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