lib/util/become_daemon.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba utility functions
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Jeremy Allison 2001-2002
   6    Copyright (C) Simo Sorce 2001
   7    Copyright (C) Jim McDonough (jmcd@us.ibm.com)  2003.
   8    Copyright (C) James J Myers 2003
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "includes.h"
  25 #include "system/filesys.h"
  26 #include "system/locale.h"
  27 #if HAVE_SYSTEMD
  28 #include <systemd/sd-daemon.h>
  29 #endif
  30
  31 /*******************************************************************
  32  Close the low 3 fd's and open dev/null in their place.
  33 ********************************************************************/
  34
  35 _PUBLIC_ int close_low_fd(int fd)
  36 {
  37 #ifndef VALGRIND
  38         int ret, dev_null;
  39
  40         dev_null = open("/dev/null", O_RDWR, 0);
  41
  42         if ((dev_null == -1) && (errno = ENFILE)) {
  43                 /*
  44                  * Try to free up an fd
  45                  */
  46                 ret = close(fd);
  47                 if (ret != 0) {
  48                         return errno;
  49                 }
  50         }
  51
  52         dev_null = open("/dev/null", O_RDWR, 0);
  53         if (dev_null == -1) {
  54                 dev_null = open("/dev/null", O_WRONLY, 0);
  55         }
  56         if (dev_null == -1) {
  57                 return errno;
  58         }
  59
  60         if (dev_null == fd) {
  61                 /*
  62                  * This can happen in the ENFILE case above
  63                  */
  64                 return 0;
  65         }
  66
  67         ret = dup2(dev_null, fd);
  68         if (ret == -1) {
  69                 int err = errno;
  70                 close(dev_null);
  71                 return err;
  72         }
  73         close(dev_null);
  74 #endif
  75         return 0;
  76 }
  77
  78 _PUBLIC_ void close_low_fds(bool stdin_too, bool stdout_too, bool stderr_too)
  79 {
  80 #ifndef VALGRIND
  81         int fd;
  82         int i;
  83
  84         if (stdin_too)
  85                 close(0);
  86         if (stdout_too)
  87                 close(1);
  88
  89         if (stderr_too)
  90                 close(2);
  91
  92         /* try and use up these file descriptors, so silly
  93                 library routines writing to stdout etc won't cause havoc */
  94         for (i=0;i<3;i++) {
  95                 if (i == 0 && !stdin_too)
  96                         continue;
  97                 if (i == 1 && !stdout_too)
  98                         continue;
  99                 if (i == 2 && !stderr_too)
 100                         continue;
 101
 102                 fd = open("/dev/null",O_RDWR,0);
 103                 if (fd < 0)
 104                         fd = open("/dev/null",O_WRONLY,0);
 105                 if (fd < 0) {
 106                         DEBUG(0,("Can't open /dev/null\n"));
 107                         return;
 108                 }
 109                 if (fd != i) {
 110                         DEBUG(0,("Didn't get file descriptor %d\n",i));
 111                         close(fd);
 112                         return;
 113                 }
 114         }
 115 #endif
 116 }
 117
 118 /****************************************************************************
 119  Become a daemon, discarding the controlling terminal.
 120 ****************************************************************************/
 121
 122 _PUBLIC_ void become_daemon(bool do_fork, bool no_process_group, bool log_stdout)
 123 {
 124         pid_t newpid;
 125         if (do_fork) {
 126                 newpid = fork();
 127                 if (newpid) {
 128 #if HAVE_SYSTEMD
 129                         sd_notifyf(0, "READY=0\nSTATUS=Starting process...\nMAINPID=%lu", (unsigned long) newpid);
 130 #endif /* HAVE_SYSTEMD */
 131                         _exit(0);
 132                 }
 133         }
 134
 135         /* detach from the terminal */
 136 #ifdef HAVE_SETSID
 137         if (!no_process_group) setsid();
 138 #elif defined(TIOCNOTTY)
 139         if (!no_process_group) {
 140                 int i = open("/dev/tty", O_RDWR, 0);
 141                 if (i != -1) {
 142                         ioctl(i, (int) TIOCNOTTY, (char *)0);
 143                         close(i);
 144                 }
 145         }
 146 #endif /* HAVE_SETSID */
 147
 148         /* Close fd's 0,1,2 as appropriate. Needed if started by rsh. */
 149         /* stdin must be open if we do not fork, for monitoring for
 150          * close.  stdout must be open if we are logging there, and we
 151          * never close stderr (but debug might dup it onto a log file) */
 152         close_low_fds(do_fork, !log_stdout, false);
 153 }
 154
 155 _PUBLIC_ void exit_daemon(const char *msg, int error)
 156 {
 157 #ifdef HAVE_SYSTEMD
 158         if (msg == NULL) {
 159                 msg = strerror(error);
 160         }
 161
 162         sd_notifyf(0, "STATUS=daemon failed to start: %s\n"
 163                                   "ERRNO=%i",
 164                                   msg,
 165                                   error);
 166 #endif
 167         DEBUG(0, ("STATUS=daemon failed to start: %s, error code %d\n", msg, error));
 168         exit(1);
 169 }
 170
 171 _PUBLIC_ void daemon_ready(const char *name)
 172 {
 173         if (name == NULL) {
 174                 name = "Samba";
 175         }
 176 #ifdef HAVE_SYSTEMD
 177         sd_notifyf(0, "READY=1\nSTATUS=%s: ready to serve connections...", name);
 178 #endif
 179         DEBUG(0, ("STATUS=daemon '%s' finished starting up and ready to serve "
 180                   "connections\n", name));
 181 }