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bdc049dfce
Signed-off-by: Martin Schwenke <martin@meltin.net> Reviewed-by: Amitay Isaacs <amitay@gmail.com> Autobuild-User(master): Amitay Isaacs <amitay@samba.org> Autobuild-Date(master): Tue Nov 29 11:22:40 CET 2016 on sn-devel-144
113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
/*
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CTDB mutex fcntl lock file helper
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Copyright (C) Martin Schwenke 2015
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "replace.h"
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#include "system/filesys.h"
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#include "system/network.h"
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#include "lib/util/sys_rw.h"
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/* protocol.h is just needed for ctdb_sock_addr, which is used in system.h */
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#include "protocol/protocol.h"
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#include "common/system.h"
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static char *progname = NULL;
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static char fcntl_lock(const char *file, int *outfd)
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{
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int fd;
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struct flock lock;
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fd = open(file, O_RDWR|O_CREAT, 0600);
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if (fd == -1) {
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fprintf(stderr, "%s: Unable to open %s - (%s)\n",
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progname, file, strerror(errno));
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return '3';
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}
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lock.l_type = F_WRLCK;
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lock.l_whence = SEEK_SET;
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lock.l_start = 0;
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lock.l_len = 1;
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lock.l_pid = 0;
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if (fcntl(fd, F_SETLK, &lock) != 0) {
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int saved_errno = errno;
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close(fd);
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fd = -1;
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if (saved_errno == EACCES ||
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saved_errno == EAGAIN) {
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/* Lock contention, fail silently */
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return '1';
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}
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/* Log an error for any other failure */
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fprintf(stderr,
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"%s: Failed to get lock on '%s' - (%s)\n",
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progname, file, strerror(saved_errno));
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return '3';
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}
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*outfd = fd;
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return '0';
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}
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int main(int argc, char *argv[])
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{
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char result;
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int ppid;
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const char *file = NULL;
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int fd = -1;
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progname = argv[0];
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if (argc != 2) {
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fprintf(stderr, "Usage: %s <file>\n", progname);
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exit(1);
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}
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ppid = getppid();
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if (ppid == 1) {
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/* The original parent is gone and the process has
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* been reparented to init. This can happen if the
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* helper is started just as the parent is killed
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* during shutdown. The error message doesn't need to
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* be stellar, since there won't be anything around to
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* capture and log it...
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*/
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fprintf(stderr, "%s: PPID == 1\n", progname);
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exit(1);
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}
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file = argv[1];
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result = fcntl_lock(file, &fd);
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sys_write(STDOUT_FILENO, &result, 1);
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ctdb_wait_for_process_to_exit(ppid);
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if (fd != -1) {
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close(fd);
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}
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return 0;
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}
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