lib/sigpipe-die.c

   1 /* Report a SIGPIPE signal and exit.
   2    Copyright (C) 2008-2020 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2008.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include "sigpipe-die.h"
  23
  24 #include <signal.h>
  25 #include <stdlib.h>
  26
  27 #include "error.h"
  28 #include "exitfail.h"
  29
  30 #include "gettext.h"
  31 #define _(msgid) gettext (msgid)
  32
  33 void
  34 sigpipe_die (void)
  35 {
  36   error (exit_failure, 0, "%s",
  37          _("error writing to a closed pipe or socket"));
  38
  39   /* Ensure that this function really does not return.  */
  40   abort ();
  41 }
  42
  43 static void (*prepare_die_hook) (void);
  44
  45 /* This is the signal handler for SIGPIPE.  It is invoked synchronously,
  46    therefore it can make library calls to malloc(), gettext(), exit() etc. -
  47    although in general it is undefined behaviour to do such calls from
  48    within signal handlers.  */
  49 static void
  50 sigpipe_die_handler (int sig)
  51 {
  52   if (prepare_die_hook != NULL)
  53     (*prepare_die_hook) ();
  54   sigpipe_die ();
  55 }
  56
  57 void
  58 install_sigpipe_die_handler (void (*prepare_die) (void))
  59 {
  60   prepare_die_hook = prepare_die;
  61
  62   /* Install the handler.  */
  63   {
  64     struct sigaction action;
  65
  66     action.sa_handler = sigpipe_die_handler;
  67     action.sa_flags = 0;
  68     sigemptyset (&action.sa_mask);
  69     if (sigaction (SIGPIPE, &action, NULL) >= 0)
  70       {
  71         /* Unblock the signal (just in case).  This is needed because if the
  72            signal was blocked in the parent process, it is also blocked in
  73            this process: the mask of blocked signals is inherited across
  74            fork/exec (except for SIGCHLD).  */
  75         sigset_t sigpipe_set;
  76
  77         sigemptyset (&sigpipe_set);
  78         sigaddset (&sigpipe_set, SIGPIPE);
  79         sigprocmask (SIG_UNBLOCK, &sigpipe_set, NULL);
  80       }
  81   }
  82 }