diff options
Diffstat (limited to 'pid.c')
| -rw-r--r-- | pid.c | 150 |
1 files changed, 150 insertions, 0 deletions
@@ -0,0 +1,150 @@ +/* $Id: pid.c 840 2007-09-09 12:17:42Z michael $ + * $URL: https://ssl.bulix.org/svn/lcd4linux/trunk/pid.c $ + * + * 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); +} |