Diffstat (limited to 'libetpan/src/data-types/maillock.c') (more/less context) (ignore whitespace changes)
| -rw-r--r-- | libetpan/src/data-types/maillock.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/libetpan/src/data-types/maillock.c b/libetpan/src/data-types/maillock.c new file mode 100644 index 0000000..b1741d0 --- a/dev/null +++ b/libetpan/src/data-types/maillock.c @@ -0,0 +1,301 @@ +/* + * libEtPan! -- a mail stuff library + * + * Copyright (C) 2001, 2005 - DINH Viet Hoa + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the libEtPan! project nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + * $Id$ + */ + +#include "maillock.h" + +#include "libetpan-config.h" + +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <unistd.h> +#include <stdio.h> +#include <time.h> +#include <string.h> +#include "config.h" + +#ifdef HAVE_LIBLOCKFILE +#include <lockfile.h> +#endif + +/* ********************************************************************** */ + +/* lock primitives */ + +/* the lock code is modified from the dot lock file code from mail.local.c */ + +/* + SENDMAIL LICENSE + +The following license terms and conditions apply, unless a different +license is obtained from Sendmail, Inc., 6425 Christie Ave, Fourth Floor, +Emeryville, CA 94608, or by electronic mail at license@sendmail.com. + +License Terms: + +Use, Modification and Redistribution (including distribution of any +modified or derived work) in source and binary forms is permitted only if +each of the following conditions is met: + +1. Redistributions qualify as "freeware" or "Open Source Software" under + one of the following terms: + + (a) Redistributions are made at no charge beyond the reasonable cost of + materials and delivery. + + (b) Redistributions are accompanied by a copy of the Source Code or by an + irrevocable offer to provide a copy of the Source Code for up to three + years at the cost of materials and delivery. Such redistributions + must allow further use, modification, and redistribution of the Source + Code under substantially the same terms as this license. For the + purposes of redistribution "Source Code" means the complete compilable + and linkable source code of sendmail including all modifications. + +2. Redistributions of source code must retain the copyright notices as they + appear in each source code file, these license terms, and the + disclaimer/limitation of liability set forth as paragraph 6 below. + +3. Redistributions in binary form must reproduce the Copyright Notice, + these license terms, and the disclaimer/limitation of liability set + forth as paragraph 6 below, in the documentation and/or other materials + provided with the distribution. For the purposes of binary distribution + the "Copyright Notice" refers to the following language: + "Copyright (c) 1998-2002 Sendmail, Inc. All rights reserved." + +4. Neither the name of Sendmail, Inc. nor the University of California nor + the names of their contributors may be used to endorse or promote + products derived from this software without specific prior written + permission. The name "sendmail" is a trademark of Sendmail, Inc. + +5. All redistributions must comply with the conditions imposed by the + University of California on certain embedded code, whose copyright + notice and conditions for redistribution are as follows: + + (a) Copyright (c) 1988, 1993 The Regents of the University of + California. All rights reserved. + + (b) Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions + are met: + + (i) Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + (ii) Redistributions in binary form must reproduce the above + copyright notice, this list of conditions and the following + disclaimer in the documentation and/or other materials provided + with the distribution. + + (iii) Neither the name of the University nor the names of its + contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + +6. Disclaimer/Limitation of Liability: THIS SOFTWARE IS PROVIDED BY + SENDMAIL, INC. AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED + WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN + NO EVENT SHALL SENDMAIL, INC., THE REGENTS OF THE UNIVERSITY OF + CALIFORNIA OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. +*/ + +/* + TODO : lock, prefer fcntl() over flock() + AND use dotlock code above +*/ + +#define LOCKTO_RM 300 /* timeout for stale lockfile removal */ +#define LOCKTO_GLOB 400 /* global timeout for lockfile creation */ + +static int lock_common(const char * filename, int fd, short locktype) +{ + char lockfilename[PATH_MAX]; + struct flock lock; + /* dot lock file */ + int statfailed = 0; + time_t start; + int r; + int res; + + /* dot lock file */ + + if (strlen(filename) + 6 > PATH_MAX) { + res = -1; + goto err; + } + + snprintf(lockfilename, PATH_MAX, "%s.lock", filename); + +#ifdef HAVE_LIBLOCKFILE + return lockfile_create(lockfilename, LOCKTO_GLOB, 0); +#else + + lock.l_start = 0; + lock.l_len = 0; + lock.l_pid = getpid(); + lock.l_type = locktype; + lock.l_whence = SEEK_SET; + + r = fcntl(fd, F_SETLKW, &lock); + if (r < 0) { + /* WARNING POSIX lock could not be applied */ + } + + time(&start); + while (1) { + int fd; + struct stat st; + time_t now; + + /* global timeout */ + time(&now); + if (now > start + LOCKTO_GLOB) { + res = -1; + goto unlock; + } + + fd = open(lockfilename, O_WRONLY|O_EXCL|O_CREAT, 0); + if (fd >= 0) { + /* defeat lock checking programs which test pid */ + write(fd, "0", 2); + close(fd); + break; + } + + /* libEtPan! - adds a delay of 5 seconds between each tries */ + sleep(5); + + if (stat(lockfilename, &st) < 0) { + if (statfailed++ > 5) { + res = -1; + goto unlock; + } + continue; + } + statfailed = 0; + time(&now); + + if (now < st.st_ctime + LOCKTO_RM) + continue; + + /* try to remove stale lockfile */ + if (unlink(lockfilename) < 0) { + res = -1; + goto unlock; + } + + /* + libEtPan! - removes this delay of 5 seconds, + maybe it was misplaced ? + */ +#if 0 + sleep(5); +#endif + } + + return 0; + + unlock: + lock.l_start = 0; + lock.l_len = 0; + lock.l_pid = getpid(); + lock.l_type = F_UNLCK; + lock.l_whence = SEEK_SET; + + r = fcntl(fd, F_SETLK, &lock); + if (r < 0) { + /* WARNING POSIX lock could not be applied */ + } +#endif + err: + return res; +} + +static int unlock_common(const char * filename, int fd) +{ + char lockfilename[PATH_MAX]; + struct flock lock; + int r; + + if (strlen(filename) + 6 > PATH_MAX) + return -1; + + snprintf(lockfilename, PATH_MAX, "%s.lock", filename); + +#ifdef HAVE_LIBLOCKFILE + return lockfile_remove(lockfilename); +#else + + unlink(lockfilename); + + lock.l_start = 0; + lock.l_len = 0; + lock.l_pid = getpid(); + lock.l_type = F_UNLCK; + lock.l_whence = SEEK_SET; + + r = fcntl(fd, F_SETLK, &lock); + if (r < 0) { + /* WARNING POSIX lock could not be applied */ + } + + return 0; +#endif +} + +int maillock_read_lock(const char * filename, int fd) +{ + return lock_common(filename, fd, F_RDLCK); +} + +int maillock_read_unlock(const char * filename, int fd) +{ + return unlock_common(filename, fd); +} + +int maillock_write_lock(const char * filename, int fd) +{ + return lock_common(filename, fd, F_WRLCK); +} + +int maillock_write_unlock(const char * filename, int fd) +{ + return unlock_common(filename, fd); +} |