Fix [Bug 1631017]

2 files changed, 33 insertions, 22 deletions

diff --git a/ChangeLog b/ChangeLog
index 8dc700f..e7ec041 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-01-22  Donal K. Fellows  <donal.k.fellows@manchester.ac.uk>
+
+	* compat/memcmp.c (memcmp): Reworked so that arithmetic is never
+	performed upon void pointers, since that is illegal. [Bug 1631017]
+
 2007-01-19  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
 
 	* generic/tclCompile.c (TclCompileScript): Reduce the frequency with
diff --git a/compat/memcmp.c b/compat/memcmp.c
index 68e18c5..43202a5 100644
--- a/compat/memcmp.c
+++ b/compat/memcmp.c
@@ -1,25 +1,23 @@
-/* 
+/*
  * memcmp.c --
  *
  *	Source code for the "memcmp" library routine.
  *
  * Copyright (c) 1998 Sun Microsystems, Inc.
  *
- * See the file "license.terms" for information on usage and redistribution
- * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ * See the file "license.terms" for information on usage and redistribution of
+ * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * SCCS: @(#) memcmp.c 1.2 98/01/19 10:48:58
+ * RCS: @(#) $Id: memcmp.c,v 1.4 2007/01/22 09:15:50 dkf Exp $
  */
 
 #include "tclPort.h"
 
 /*
- * Here is the prototype just in case it is not included
- * in tclPort.h.
+ * Here is the prototype just in case it is not included in tclPort.h.
  */
 
-int		memcmp _ANSI_ARGS_((CONST VOID *s1,
-			    CONST VOID *s2, size_t n));
+int		memcmp(CONST VOID *s1, CONST VOID *s2, size_t n);
 
 /*
  *----------------------------------------------------------------------
@@ -29,11 +27,10 @@ int		memcmp _ANSI_ARGS_((CONST VOID *s1,
  *	Compares two bytes sequences.
  *
  * Results:
- *     compares  its  arguments, looking at the first n
- *     bytes (each interpreted as an unsigned char), and  returns
- *     an integer less than, equal to, or greater than 0, accord-
- *     ing as s1 is less  than,  equal  to,  or
- *     greater than s2 when taken to be unsigned 8 bit numbers.
+ *	Compares its arguments, looking at the first n bytes (each interpreted
+ *	as an unsigned char), and returns an integer less than, equal to, or
+ *	greater than 0, according as s1 is less than, equal to, or greater
+ *	than s2 when taken to be unsigned 8 bit numbers.
  *
  * Side effects:
  *	None.
@@ -42,19 +39,28 @@ int		memcmp _ANSI_ARGS_((CONST VOID *s1,
  */
 
 int
-memcmp(s1, s2, n)
-    CONST VOID *s1;			/* First string. */
-    CONST VOID *s2;			/* Second string. */
-    size_t      n;                      /* Length to compare. */
+memcmp(
+    CONST VOID *s1,		/* First string. */
+    CONST VOID *s2,		/* Second string. */
+    size_t n)			/* Length to compare. */
 {
-    unsigned char u1, u2;
+    CONST unsigned char *ptr1 = (CONST unsigned char *) s1;
+    CONST unsigned char *ptr2 = (CONST unsigned char *) s2;
+
+    for ( ; n-- ; ptr1++, ptr2++) {
+	unsigned char u1 = *ptr1, u2 = *ptr2;
 
-    for ( ; n-- ; s1++, s2++) {
-	u1 = * (unsigned char *) s1;
-	u2 = * (unsigned char *) s2;
-	if ( u1 != u2) {
+	if (u1 != u2) {
 	    return (u1-u2);
 	}
     }
     return 0;
 }
+
+/*
+ * Local Variables:
+ * mode: c
+ * c-basic-offset: 4
+ * fill-column: 78
+ * End:
+ */