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         if (asprintf(&pidFile, "%s/%s.pid", piddir, name) < 0) {
  42                 return 0;
  43         }
  44
  45         fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  46
  47         if (fd == -1) {
  48                 SAFE_FREE(pidFile);
  49                 return 0;
  50         }
  51
  52         ZERO_STRUCT(pidstr);
  53
  54         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  55                 goto noproc;
  56         }
  57
  58         ret = (pid_t)atoi(pidstr);
  59
  60         if (!process_exists_by_pid(ret)) {
  61                 goto noproc;
  62         }
  63
  64         if (fcntl_lock(fd,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         SAFE_FREE(pidFile);
  71         return ret;
  72
  73  noproc:
  74         close(fd);
  75         unlink(pidFile);
  76         SAFE_FREE(pidFile);
  77         return 0;
  78 }
  79
  80 /**
  81  * create a pid file in the pid directory. open it and leave it locked
  82  */
  83 void pidfile_create(const char *piddir, const char *name)
  84 {
  85         int     fd;
  86         char    buf[20];
  87         char *pidFile;
  88         pid_t pid;
  89
  90         if (asprintf(&pidFile, "%s/%s.pid", piddir, name) < 0) {
  91                 DEBUG(0,("ERROR: Out of memory\n"));
  92                 exit(1);
  93         }
  94
  95         pid = pidfile_pid(piddir, name);
  96         if (pid != 0) {
  97                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
  98                          name, pidFile, (int)pid));
  99                 exit(1);
 100         }
 101
 102         fd = open(pidFile, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL, 0644);
 103         if (fd == -1) {
 104                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile,
 105                          strerror(errno)));
 106                 exit(1);
 107         }
 108
 109         if (fcntl_lock(fd,F_SETLK,0,1,F_WRLCK)==false) {
 110                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 111               name, pidFile, strerror(errno)));
 112                 exit(1);
 113         }
 114
 115         memset(buf, 0, sizeof(buf));
 116         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int) getpid());
 117         if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) {
 118                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 119                          pidFile, strerror(errno)));
 120                 exit(1);
 121         }
 122
 123         /* Leave pid file open & locked for the duration... */
 124         SAFE_FREE(pidFile);
 125 }