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-rw-r--r--camel/camel-lock.c420
1 files changed, 0 insertions, 420 deletions
diff --git a/camel/camel-lock.c b/camel/camel-lock.c
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--- a/camel/camel-lock.c
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-/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
- *
- * Author: Michael Zucchi <notzed@ximian.com>
- *
- * Copyright (C) 1999 Ximian (www.ximian.com/).
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of version 2 of the GNU General Public
- * License as published by the Free Software Foundation.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
- * USA
- */
-
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <sys/stat.h>
-#include <unistd.h>
-#include <errno.h>
-#ifdef HAVE_ALLOCA_H
-#include <alloca.h>
-#endif
-#include <time.h>
-
-#ifdef USE_DOT
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#endif
-
-#ifdef USE_FCNTL
-#include <unistd.h>
-#include <fcntl.h>
-#endif
-
-#ifdef USE_FLOCK
-#include <sys/file.h>
-#endif
-
-#include "camel-lock.h"
-
-#include <glib.h>
-#include <libgnome/gnome-defs.h>
-#include <libgnome/gnome-i18n.h> /* for _() */
-
-
-#define d(x) /*(printf("%s(%d): ", __FILE__, __LINE__),(x))*/
-
-/**
- * camel_lock_dot:
- * @path:
- * @ex:
- *
- * Create an exclusive lock using .lock semantics.
- * All locks are equivalent to write locks (exclusive).
- *
- * Return value: -1 on error, sets @ex appropriately.
- **/
-int
-camel_lock_dot(const char *path, CamelException *ex)
-{
-#ifdef USE_DOT
- char *locktmp, *lock;
- int retry = 0;
- int fdtmp;
- struct stat st;
-
- /* TODO: Is there a reliable way to refresh the lock, if we're still busy with it?
- Does it matter? We will normally also use fcntl too ... */
-
- /* use alloca, save cleaning up afterwards */
- lock = alloca(strlen(path) + strlen(".lock") + 1);
- sprintf(lock, "%s.lock", path);
- locktmp = alloca(strlen(path) + strlen("XXXXXX") + 1);
-
-#ifndef HAVE_MKSTEMP
- sprintf(locktmp, "%sXXXXXX", path);
- if (mktemp(locktmp) == NULL) {
- /* well, this is really only a programatic error */
- camel_exception_setv(ex, CAMEL_EXCEPTION_SYSTEM, _("Could not create lock file for %s: %s"), path, strerror(errno));
- return -1;
- }
-#endif
-
- while (retry < CAMEL_LOCK_DOT_RETRY) {
-
- d(printf("trying to lock '%s', attempt %d\n", lock, retry));
-
- if (retry > 0)
- sleep(CAMEL_LOCK_DOT_DELAY);
-
-#ifdef HAVE_MKSTEMP
- sprintf(locktmp, "%sXXXXXX", path);
- fdtmp = mkstemp(locktmp);
-#else
- fdtmp = open(locktmp, O_RDWR|O_CREAT|O_EXCL, 0600);
-#endif
- if (fdtmp == -1) {
- camel_exception_setv(ex, CAMEL_EXCEPTION_SYSTEM, _("Could not create lock file for %s: %s"), path, strerror(errno));
- return -1;
- }
- close(fdtmp);
-
- /* apparently return code from link can be unreliable for nfs (see link(2)), so we ignore it */
- link(locktmp, lock);
-
- /* but we check stat instead (again, see link(2)) */
- if (stat(locktmp, &st) == -1) {
- d(printf("Our lock file %s vanished!?\n", locktmp));
-
- /* well that was unexpected, try cleanup/retry */
- unlink(locktmp);
- unlink(lock);
- } else {
- d(printf("tmp lock created, link count is %d\n", st.st_nlink));
-
- unlink(locktmp);
-
- /* if we had 2 links, we have created the .lock, return ok, otherwise we need to keep trying */
- if (st.st_nlink == 2)
- return 0;
- }
-
- /* check for stale lock, kill it */
- if (stat(lock, &st) == 0) {
- time_t now = time(0);
- (printf("There is an existing lock %ld seconds old\n", now-st.st_ctime));
- if (st.st_ctime < now - CAMEL_LOCK_DOT_STALE) {
- d(printf("Removing it now\n"));
- unlink(lock);
- }
- }
-
- retry++;
- }
-
- d(printf("failed to get lock after %d retries\n", retry));
-
- camel_exception_setv(ex, CAMEL_EXCEPTION_SYSTEM, _("Timed out trying to get lock file on %s. Try again later."), path);
- return -1;
-#else /* ! USE_DOT */
- return 0;
-#endif
-}
-
-/**
- * camel_unlock_dot:
- * @path:
- *
- * Attempt to unlock a .lock lock.
- **/
-void
-camel_unlock_dot(const char *path)
-{
-#ifdef USE_DOT
- char *lock;
-
- lock = alloca(strlen(path) + strlen(".lock") + 1);
- sprintf(lock, "%s.lock", path);
- d(printf("unlocking %s\n", lock));
- (void)unlink(lock);
-#endif
-}
-
-/**
- * camel_lock_fcntl:
- * @fd:
- * @type:
- * @ex:
- *
- * Create a lock using fcntl(2).
- *
- * @type is CAMEL_LOCK_WRITE or CAMEL_LOCK_READ,
- * to create exclusive or shared read locks
- *
- * Return value: -1 on error.
- **/
-int
-camel_lock_fcntl(int fd, CamelLockType type, CamelException *ex)
-{
-#ifdef USE_FCNTL
- struct flock lock;
-
- d(printf("fcntl locking %d\n", fd));
-
- memset(&lock, 0, sizeof(lock));
- lock.l_type = type==CAMEL_LOCK_READ?F_RDLCK:F_WRLCK;
- if (fcntl(fd, F_SETLK, &lock) == -1) {
- /* If we get a 'locking not vailable' type error,
- we assume the filesystem doesn't support fcntl() locking */
- /* this is somewhat system-dependent */
- if (errno != EINVAL && errno != ENOLCK) {
- camel_exception_setv(ex, CAMEL_EXCEPTION_SYSTEM, _("Failed to get lock using fcntl(2): %s"),
- strerror(errno));
- return -1;
- } else {
- static int failed = 0;
-
- if (failed == 0)
- fprintf(stderr, "fcntl(2) locking appears not to work on this filesystem");
- failed++;
- }
- }
-#endif
- return 0;
-}
-
-/**
- * camel_unlock_fcntl:
- * @fd:
- *
- * Unlock an fcntl lock.
- **/
-void
-camel_unlock_fcntl(int fd)
-{
-#ifdef USE_FCNTL
- struct flock lock;
-
- d(printf("fcntl unlocking %d\n", fd));
-
- memset(&lock, 0, sizeof(lock));
- lock.l_type = F_UNLCK;
- fcntl(fd, F_SETLK, &lock);
-#endif
-}
-
-/**
- * camel_lock_flock:
- * @fd:
- * @type:
- * @ex:
- *
- * Create a lock using flock(2).
- *
- * @type is CAMEL_LOCK_WRITE or CAMEL_LOCK_READ,
- * to create exclusive or shared read locks
- *
- * Return value: -1 on error.
- **/
-int
-camel_lock_flock(int fd, CamelLockType type, CamelException *ex)
-{
-#ifdef USE_FLOCK
- int op;
-
- d(printf("flock locking %d\n", fd));
-
- if (type == CAMEL_LOCK_READ)
- op = LOCK_SH|LOCK_NB;
- else
- op = LOCK_EX|LOCK_NB;
-
- if (flock(fd, op) == -1) {
- camel_exception_setv(ex, CAMEL_EXCEPTION_SYSTEM, _("Failed to get lock using flock(2): %s"), strerror(errno));
- return -1;
- }
-#endif
- return 0;
-}
-
-/**
- * camel_unlock_flock:
- * @fd:
- *
- * Unlock an flock lock.
- **/
-void
-camel_unlock_flock(int fd)
-{
-#ifdef USE_FLOCK
- d(printf("flock unlocking %d\n", fd));
-
- (void)flock(fd, LOCK_UN);
-#endif
-}
-
-/**
- * camel_lock_folder:
- * @path: Path to the file to lock (used for .locking only).
- * @fd: Open file descriptor of the right type to lock.
- * @type: Type of lock, CAMEL_LOCK_READ or CAMEL_LOCK_WRITE.
- * @ex:
- *
- * Attempt to lock a folder, multiple attempts will be made using all
- * locking strategies available.
- *
- * Return value: -1 on error, @ex will describe the locking system that failed.
- **/
-int
-camel_lock_folder(const char *path, int fd, CamelLockType type, CamelException *ex)
-{
- int retry = 0;
-
- while (retry < CAMEL_LOCK_RETRY) {
- if (retry > 0)
- sleep(CAMEL_LOCK_DELAY);
-
- camel_exception_clear(ex);
-
- if (camel_lock_fcntl(fd, type, ex) == 0) {
- if (camel_lock_flock(fd, type, ex) == 0) {
- if (camel_lock_dot(path, ex) == 0)
- return 0;
- camel_unlock_flock(fd);
- }
- camel_unlock_fcntl(fd);
- }
- retry++;
- }
-
- return -1;
-}
-
-/**
- * camel_unlock_folder:
- * @path: Filename of folder.
- * @fd: Open descrptor on which locks were placed.
- *
- * Free a lock on a folder.
- **/
-void
-camel_unlock_folder(const char *path, int fd)
-{
- camel_unlock_dot(path);
- camel_unlock_flock(fd);
- camel_unlock_fcntl(fd);
-}
-
-#if 0
-int main(int argc, char **argv)
-{
- CamelException *ex;
- int fd1, fd2;
-
- ex = camel_exception_new();
-
-#if 0
- if (camel_lock_dot("mylock", ex) == 0) {
- if (camel_lock_dot("mylock", ex) == 0) {
- printf("Got lock twice?\n");
- } else {
- printf("failed to get lock 2: %s\n", camel_exception_get_description(ex));
- }
- camel_unlock_dot("mylock");
- } else {
- printf("failed to get lock 1: %s\n", camel_exception_get_description(ex));
- }
-
- camel_exception_clear(ex);
-#endif
-
- fd1 = open("mylock", O_RDWR);
- fd2 = open("mylock", O_RDWR);
-
- if (camel_lock_fcntl(fd1, CAMEL_LOCK_WRITE, ex) == 0) {
- printf("got fcntl write lock once\n");
- sleep(5);
- if (camel_lock_fcntl(fd2, CAMEL_LOCK_WRITE, ex) == 0) {
- printf("got fcntl write lock twice!\n");
- } else {
- printf("failed to get write lock: %s\n", camel_exception_get_description(ex));
- }
-
- camel_exception_clear(ex);
-
- if (camel_lock_fcntl(fd2, CAMEL_LOCK_READ, ex) == 0) {
- printf("got fcntl read lock as well?\n");
- camel_unlock_fcntl(fd2);
- } else {
- printf("failed to get read lock: %s\n", camel_exception_get_description(ex));
- }
-
- camel_exception_clear(ex);
- camel_unlock_fcntl(fd1);
- } else {
- printf("failed to get write lock at all: %s\n", camel_exception_get_description(ex));
- }
-
- if (camel_lock_fcntl(fd1, CAMEL_LOCK_READ, ex) == 0) {
- printf("got fcntl read lock once\n");
- sleep(5);
- if (camel_lock_fcntl(fd2, CAMEL_LOCK_WRITE, ex) == 0) {
- printf("got fcntl write lock too?!\n");
- } else {
- printf("failed to get write lock: %s\n", camel_exception_get_description(ex));
- }
-
- camel_exception_clear(ex);
-
- if (camel_lock_fcntl(fd2, CAMEL_LOCK_READ, ex) == 0) {
- printf("got fcntl read lock twice\n");
- camel_unlock_fcntl(fd2);
- } else {
- printf("failed to get read lock: %s\n", camel_exception_get_description(ex));
- }
-
- camel_exception_clear(ex);
- camel_unlock_fcntl(fd1);
- }
-
- close(fd1);
- close(fd2);
-
- return 0;
-}
-#endif