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 *program_name)
  34 {
  35         int fd;
  36         char pidstr[20];
  37         pid_t pid;
  38         unsigned int ret;
  39         char *name;
  40         const char *short_configfile;
  41         char * pidFile;
  42
  43         /* Add a suffix to the program name if this is a process with a
  44          * none default configuration file name. */
  45         if (strcmp( CONFIGFILE, get_dyn_CONFIGFILE()) == 0) {
  46                 name = SMB_STRDUP(program_name);
  47         } else {
  48                 short_configfile = strrchr( get_dyn_CONFIGFILE(), '/');
  49                 if (short_configfile == NULL) {
  50                         /* conf file in current directory */
  51                         short_configfile = get_dyn_CONFIGFILE();
  52                 } else {
  53                         /* full/relative path provided */
  54                         short_configfile++;
  55                 }
  56                 if (asprintf(&name, "%s-%s", program_name,
  57                                 short_configfile) == -1) {
  58                         smb_panic("asprintf failed");
  59                 }
  60         }
  61
  62         if (asprintf(&pidFile, "%s/%s.pid", lp_piddir(), name) == -1) {
  63                 SAFE_FREE(name);
  64                 return 0;
  65         }
  66
  67         SAFE_FREE(name);
  68
  69         fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
  70         if (fd == -1) {
  71                 SAFE_FREE(pidFile);
  72                 return 0;
  73         }
  74
  75         ZERO_ARRAY(pidstr);
  76
  77         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
  78                 goto noproc;
  79         }
  80
  81         ret = atoi(pidstr);
  82
  83         if (ret == 0) {
  84                 /* Obviously we had some garbage in the pidfile... */
  85                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
  86                           pidFile));
  87                 goto noproc;
  88         }
  89
  90         pid = (pid_t)ret;
  91         if (!process_exists_by_pid(pid)) {
  92                 goto noproc;
  93         }
  94
  95         if (fcntl_lock(fd,F_SETLK,0,1,F_RDLCK)) {
  96                 /* we could get the lock - it can't be a Samba process */
  97                 goto noproc;
  98         }
  99
 100         SAFE_FREE(pidFile);
 101         close(fd);
 102         return (pid_t)ret;
 103
 104  noproc:
 105         close(fd);
 106         unlink(pidFile);
 107         SAFE_FREE(pidFile);
 108         return 0;
 109 }
 110
 111 /* create a pid file in the pid directory. open it and leave it locked */
 112 void pidfile_create(const char *program_name)
 113 {
 114         int     fd;
 115         char    buf[20];
 116         const char    *short_configfile;
 117         char *name;
 118         pid_t pid;
 119
 120         /* Add a suffix to the program name if this is a process with a
 121          * none default configuration file name. */
 122         if (strcmp( CONFIGFILE, get_dyn_CONFIGFILE()) == 0) {
 123                 name = SMB_STRDUP(program_name);
 124         } else {
 125                 short_configfile = strrchr( get_dyn_CONFIGFILE(), '/');
 126                 if (short_configfile == NULL) {
 127                         /* conf file in current directory */
 128                         short_configfile = get_dyn_CONFIGFILE();
 129                 } else {
 130                         /* full/relative path provided */
 131                         short_configfile++;
 132                 }
 133                 if (asprintf(&name, "%s-%s", program_name,
 134                              short_configfile) == -1) {
 135                         smb_panic("asprintf failed");
 136                 }
 137         }
 138
 139         if (asprintf(&pidFile_name, "%s/%s.pid", lp_piddir(), name) == -1) {
 140                 smb_panic("asprintf failed");
 141         }
 142
 143         pid = pidfile_pid(name);
 144         if (pid != 0) {
 145                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
 146                          name, pidFile_name, (int)pid));
 147                 exit(1);
 148         }
 149
 150         fd = open(pidFile_name, O_NONBLOCK | O_CREAT | O_WRONLY | O_EXCL,
 151                       0644);
 152         if (fd == -1) {
 153                 DEBUG(0,("ERROR: can't open %s: Error was %s\n", pidFile_name,
 154                          strerror(errno)));
 155                 exit(1);
 156         }
 157
 158         if (fcntl_lock(fd,F_SETLK,0,1,F_WRLCK)==False) {
 159                 DEBUG(0,("ERROR: %s : fcntl lock of file %s failed. Error was %s\n",
 160                          name, pidFile_name, strerror(errno)));
 161                 exit(1);
 162         }
 163
 164         memset(buf, 0, sizeof(buf));
 165         slprintf(buf, sizeof(buf) - 1, "%u\n", (unsigned int)getpid());
 166         if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) {
 167                 DEBUG(0,("ERROR: can't write to file %s: %s\n",
 168                          pidFile_name, strerror(errno)));
 169                 exit(1);
 170         }
 171         /* Leave pid file open & locked for the duration... */
 172         SAFE_FREE(name);
 173
 174         /* set the close on exec so that we don't leak the fd */
 175         fcntl(fd, F_SETFD, FD_CLOEXEC);
 176 }
 177
 178 void pidfile_unlink(void)
 179 {
 180         if (pidFile_name == NULL) {
 181                 return;
 182         }
 183         unlink(pidFile_name);
 184         SAFE_FREE(pidFile_name);
 185 }