[PATCH] Re: [perl #22718] core function index() returns -1 when search string contains spaces

[Luke Palmer]

> # New Ticket Created by  "Clinton A. Pierce" 
> # Please include the string:  [perl #22718]
> # in the subject line of all future correspondence about this issue. 
> # <URL: http://rt.perl.org/rt2/Ticket/Display.html?id=22718 >
> 
> 
> In this code:
> 
> .sub _main
>          .local string source
>          .local string lookfor
> 
>          source="This is not quite right"
>          lookfor=" is "
> 
>          index $I0, source, lookfor, 0
>          print "(expect 4) $I0 = "
>          print $I0                    # you'll actually get -1
> 
>          lookfor="is"
>          index $I0, source, lookfor, 0
>          print "\n(expect 2) $I0 = "
>          print $I0                    # You will correctly get 2
>          end
> .end
> 
> The string " is " (note the spaces) will not be found within "This is not 
> quite right".  Removing the spaces has the expected results.  I looked 
> briefly for an explanation in strings.c but my eyes glazed over at the 
> sight of the multibyte and encoding stuff.  

The bug wasn't in the multibyte part though ;-)

I made a slight error in implementing the algorithm.  It must've been
some strange coincidence that all the tests passed anyway.

Well, here's the new one:

Index: string.c
===================================================================
RCS file: /cvs/public/parrot/string.c,v
retrieving revision 1.132
diff -u -r1.132 string.c
--- string.c    22 Jun 2003 08:57:49 -0000      1.132
+++ string.c    23 Jun 2003 05:53:20 -0000
@@ -370,7 +370,7 @@
     const UINTVAL              find_strlen   = find->strlen;
     const UINTVAL              str_strlen    = str->strlen;
     const unsigned char* const lastmatch     =
-                                   str_strstart + str_strlen - find_strlen;
+                                   str_strstart + str_strlen;
     UINTVAL* p;
     const unsigned char* cp;
     UINTVAL endct, pos;
@@ -393,9 +393,9 @@
     /* Perform the match */
 
     pos = start;
-    cp = str_strstart + start;
+    cp = str_strstart + start + find_strlen;
     while (cp <= lastmatch) {
-        register const unsigned char* sp = cp + find_strlen;
+        register const unsigned char* sp = cp;
         register const unsigned char* fp = find_strstart + find_strlen;
 
         while (fp > find_strstart) {
@@ -406,7 +406,7 @@
             return pos;
         }
         else {
-            register UINTVAL bsi = badshift[*sp];
+            register UINTVAL bsi = badshift[*(cp-1)];
             cp  += bsi;
             pos += bsi;
         }