bring in --fast-read code from freebsd.

gnu/dist/tar/src/common.h

@@ -152,6 +152,9 @@ GLOBAL int dereference_option;
 /* Patterns that match file names to be excluded.  */
 GLOBAL struct exclude *excluded;
 
+/* Boolean value.  */
+GLOBAL int fast_read_option;
+
 /* Specified file containing names to work on.  */
 GLOBAL const char *files_from_option;
 
@@ -196,6 +199,9 @@ GLOBAL struct mode_change *mode_option;
 /* Boolean value.  */
 GLOBAL int multi_volume_option;
 
+/* Boolean value.  */
+GLOBAL int namelist_freed;
+
 /* The same variable hold the time, whether mtime or ctime.  Just fake a
    non-existing option, for making the code clearer, elsewhere.  */
 #define newer_ctime_option newer_mtime_option

gnu/dist/tar/src/list.c

@@ -78,6 +78,10 @@ read_and (void (*do_something) ())
     {
       prev_status = status;
       status = read_header (0);
+      /* check if the namelist got emptied during the course of reading */
+      /* the tape, if so stop by setting status to EOF */
+      if (namelist_freed)
+        status = HEADER_END_OF_FILE;
       switch (status)
 	{
 	case HEADER_STILL_UNREAD:

gnu/dist/tar/src/names.c

@@ -549,6 +549,7 @@ name_match (const char *path)
   while (1)
     {
       struct name *cursor = namelist;
+      struct name *tmpnlp;
 
       if (!cursor)
 	return ! files_from_option;
@@ -572,6 +573,38 @@ name_match (const char *path)
 	      nametail = &namelist;
 	    }
 	  chdir_do (cursor->change_dir);
+	  if (fast_read_option)
+	    {
+	    /* remove the current entry, since we found a match */
+	      if (namelist->next == NULL)
+	        {
+	          /* the list contains one element */
+	          free(namelist);
+	          namelist = 0;
+	          nametail = &namelist;
+	          /* set a boolean to decide wether we started with a */
+	          /* non-empty  namelist, that was emptied */
+	          namelist_freed = 1;
+	        }
+	      else
+	        {
+	          if (cursor == namelist)
+	            {
+	              /* the first element is the one */
+	              tmpnlp = namelist->next;
+	              free(namelist);
+	              namelist = tmpnlp;
+	            }
+	          else
+	            {
+	              tmpnlp = namelist;
+	              while (tmpnlp->next != cursor)
+	                tmpnlp = tmpnlp->next;
+	              tmpnlp->next = cursor->next;
+	              free(cursor);
+	            }
+	        }
+	    }
   
 	  /* We got a match.  */
 	  return 1;

gnu/dist/tar/src/tar.c

@@ -200,7 +200,7 @@ static struct option long_options[] =
   {"exclude", required_argument, 0, EXCLUDE_OPTION},
   {"exclude-from", required_argument, 0, 'X'},
   {"extract", no_argument, 0, 'x'},
-  {"fast-read", no_argument, 0, 0},
+  {"fast-read", no_argument, &fast_read_option, 1},
   {"file", required_argument, 0, 'f'},
   {"files-from", required_argument, 0, 'T'},
   {"force-local", no_argument, &force_local_option, 1},
@@ -337,8 +337,9 @@ Operation modifiers:\n\
   -G, --incremental          handle old GNU-format incremental backup\n\
   -g, --listed-incremental=FILE\n\
                              handle new GNU-format incremental backup\n\
-      --ignore-failed-read   do not exit with nonzero on unreadable files\n"),
-	     stdout);
+      --ignore-failed-read   do not exit with nonzero on unreadable files\n\
+      --fast-read            stop after desired names in archive have been found\n"),
+	    stdout);
       fputs (_("\
 \n\
 Handling of file attributes:\n\
@@ -512,6 +513,7 @@ decode_options (int argc, char **argv)
   excluded = new_exclude ();
   newer_mtime_option = TYPE_MINIMUM (time_t);
   recursion_option = FNM_LEADING_DIR;
+  namelist_freed = 0;
 
   owner_option = -1;
   group_option = -1;