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lock-file: various updates

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This commit is contained in:
Lennart Poettering
2022-12-23 17:35:21 +01:00
parent 020b66d850
commit 937362e02c
1 changed files with 19 additions and 25 deletions
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src/shared/lockfile-util.c
+19 -25
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@@ -20,15 +20,15 @@ int make_lock_file(const char *p, int operation, LockFile *ret) {
_cleanup_free_ char *t = NULL;
int r;
assert(p);
assert(ret);
/*
* We use UNPOSIX locks if they are available. They have nice
* semantics, and are mostly compatible with NFS. However,
* they are only available on new kernels. When we detect we
* are running on an older kernel, then we fall back to good
* old BSD locks. They also have nice semantics, but are
* slightly problematic on NFS, where they are upgraded to
* POSIX locks, even though locally they are orthogonal to
* POSIX locks.
* We use UNPOSIX locks if they are available. They have nice semantics, and are mostly compatible
* with NFS. However, they are only available on new kernels. When we detect we are running on an
* older kernel, then we fall back to good old BSD locks. They also have nice semantics, but are
* slightly problematic on NFS, where they are upgraded to POSIX locks, even though locally they are
* orthogonal to POSIX locks.
*/
t = strdup(p);
@@ -48,23 +48,18 @@ int make_lock_file(const char *p, int operation, LockFile *ret) {
r = fcntl(fd, (operation & LOCK_NB) ? F_OFD_SETLK : F_OFD_SETLKW, &fl);
if (r < 0) {
/* If the kernel is too old, use good old BSD locks */
if (errno == EINVAL)
if (errno == EINVAL || ERRNO_IS_NOT_SUPPORTED(errno))
r = flock(fd, operation);
if (r < 0)
return errno == EAGAIN ? -EBUSY : -errno;
}
/* If we acquired the lock, let's check if the file
* still exists in the file system. If not, then the
* previous exclusive owner removed it and then closed
* it. In such a case our acquired lock is worthless,
* hence try again. */
/* If we acquired the lock, let's check if the file still exists in the file system. If not,
* then the previous exclusive owner removed it and then closed it. In such a case our
* acquired lock is worthless, hence try again. */
r = fstat(fd, &st);
if (r < 0)
if (fstat(fd, &st) < 0)
return -errno;
if (st.st_nlink > 0)
break;
@@ -72,12 +67,11 @@ int make_lock_file(const char *p, int operation, LockFile *ret) {
fd = safe_close(fd);
}
ret->path = t;
ret->fd = fd;
ret->operation = operation;
fd = -EBADF;
t = NULL;
*ret = (LockFile) {
.path = TAKE_PTR(t),
.fd = TAKE_FD(fd),
.operation = operation,
};
return r;
}
@@ -124,7 +118,7 @@ void release_lock_file(LockFile *f) {
};
r = fcntl(f->fd, F_OFD_SETLK, &fl);
if (r < 0 && errno == EINVAL)
if (r < 0 && (errno == EINVAL || ERRNO_IS_NOT_SUPPORTED(errno)))
r = flock(f->fd, LOCK_EX|LOCK_NB);
if (r >= 0)