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 /**
  31  * @file
  32  * @brief Pid file handling
  33  */
  34
  35 int pidfile_path_create(const char *path, int *outfd)
  36 {
  37         struct flock lck;
  38         char tmp[64] = { 0 };
  39         pid_t pid;
  40         int fd, ret = 0;
  41         int len;
  42         ssize_t nwritten;
  43
  44         pid = getpid();
  45
  46         fd = open(path, O_CREAT|O_WRONLY|O_NONBLOCK, 0644);
  47         if (fd == -1) {
  48                 return errno;
  49         }
  50
  51         if (! set_close_on_exec(fd)) {
  52                 close(fd);
  53                 return EIO;
  54         }
  55
  56         lck = (struct flock) {
  57                 .l_type = F_WRLCK,
  58                 .l_whence = SEEK_SET,
  59         };
  60
  61         do {
  62                 ret = fcntl(fd, F_SETLK, &lck);
  63         } while ((ret == -1) && (errno == EINTR));
  64
  65         if (ret != 0) {
  66                 ret = errno;
  67                 close(fd);
  68                 return ret;
  69         }
  70
  71         /*
  72          * PID file is locked by us so from here on we should unlink
  73          * on failure
  74          */
  75
  76         do {
  77                 ret = ftruncate(fd, 0);
  78         } while ((ret == -1) && (errno == EINTR));
  79
  80         if (ret == -1) {
  81                 ret = EIO;
  82                 goto fail_unlink;
  83         }
  84
  85         len = snprintf(tmp, sizeof(tmp), "%u\n", pid);
  86         if (len < 0) {
  87                 ret = errno;
  88                 goto fail_unlink;
  89         }
  90         if (len >= sizeof(tmp)) {
  91                 ret = ENOSPC;
  92                 goto fail_unlink;
  93         }
  94
  95         do {
  96                 nwritten = write(fd, tmp, len);
  97         } while ((nwritten == -1) && (errno == EINTR));
  98
  99         if ((nwritten == -1) || (nwritten != len)) {
 100                 ret = EIO;
 101                 goto fail_unlink;
 102         }
 103
 104         if (outfd != NULL) {
 105                 *outfd = fd;
 106         }
 107         return 0;
 108
 109 fail_unlink:
 110         unlink(path);
 111         close(fd);
 112         return ret;
 113 }
 114
 115 void pidfile_fd_close(int fd)
 116 {
 117         struct flock lck = {
 118                 .l_type = F_UNLCK,
 119                 .l_whence = SEEK_SET,
 120         };
 121         int ret;
 122
 123         do {
 124                 ret = fcntl(fd, F_SETLK, &lck);
 125         } while ((ret == -1) && (errno == EINTR));
 126
 127         do {
 128                 ret = close(fd);
 129         } while ((ret == -1) && (errno == EINTR));
 130 }
 131
 132
 133 /**
 134  * return the pid in a pidfile. return 0 if the process (or pidfile)
 135  * does not exist
 136  */
 137 pid_t pidfile_pid(const char *piddir, const char *name)
 138 {
 139         size_t len = strlen(piddir) + strlen(name) + 6;
 140         char pidFile[len];
 141         int fd;
 142         char pidstr[20];
 143         pid_t ret = -1;
 144
 145         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
 146
 147         fd = open(pidFile, O_NONBLOCK | O_RDONLY, 0644);
 148
 149         if (fd == -1) {
 150                 return 0;
 151         }
 152
 153         ZERO_STRUCT(pidstr);
 154
 155         if (read(fd, pidstr, sizeof(pidstr)-1) <= 0) {
 156                 goto noproc;
 157         }
 158
 159         ret = (pid_t)atoi(pidstr);
 160         if (ret <= 0) {
 161                 DEBUG(1, ("Could not parse contents of pidfile %s\n",
 162                         pidFile));
 163                 goto noproc;
 164         }
 165
 166         if (!process_exists_by_pid(ret)) {
 167                 DEBUG(10, ("Process with PID=%d does not exist.\n", (int)ret));
 168                 goto noproc;
 169         }
 170
 171         if (fcntl_lock(fd,F_SETLK,0,1,F_RDLCK)) {
 172                 /* we could get the lock - it can't be a Samba process */
 173                 DEBUG(10, ("Process with PID=%d is not a Samba process.\n",
 174                         (int)ret));
 175                 goto noproc;
 176         }
 177
 178         close(fd);
 179         DEBUG(10, ("Process with PID=%d is running.\n", (int)ret));
 180         return ret;
 181
 182  noproc:
 183         close(fd);
 184         return 0;
 185 }
 186
 187 /**
 188  * create a pid file in the pid directory. open it and leave it locked
 189  */
 190 void pidfile_create(const char *piddir, const char *name)
 191 {
 192         size_t len = strlen(piddir) + strlen(name) + 6;
 193         char pidFile[len];
 194         pid_t pid;
 195         int ret;
 196
 197         snprintf(pidFile, sizeof(pidFile), "%s/%s.pid", piddir, name);
 198
 199         pid = pidfile_pid(piddir, name);
 200         if (pid != 0) {
 201                 DEBUG(0,("ERROR: %s is already running. File %s exists and process id %d is running.\n",
 202                          name, pidFile, (int)pid));
 203                 exit(1);
 204         }
 205
 206         ret = pidfile_path_create(pidFile, NULL);
 207         if (ret != 0) {
 208                 DBG_ERR("ERROR: Failed to create PID file %s (%s)\n",
 209                         pidFile, strerror(ret));
 210                 exit(1);
 211         }
 212
 213         /* Leave pid file open & locked for the duration... */
 214 }
 215
 216 void pidfile_unlink(const char *piddir, const char *name)
 217 {
 218         int ret;
 219         char *pidFile = NULL;
 220
 221         if (asprintf(&pidFile, "%s/%s.pid", piddir, name) < 0) {
 222                 DEBUG(0,("ERROR: Out of memory\n"));
 223                 exit(1);
 224         }
 225         ret = unlink(pidFile);
 226         if (ret == -1) {
 227                 DEBUG(0,("Failed to delete pidfile %s. Error was %s\n",
 228                         pidFile, strerror(errno)));
 229         }
 230 }