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         unsigned ret;
  36         pstring pidFile;
  37
  38         slprintf(pidFile, sizeof(pidFile)-1, "%s/%s.pid", lp_piddir(), name);
  39
  40         fd = sys_open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  41         if (fd == -1) {
  42                 return 0;
  43         }
  44
  45         ZERO_ARRAY(pidstr);
  46
  47         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  48                 goto noproc;
  49         }
  50
  51         ret = atoi(pidstr);
  52
  53         if (ret == 0) {
  54                 /* Obviously we had some garbage in the pidfile... */
  55                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
  56                           pidFile));
  57                 goto noproc;
  58         }
  59
  60         if (!process_exists((pid_t)ret)) {
  61                 goto noproc;
  62         }
  63
  64         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_RDLCK)) {
  65                 /* we could get the lock - it can't be a Samba process */
  66                 goto noproc;
  67         }
  68
  69         close(fd);
  70         return (pid_t)ret;
  71
  72  noproc:
  73         close(fd);
  74         unlink(pidFile);
  75         return 0;
  76 }
  77
  78 /* create a pid file in the pid directory. open it and leave it locked */
  79 void pidfile_create(const char *name)
  80 {
  81         int     fd;
  82         char    buf[20];
  83         pstring pidFile;
  84         pid_t pid;
  85
  86         slprintf(pidFile, sizeof(pidFile)-1, "%s/%s.pid", lp_piddir(), name);
  87
  88         pid = pidfile_pid(name);
  89         if (pid != 0) {
  90                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
  91                          name, pidFile, (int)pid));
  92                 exit(1);
  93         }
  94
  95         fd = sys_open(pidFile, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL, 0644);
  96         if (fd == -1) {
  97                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile,
  98                          strerror(errno)));
  99                 exit(1);
 100         }
 101
 102         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_WRLCK)==False) {
 103                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 104               name, pidFile, strerror(errno)));
 105                 exit(1);
 106         }
 107
 108         memset(buf, 0, sizeof(buf));
 109         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int) sys_getpid());
 110         if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) {
 111                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 112                          pidFile, strerror(errno)));
 113                 exit(1);
 114         }
 115         /* Leave pid file open & locked for the duration... */
 116 }