lib/util/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 #include "lib/util/pidfile.h"
  25
  26 /**
  27  * @file
  28  * @brief Pid file handling
  29  */
  30
  31 /**
  32  * return the pid in a pidfile. return 0 if the process (or pidfile)
  33  * does not exist
  34  */
  35 pid_t pidfile_pid(const char *piddir, const char *name)
  36 {
  37         size_t len = strlen(piddir) + strlen(name) + 6;
  38         char pidFile[len];
  39         int fd;
  40         char pidstr[20];
  41         pid_t ret = -1;
  42
  43         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
  44
  45         fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  46
  47         if (fd == -1) {
  48                 return 0;
  49         }
  50
  51         ZERO_STRUCT(pidstr);
  52
  53         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  54                 goto noproc;
  55         }
  56
  57         ret = (pid_t)atoi(pidstr);
  58         if (ret <= 0) {
  59                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
  60                         pidFile));
  61                 goto noproc;
  62         }
  63
  64         if (!process_exists_by_pid(ret)) {
  65                 DEBUG(10, ("Process with PID=%d does not exist.\n", (int)ret));
  66                 goto noproc;
  67         }
  68
  69         if (fcntl_lock(fd,F_SETLK,0,1,F_RDLCK)) {
  70                 /* we could get the lock - it can't be a Samba process */
  71                 DEBUG(10, ("Process with PID=%d is not a Samba process.\n",
  72                         (int)ret));
  73                 goto noproc;
  74         }
  75
  76         close(fd);
  77         DEBUG(10, ("Process with PID=%d is running.\n", (int)ret));
  78         return ret;
  79
  80  noproc:
  81         close(fd);
  82         DEBUG(10, ("Deleting %s, since %d is not a Samba process.\n", pidFile,
  83                 (int)ret));
  84         unlink(pidFile);
  85         return 0;
  86 }
  87
  88 /**
  89  * create a pid file in the pid directory. open it and leave it locked
  90  */
  91 void pidfile_create(const char *piddir, const char *name)
  92 {
  93         size_t len = strlen(piddir) + strlen(name) + 6;
  94         char pidFile[len];
  95         int     fd;
  96         char    buf[20];
  97         pid_t pid;
  98
  99         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
 100
 101         pid = pidfile_pid(piddir, name);
 102         if (pid != 0) {
 103                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
 104                          name, pidFile, (int)pid));
 105                 exit(1);
 106         }
 107
 108         fd = open(pidFile, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL, 0644);
 109         if (fd == -1) {
 110                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile,
 111                          strerror(errno)));
 112                 exit(1);
 113         }
 114
 115         smb_set_close_on_exec(fd);
 116
 117         if (fcntl_lock(fd,F_SETLK,0,1,F_WRLCK)==false) {
 118                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 119               name, pidFile, strerror(errno)));
 120                 exit(1);
 121         }
 122
 123         memset(buf, 0, sizeof(buf));
 124         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int) getpid());
 125         if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) {
 126                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 127                          pidFile, strerror(errno)));
 128                 exit(1);
 129         }
 130
 131         /* Leave pid file open & locked for the duration... */
 132 }
 133
 134 void pidfile_unlink(const char *piddir, const char *name)
 135 {
 136         int ret;
 137         char *pidFile = NULL;
 138
 139         if (asprintf(&pidFile, "%s/%s.pid", piddir, name) < 0) {
 140                 DEBUG(0,("ERROR: Out of memory\n"));
 141                 exit(1);
 142         }
 143         ret = unlink(pidFile);
 144         if (ret == -1) {
 145                 DEBUG(0,("Failed to delete pidfile %s. Error was %s\n",
 146                         pidFile, strerror(errno)));
 147         }
 148 }