tests/test-sigpipe.c

   1 /* Test of SIGPIPE handling.
   2    Copyright (C) 2008-2024 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, or (at your option)
   7    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 #include <config.h>
  18
  19 #include <signal.h>
  20
  21 /* Check that SIGPIPE is defined.  */
  22 int s = SIGPIPE;
  23
  24 #include <errno.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28
  29 #include "macros.h"
  30
  31 static void
  32 handler (int sig)
  33 {
  34   _exit (0);
  35 }
  36
  37 int
  38 main (int argc, char **argv)
  39 {
  40   char mode = argv[1][0];
  41
  42   switch (mode)
  43     {
  44     case 'A': signal (SIGPIPE, SIG_DFL); break;
  45     case 'B': signal (SIGPIPE, SIG_IGN); break;
  46     case 'C': signal (SIGPIPE, handler); break;
  47     }
  48
  49   /* Produce infinite output.  Since it is piped into "head -n 1", the writes
  50      must ultimately fail.  */
  51   for (;;)
  52     {
  53       char c[2] = { 'y', '\n' };
  54       int ret = write (1, c, sizeof (c));
  55       if (ret <= 0)
  56         {
  57           switch (mode)
  58             {
  59             case 'B': /* The write() call should have failed with EPIPE.  */
  60               if (ret < 0 && errno == EPIPE)
  61                 exit (0);
  62               FALLTHROUGH;
  63             case 'A': /* The process should silently die.  */
  64             case 'C': /* The handler should have been called.  */
  65               fprintf (stderr, "write() returned %d with error %d.\n", ret, errno);
  66               exit (1);
  67             }
  68         }
  69     }
  70 }