Fix fencepost bug.

diff --git a/v7/src/runtime/string.scm b/v7/src/runtime/string.scm
index 27a2309eef77d4ba1f3bd969a6781c7f6d37639d..64f160a944e02917f270bde8e7ab2a2d045d4a45 100644 (file)
--- a/v7/src/runtime/string.scm
+++ b/v7/src/runtime/string.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Id: string.scm,v 14.20 1999/05/07 21:26:13 cph Exp $
+$Id: string.scm,v 14.21 1999/05/07 21:41:13 cph Exp $
 
 Copyright (c) 1988-1999 Massachusetts Institute of Technology
 
@@ -683,19 +683,20 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 (define (%dumb-substring-search-backward text tstart tend pattern pstart pend)
   (if (fix:= pstart pend)
       0
-      (let* ((trailer (string-ref pattern (fix:- pend 1)))
+      (let* ((pend-1 (fix:- pend 1))
+            (trailer (string-ref pattern pend-1))
             (plen (fix:- pend pstart))
-            (tstart (fix:+ tstart plen)))
+            (tstart+plen (fix:+ tstart plen)))
        (let loop ((tend tend))
          (let ((tend
                 (let find-trailer ((tend tend))
-                  (and (fix:< tstart tend)
+                  (and (fix:<= tstart+plen tend)
                        (if (char=? trailer (string-ref text (fix:- tend 1)))
                            tend
                            (find-trailer (fix:- tend 1)))))))
            (and tend
                 (if (substring=? text (fix:- tend plen) (fix:- tend 1)
-                                 pattern pstart (fix:- pend 1))
+                                 pattern pstart pend-1)
                     tend
                     (loop (fix:- tend 1)))))))))
 \f