gnulib/tests/test-sigpipe.c

/* Test of SIGPIPE handling.
   Copyright (C) 2008-2020 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

#include <signal.h>

/* Check that SIGPIPE is defined.  */
int s = SIGPIPE;

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "macros.h"

static void
handler (int sig)
{
  exit (0);
}

int
main (int argc, char **argv)
{
  char mode = argv[1][0];

  switch (mode)
    {
    case 'A': signal (SIGPIPE, SIG_DFL); break;
    case 'B': signal (SIGPIPE, SIG_IGN); break;
    case 'C': signal (SIGPIPE, handler); break;
    }

  /* Produce infinite output.  Since it is piped into "head -1", the writes
     must ultimately fail.  */
  for (;;)
    {
      char c[2] = { 'y', '\n' };
      int ret = write (1, c, sizeof (c));
      if (ret <= 0)
        {
          switch (mode)
            {
            case 'B': /* The write() call should have failed with EPIPE.  */
              if (ret < 0 && errno == EPIPE)
                exit (0);
              FALLTHROUGH;
            case 'A': /* The process should silently die.  */
            case 'C': /* The handler should have been called.  */
              fprintf (stderr, "write() returned %d with error %d.\n", ret, errno);
              exit (1);
            }
        }
    }
}