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core/dynamic-user: use _cleanup_ in dynamic user locking

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This makes the code a bit easier to read.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2017-10-20 12:41:04 +02:00
parent dd202fa492
commit 362d90b7f2
1 changed files with 43 additions and 35 deletions
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78
src/core/dynamic-user.c
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@ -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) {