From 56fe0eb7f350b8c75fd952ce930a9ef0f00d45fc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Fri, 20 Oct 2017 12:41:04 +0200 Subject: [PATCH] core/dynamic-user: use _cleanup_ in dynamic user locking This makes the code a bit easier to read. (cherry picked from commit 362d90b7f2776f7fabf78274587fd38ceb1b1c12) --- src/core/dynamic-user.c | 78 +++++++++++++++++++++++++++---------------------- 1 file changed, 43 insertions(+), 35 deletions(-) diff --git a/src/core/dynamic-user.c b/src/core/dynamic-user.c index 8f229d27ff..0f4ec15721 100644 --- a/src/core/dynamic-user.c +++ b/src/core/dynamic-user.c @@ -421,9 +421,25 @@ static void unlink_uid_lock(int lock_fd, uid_t uid, const char *name) { (void) make_uid_symlinks(uid, name, false); /* remove direct lookup symlinks */ } +static int lockfp(int fd, int *fd_lock) { + if (lockf(fd, F_LOCK, 0) < 0) + return -errno; + *fd_lock = fd; + return 0; +} + +static void unlockfp(int *fd_lock) { + if (*fd_lock < 0) + return; + lockf(*fd_lock, F_ULOCK, 0); + *fd_lock = -1; +} + static int dynamic_user_realize(DynamicUser *d, char **suggested_dirs, uid_t *ret, bool is_user) { - _cleanup_close_ int etc_passwd_lock_fd = -1, uid_lock_fd = -1; + _cleanup_(unlockfp) int storage_socket0_lock = -1; + _cleanup_close_ int uid_lock_fd = -1; + _cleanup_close_ int etc_passwd_lock_fd = -1; uid_t uid = UID_INVALID; int r; @@ -432,8 +448,9 @@ static int dynamic_user_realize(DynamicUser *d, char **suggested_dirs, uid_t *re /* Acquire a UID for the user name. This will allocate a UID for the user name if the user doesn't exist * yet. If it already exists its existing UID/GID will be reused. */ - if (lockf(d->storage_socket[0], F_LOCK, 0) < 0) - return -errno; + r = lockfp(d->storage_socket[0], &storage_socket0_lock); + if (r < 0) + return r; r = dynamic_user_pop(d, &uid, &uid_lock_fd); if (r < 0) { @@ -441,11 +458,11 @@ static int dynamic_user_realize(DynamicUser *d, char **suggested_dirs, uid_t *re uid_t new_uid; if (r != -EAGAIN) - goto finish; + return r; /* OK, nothing stored yet, let's try to find something useful. While we are working on this release the * lock however, so that nobody else blocks on our NSS lookups. */ - (void) lockf(d->storage_socket[0], F_ULOCK, 0); + unlockfp(&storage_socket0_lock); /* Let's see if a proper, static user or group by this name exists. Try to take the lock on * /etc/passwd, if that fails with EROFS then /etc is read-only. In that case it's fine if we don't @@ -494,9 +511,10 @@ static int dynamic_user_realize(DynamicUser *d, char **suggested_dirs, uid_t *re } /* So, we found a working UID/lock combination. Let's see if we actually still need it. */ - if (lockf(d->storage_socket[0], F_LOCK, 0) < 0) { + r = lockfp(d->storage_socket[0], &storage_socket0_lock); + if (r < 0) { unlink_uid_lock(uid_lock_fd, uid, d->name); - return -errno; + return r; } r = dynamic_user_pop(d, &new_uid, &new_uid_lock_fd); @@ -504,7 +522,7 @@ static int dynamic_user_realize(DynamicUser *d, char **suggested_dirs, uid_t *re if (r != -EAGAIN) { /* OK, something bad happened, let's get rid of the bits we acquired. */ unlink_uid_lock(uid_lock_fd, uid, d->name); - goto finish; + return r; } /* Great! Nothing is stored here, still. Store our newly acquired data. */ @@ -525,17 +543,14 @@ static int dynamic_user_realize(DynamicUser *d, char **suggested_dirs, uid_t *re * dynamically right here, push that in along with the lock fd for it. */ r = dynamic_user_push(d, uid, uid_lock_fd); if (r < 0) - goto finish; + return r; *ret = uid; - r = 0; - -finish: - (void) lockf(d->storage_socket[0], F_ULOCK, 0); - return r; + return 0; } static int dynamic_user_current(DynamicUser *d, uid_t *ret) { + _cleanup_(unlockfp) int storage_socket0_lock = -1; _cleanup_close_ int lock_fd = -1; uid_t uid; int r; @@ -545,23 +560,20 @@ static int dynamic_user_current(DynamicUser *d, uid_t *ret) { /* Get the currently assigned UID for the user, if there's any. This simply pops the data from the storage socket, and pushes it back in right-away. */ - if (lockf(d->storage_socket[0], F_LOCK, 0) < 0) - return -errno; + r = lockfp(d->storage_socket[0], &storage_socket0_lock); + if (r < 0) + return r; r = dynamic_user_pop(d, &uid, &lock_fd); if (r < 0) - goto finish; + return r; r = dynamic_user_push(d, uid, lock_fd); if (r < 0) - goto finish; + return r; *ret = uid; - r = 0; - -finish: - (void) lockf(d->storage_socket[0], F_ULOCK, 0); - return r; + return 0; } static DynamicUser* dynamic_user_ref(DynamicUser *d) { @@ -589,6 +601,7 @@ static DynamicUser* dynamic_user_unref(DynamicUser *d) { } static int dynamic_user_close(DynamicUser *d) { + _cleanup_(unlockfp) int storage_socket0_lock = -1; _cleanup_close_ int lock_fd = -1; uid_t uid; int r; @@ -596,25 +609,20 @@ static int dynamic_user_close(DynamicUser *d) { /* Release the user ID, by releasing the lock on it, and emptying the storage socket. After this the user is * unrealized again, much like it was after it the DynamicUser object was first allocated. */ - if (lockf(d->storage_socket[0], F_LOCK, 0) < 0) - return -errno; + r = lockfp(d->storage_socket[0], &storage_socket0_lock); + if (r < 0) + return r; r = dynamic_user_pop(d, &uid, &lock_fd); - if (r == -EAGAIN) { + if (r == -EAGAIN) /* User wasn't realized yet, nothing to do. */ - r = 0; - goto finish; - } + return 0; if (r < 0) - goto finish; + return r; /* This dynamic user was realized and dynamically allocated. In this case, let's remove the lock file. */ unlink_uid_lock(lock_fd, uid, d->name); - r = 1; - -finish: - (void) lockf(d->storage_socket[0], F_ULOCK, 0); - return r; + return 1; } static DynamicUser* dynamic_user_destroy(DynamicUser *d) {