source/lib/pidfile.c

   1 /* this code is broken - there is a race condition with the unlink (tridge) */
   2
   3 /*
   4    Unix SMB/Netbios implementation.
   5    Version 1.9.
   6    pidfile handling
   7    Copyright (C) Andrew Tridgell 1998
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25
  26
  27 extern int DEBUGLEVEL;
  28
  29 #ifndef O_NONBLOCK
  30 #define O_NONBLOCK
  31 #endif
  32
  33 /* return the pid in a pidfile. return 0 if the process (or pidfile)
  34    does not exist */
  35 pid_t pidfile_pid(char *name)
  36 {
  37         int fd;
  38         char pidstr[20];
  39         unsigned ret;
  40         pstring pidFile;
  41
  42         slprintf(pidFile, sizeof(pidFile)-1, "%s/%s.pid", lp_lockdir(), name);
  43
  44         fd = sys_open(pidFile, O_NONBLOCK | O_RDWR, 0644);
  45         if (fd == -1) {
  46                 return 0;
  47         }
  48
  49         ZERO_ARRAY(pidstr);
  50
  51         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  52                 goto ok;
  53         }
  54
  55         ret = atoi(pidstr);
  56
  57         if (!process_exists((pid_t)ret)) {
  58                 goto ok;
  59         }
  60
  61         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_WRLCK)) {
  62                 /* we could get the lock - it can't be a Samba process */
  63                 goto ok;
  64         }
  65
  66         close(fd);
  67         return (pid_t)ret;
  68
  69  ok:
  70         close(fd);
  71         unlink(pidFile);
  72         return 0;
  73 }
  74
  75 /* create a pid file in the lock directory. open it and leave it locked */
  76 void pidfile_create(char *name)
  77 {
  78         int     fd;
  79         char    buf[20];
  80         pstring pidFile;
  81         pid_t pid;
  82
  83         slprintf(pidFile, sizeof(pidFile)-1, "%s/%s.pid", lp_lockdir(), name);
  84
  85         pid = pidfile_pid(name);
  86         if (pid != 0) {
  87                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
  88                          name, pidFile, (int)pid));
  89                 exit(1);
  90         }
  91
  92         fd = sys_open(pidFile, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL, 0644);
  93         if (fd == -1) {
  94                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile,
  95                          strerror(errno)));
  96                 exit(1);
  97         }
  98
  99         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_WRLCK)==False) {
 100                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 101               name, pidFile, strerror(errno)));
 102                 exit(1);
 103         }
 104
 105         memset(buf, 0, sizeof(buf));
 106         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int) sys_getpid());
 107         if (write(fd, buf, sizeof(buf)) != sizeof(buf)) {
 108                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 109                          pidFile, strerror(errno)));
 110                 exit(1);
 111         }
 112         /* Leave pid file open & locked for the duration... */
 113 }