Take into account chdir_fd when extracting from incremental dumps.

* src/common.h (tar_savedir): New prototype.
* src/misc.c (tar_savedir): New function.
(remove_any_file): Use tar_savedir.
* src/incremen.c (try_purge_directory): Use tar_savedir.
* src/update.c (update_archive): Use tar_savedir.
* tests/incr07.at: New testcase.
* tests/Makefile.am (TESTSUITE_AT): Add new test.
* tests/testsuite.at: Likewise.
* THANKS: Updated.

src/common.h

@@ -596,6 +596,7 @@ char *zap_slashes (char *name);
 char *normalize_filename (const char *name);
 void replace_prefix (char **pname, const char *samp, size_t slen,
 		     const char *repl, size_t rlen);
+char *tar_savedir (const char *name, int must_exist);
 
 typedef struct namebuf *namebuf_t;
 namebuf_t namebuf_create (const char *dir);

src/incremen.c

@@ -1582,7 +1582,7 @@ try_purge_directory (char const *directory_name)
   if (!is_dumpdir (&current_stat_info))
     return false;
 
-  current_dir = savedir (directory_name);
+  current_dir = tar_savedir (directory_name, 0);
 
   if (!current_dir)
     /* The directory doesn't exist now.  It'll be created.  In any

src/misc.c

@@ -631,7 +631,7 @@ remove_any_file (const char *file_name, enum remove_option option)
 
 	case RECURSIVE_REMOVE_OPTION:
 	  {
-	    char *directory = savedir (file_name);
+	    char *directory = tar_savedir (file_name, 0);
 	    char const *entry;
 	    size_t entrylen;
 
@@ -1144,3 +1144,31 @@ namebuf_name (namebuf_t buf, const char *name)
   strcpy (buf->buffer + buf->dir_length, name);
   return buf->buffer;
 }
+
+/* Return the filenames in directory NAME, relative to the chdir_fd.
+   If the directory does not exist, report error if MUST_EXIST is
+   true.
+
+   Return NULL on errors.
+*/
+char *
+tar_savedir (const char *name, int must_exist)
+{
+  char *ret = NULL;
+  DIR *dir = NULL;
+  int fd = openat (chdir_fd, name, open_read_flags | O_DIRECTORY);
+  if (fd < 0)
+    {
+      if (!must_exist && errno == ENOENT)
+	return NULL;
+      open_error (name);
+    }
+  else if (! ((dir = fdopendir (fd))
+	      && (ret = streamsavedir (dir))))
+    savedir_error (name);
+
+  if (dir ? closedir (dir) != 0 : 0 <= fd && close (fd) != 0)
+    savedir_error (name);
+
+  return ret;
+}

src/update.c

@@ -145,16 +145,8 @@ update_archive (void)
 		  {
 		    if (S_ISDIR (s.st_mode))
 		      {
-			char *p, *dirp;
-			DIR *stream = NULL;
-			int fd = openat (chdir_fd, name->name,
-					 open_read_flags | O_DIRECTORY);
-			if (fd < 0)
-			  open_error (name->name);
-			else if (! ((stream = fdopendir (fd))
-				    && (dirp = streamsavedir (stream))))
-			  savedir_error (name->name);
-			else
+			char *p, *dirp = tar_savedir (name->name, 1);
+			if (dirp)
 			  {
 			    namebuf_t nbuf = namebuf_create (name->name);
 
@@ -167,11 +159,6 @@ update_archive (void)
 
 			    remname (name);
 			  }
-
-			if (stream
-			    ? closedir (stream) != 0
-			    : 0 <= fd && close (fd) != 0)
-			  savedir_error (name->name);
 		      }
 		    else if (tar_timespec_cmp (get_stat_mtime (&s),
 					       current_stat_info.mtime)