ls: fix off by one error when determining max display columns

* src/ls.c (main): Account for the first column not including
a separator when calculating max_idx.
* tests/ls/w-option.sh: Add a test case.
* NEWS: Mention the bug fix.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/ls.c b/src/ls.c
index 0c9dc78db..ef372553f 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -1979,7 +1979,11 @@ decode_switches (int argc, char **argv)
         }
     }
 
-  max_idx = MAX (1, line_length / MIN_COLUMN_WIDTH);
+  /* Determine the max possible number of display columns.  */
+  max_idx = line_length / MIN_COLUMN_WIDTH;
+  /* Account for first display column not having a separator,
+     or line_lengths shorter than MIN_COLUMN_WIDTH.  */
+  max_idx += line_length % MIN_COLUMN_WIDTH != 0;
 
   filename_quoting_options = clone_quoting_options (NULL);
   if (get_quoting_style (filename_quoting_options) == escape_quoting_style)