[src/trunk]: src/usr.bin/make make(1): fix :hash modifier on 16-bit platforms

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c7c6570fd4db
branches:  trunk
changeset: 935518:c7c6570fd4db
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Jul 04 15:44:07 2020 +0000

description:
make(1): fix :hash modifier on 16-bit platforms

On platforms where int has only 16 bits the shifts would have been in
16-bit arithmetic, which would invoke undefined behavior for "ustr[3] <<
24" as well as "ustr[2] << 16" (C99, 6.5.7p3).

diffstat:

 usr.bin/make/var.c |  21 ++++++++++++---------
 1 files changed, 12 insertions(+), 9 deletions(-)

diffs (67 lines):

diff -r 9ef4b48824d1 -r c7c6570fd4db usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sat Jul 04 15:14:56 2020 +0000
+++ b/usr.bin/make/var.c        Sat Jul 04 15:44:07 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.251 2020/07/04 10:49:09 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.252 2020/07/04 15:44:07 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -69,14 +69,14 @@
  */
 
 #ifndef MAKE_NATIVE
-static char rcsid[] = "$NetBSD: var.c,v 1.251 2020/07/04 10:49:09 rillig Exp $";
+static char rcsid[] = "$NetBSD: var.c,v 1.252 2020/07/04 15:44:07 rillig Exp $";
 #else
 #include <sys/cdefs.h>
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)var.c      8.3 (Berkeley) 3/19/94";
 #else
-__RCSID("$NetBSD: var.c,v 1.251 2020/07/04 10:49:09 rillig Exp $");
+__RCSID("$NetBSD: var.c,v 1.252 2020/07/04 15:44:07 rillig Exp $");
 #endif
 #endif /* not lint */
 #endif
@@ -2104,12 +2104,12 @@
  *-----------------------------------------------------------------------
  */
 static char *
-VarHash(char *str)
+VarHash(const char *str)
 {
     static const char    hexdigits[16] = "0123456789abcdef";
     Buffer         buf;
     size_t         len, len2;
-    unsigned char  *ustr = (unsigned char *)str;
+    const unsigned char *ustr = (const unsigned char *)str;
     uint32_t       h, k, c1, c2;
 
     h  = 0x971e137bU;
@@ -2121,18 +2121,21 @@
        k = 0;
        switch (len) {
        default:
-           k = (ustr[3] << 24) | (ustr[2] << 16) | (ustr[1] << 8) | ustr[0];
+           k = ((uint32_t)ustr[3] << 24) |
+               ((uint32_t)ustr[2] << 16) |
+               ((uint32_t)ustr[1] << 8) |
+               (uint32_t)ustr[0];
            len -= 4;
            ustr += 4;
            break;
        case 3:
-           k |= (ustr[2] << 16);
+           k |= (uint32_t)ustr[2] << 16;
            /* FALLTHROUGH */
        case 2:
-           k |= (ustr[1] << 8);
+           k |= (uint32_t)ustr[1] << 8;
            /* FALLTHROUGH */
        case 1:
-           k |= ustr[0];
+           k |= (uint32_t)ustr[0];
            len = 0;
        }
        c1 = c1 * 5 + 0x7b7d159cU;