lib/util/pidfile.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    pidfile handling
   4    Copyright (C) Andrew Tridgell 1998
   5    Copyright (C) Amitay Isaccs  2016
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "replace.h"
  22 #include "system/filesys.h"
  23
  24 #include "lib/util/blocking.h"
  25 #include "lib/util/debug.h"
  26 #include "lib/util/samba_util.h"  /* For process_exists_by_pid() */
  27
  28 #include "lib/util/pidfile.h"
  29
  30 int pidfile_path_create(const char *path, int *outfd)
  31 {
  32         struct flock lck;
  33         char tmp[64] = { 0 };
  34         pid_t pid;
  35         int fd, ret = 0;
  36         int len;
  37         ssize_t nwritten;
  38
  39         pid = getpid();
  40
  41         fd = open(path, O_CREAT|O_WRONLY|O_NONBLOCK, 0644);
  42         if (fd == -1) {
  43                 return errno;
  44         }
  45
  46         if (! set_close_on_exec(fd)) {
  47                 close(fd);
  48                 return EIO;
  49         }
  50
  51         lck = (struct flock) {
  52                 .l_type = F_WRLCK,
  53                 .l_whence = SEEK_SET,
  54         };
  55
  56         do {
  57                 ret = fcntl(fd, F_SETLK, &lck);
  58         } while ((ret == -1) && (errno == EINTR));
  59
  60         if (ret != 0) {
  61                 ret = errno;
  62                 close(fd);
  63                 return ret;
  64         }
  65
  66         /*
  67          * PID file is locked by us so from here on we should unlink
  68          * on failure
  69          */
  70
  71         do {
  72                 ret = ftruncate(fd, 0);
  73         } while ((ret == -1) && (errno == EINTR));
  74
  75         if (ret == -1) {
  76                 ret = EIO;
  77                 goto fail_unlink;
  78         }
  79
  80         len = snprintf(tmp, sizeof(tmp), "%u\n", pid);
  81         if (len < 0) {
  82                 ret = errno;
  83                 goto fail_unlink;
  84         }
  85         if ((size_t)len >= sizeof(tmp)) {
  86                 ret = ENOSPC;
  87                 goto fail_unlink;
  88         }
  89
  90         do {
  91                 nwritten = write(fd, tmp, len);
  92         } while ((nwritten == -1) && (errno == EINTR));
  93
  94         if ((nwritten == -1) || (nwritten != len)) {
  95                 ret = EIO;
  96                 goto fail_unlink;
  97         }
  98
  99         if (outfd != NULL) {
 100                 *outfd = fd;
 101         }
 102         return 0;
 103
 104 fail_unlink:
 105         unlink(path);
 106         close(fd);
 107         return ret;
 108 }
 109
 110 void pidfile_fd_close(int fd)
 111 {
 112         struct flock lck = {
 113                 .l_type = F_UNLCK,
 114                 .l_whence = SEEK_SET,
 115         };
 116         int ret;
 117
 118         do {
 119                 ret = fcntl(fd, F_SETLK, &lck);
 120         } while ((ret == -1) && (errno == EINTR));
 121
 122         do {
 123                 ret = close(fd);
 124         } while ((ret == -1) && (errno == EINTR));
 125 }
 126
 127
 128 /**
 129  * return the pid in a pidfile. return 0 if the process (or pidfile)
 130  * does not exist
 131  */
 132 pid_t pidfile_pid(const char *piddir, const char *name)
 133 {
 134         size_t len = strlen(piddir) + strlen(name) + 6;
 135         char pidFile[len];
 136         int fd;
 137         char pidstr[20] = { 0, };
 138         pid_t ret = -1;
 139
 140         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
 141
 142         fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
 143
 144         if (fd == -1) {
 145                 return 0;
 146         }
 147
 148         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
 149                 goto noproc;
 150         }
 151
 152         ret = (pid_t)atoi(pidstr);
 153         if (ret <= 0) {
 154                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
 155                         pidFile));
 156                 goto noproc;
 157         }
 158
 159         if (!process_exists_by_pid(ret)) {
 160                 DEBUG(10, ("Process with PID=%d does not exist.\n", (int)ret));
 161                 goto noproc;
 162         }
 163
 164         if (fcntl_lock(fd,F_SETLK,0,1,F_RDLCK)) {
 165                 /* we could get the lock - it can't be a Samba process */
 166                 DEBUG(10, ("Process with PID=%d is not a Samba process.\n",
 167                         (int)ret));
 168                 goto noproc;
 169         }
 170
 171         close(fd);
 172         DEBUG(10, ("Process with PID=%d is running.\n", (int)ret));
 173         return ret;
 174
 175  noproc:
 176         close(fd);
 177         return 0;
 178 }
 179
 180 /**
 181  * create a pid file in the pid directory. open it and leave it locked
 182  */
 183 void pidfile_create(const char *piddir, const char *name)
 184 {
 185         size_t len = strlen(piddir) + strlen(name) + 6;
 186         char pidFile[len];
 187         pid_t pid;
 188         int ret;
 189
 190         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
 191
 192         pid = pidfile_pid(piddir, name);
 193         if (pid != 0) {
 194                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
 195                          name, pidFile, (int)pid));
 196                 exit(1);
 197         }
 198
 199         ret = pidfile_path_create(pidFile, NULL);
 200         if (ret != 0) {
 201                 DBG_ERR("ERROR: Failed to create PID file %s (%s)\n",
 202                         pidFile, strerror(ret));
 203                 exit(1);
 204         }
 205
 206         /* Leave pid file open & locked for the duration... */
 207 }
 208
 209 void pidfile_unlink(const char *piddir, const char *name)
 210 {
 211         size_t len = strlen(piddir) + strlen(name) + 6;
 212         char pidFile[len];
 213         int ret;
 214
 215         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
 216
 217         ret = unlink(pidFile);
 218         if (ret == -1) {
 219                 DEBUG(0,("Failed to delete pidfile %s. Error was %s\n",
 220                         pidFile, strerror(errno)));
 221         }
 222 }