/* CTDB mutex fcntl lock file helper Copyright (C) Martin Schwenke 2015 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. 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, see . */ #include "replace.h" #include "system/filesys.h" #include "system/network.h" /* protocol.h is just needed for ctdb_sock_addr, which is used in system.h */ #include "protocol/protocol.h" #include "common/system.h" static char *progname = NULL; static char fcntl_lock(const char *file) { int fd; struct flock lock; fd = open(file, O_RDWR|O_CREAT, 0600); if (fd == -1) { fprintf(stderr, "%s: Unable to open %s - (%s)\n", progname, file, strerror(errno)); return '3'; } lock.l_type = F_WRLCK; lock.l_whence = SEEK_SET; lock.l_start = 0; lock.l_len = 1; lock.l_pid = 0; if (fcntl(fd, F_SETLK, &lock) != 0) { int saved_errno = errno; close(fd); fd = -1; if (saved_errno == EACCES || saved_errno == EAGAIN) { /* Lock contention, fail silently */ return '1'; } /* Log an error for any other failure */ fprintf(stderr, "%s: Failed to get lock on '%s' - (%s)\n", progname, file, strerror(saved_errno)); return '3'; } return '0'; } int main(int argc, char *argv[]) { char result; int ppid; const char *file = NULL; progname = argv[0]; if (argc != 2) { fprintf(stderr, "Usage: %s \n", progname); exit(1); } ppid = getppid(); file = argv[1]; result = fcntl_lock(file); sys_write(STDOUT_FILENO, &result, 1); ctdb_wait_for_process_to_exit(ppid); return 0; }