Use stdopen from gnulib

* gnulib.modules: Request stdopen
* lib/Makefile.am: Remove stdopen.c and stdopen.h
* lib/stdopen.c: Remove.
* lib/stdopen.h: Remove.
* src/tar.c: stdopen returns 0 on success.

gnulib.modules

@@ -83,6 +83,7 @@ stat-time
 stdbool
 stdint
 stpcpy
+stdopen
 strdup-posix
 strerror
 strnlen

lib/Makefile.am

@@ -32,7 +32,6 @@ AM_CFLAGS = $(GNULIB_WARN_CFLAGS) $(WERROR_CFLAGS)
 noinst_HEADERS = \
  paxlib.h\
  rmt.h\
- stdopen.h\
  system.h\
  system-ioctl.h\
  wordsplit.h\
@@ -42,7 +41,6 @@ libtar_a_SOURCES = \
   paxerror.c paxexit-status.c paxlib.h paxnames.c \
   rtapelib.c \
   rmt.h \
-  stdopen.c stdopen.h \
   system.h system-ioctl.h \
   wordsplit.c\
   xattr-at.c

lib/stdopen.c

@@ -1,83 +0,0 @@
-/* stdopen.c - ensure that the three standard file descriptors are in use
-
-   Copyright 2005-2021 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 <http://www.gnu.org/licenses/>.  */
-
-/* Written by Paul Eggert and Jim Meyering.  */
-
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
-
-#include "stdopen.h"
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <errno.h>
-
-/* Try to ensure that all of the standard file numbers (0, 1, 2)
-   are in use.  Without this, each application would have to guard
-   every call to open, dup, fopen, etc. with tests to ensure they
-   don't use one of the special file numbers when opening a file.
-   Return false if at least one of the file descriptors is initially
-   closed and an attempt to reopen it fails.  Otherwise, return true.  */
-bool
-stdopen (void)
-{
-  int fd;
-  bool ok = true;
-
-  for (fd = 0; fd <= 2; fd++)
-    {
-      if (fcntl (fd, F_GETFD) < 0)
-        {
-          if (errno != EBADF)
-            ok = false;
-          else
-            {
-              static const int contrary_mode[]
-                = { O_WRONLY, O_RDONLY, O_RDONLY };
-              int mode = contrary_mode[fd];
-              int new_fd = -1;
-              /* Open /dev/null with the contrary mode so that the typical
-                 read (stdin) or write (stdout, stderr) operation will fail.
-                 With descriptor 0, we can do even better on systems that
-                 have /dev/full, by opening that write-only instead of
-                 /dev/null.  The only drawback is that a write-provoked
-                 failure comes with a misleading errno value, ENOSPC.  */
-              if (mode == O_WRONLY)
-		{
-		  if ((new_fd = open ("/dev/full", mode)) != fd)
-		    {
-		      close (new_fd);
-		      new_fd = -1;
-		    }
-		}
-	      if (new_fd == -1)
-                new_fd = open ("/dev/null", mode);
-              if (new_fd != fd)
-                {
-                  if (0 <= new_fd)
-                    close (new_fd);
-                  ok = false;
-                }
-            }
-        }
-    }
-
-  return ok;
-}

lib/stdopen.h

@@ -1,16 +0,0 @@
-#ifndef STDOPEN_H
-# define STDOPEN_H 1
-
-# include <stdbool.h>
-
-# ifdef __cplusplus
-extern "C" {
-# endif
-
-bool stdopen (void);
-
-# ifdef __cplusplus
-}
-# endif
-
-#endif

src/tar.c

@@ -2753,9 +2753,9 @@ main (int argc, char **argv)
 
   close_stdout_set_file_name (_("stdout"));
   /* Make sure we have first three descriptors available */
-  if (!stdopen ())
-    FATAL_ERROR ((0, errno, "%s",
-		  _("failed to ensure first three descriptors are available")));
+  if (stdopen ())
+    FATAL_ERROR ((0, 0, "%s",
+		  _("failed to assert availability of the standard file descriptors")));
 
   /* Pre-allocate a few structures.  */