tar: no need to report getcwd error if never using the result

* src/misc.c (struct wd): Rename 'saved' to 'err', with new semantics.
(chdir_arg, chdir_do): Adjust to new semantics.  Do not report an
error merely because save_cwd fails; report an error only if
save_cwd's result is needed later.
* tests/extrac09.at: New file, to test for bug that was fixed.
* tests/testsuite.at: Include it.
* tests/Makefile.am (TESTSUITE_AT): Add it.

src/misc.c

@@ -640,8 +640,15 @@ set_file_atime (int fd, char const *file, struct timespec const timespec[2])
 /* A description of a working directory.  */
 struct wd
 {
+  /* The directory's name.  */
   char const *name;
-  int saved;
+
+  /* A negative value if no attempt has been made to save the
+     directory, 0 if it was saved successfully, and a positive errno
+     value if it was not saved successfully.  */
+  int err;
+
+  /* The saved version of the directory, if SAVED == 1.  */
   struct saved_cwd saved_cwd;
 };
 
@@ -680,7 +687,7 @@ chdir_arg (char const *dir)
       if (! wd_count)
 	{
 	  wd[wd_count].name = ".";
-	  wd[wd_count].saved = 0;
+	  wd[wd_count].err = -1;
 	  wd_count++;
 	}
     }
@@ -697,7 +704,7 @@ chdir_arg (char const *dir)
     }
 
   wd[wd_count].name = dir;
-  wd[wd_count].saved = 0;
+  wd[wd_count].err = -1;
   return wd_count++;
 }
 
@@ -713,12 +720,11 @@ chdir_do (int i)
       struct wd *prev = &wd[previous];
       struct wd *curr = &wd[i];
 
-      if (! prev->saved)
+      if (prev->err < 0)
 	{
-	  int err = 0;
-	  prev->saved = 1;
+	  prev->err = 0;
 	  if (save_cwd (&prev->saved_cwd) != 0)
-	    err = errno;
+	    prev->err = errno;
 	  else if (0 <= prev->saved_cwd.desc)
 	    {
 	      /* Make sure we still have at least one descriptor available.  */
@@ -733,20 +739,20 @@ chdir_do (int i)
 		  prev->saved_cwd.desc = -1;
 		  prev->saved_cwd.name = xgetcwd ();
 		  if (! prev->saved_cwd.name)
-		    err = errno;
+		    prev->err = errno;
 		}
 	      else
-		err = errno;
+		prev->err = errno;
 	    }
-
-	  if (err)
-	    FATAL_ERROR ((0, err, _("Cannot save working directory")));
 	}
 
-      if (curr->saved)
+      if (0 <= curr->err)
 	{
-	  if (restore_cwd (&curr->saved_cwd))
-	    FATAL_ERROR ((0, 0, _("Cannot change working directory")));
+	  int err = curr->err;
+	  if (err == 0 && restore_cwd (&curr->saved_cwd) != 0)
+	    err = errno;
+	  if (err)
+	    FATAL_ERROR ((0, err, _("Cannot restore working directory")));
 	}
       else
 	{

tests/Makefile.am

@@ -75,6 +75,7 @@ TESTSUITE_AT = \
  extrac06.at\
  extrac07.at\
  extrac08.at\
+ extrac09.at\
  filerem01.at\
  filerem02.at\
  gzip.at\

tests/extrac09.at

@@ -0,0 +1,46 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+
+# Test suite for GNU tar.
+# Copyright (C) 2010 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/>.
+
+# This checks for the --listed-incremental bug reported by J Chapman Flack at
+# http://lists.gnu.org/archive/html/bug-tar/2010-06/msg00000.html
+
+AT_SETUP([no need to save dir with unreadable . and ..])
+AT_KEYWORDS([extract extrac09])
+
+AT_TAR_CHECK([
+mkdir dir
+mkdir dir/sub
+mkdir dir/sub/extract
+genfile --file dir/sub/f
+cd dir/sub
+
+tar -cf archive.tar f
+
+chmod a-r . ..
+tar -xvf archive.tar -C extract f
+status=$?
+chmod a+r . ..
+cmp f extract/f || status=$?
+exit $status
+],
+[0],
+[f
+],
+[],[],[],[gnu])
+
+AT_CLEANUP

tests/testsuite.at

@@ -146,6 +146,7 @@ m4_include([extrac05.at])
 m4_include([extrac06.at])
 m4_include([extrac07.at])
 m4_include([extrac08.at])
+m4_include([extrac09.at])
 
 m4_include([label01.at])
 m4_include([label02.at])