/* Invoke the system diff tool to compare two strings.

   Copyright (C) 2016-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <support/run_diff.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <support/check.h>

#include <support/support.h>

#include <support/temp_file.h>

#include <support/xunistd.h>

#include <sys/wait.h>

static char *

write_to_temp_file (const char *prefix, const char *str)

{

  char *template = xasprintf ("run_diff-%s", prefix);

  char *name = NULL;

  int fd = create_temp_file (template, &name);

  TEST_VERIFY_EXIT (fd >= 0);

  free (template);

  xwrite (fd, str, strlen (str));

  xclose (fd);

  return name;

}

void

support_run_diff (const char *left_label, const char *left,

                  const char *right_label, const char *right)

{

  /* Ensure that the diff command output is ordered properly with

     standard output.  */

  TEST_VERIFY_EXIT (fflush (stdout) == 0);

  char *left_path = write_to_temp_file ("left-diff", left);

  char *right_path = write_to_temp_file ("right-diff", right);

  pid_t pid = xfork ();

  if (pid == 0)

    {

      execlp ("diff", "diff", "-u",

              "--label", left_label, "--label", right_label,

              "--", left_path, right_path,

              NULL);

      _exit (17);

    }

  else

    {

      int status;

      xwaitpid (pid, &status, 0);

      if (!WIFEXITED (status) || WEXITSTATUS (status) != 1)

        printf ("warning: could not run diff, exit status: %d\n"

                "*** %s ***\n%s\n"

                "*** %s ***\n%s\n",

                status, left_label, left, right_label, right);

    }

  free (right_path);

  free (left_path);

}