diff options
| -rw-r--r-- | libc/pwd_grp/lckpwdf.c | 284 |
1 files changed, 148 insertions, 136 deletions
diff --git a/libc/pwd_grp/lckpwdf.c b/libc/pwd_grp/lckpwdf.c index 69d2c6718..3509f44bd 100644 --- a/libc/pwd_grp/lckpwdf.c +++ b/libc/pwd_grp/lckpwdf.c @@ -1,23 +1,23 @@ /* vi: set sw=4 ts=4: */ /* Handle locking of password file. - Copyright (C) 1996, 1998 Free Software Foundation, Inc. + Copyright (C) 1996,98,2000,02 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Library General Public License as - published by the Free Software Foundation; either version 2 of the - License, or (at your option) any later version. + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Library General Public License for more details. + Lesser General Public License for more details. - You should have received a copy of the GNU Library General Public - License along with the GNU C Library; see the file COPYING.LIB. If not, - write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, - Boston, MA 02111-1307, USA. */ + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ #include <features.h> #include <fcntl.h> @@ -39,6 +39,15 @@ libc_hidden_proto(sigaddset) libc_hidden_proto(sigemptyset) libc_hidden_proto(alarm) +/* How long to wait for getting the lock before returning with an + error. */ +#define TIMEOUT 15 /* sec */ + + +/* File descriptor for lock file. */ +static int lock_fd = -1; + +/* Prevent problems in multithreaded program by using mutex. */ #ifdef __UCLIBC_HAS_THREADS__ # include <pthread.h> static pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER; @@ -46,145 +55,148 @@ static pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER; #define LOCK __pthread_mutex_lock(&mylock) #define UNLOCK __pthread_mutex_unlock(&mylock) -/* How long to wait for getting the lock before returning with an - error. */ -#define TIMEOUT 15 /* sec */ - -/* File descriptor for lock file. */ -static int lock_fd = -1; /* Prototypes for local functions. */ static void noop_handler (int __sig); -int lckpwdf (void) +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); - - /* 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); - - if (result < 0) { - close(lock_fd); - lock_fd = -1; - UNLOCK; - return -1; - } - - UNLOCK; - return 0; + 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; + + /* Prevent problems caused by multiple threads. */ + 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); + + /* 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); + + if (result < 0) { + close(lock_fd); + lock_fd = -1; + UNLOCK; + return -1; + } + + UNLOCK; + return 0; } -int ulckpwdf (void) +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 + { + /* Prevent problems caused by multiple threads. */ + LOCK; + + result = close (lock_fd); + + /* Mark descriptor as unused. */ + lock_fd = -1; + + /* Clear mutex. */ + UNLOCK; + } + + return result; } -static void noop_handler (attribute_unused int sig) +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. */ } |