Daniel Berrangé suggested to use fcntl() locks rather than lockf().
'man lockf':
On Linux, lockf() is just an interface on top of fcntl(2) locking.
Many other systems implement lockf() in this way, but note that
POSIX.1 leaves the relationship between lockf() and fcntl(2) locks
unspecified. A portable application should probably avoid mixing
calls to these interfaces.
IOW, if its just a shim around fcntl() on many systems, it is clearer
if we just use fcntl() directly, as we then know how fcntl() locks will
behave if they're on a network filesystem like NFS.
Suggested-by: Daniel P. Berrangé <berra...@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
util/oslib-posix.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 0e3ab9d959..fbd0dc8c57 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -95,6 +95,11 @@ bool qemu_write_pidfile(const char *path, Error **errp)
while (1) {
struct stat a, b;
+ struct flock lock = {
+ .l_type = F_WRLCK,
+ .l_whence = SEEK_SET,
+ .l_len = 0,
+ };
fd = qemu_open(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
if (fd == -1) {
@@ -107,7 +112,7 @@ bool qemu_write_pidfile(const char *path, Error **errp)
goto fail_close;
}
- if (lockf(fd, F_TLOCK, 0) < 0) {
+ if (fcntl(fd, F_SETLK, &lock)) {
error_setg_errno(errp, errno, "Cannot lock pid file");
goto fail_close;
}
--
2.19.0.rc1
