New option --sort=ORDER

This option makes tar sort the entries of directories that will be
added to an archive according to ORDER (none, name, or order).

Based on proposition by Dick Streefland (https://savannah.gnu.org/patch/?7892).

* src/common.h (savedir_sort_order): New global.
* src/create.c: Pass savedir_sort_order to streamsavedir.
* src/misc.c: Likewise.
* src/tar.c: New option --sort.

* NEWS: Update.
* doc/tar.texi: Document the --sort option.
* doc/tar.1: Likewise.

src/common.h

@@ -386,6 +386,8 @@ GLOBAL dev_t root_device;
 /* Unquote filenames */
 GLOBAL bool unquote_option;
 
+GLOBAL int savedir_sort_order;
+
 /* Show file or archive names after transformation.
    In particular, when creating archive in verbose mode, list member names
    as stored in the archive */

src/create.c

@@ -1288,7 +1288,7 @@ get_directory_entries (struct tar_stat_info *st)
   while (! (st->dirstream = fdopendir (st->fd)))
     if (! open_failure_recover (st))
       return 0;
-  return streamsavedir (st->dirstream);
+  return streamsavedir (st->dirstream, savedir_sort_order);
 }
 
 /* Dump the directory ST.  Return true if successful, false (emitting

src/misc.c

@@ -1239,7 +1239,7 @@ tar_savedir (const char *name, int must_exist)
       open_error (name);
     }
   else if (! ((dir = fdopendir (fd))
-	      && (ret = streamsavedir (dir))))
+	      && (ret = streamsavedir (dir, savedir_sort_order))))
     savedir_error (name);
 
   if (dir ? closedir (dir) != 0 : 0 <= fd && close (fd) != 0)

src/tar.c

@@ -51,6 +51,7 @@
 #include <xstrtol.h>
 #include <stdopen.h>
 #include <priv-set.h>
+#include <savedir.h>
 
 /* Local declarations.  */
 
@@ -342,6 +343,7 @@ enum
   SHOW_SNAPSHOT_FIELD_RANGES_OPTION,
   SHOW_TRANSFORMED_NAMES_OPTION,
   SKIP_OLD_FILES_OPTION,
+  SORT_OPTION,
   SPARSE_VERSION_OPTION,
   STRIP_COMPONENTS_OPTION,
   SUFFIX_OPTION,
@@ -551,6 +553,13 @@ static struct argp_option options[] = {
       " directories until the end of extraction"), GRID+1 },
   {"no-delay-directory-restore", NO_DELAY_DIRECTORY_RESTORE_OPTION, 0, 0,
    N_("cancel the effect of --delay-directory-restore option"), GRID+1 },
+  {"sort", SORT_OPTION, N_("ORDER"), 0,
+#if D_INO_IN_DIRENT
+   N_("directory sorting order: none (default), name or inode"
+#else
+   N_("directory sorting order: none (default) or name"
+#endif
+     ), GRID+1 },
 #undef GRID
 
 #define GRID 55
@@ -1310,6 +1319,21 @@ parse_owner_group (char *arg, uintmax_t field_max, char const **name_option)
 /* Either NL or NUL, as decided by the --null option.  */
 static char filename_terminator;
 
+static char const *const sort_mode_arg[] = {
+  "none",
+  "name",
+  "inode",
+  NULL
+};
+
+static int sort_mode_flag[] = {
+    SAVEDIR_SORT_NONE,
+    SAVEDIR_SORT_NAME,
+    SAVEDIR_SORT_INODE
+};
+
+ARGMATCH_VERIFY (sort_mode_arg, sort_mode_flag);
+
 static error_t
 parse_opt (int key, char *arg, struct argp_state *state)
 {
@@ -1997,6 +2021,11 @@ parse_opt (int key, char *arg, struct argp_state *state)
       show_transformed_names_option = true;
       break;
 
+    case SORT_OPTION:
+      savedir_sort_order = XARGMATCH ("--sort", arg,
+				      sort_mode_arg, sort_mode_flag);
+      break;
+
     case SUFFIX_OPTION:
       backup_option = true;
       args->backup_suffix_string = arg;
@@ -2274,6 +2303,8 @@ decode_options (int argc, char **argv)
   tar_sparse_major = 1;
   tar_sparse_minor = 0;
 
+  savedir_sort_order = SAVEDIR_SORT_NONE;
+  
   owner_option = -1; owner_name_option = NULL;
   group_option = -1; group_name_option = NULL;