make 3.79.1: segfault in $(if ...) expansion

[Jonathan Kamens]

The following Makefile causes make 3.79.1 to segfault on Linux:

-----cut here-----
foo:
        @echo $(if $(findstring foo,bar),,foo) foo
-----cut here-----

The problem here is that func_if in function.c assumes that there will
be an empty string marking the end of the arguments, when in fact
there might not be.  If I understand the code correctly, what marks
the empty arguments is a pointer to any string, empty or not, followed
by a null pointer; in this case, the string pointer immediately
preceding the null pointer is considered the end pointer for the final
argument, i.e., it points to one past the final argument.

If my understanding is correct, then the patch below fixes this bug
(and it does seem to work for me).

Please remember to respond to me in addition to address@hidden; I
don't read bug-make.

Thanks,

  Jonathan Kamens

Index: function.c
===================================================================
RCS file: /projects/systems/cvs-root/gnu/make/function.c,v
retrieving revision 1.1.1.2
diff -u -r1.1.1.2 function.c
--- function.c  1999/10/20 21:57:50     1.1.1.2
+++ function.c  2001/12/05 23:08:28
@@ -1122,7 +1122,7 @@
       /* If we're doing the else-clause, make sure we concatenate any
          potential extra arguments into the last argument.  */
       if (!result)
-        while (*endp && **endp != '\0')
+        while (*endp && **endp != '\0' && endp[1])
           ++endp;
 
       expansion = expand_argument (*argv, *endp-1);