source/lib/pidfile.c

   1 /* this code is broken - there is a race condition with the unlink (tridge) */
   2
   3 /*
   4    Unix SMB/CIFS implementation.
   5    pidfile handling
   6    Copyright (C) Andrew Tridgell 1998
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24
  25 #ifndef O_NONBLOCK
  26 #define O_NONBLOCK
  27 #endif
  28
  29 /* return the pid in a pidfile. return 0 if the process (or pidfile)
  30    does not exist */
  31 pid_t pidfile_pid(const char *name)
  32 {
  33         int fd;
  34         char pidstr[20];
  35         pid_t pid;
  36         unsigned int ret;
  37         pstring pidFile;
  38
  39         slprintf(pidFile, sizeof(pidFile)-1, "%s/%s.pid", lp_piddir(), name);
  40
  41         fd = sys_open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  42         if (fd == -1) {
  43                 return 0;
  44         }
  45
  46         ZERO_ARRAY(pidstr);
  47
  48         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  49                 goto noproc;
  50         }
  51
  52         ret = atoi(pidstr);
  53
  54         if (ret == 0) {
  55                 /* Obviously we had some garbage in the pidfile... */
  56                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
  57                           pidFile));
  58                 goto noproc;
  59         }
  60
  61         pid = (pid_t)ret;
  62         if (!process_exists_by_pid(pid)) {
  63                 goto noproc;
  64         }
  65
  66         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_RDLCK)) {
  67                 /* we could get the lock - it can't be a Samba process */
  68                 goto noproc;
  69         }
  70
  71         close(fd);
  72         return (pid_t)ret;
  73
  74  noproc:
  75         close(fd);
  76         unlink(pidFile);
  77         return 0;
  78 }
  79
  80 /* create a pid file in the pid directory. open it and leave it locked */
  81 void pidfile_create(const char *name)
  82 {
  83         int     fd;
  84         char    buf[20];
  85         pstring pidFile;
  86         pid_t pid;
  87
  88         slprintf(pidFile, sizeof(pidFile)-1, "%s/%s.pid", lp_piddir(), name);
  89
  90         pid = pidfile_pid(name);
  91         if (pid != 0) {
  92                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
  93                          name, pidFile, (int)pid));
  94                 exit(1);
  95         }
  96
  97         fd = sys_open(pidFile, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL, 0644);
  98         if (fd == -1) {
  99                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile,
 100                          strerror(errno)));
 101                 exit(1);
 102         }
 103
 104         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_WRLCK)==False) {
 105                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 106               name, pidFile, strerror(errno)));
 107                 exit(1);
 108         }
 109
 110         memset(buf, 0, sizeof(buf));
 111         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int) sys_getpid());
 112         if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) {
 113                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 114                          pidFile, strerror(errno)));
 115                 exit(1);
 116         }
 117         /* Leave pid file open & locked for the duration... */
 118 }