: length of the lock (0 to specify entire remaining file from @start)
+ * @pid: variable to return the PID of the process owning the lock
+ *
+ * Attempt to retrieve the PID of the process holding an exclusive lock
+ * on the file @fd.
+ *
+ * Returns 0 on success, or -errno on error. If the file is not locked @pid
+ * will be set ot -1.
+ */
+int virFileGetLockOwner(int fd,
+ off_t start,
+ off_t len,
+ pid_t *pid)
+{
+ struct flock fl = {
+ .l_type = F_WRLCK,
+ .l_whence = SEEK_SET,
+ .l_start = start,
+ .l_len = len,
+ };
+
+ *pid = -1;
+
+ if (fcntl(fd, F_GETLK, &fl) < 0)
+ return -errno;
+
+ if (fl.l_type != F_UNLCK)
+ *pid = fl.l_pid;
+
+ return 0;
+}
+
+
#else /* WIN32 */
@@ -480,6 +517,14 @@ int virFileUnlock(int fd G_GNUC_UNUSED,
return -ENOSYS;
}
+int virFileGetLockOwner(int fd G_GNUC_UNUSED,
+ off_t start G_GNUC_UNUSED,
+ off_t len G_GNUC_UNUSED,
+ pid_t *pid G_GNUC_UNUSED)
+{
+ return -ENOSYS;
+}
+
#endif /* WIN32 */
diff --git a/src/util/virfile.h b/src/util/virfile.h
index 967c9a9b4f..0f4aa6e441 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -122,6 +122,8 @@ int virFileLock(int fd, bool shared, off_t start, off_t len, bool
waitForLock)
G_GNUC_NO_INLINE;
int virFileUnlock(int fd, off_t start, off_t len)
G_GNUC_NO_INLINE;
+int virFileGetLockOwner(int fd, off_t start, off_t len, pid_t *pid)
+ G_GNUC_NO_INLINE;
typedef int (*virFileRewriteFunc)(int fd, const void *opaque);
int virFileRewrite(const char *path,
--
2.34.1