/* $Id$ * $URL$ * * PID file handling * * Copyright (C) 1999, 2000 Michael Reinelt <michael@reinelt.co.at> * * This file is part of LCD4Linux. * * LCD4Linux 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 2, or (at your option) * any later version. * * LCD4Linux 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., 675 Mass Ave, Cambridge, MA 02139, USA. * */ /* * exported functions: * * int pid_init (const char *pidfile) * returns 0 if PID file could be successfully created * returns PID of an already running process * returns -1 in case of an error * int pid_exit (const char *pidfile) * returns 0 if PID file could be successfully deleted * otherwise returns error from unlink() call * */ #include "config.h" #include <stdlib.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <signal.h> #include <sys/types.h> #include <sys/stat.h> #include "debug.h" #include "pid.h" #include "qprintf.h" #ifdef WITH_DMALLOC #include <dmalloc.h> #endif int pid_init(const char *pidfile) { char tmpfile[256]; char buffer[16]; int fd, len, pid; qprintf(tmpfile, sizeof(tmpfile), "%s.%s", pidfile, "XXXXXX"); if ((fd = mkstemp(tmpfile)) == -1) { error("mkstemp(%s) failed: %s", tmpfile, strerror(errno)); return -1; } if (fchmod(fd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) == -1) { error("fchmod(%s) failed: %s", tmpfile, strerror(errno)); close(fd); unlink(tmpfile); return -1; } qprintf(buffer, sizeof(buffer), "%d\n", (int) getpid()); len = strlen(buffer); if (write(fd, buffer, len) != len) { error("write(%s) failed: %s", tmpfile, strerror(errno)); close(fd); unlink(tmpfile); return -1; } close(fd); while (link(tmpfile, pidfile) == -1) { if (errno != EEXIST) { error("link(%s, %s) failed: %s", tmpfile, pidfile, strerror(errno)); unlink(tmpfile); return -1; } if ((fd = open(pidfile, O_RDONLY)) == -1) { if (errno == ENOENT) continue; /* pidfile disappared */ error("open(%s) failed: %s", pidfile, strerror(errno)); unlink(tmpfile); return -1; } len = read(fd, buffer, sizeof(buffer) - 1); if (len < 0) { error("read(%s) failed: %s", pidfile, strerror(errno)); unlink(tmpfile); return -1; } buffer[len] = '\0'; if (sscanf(buffer, "%d", &pid) != 1 || pid == 0) { error("scan(%s) failed.", pidfile); unlink(tmpfile); return -1; } if (pid == getpid()) { error("%s already locked by us. uh-oh...", pidfile); unlink(tmpfile); return 0; } if ((kill(pid, 0) == -1) && errno == ESRCH) { error("removing stale PID file %s", pidfile); if (unlink(pidfile) == -1 && errno != ENOENT) { error("unlink(%s) failed: %s", pidfile, strerror(errno)); unlink(tmpfile); return pid; } continue; } unlink(tmpfile); return pid; } unlink(tmpfile); return 0; } int pid_exit(const char *pidfile) { return unlink(pidfile); }