[src/trunk]: src/usr.bin/make make(1): document undefined behavior in Parse_I...

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

details:   https://anonhg.NetBSD.org/src/rev/fb349105a850
branches:  trunk
changeset: 956631:fb349105a850
user:      rillig <rillig%NetBSD.org@localhost>
date:      Mon Nov 02 22:44:29 2020 +0000

description:
make(1): document undefined behavior in Parse_IsVar

Sigh.  If only C could be compiled in strict mode that detects these
out-of-bounds memory accesses.

diffstat:

 usr.bin/make/parse.c                |  6 ++++--
 usr.bin/make/unit-tests/varname.exp |  6 +++---
 usr.bin/make/unit-tests/varname.mk  |  6 +++++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diffs (70 lines):

diff -r e2cf2ffc6739 -r fb349105a850 usr.bin/make/parse.c
--- a/usr.bin/make/parse.c      Mon Nov 02 22:29:48 2020 +0000
+++ b/usr.bin/make/parse.c      Mon Nov 02 22:44:29 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: parse.c,v 1.420 2020/11/01 00:24:57 rillig Exp $       */
+/*     $NetBSD: parse.c,v 1.421 2020/11/02 22:44:29 rillig Exp $       */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -117,7 +117,7 @@
 #include "pathnames.h"
 
 /*     "@(#)parse.c    8.3 (Berkeley) 3/19/94" */
-MAKE_RCSID("$NetBSD: parse.c,v 1.420 2020/11/01 00:24:57 rillig Exp $");
+MAKE_RCSID("$NetBSD: parse.c,v 1.421 2020/11/02 22:44:29 rillig Exp $");
 
 /* types and constants */
 
@@ -1850,6 +1850,8 @@
 #endif
 
     /* Scan for one of the assignment operators outside a variable expansion */
+    /* FIXME: undefined behavior. In unit-tests/varname.mk:try1, at the end
+     * of the loop, p already points to the next line. */
     while ((ch = *p++) != 0) {
        if (ch == '(' || ch == '{') {
            level++;
diff -r e2cf2ffc6739 -r fb349105a850 usr.bin/make/unit-tests/varname.exp
--- a/usr.bin/make/unit-tests/varname.exp       Mon Nov 02 22:29:48 2020 +0000
+++ b/usr.bin/make/unit-tests/varname.exp       Mon Nov 02 22:44:29 2020 +0000
@@ -9,16 +9,16 @@
 Result of ${:UVAR(((} is "VAR(((" (VARE_UNDEFERR|VARE_WANTRES, none, VEF_UNDEF|VEF_DEF)
 Global:.ALLTARGETS =  VAR(((=)
 No closing parenthesis in archive specification
-make: "varname.mk" line 26: Error in archive specification: "VAR"
+make: "varname.mk" line 29: Error in archive specification: "VAR"
 Var_Parse: ${:UVAR\(\(\(}=     try2 with VARE_UNDEFERR|VARE_WANTRES
 Applying ${:U...} to "" (VARE_UNDEFERR|VARE_WANTRES, none, VEF_UNDEF)
 Result of ${:UVAR\(\(\(} is "VAR\(\(\(" (VARE_UNDEFERR|VARE_WANTRES, none, VEF_UNDEF|VEF_DEF)
 Global:.ALLTARGETS =  VAR(((=) VAR\(\(\(=
-make: "varname.mk" line 27: Need an operator
+make: "varname.mk" line 30: Need an operator
 Var_Parse: ${:UVAR\(\(\(}=     try3 with VARE_UNDEFERR|VARE_WANTRES
 Applying ${:U...} to "" (VARE_UNDEFERR|VARE_WANTRES, none, VEF_UNDEF)
 Result of ${:UVAR\(\(\(} is "VAR\(\(\(" (VARE_UNDEFERR|VARE_WANTRES, none, VEF_UNDEF|VEF_DEF)
-make: "varname.mk" line 28: Need an operator
+make: "varname.mk" line 31: Need an operator
 Global:.MAKEFLAGS =  -r -k -d v -d
 Global:.MAKEFLAGS =  -r -k -d v -d 0
 make: Fatal errors encountered -- cannot continue
diff -r e2cf2ffc6739 -r fb349105a850 usr.bin/make/unit-tests/varname.mk
--- a/usr.bin/make/unit-tests/varname.mk        Mon Nov 02 22:29:48 2020 +0000
+++ b/usr.bin/make/unit-tests/varname.mk        Mon Nov 02 22:44:29 2020 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: varname.mk,v 1.6 2020/11/02 22:29:48 rillig Exp $
+# $NetBSD: varname.mk,v 1.7 2020/11/02 22:44:29 rillig Exp $
 #
 # Tests for special variables, such as .MAKE or .PARSEDIR.
 # And for variable names in general.
@@ -23,6 +23,10 @@
 
 # In the above test, the variable name is constructed indirectly.  Neither
 # of the following expressions produces the intended effect.
+#
+# This is not a variable assignment since the parentheses and braces are not
+# balanced.  At the end of the line, there are still 3 levels open, which
+# means the variable name is not finished.
 ${:UVAR(((}=   try1
 ${:UVAR\(\(\(}=        try2
 ${:UVAR\(\(\(}=        try3