ls -U1 now uses constant memory

When printing one name per line and not sorting, ls now uses
constant memory per directory, no matter how many files are in
the directory.
* ls.c (print_dir): Print each file name immediately, when possible.
* NEWS: Mention the improvement.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/ls.c b/src/ls.c
index 4b69f7d22..a661c063f 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -2402,6 +2402,20 @@ print_dir (char const *name, char const *realname, bool command_line_arg)
 #endif
 	      total_blocks += gobble_file (next->d_name, type, D_INO (next),
 					   false, name);
+
+	      /* In this narrow case, print out each name right away, so
+		 ls uses constant memory while processing the entries of
+		 this directory.  Useful when there are many (millions)
+		 of entries in a directory.  */
+	      if (format == one_per_line && sort_type == sort_none)
+		{
+		  /* We must call sort_files in spite of
+		     "sort_type == sort_none" for its initialization
+		     of the sorted_file vector.  */
+		  sort_files ();
+		  print_current_files ();
+		  clear_files ();
+		}
 	    }
 	}
       else if (errno != 0)