tar: don't crash if getcwd fails

* src/extract.c: Don't include xgetcwd.h.
(extract_dir): stat "." rather than statting getcwd's output.
* src/misc.c (normalize_filename_x): Rewrite so as not to resolve
/../, which can't be done reliably in the presence of symlinks.
Don't reject valid names such as ".".
(normalize_filename): Don't make it absolute; that way, we don't
have to invoke xgetcwd which might fail.  Don't bother to realloc
at the end, since that uses time and now saves little space.
(chdir_do): Don't crash if xgetcwd fails.
* tests/Makefile.am (TESTSUITE_AT): Add listed03.at.
* tests/listed03.at: New file.
* tests/testsuite.at: Include listed03.at.

src/extract.c

@@ -23,7 +23,6 @@
 #include <quotearg.h>
 #include <utimens.h>
 #include <errno.h>
-#include <xgetcwd.h>
 #include <priv-set.h>
 
 #include "common.h"
@@ -648,13 +647,11 @@ extract_dir (char *file_name, int typeflag)
   if (one_file_system_option && root_device == 0)
     {
       struct stat st;
-      char *dir = xgetcwd ();
 
-      if (deref_stat (true, dir, &st))
+      if (stat (".", &st) != 0)
-	stat_diag (dir);
+	stat_diag (".");
       else
 	root_device = st.st_dev;
-      free (dir);
     }
 
   if (incremental_option)

src/misc.c

@@ -1,7 +1,7 @@
 /* Miscellaneous functions, not really specific to GNU tar.
 
    Copyright (C) 1988, 1992, 1994, 1995, 1996, 1997, 1999, 2000, 2001,
-   2003, 2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
+   2003, 2004, 2005, 2006, 2007, 2009, 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
@@ -233,99 +233,54 @@ zap_slashes (char *name)
   return name;
 }
 
-/* Normalize NAME by resolving any relative references and
+/* Normalize FILE_NAME by removing redundant slashes and "."
-   removing trailing slashes.  Destructive version: modifies its argument. */
+   components, including redundant trailing slashes.  Leave ".."
-static int
+   alone, as it may be significant in the presence of symlinks and on
-normalize_filename_x (char *name)
+   platforms where "/.." != "/".  Destructive version: modifies its
+   argument. */
+static void
+normalize_filename_x (char *file_name)
 {
-  char *p, *q;
+  char *name = file_name + FILE_SYSTEM_PREFIX_LEN (file_name);
+  char *p;
+  char const *q;
+  char c;
 
-  p = name;
+  /* Don't squeeze leading "//" to "/", on hosts where they're distinct.  */
-  if (DOUBLE_SLASH_IS_DISTINCT_ROOT && ISSLASH (*p))
+  name += (DOUBLE_SLASH_IS_DISTINCT_ROOT
-    p++;
+	   && ISSLASH (*name) && ISSLASH (name[1]) && ! ISSLASH (name[2]));
 
-  /* Remove /./, resolve /../ and compress sequences of slashes */
+  /* Omit redundant leading "." components.  */
-  for (q = p; *q; )
+  for (q = p = name; (*p = *q) == '.' && ISSLASH (q[1]); p += !*q)
+    for (q += 2; ISSLASH (*q); q++)
+      continue;
+
+  /* Copy components from Q to P, omitting redundant slashes and
+     internal "."  components.  */
+  while ((*p++ = c = *q++) != '\0')
+    if (ISSLASH (c))
+      while (ISSLASH (q[*q == '.']))
+	q += (*q == '.') + 1;
+
+  /* Omit redundant trailing "." component and slash.  */
+  if (2 < p - name)
     {
-      if (ISSLASH (*q))
+      p -= p[-2] == '.' && ISSLASH (p[-3]);
-	{
+      p -= 2 < p - name && ISSLASH (p[-2]);
-	  *p++ = *q++;
+      p[-1] = '\0';
-	  while (ISSLASH (*q))
-	    q++;
-	  continue;
-	}
-      else if (p == name)
-	{
-	  if (*q == '.')
-	    {
-	      if (ISSLASH (q[1]))
-		{
-		  q += 2;
-		  continue;
-		}
-	      if (q[1] == '.' && ISSLASH (q[2]))
-		return 1;
-	    }
-	}
-      else
-	{
-	  if (*q == '.' && ISSLASH (p[-1]))
-	    {
-	      if (ISSLASH (q[1]))
-		{
-		  q += 2;
-		  while (ISSLASH (*q))
-		    q++;
-		  continue;
-		}
-	      else if (q[1] == '.' && ISSLASH (q[2]))
-		{
-		  do
-		    {
-		      --p;
-		    }
-		  while (p > name && !ISSLASH (p[-1]));
-		  q += 3;
-		  continue;
-		}
-	    }
-	}
-      *p++ = *q++;
     }
-
-  /* Remove trailing slashes */
-  while (p - 1 > name && ISSLASH (p[-1]))
-    p--;
-
-  *p = 0;
-  return 0;
 }
 
-/* Normalize NAME by resolving any relative references, removing trailing
+/* Normalize NAME by removing redundant slashes and "." components,
-   slashes, and converting it to absolute file name.  Return the normalized
+   including redundant trailing slashes.  Return a normalized
-   name, or NULL in case of error. */
+   newly-allocated copy.  */
 
 char *
 normalize_filename (const char *name)
 {
-  char *copy;
+  char *copy = xstrdup (name);
-
+  normalize_filename_x (copy);
-  if (name[0] != '/')
+  return copy;
-    {
-      copy = xgetcwd ();
-      copy = xrealloc (copy, strlen (copy) + strlen (name) + 2);
-
-      strcat (copy, "/");
-      strcat (copy, name);
-    }
-  else
-    copy = xstrdup (name);
-  if (normalize_filename_x (copy))
-    {
-      free (copy);
-      return NULL;
-    }
-  return xrealloc (copy, strlen (copy) + 1);
 }
 
 
@@ -752,6 +707,8 @@ chdir_do (int i)
 		  close (fd1);
 		  prev->saved_cwd.desc = -1;
 		  prev->saved_cwd.name = xgetcwd ();
+		  if (! prev->saved_cwd.name)
+		    err = errno;
 		}
 	      else
 		err = errno;

tests/Makefile.am

@@ -1,6 +1,6 @@
 # Makefile for GNU tar regression tests.
 
-# Copyright (C) 1996, 1997, 1999, 2000, 2001, 2003, 2004, 2005, 
+# Copyright (C) 1996, 1997, 1999, 2000, 2001, 2003, 2004, 2005,
 # 2006, 2007, 2009 Free Software Foundation, Inc.
 
 # François Pinard <pinard@iro.umontreal.ca>, 1988.
@@ -98,6 +98,7 @@ TESTSUITE_AT = \
  link03.at\
  listed01.at\
  listed02.at\
+ listed03.at\
  long01.at\
  longv7.at\
  lustar01.at\

tests/listed03.at

@@ -0,0 +1,45 @@
+# 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([incremental dump when the parent directory is unreadable])
+AT_KEYWORDS([listed incremental listed03])
+
+AT_TAR_CHECK([
+mkdir dir
+mkdir dir/sub
+mkdir dir/sub/a
+genfile --file dir/sub/a/file
+cd dir/sub
+
+chmod a-r ..
+tar -c -f archive.tar --listed-incremental=db.1 -v a
+status=$?
+chmod a+r ..
+exit $status
+],
+[0],
+[a/
+a/file
+],
+[tar: a: Directory is new
+],[],[],[gnu])
+
+AT_CLEANUP

tests/testsuite.at

@@ -41,13 +41,13 @@ $1)],$2,$3,$4,$5,$6)
 m4_define([AT_TAR_WITH_HOOK],[
   m4_pushdef([AT_TAR_CHECK_HOOK],[$1])
   $2
-  
+
   m4_popdef([AT_TAR_CHECK_HOOK])])
 
 m4_define([TAR_IGNREC_HOOK],[
   AT_CHECK([grep -v '^.*tar: Record size = ' stderr; exit 0])
 ])
-  
+
 m4_define([RE_CHECK],[
 AT_DATA([$1.re],[$2])
 awk '{print NR " " $[]0}' $1 > $[]$.1
@@ -162,6 +162,7 @@ m4_include([incr01.at])
 m4_include([incr02.at])
 m4_include([listed01.at])
 m4_include([listed02.at])
+m4_include([listed03.at])
 m4_include([incr03.at])
 m4_include([incr04.at])
 m4_include([incr05.at])