diff options
Diffstat (limited to 'libc/pwd_grp/lckpwdf.c')
| -rw-r--r-- | libc/pwd_grp/lckpwdf.c | 227 |
1 files changed, 114 insertions, 113 deletions
diff --git a/libc/pwd_grp/lckpwdf.c b/libc/pwd_grp/lckpwdf.c index 6b20bd7e4..e09b611e2 100644 --- a/libc/pwd_grp/lckpwdf.c +++ b/libc/pwd_grp/lckpwdf.c @@ -1,3 +1,4 @@ +/* vi: set sw=4 ts=4: */ /* Handle locking of password file. Copyright (C) 1996, 1998 Free Software Foundation, Inc. This file is part of the GNU C Library. @@ -49,132 +50,132 @@ static void noop_handler __P ((int __sig)); int lckpwdf (void) { - int flags; - sigset_t saved_set; /* Saved set of caught signals. */ - struct sigaction saved_act; /* Saved signal action. */ - sigset_t new_set; /* New set of caught signals. */ - struct sigaction new_act; /* New signal action. */ - struct flock fl; /* Information struct for locking. */ - int result; - - if (lock_fd != -1) - /* Still locked by own process. */ - return -1; - - LOCK; - - lock_fd = open (_PATH_PASSWD, O_WRONLY); - if (lock_fd == -1) { - /* Cannot create lock file. */ - UNLOCK; - return -1; - } - - /* Make sure file gets correctly closed when process finished. */ - flags = fcntl (lock_fd, F_GETFD, 0); - if (flags == -1) { - /* Cannot get file flags. */ - close(lock_fd); - lock_fd = -1; - UNLOCK; - return -1; - } - flags |= FD_CLOEXEC; /* Close on exit. */ - if (fcntl (lock_fd, F_SETFD, flags) < 0) { - /* Cannot set new flags. */ - close(lock_fd); - lock_fd = -1; - UNLOCK; - return -1; - } - - /* Now we have to get exclusive write access. Since multiple - process could try this we won't stop when it first fails. - Instead we set a timeout for the system call. Once the timer - expires it is likely that there are some problems which cannot be - resolved by waiting. - - It is important that we don't change the signal state. We must - restore the old signal behaviour. */ - memset (&new_act, '\0', sizeof (struct sigaction)); - new_act.sa_handler = noop_handler; - sigfillset (&new_act.sa_mask); - new_act.sa_flags = 0ul; - - /* Install new action handler for alarm and save old. */ - if (sigaction (SIGALRM, &new_act, &saved_act) < 0) { - /* Cannot install signal handler. */ - close(lock_fd); - lock_fd = -1; - UNLOCK; - return -1; - } - - /* Now make sure the alarm signal is not blocked. */ - sigemptyset (&new_set); - sigaddset (&new_set, SIGALRM); - if (sigprocmask (SIG_UNBLOCK, &new_set, &saved_set) < 0) { - sigaction (SIGALRM, &saved_act, NULL); - close(lock_fd); - lock_fd = -1; - UNLOCK; - return -1; - } - - /* Start timer. If we cannot get the lock in the specified time we - get a signal. */ - alarm (TIMEOUT); + int flags; + sigset_t saved_set; /* Saved set of caught signals. */ + struct sigaction saved_act; /* Saved signal action. */ + sigset_t new_set; /* New set of caught signals. */ + struct sigaction new_act; /* New signal action. */ + struct flock fl; /* Information struct for locking. */ + int result; + + if (lock_fd != -1) + /* Still locked by own process. */ + return -1; - /* Try to get the lock. */ - memset (&fl, '\0', sizeof (struct flock)); - fl.l_type = F_WRLCK; - fl.l_whence = SEEK_SET; - result = fcntl (lock_fd, F_SETLKW, &fl); - - /* Clear alarm. */ - alarm (0); + LOCK; - /* Restore old set of handled signals. We don't need to know - about the current one.*/ - sigprocmask (SIG_SETMASK, &saved_set, NULL); + lock_fd = open (_PATH_PASSWD, O_WRONLY); + if (lock_fd == -1) { + /* Cannot create lock file. */ + UNLOCK; + return -1; + } + + /* Make sure file gets correctly closed when process finished. */ + flags = fcntl (lock_fd, F_GETFD, 0); + if (flags == -1) { + /* Cannot get file flags. */ + close(lock_fd); + lock_fd = -1; + UNLOCK; + return -1; + } + flags |= FD_CLOEXEC; /* Close on exit. */ + if (fcntl (lock_fd, F_SETFD, flags) < 0) { + /* Cannot set new flags. */ + close(lock_fd); + lock_fd = -1; + UNLOCK; + return -1; + } + + /* Now we have to get exclusive write access. Since multiple + process could try this we won't stop when it first fails. + Instead we set a timeout for the system call. Once the timer + expires it is likely that there are some problems which cannot be + resolved by waiting. + + It is important that we don't change the signal state. We must + restore the old signal behaviour. */ + memset (&new_act, '\0', sizeof (struct sigaction)); + new_act.sa_handler = noop_handler; + sigfillset (&new_act.sa_mask); + new_act.sa_flags = 0ul; + + /* Install new action handler for alarm and save old. */ + if (sigaction (SIGALRM, &new_act, &saved_act) < 0) { + /* Cannot install signal handler. */ + close(lock_fd); + lock_fd = -1; + UNLOCK; + return -1; + } + + /* Now make sure the alarm signal is not blocked. */ + sigemptyset (&new_set); + sigaddset (&new_set, SIGALRM); + if (sigprocmask (SIG_UNBLOCK, &new_set, &saved_set) < 0) { + sigaction (SIGALRM, &saved_act, NULL); + close(lock_fd); + lock_fd = -1; + UNLOCK; + return -1; + } + + /* Start timer. If we cannot get the lock in the specified time we + get a signal. */ + alarm (TIMEOUT); + + /* Try to get the lock. */ + memset (&fl, '\0', sizeof (struct flock)); + fl.l_type = F_WRLCK; + fl.l_whence = SEEK_SET; + result = fcntl (lock_fd, F_SETLKW, &fl); + + /* Clear alarm. */ + alarm (0); + + /* Restore old set of handled signals. We don't need to know + about the current one.*/ + sigprocmask (SIG_SETMASK, &saved_set, NULL); + + /* Restore old action handler for alarm. We don't need to know + about the current one. */ + sigaction (SIGALRM, &saved_act, NULL); - /* Restore old action handler for alarm. We don't need to know - about the current one. */ - sigaction (SIGALRM, &saved_act, NULL); + if (result < 0) { + close(lock_fd); + lock_fd = -1; + UNLOCK; + return -1; + } - if (result < 0) { - close(lock_fd); - lock_fd = -1; UNLOCK; - return -1; - } - - UNLOCK; - return 0; + return 0; } int ulckpwdf (void) { - int result; - - if (lock_fd == -1) { - /* There is no lock set. */ - result = -1; - } - else { - LOCK; - result = close (lock_fd); - /* Mark descriptor as unused. */ - lock_fd = -1; - UNLOCK; - } - - return result; + int result; + + if (lock_fd == -1) { + /* There is no lock set. */ + result = -1; + } + else { + LOCK; + result = close (lock_fd); + /* Mark descriptor as unused. */ + lock_fd = -1; + UNLOCK; + } + + return result; } static void noop_handler (int sig) { - /* We simply return which makes the `fcntl' call return with an error. */ + /* We simply return which makes the `fcntl' call return with an error. */ } |