m4: import patch from OpenBSD

by espie@
ifelse is special, fix argv parsing to avoid segfault

problem noticed by Matthew Green (netbsd), slightly different fix
so that argc counting makes more sense.

we might want to warn on wrong number of parameters later, but this is
somewhat inconsistent depending on the builtin right now.

okay millert@

Obtained from:	OpenBSD

diff --git a/usr.bin/m4/eval.c b/usr.bin/m4/eval.c
index 1630b461f4239f4b533d793432374882aa24a7bc..ee7ce2644bebe194dcbb2ef3d028aed5a093b824 100644 (file)
--- a/usr.bin/m4/eval.c
+++ b/usr.bin/m4/eval.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: eval.c,v 1.75 2017/06/15 13:48:42 bcallah Exp $       */
+/*     $OpenBSD: eval.c,v 1.76 2017/10/23 15:21:19 espie Exp $ */
 /*     $NetBSD: eval.c,v 1.7 1996/11/10 21:21:29 pk Exp $      */
 
 /*-
@@ -201,8 +201,7 @@ expand_builtin(const char *argv[], int argc, int td)
        }
 
        case IFELTYPE:
-               if (argc > 4)
-                       doifelse(argv, argc);
+               doifelse(argv, argc);
                break;
 
        case IFDFTYPE:
@@ -695,17 +694,17 @@ dotrace(const char *argv[], int argc, int on)
 static void
 doifelse(const char *argv[], int argc)
 {
-       cycle {
-               if (STREQ(argv[2], argv[3]))
+       while (argc > 4) {
+               if (STREQ(argv[2], argv[3])) {
                        pbstr(argv[4]);
-               else if (argc == 6)
+                       break;
+               } else if (argc == 6) {
                        pbstr(argv[5]);
-               else if (argc > 6) {
+                       break;
+               } else {
                        argv += 3;
                        argc -= 3;
-                       continue;
                }
-               break;
        }
 }