[PATCH v4 08/32] lock_file(): always add lock_file object to lock_file_list
From: Michael Haggerty <hidden>
Date: 2016-06-15 23:02:27
Subsystem:
the rest · Maintainer:
Linus Torvalds
It used to be that if locking failed, lock_file() usually did not register the lock_file object in lock_file_list but sometimes it did. This confusion was compounded if lock_file() was called via hold_lock_file_for_append(), which has its own failure modes. The ambiguity didn't have any ill effects, because lock_file objects cannot be removed from the lock_file_list anyway. But it is unnecessary to leave this behavior inconsistent. So change lock_file() to *always* ensure that the lock_file object is registered in lock_file_list regardless of whether an error occurs. Signed-off-by: Michael Haggerty <redacted> --- lockfile.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/lockfile.c b/lockfile.c
index 983c3ec..00c972c 100644
--- a/lockfile.c
+++ b/lockfile.c@@ -129,6 +129,22 @@ static int lock_file(struct lock_file *lk, const char *path, int flags) */ static const size_t max_path_len = sizeof(lk->filename) - 5; + if (!lock_file_list) { + /* One-time initialization */ + sigchain_push_common(remove_lock_file_on_signal); + atexit(remove_lock_file); + } + + if (!lk->on_list) { + /* Initialize *lk and add it to lock_file_list: */ + lk->fd = -1; + lk->owner = 0; + lk->on_list = 1; + lk->filename[0] = 0; + lk->next = lock_file_list; + lock_file_list = lk; + } + if (strlen(path) >= max_path_len) { errno = ENAMETOOLONG; return -1;
@@ -139,16 +155,7 @@ static int lock_file(struct lock_file *lk, const char *path, int flags) strcat(lk->filename, ".lock"); lk->fd = open(lk->filename, O_RDWR | O_CREAT | O_EXCL, 0666); if (0 <= lk->fd) { - if (!lock_file_list) { - sigchain_push_common(remove_lock_file_on_signal); - atexit(remove_lock_file); - } lk->owner = getpid(); - if (!lk->on_list) { - lk->next = lock_file_list; - lock_file_list = lk; - lk->on_list = 1; - } if (adjust_shared_perm(lk->filename)) { int save_errno = errno; error("cannot fix permission bits on %s",
--
2.1.0