source3/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 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 #ifndef O_NONBLOCK
  26 #define O_NONBLOCK
  27 #endif
  28
  29 static char *pidFile_name = NULL;
  30
  31 /* return the pid in a pidfile. return 0 if the process (or pidfile)
  32    does not exist */
  33 pid_t pidfile_pid(const char *name)
  34 {
  35         int fd;
  36         char pidstr[20];
  37         pid_t pid;
  38         unsigned int ret;
  39         char * pidFile;
  40
  41         if (asprintf(&pidFile, "%s/%s.pid", lp_piddir(), name) == -1) {
  42                 return 0;
  43         }
  44
  45         fd = sys_open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  46         if (fd == -1) {
  47                 SAFE_FREE(pidFile);
  48                 return 0;
  49         }
  50
  51         ZERO_ARRAY(pidstr);
  52
  53         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  54                 goto noproc;
  55         }
  56
  57         ret = atoi(pidstr);
  58
  59         if (ret == 0) {
  60                 /* Obviously we had some garbage in the pidfile... */
  61                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
  62                           pidFile));
  63                 goto noproc;
  64         }
  65
  66         pid = (pid_t)ret;
  67         if (!process_exists_by_pid(pid)) {
  68                 goto noproc;
  69         }
  70
  71         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_RDLCK)) {
  72                 /* we could get the lock - it can't be a Samba process */
  73                 goto noproc;
  74         }
  75
  76         SAFE_FREE(pidFile);
  77         close(fd);
  78         return (pid_t)ret;
  79
  80  noproc:
  81         close(fd);
  82         unlink(pidFile);
  83         SAFE_FREE(pidFile);
  84         return 0;
  85 }
  86
  87 /* create a pid file in the pid directory. open it and leave it locked */
  88 void pidfile_create(const char *program_name)
  89 {
  90         int     fd;
  91         char    buf[20];
  92         const char    *short_configfile;
  93         char *name;
  94         pid_t pid;
  95
  96         /* Add a suffix to the program name if this is a process with a
  97          * none default configuration file name. */
  98         if (strcmp( CONFIGFILE, get_dyn_CONFIGFILE()) == 0) {
  99                 name = SMB_STRDUP(program_name);
 100         } else {
 101                 short_configfile = strrchr( get_dyn_CONFIGFILE(), '/');
 102                 if (short_configfile == NULL) {
 103                         /* conf file in current directory */
 104                         short_configfile = get_dyn_CONFIGFILE();
 105                 } else {
 106                         /* full/relative path provided */
 107                         short_configfile++;
 108                 }
 109                 if (asprintf(&name, "%s-%s", program_name,
 110                              short_configfile) == -1) {
 111                         smb_panic("asprintf failed");
 112                 }
 113         }
 114
 115         if (asprintf(&pidFile_name, "%s/%s.pid", lp_piddir(), name) == -1) {
 116                 smb_panic("asprintf failed");
 117         }
 118
 119         pid = pidfile_pid(name);
 120         if (pid != 0) {
 121                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
 122                          name, pidFile_name, (int)pid));
 123                 exit(1);
 124         }
 125
 126         fd = sys_open(pidFile_name, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL,
 127                       0644);
 128         if (fd == -1) {
 129                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile_name,
 130                          strerror(errno)));
 131                 exit(1);
 132         }
 133
 134         if (fcntl_lock(fd,SMB_F_SETLK,0,1,F_WRLCK)==False) {
 135                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 136                          name, pidFile_name, strerror(errno)));
 137                 exit(1);
 138         }
 139
 140         memset(buf, 0, sizeof(buf));
 141         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int) sys_getpid());
 142         if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) {
 143                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 144                          pidFile_name, strerror(errno)));
 145                 exit(1);
 146         }
 147         /* Leave pid file open & locked for the duration... */
 148         SAFE_FREE(name);
 149
 150         /* set the close on exec so that we don't leak the fd */
 151         fcntl(fd, F_SETFD, FD_CLOEXEC);
 152 }
 153
 154 void pidfile_unlink(void)
 155 {
 156         if (pidFile_name == NULL) {
 157                 return;
 158         }
 159         unlink(pidFile_name);
 160         SAFE_FREE(pidFile_name);
 161 }