Put cycle-detecting code inside an

#ifdef ENABLE_CYCLE_CHECK, for systems lacking d_ino.
[D_INO_IN_DIRENT]: Define ENABLE_CYCLE_CHECK.

(ASSIGN_STRDUPA): Clean up.
(right_justify): Use memcpy return value directly.
Suggestions from Ulrich Drepper.

(remove_cwd_entries) [! defined HAVE_WORKING_READDIR]: Impose overhead
of working around non-POSIX readdir implementation only on systems
that need it.
(remove_cwd_entries): Temporarily save a copy of each entry name in
an obstack rather than on the stack via alloca, then free it in the
likely event that we don't save the entry in the hash table.

src/rm.c

@@ -22,7 +22,7 @@
 
    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' remove_cwd_entries)
+   reply), the failure is noted (see description of `ht' in remove_cwd_entries)
    so that when/if the containing directory is reopened, RM doesn't try to
    remove the entry again.
 
@@ -89,10 +89,10 @@
 # define ASSIGN_STRDUPA(DEST, S)		\
   do						\
     {						\
-      size_t len_ = strlen (S) + 1;		\
+      const char *s_ = (S);			\
+      size_t len_ = strlen (s_) + 1;		\
       char *tmp_dest_ = alloca (len_);		\
-      memcpy (tmp_dest_, (S), len_);		\
-      DEST = tmp_dest_;				\
+      DEST = memcpy (tmp_dest_, (s_), len_);	\
     }						\
   while (0)
 #endif
@@ -378,9 +378,7 @@ right_justify (char *dst, size_t dst_len, const char *src, size_t src_len,
       *truncated = 1;
     }
 
-  memcpy (dp, sp, src_len);
-
-  *result = dp;
+  *result = memcpy (dp, sp, src_len);
   return dst_len - src_len;
 }
 
@@ -434,10 +432,11 @@ full_filename (const char *filename)
 	}
     }
 
-  /* Copy directory part, including trailing slash.  */
+  /* Copy directory part, including trailing slash, and then
+     append the filename part, including a trailing zero byte.  */
+  /* FIXME: use mempcpy like this instead of two memcpy calls:
+     mempcpy (mempcpy (buf, dir_name, dir_len), filename, filename_len + 1); */
   memcpy (buf, dir_name, dir_len);
-
-  /* Append filename part, including trailing zero byte.  */
   memcpy (buf + dir_len, filename, filename_len + 1);
 
   assert (strlen (buf) + 1 == n_bytes_needed);
@@ -532,6 +531,9 @@ remove_cwd_entries (void)
      due either to an error or to an interactive `no' response.  */
   struct HT *ht = NULL;
 
+  /* FIXME: describe */
+  struct obstack entry_name_pool;
+
   enum RM_status status = RM_OK;
 
   if (dirp)
@@ -568,12 +570,34 @@ remove_cwd_entries (void)
 	  enum RM_status tmp_status;
 	  struct dirent *dp;
 
+	  obstack_init (&entry_name_pool);
+
 /* FILE should be skipped if it is `.' or `..', or if it is in
    the table, HT, of entries we've already processed.  */
 #define SKIPPABLE(Ht, File) (DOT_OR_DOTDOT(File) \
 			     || (Ht && hash_query_in_table (Ht, File)))
 
+	  /* FIXME: use readdir_r directly into an obstack to avoid
+	     the obstack_copy0 below --
+	     Suggestion from Uli.  Be careful -- there are different
+	     prototypes on e.g. Solaris.
+
+	     Do something like this:
+	     #define NAME_MAX_FOR(Parent_dir) pathconf ((Parent_dir),
+	                                                 _PC_NAME_MAX);
+	     dp = obstack_alloc (sizeof (struct dirent)
+	                         + NAME_MAX_FOR (".") + 1);
+	     fail = xreaddir (dirp, dp);
+	     where xreaddir is ...
+
+	     But what about systems like the hurd where NAME_MAX is supposed
+	     to be effectively unlimited.  We don't want to have to allocate
+	     a huge buffer to accommodate maximum possible entry name.  */
+
 	  dp = readdir (dirp);
+
+/* FIXME: add autoconf test to detect this.  */
+#ifndef HAVE_WORKING_READDIR
 	  if (dp == NULL)
 	    {
 	      /* Since we have probably modified the directory since it
@@ -587,6 +611,7 @@ remove_cwd_entries (void)
 		  /* empty */
 		}
 	    }
+#endif
 
 	  if (dp == NULL)
 	    break;
@@ -598,7 +623,8 @@ remove_cwd_entries (void)
 
 	  /* Save a copy of the name of this entry, in case we have
 	     to add it to the set of unremoved entries below.  */
-	  ASSIGN_STRDUPA (entry_name, dp->d_name);
+	  entry_name = obstack_copy0 (&entry_name_pool,
+				      dp->d_name, NLENGTH (dp));
 
 	  /* CAUTION: after this call to rm, DP may not be valid --
 	     it may have been freed due to a close in a recursive call
@@ -628,6 +654,11 @@ remove_cwd_entries (void)
 	      if (fail)
 		error (1, 0, _("Memory exhausted"));
 	    }
+	  else
+	    {
+	      /* This entry was not saved in the hash table.  Free it.  */
+	      obstack_free (&entry_name_pool, entry_name);
+	    }
 
 	  if (dirp == NULL)
 	    break;
@@ -647,6 +678,8 @@ remove_cwd_entries (void)
       hash_free (ht);
     }
 
+  obstack_free (&entry_name_pool, NULL);
+
   return status;
 }