support/support_run_diff.c

   1 /* Invoke the system diff tool to compare two strings.
   2    Copyright (C) 2016-2020 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 }