source4/smbd/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 3 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, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "system/filesys.h"
  24
  25 /**
  26  * @file
  27  * @brief Pid file handling
  28  */
  29
  30 /**
  31  * return the pid in a pidfile. return 0 if the process (or pidfile)
  32  * does not exist
  33  */
  34 pid_t pidfile_pid(const char *piddir, const char *name)
  35 {
  36         int fd;
  37         char pidstr[20];
  38         pid_t ret;
  39         char *pidFile;
  40
  41         asprintf(&pidFile, "%s/%s.pid", piddir, name);
  42
  43         fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  44
  45         if (fd == -1) {
  46                 SAFE_FREE(pidFile);
  47                 return 0;
  48         }
  49
  50         ZERO_STRUCT(pidstr);
  51
  52         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  53                 goto noproc;
  54         }
  55
  56         ret = (pid_t)atoi(pidstr);
  57
  58         if (!process_exists_by_pid(ret)) {
  59                 goto noproc;
  60         }
  61
  62         if (fcntl_lock(fd,F_SETLK,0,1,F_RDLCK)) {
  63                 /* we could get the lock - it can't be a Samba process */
  64                 goto noproc;
  65         }
  66
  67         close(fd);
  68         SAFE_FREE(pidFile);
  69         return ret;
  70
  71  noproc:
  72         close(fd);
  73         unlink(pidFile);
  74         SAFE_FREE(pidFile);
  75         return 0;
  76 }
  77
  78 /**
  79  * create a pid file in the pid directory. open it and leave it locked
  80  */
  81 void pidfile_create(const char *piddir, const char *name)
  82 {
  83         int     fd;
  84         char    buf[20];
  85         char *pidFile;
  86         pid_t pid;
  87
  88         asprintf(&pidFile, "%s/%s.pid", piddir, name);
  89
  90         pid = pidfile_pid(piddir, 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 = 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,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) 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
 118         /* Leave pid file open & locked for the duration... */
 119         SAFE_FREE(pidFile);
 120 }