diff options
Diffstat (limited to 'nis/lckcache.c')
| -rw-r--r-- | nis/lckcache.c | 181 |
1 files changed, 0 insertions, 181 deletions
diff --git a/nis/lckcache.c b/nis/lckcache.c deleted file mode 100644 index f8c0a97..0000000 --- a/nis/lckcache.c +++ /dev/null @@ -1,181 +0,0 @@ -/* Handle locking of NIS+ cache file. - Copyright (C) 1996, 1997 Free Software Foundation, Inc. - This file is part of the GNU C Library and based on shadow/lckfile.c. - - 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. - - 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. - - 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. */ - -#include <fcntl.h> -#include <bits/libc-lock.h> -#include <shadow.h> -#include <signal.h> -#include <string.h> -#include <unistd.h> -#include <sys/file.h> -#include <rpcsvc/nis.h> -#include <rpcsvc/nislib.h> -#include <rpcsvc/nis_cache.h> - -/* How long to wait for getting the lock before returning with an - error. */ -#define TIMEOUT 5 /* sec */ - - -/* File descriptor for lock file. */ -static int lock_fd = -1; - -/* Prevent problems in multithreaded program by using mutex. */ -__libc_lock_define_initialized (static, lock) - - -/* Prototypes for local functions. */ -static void noop_handler __P ((int __sig)); - - -/* We cannot simply return in error cases. We have to close the file - and perhaps restore the signal handler. */ -#define RETURN_CLOSE_FD(code) \ - do { \ - if ((code) < 0 && lock_fd >= 0) \ - { \ - close (lock_fd); \ - lock_fd = -1; \ - } \ - __libc_lock_unlock (lock); \ - return (code); \ - } while (0) - -#define RETURN_RESTORE_HANDLER(code) \ - do { \ - /* Restore old action handler for alarm. We don't need to know \ - about the current one. */ \ - sigaction (SIGALRM, &saved_act, NULL); \ - RETURN_CLOSE_FD (code); \ - } while (0) - -#define RETURN_CLEAR_ALARM(code) \ - do { \ - /* 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); \ - RETURN_RESTORE_HANDLER (code); \ - } while (0) - - -int -__nis_lock_cache (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; - - /* Prevent problems caused by multiple threads. */ - __libc_lock_lock (lock); - - lock_fd = open (CACHELOCK, O_RDONLY|O_CREAT, 0666); - if (lock_fd == -1) - /* Cannot create lock file. */ - RETURN_CLOSE_FD (-1); - - /* Make sure file gets correctly closed when process finished. */ - flags = fcntl (lock_fd, F_GETFD, 0); - if (flags == -1) - /* Cannot get file flags. */ - RETURN_CLOSE_FD (-1); - flags |= FD_CLOEXEC; /* Close on exit. */ - if (fcntl (lock_fd, F_SETFD, flags) < 0) - /* Cannot set new flags. */ - RETURN_CLOSE_FD (-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. */ - RETURN_CLOSE_FD (-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) - RETURN_RESTORE_HANDLER (-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_RDLCK; - fl.l_whence = SEEK_SET; - result = fcntl (lock_fd, F_SETLKW, &fl); - - RETURN_CLEAR_ALARM (result); -} - - -int -__nis_unlock_cache () -{ - int result; - - if (lock_fd == -1) - /* There is no lock set. */ - result = -1; - else - { - /* Prevent problems caused by multiple threads. */ - __libc_lock_lock (lock); - - result = close (lock_fd); - - /* Mark descriptor as unused. */ - lock_fd = -1; - - /* Clear mutex. */ - __libc_lock_unlock (lock); - } - - return result; -} - - -static void -noop_handler (sig) - int sig; -{ - /* We simply return which makes the `fcntl' call return with an error. */ -} |