cut: improve detection of invalid ranges

Commit 0068ce2fa (cut: add toybox-compatible options -O OUTSEP,
-D, -F LIST) added detection of reversed ranges.  Further
improvements are possible.

- The test for reversed ranges compared the start after it had been
  decremented with the end before decrement.  It thus missed ranges
  of the form 2-1.

- Zero isn't a valid start value for a range.  (Nor is it a valid
  end value, but that's caught by the test for a reversed range.)

- The code

        if (!*ltok)
            e = INT_MAX;

  duplicates a check that's already been made.

- Display the actual range in the error message to make it easier
  to find which range was at fault.

Adds 0-48 bytes.

(GitHub issue #467)

1 files changed, 11 insertions, 8 deletions

diff --git a/coreutils/cut.c b/coreutils/cut.c
index 8cae2eca3..f7b501a46 100644
--- a/coreutils/cut.c
+++ b/coreutils/cut.c
@@ -276,8 +276,12 @@ int cut_main(int argc UNUSED_PARAM, char **argv)
                                 s = xatoi_positive(ntok);
                                 /* account for the fact that arrays are zero based, while
                                  * the user expects the first char on the line to be char #1 */
+#if !ENABLE_PLATFORM_MINGW32
                                 if (s != 0)
                                         s--;
+#else
+                                s--;
+#endif
                         }
 
                         /* get the end pos */
@@ -287,21 +291,20 @@ int cut_main(int argc UNUSED_PARAM, char **argv)
                                 e = INT_MAX;
                         } else {
                                 e = xatoi_positive(ltok);
-                                /* if the user specified and end position of 0,
+                                /* if the user specified no end position,
                                  * that means "til the end of the line" */
+#if !ENABLE_PLATFORM_MINGW32
                                 if (!*ltok)
                                         e = INT_MAX;
-#if !ENABLE_PLATFORM_MINGW32
                                 else if (e < s)
                                         bb_error_msg_and_die("%d<%d", e, s);
-                                e--;    /* again, arrays are zero based, lines are 1 based */
-#else
-                                else if (e != 0)
-                                        e--;    /* again, zero based arrays, one based lines */
-                                if (e < s)
-                                        bb_error_msg_and_die("%d<%d", e, s);
 #endif
+                                e--;    /* again, arrays are zero based, lines are 1 based */
                         }
+#if ENABLE_PLATFORM_MINGW32
+                        if (s < 0 || e < s)
+                                bb_error_msg_and_die("invalid range %s-%s", ntok, ltok ?: ntok);
+#endif
 
                         /* add the new list */
                         cut_lists = xrealloc_vector(cut_lists, 4, nlists);