1  /* Invoke the system diff tool to compare two strings.
       2     Copyright (C) 2016-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <support/run_diff.h>
      20  
      21  #include <stdio.h>
      22  #include <stdlib.h>
      23  #include <string.h>
      24  #include <support/check.h>
      25  #include <support/support.h>
      26  #include <support/temp_file.h>
      27  #include <support/xunistd.h>
      28  #include <sys/wait.h>
      29  
      30  static char *
      31  write_to_temp_file (const char *prefix, const char *str)
      32  {
      33    char *template = xasprintf ("run_diff-%s", prefix);
      34    char *name = NULL;
      35    int fd = create_temp_file (template, &name);
      36    TEST_VERIFY_EXIT (fd >= 0);
      37    free (template);
      38    xwrite (fd, str, strlen (str));
      39    xclose (fd);
      40    return name;
      41  }
      42  
      43  void
      44  support_run_diff (const char *left_label, const char *left,
      45                    const char *right_label, const char *right)
      46  {
      47    /* Ensure that the diff command output is ordered properly with
      48       standard output.  */
      49    TEST_VERIFY_EXIT (fflush (stdout) == 0);
      50  
      51    char *left_path = write_to_temp_file ("left-diff", left);
      52    char *right_path = write_to_temp_file ("right-diff", right);
      53  
      54    pid_t pid = xfork ();
      55    if (pid == 0)
      56      {
      57        execlp ("diff", "diff", "-u",
      58                "--label", left_label, "--label", right_label,
      59                "--", left_path, right_path,
      60                NULL);
      61        _exit (17);
      62      }
      63    else
      64      {
      65        int status;
      66        xwaitpid (pid, &status, 0);
      67        if (!WIFEXITED (status) || WEXITSTATUS (status) != 1)
      68          printf ("warning: could not run diff, exit status: %d\n"
      69                  "*** %s ***\n%s\n"
      70                  "*** %s ***\n%s\n",
      71                  status, left_label, left, right_label, right);
      72      }
      73  
      74    free (right_path);
      75    free (left_path);
      76  }