diff options
author | Colin Walters <walters@verbum.org> | 2015-05-04 16:12:46 -0400 |
---|---|---|
committer | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2015-05-05 22:35:29 -0400 |
commit | cd2eb9e942eb380a5419cc978ad494807540d357 (patch) | |
tree | 80bcd2d6237236648e38b45b74e6d866a9c9bd74 /src/shared/util.c | |
parent | 7e7cddb22493642dad826ec42ac00979f40b2d17 (diff) |
lockfile-util.[ch]: Split out from util.[ch]
Continuing the general trend of splitting up util.[ch]. I specifically
want to reuse this code in https://github.com/GNOME/libglnx and
having it split up will make future copy-pasting easier.
Diffstat (limited to 'src/shared/util.c')
-rw-r--r-- | src/shared/util.c | 122 |
1 files changed, 0 insertions, 122 deletions
diff --git a/src/shared/util.c b/src/shared/util.c index d9bd34b3b6..c5c1b0ccbf 100644 --- a/src/shared/util.c +++ b/src/shared/util.c @@ -6065,128 +6065,6 @@ int read_attr_path(const char *p, unsigned *ret) { return read_attr_fd(fd, ret); } -int make_lock_file(const char *p, int operation, LockFile *ret) { - _cleanup_close_ int fd = -1; - _cleanup_free_ char *t = NULL; - int r; - - /* - * 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); - if (!t) - return -ENOMEM; - - for (;;) { - struct flock fl = { - .l_type = (operation & ~LOCK_NB) == LOCK_EX ? F_WRLCK : F_RDLCK, - .l_whence = SEEK_SET, - }; - struct stat st; - - fd = open(p, O_CREAT|O_RDWR|O_NOFOLLOW|O_CLOEXEC|O_NOCTTY, 0600); - if (fd < 0) - return -errno; - - 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) - 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. */ - - r = fstat(fd, &st); - if (r < 0) - return -errno; - if (st.st_nlink > 0) - break; - - fd = safe_close(fd); - } - - ret->path = t; - ret->fd = fd; - ret->operation = operation; - - fd = -1; - t = NULL; - - return r; -} - -int make_lock_file_for(const char *p, int operation, LockFile *ret) { - const char *fn; - char *t; - - assert(p); - assert(ret); - - fn = basename(p); - if (!filename_is_valid(fn)) - return -EINVAL; - - t = newa(char, strlen(p) + 2 + 4 + 1); - stpcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), ".#"), fn), ".lck"); - - return make_lock_file(t, operation, ret); -} - -void release_lock_file(LockFile *f) { - int r; - - if (!f) - return; - - if (f->path) { - - /* If we are the exclusive owner we can safely delete - * the lock file itself. If we are not the exclusive - * owner, we can try becoming it. */ - - if (f->fd >= 0 && - (f->operation & ~LOCK_NB) == LOCK_SH) { - static const struct flock fl = { - .l_type = F_WRLCK, - .l_whence = SEEK_SET, - }; - - r = fcntl(f->fd, F_OFD_SETLK, &fl); - if (r < 0 && errno == EINVAL) - r = flock(f->fd, LOCK_EX|LOCK_NB); - - if (r >= 0) - f->operation = LOCK_EX|LOCK_NB; - } - - if ((f->operation & ~LOCK_NB) == LOCK_EX) - unlink_noerrno(f->path); - - free(f->path); - f->path = NULL; - } - - f->fd = safe_close(f->fd); - f->operation = 0; -} - static size_t nul_length(const uint8_t *p, size_t sz) { size_t n = 0; |