rm: rewrite to use fts

* remove.c: Don't include "unlinkdir.h"; no longer used.
Do not include <setjmp.h> or "cycle-check.h".  Likewise.
Include "xfts.h".
(dir_name, dir_len): Remove definitions.
(CONSECUTIVE_READDIR_UNLINK_THRESHOLD): Likewise.
(INODE_SORT_DIR_ENTRIES_THRESHOLD, NEED_REWIND, D_TYPE): Likewise.
(struct dirstack_state, Dirstack_state): Likewise.
(g_buf, g_n_allocated): Remove declarations.
(hash_freer, hash_compare_strings, rm_malloc): Remove functions.
(rm_free, push_dir, top_dir, pop_dir, right_justify): Likewise.
(full_filename0, xfull_filename, full_filename_): Likewise.
(AD_stack_height, AD_stack_top, AD_stack_pop, AD_stack_clear): Likewise.
(obstack_init_minimal, ds_init, ds_clear, ds_free): Likewise.
(AD_pop_and_chdir, AD_ensure_initialized, AD_mark_helper): Likewise.
(AD_mark_as_unremovable, AD_mark_current_as_unremovable): Likewise.
(AD_push_initial, AD_push, AD_push, AD_is_removable): Likewise.
(write_protected_non_symlink): Change 3rd parameter from
dirstack_state "ds" to full_name.
(prompt): Adjust parameters.  Now, state comes from FTS/FTSENT pair.
Those replace fd_cwd and "ds".  Remove "filename".  Remove pdirent_type
in favor of new "is_dir" parameter.  Rename is_empty to is_empty_p.
(DO_RMDIR, DO_UNLINK): Remove definitions.
(remove_entry, fd_to_subdirp, compare_ino): Remove functions.
(dirent_count, dirent_inode_sort_may_be_useful): Likewise.
(preprocess_dir): Likewise.
(fts_skip_tree, mark_ancestor_dirs, excise, rm_fts): New functions.
(remove_cwd_entries, remove_dir, rm_1): Remove functions.
(rm): Rewrite as a simple loop calling fts_read and dispatching
each entry via rm_fts.
* src/rm.c (main): Adapt to new signature of rm().
* bootstrap.conf (gnulib_modules): Remove unlinkdir, no longer used.
* src/Makefile.am (sc_tight_scope): Also recognize an extern "enum"
declaration.
* tests/rm/empty-name: Adjust expected output to match new diagnostic.
* NEWS (Improvements): Mention it.

NEWS

@@ -2,6 +2,12 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Improvements
+
+  rm: rewrite to use gnulib's fts
+  This makes rm -rf significantly faster (400-500%) in some pathological
+  cases, and slightly slower (20%) in at least one pathological case.
+
 
 * Noteworthy changes in release 7.6 (2009-09-11) [stable]
 

bootstrap.conf

@@ -209,7 +209,6 @@ gnulib_modules="
   unicodeio
   unistd-safer
   unlink-busy
-  unlinkdir
   unlocked-io
   update-copyright
   uptime

src/Makefile.am

@@ -453,7 +453,7 @@ sc_tight_scope: $(bin_PROGRAMS)
 	( printf 'main\nusage\n_.*\n';					\
 	  grep -h -A1 '^extern .*[^;]$$' $$src				\
 	    | grep -vE '^(extern |--)' | sed 's/ .*//';			\
-	  perl -ne '/^extern \S+ (\S*) \(/ and print "$$1\n"' $$hdr;	\
+	  perl -ne '/^extern (?:enum )?\S+ (\S*) \(/ and print "$$1\n"' $$hdr;	\
 	) | $(ASSORT) -u | sed 's/^/^/;s/$$/$$/' > $$t;			\
 	nm -e *.$(OBJEXT)						\
 	    | sed -n 's/.* T //p'					\

src/mv.c

@@ -219,11 +219,14 @@ do_move (const char *source, const char *dest, const struct cp_options *x)
         {
           struct rm_options rm_options;
           enum RM_status status;
+          char const *dir[2];
 
           rm_option_init (&rm_options);
           rm_options.verbose = x->verbose;
+          dir[0] = dir_to_remove;
+          dir[1] = NULL;
 
-          status = rm (1, &dir_to_remove, &rm_options);
+          status = rm ((void*) dir, &rm_options);
           assert (VALID_STATUS (status));
           if (status == RM_ERROR)
             ok = false;

src/remove.h

@@ -37,6 +37,7 @@ struct rm_options
   /* If true, query the user about whether to remove each file.  */
   enum rm_interactive interactive;
 
+  // FIXME: remove
   /* If true, do not traverse into (or remove) any directory that is
      on a file system (i.e., that has a different device number) other
      than that of the corresponding command line argument.  Note that
@@ -88,7 +89,6 @@ enum RM_status
     }								\
   while (0)
 
-enum RM_status rm (size_t n_files, char const *const *file,
-                   struct rm_options const *x);
+extern enum RM_status rm (char *const *file, struct rm_options const *x);
 
 #endif

src/rm.c

@@ -14,32 +14,9 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-/* Written by Paul Rubin, David MacKenzie, and Richard Stallman.
-   Reworked to use chdir and avoid recursion by Jim Meyering.  */
-
-/* Implementation overview:
-
-   In the `usual' case, RM saves no state for directories it is processing.
-   When a removal fails (either due to an error or to an interactive `no'
-   reply), the failure is noted (see description of `ht' in remove.c's
-   remove_cwd_entries function) so that when/if the containing directory
-   is reopened, RM doesn't try to remove the entry again.
-
-   RM may delete arbitrarily deep hierarchies -- even ones in which file
-   names (from root to leaf) are longer than the system-imposed maximum.
-   It does this by using chdir to change to each directory in turn before
-   removing the entries in that directory.
-
-   RM detects directory cycles lazily.  See lib/cycle-check.c.
-
-   RM is careful to avoid forming full file names whenever possible.
-   A full file name is formed only when it is about to be used -- e.g.
-   in a diagnostic or in an interactive-mode prompt.
-
-   RM minimizes the number of lstat system calls it makes.  On systems
-   that have valid d_type data in directory entries, RM makes only one
-   lstat call per command line argument -- regardless of the depth of
-   the hierarchy.  */
+/* Initially written by Paul Rubin, David MacKenzie, and Richard Stallman.
+   Reworked to use chdir and avoid recursion, and later, rewritten
+   once again, to use fts, by Jim Meyering.  */
 
 #include <config.h>
 #include <stdio.h>
@@ -358,7 +335,7 @@ main (int argc, char **argv)
     }
 
   size_t n_files = argc - optind;
-  char const *const *file = (char const *const *) argv + optind;
+  char **file =  argv + optind;
 
   if (prompt_once && (x.recursive || 3 < n_files))
     {
@@ -370,7 +347,8 @@ main (int argc, char **argv)
       if (!yesno ())
         exit (EXIT_SUCCESS);
     }
-  enum RM_status status = rm (n_files, file, &x);
+
+  enum RM_status status = rm (file, &x);
   assert (VALID_STATUS (status));
   exit (status == RM_ERROR ? EXIT_FAILURE : EXIT_SUCCESS);
 }

tests/rm/empty-name

@@ -34,7 +34,7 @@ my @Tests =
      # test-name options input expected-output
      #
      ['empty-name-1', "''", {EXIT => 1},
-      {ERR => "$prog: cannot remove `': No such file or directory\n"}],
+      {ERR => "$prog: invalid argument: `'\n"}],
     );
 
 my $save_temps = $ENV{SAVE_TEMPS};