kbuild: fix headers_exports with boolean expression
When we had code like this in a header unifdef failed to
deduct that the expression was always false - and we had code exported
that was not intended for userspace.
#if defined(__KERNEL__) && !defined(__ASSEMBLY__)
int a;
#endif
This commit implment support in unidef which allows it to work out if
an #if expression always evaluates true or false for symbols which
are being undefined/always defined.
The patch is slightly more complicated than I'd hoped because unifdef
needs to see lines fully evaluated - doing otherwise causes it to
mark the line as "dirty" and copy it over no matter what.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/unifdef.c b/scripts/unifdef.c
index 05a31a6..30d459f 100644
--- a/scripts/unifdef.c
+++ b/scripts/unifdef.c
@@ -678,8 +678,10 @@
if (*cp == '!') {
debug("eval%d !", ops - eval_ops);
cp++;
- if (eval_unary(ops, valp, &cp) == LT_IF)
+ if (eval_unary(ops, valp, &cp) == LT_IF) {
+ *cpp = cp;
return (LT_IF);
+ }
*valp = !*valp;
} else if (*cp == '(') {
cp++;
@@ -700,13 +702,16 @@
return (LT_IF);
cp = skipcomment(cp);
sym = findsym(cp);
- if (sym < 0)
- return (LT_IF);
- *valp = (value[sym] != NULL);
cp = skipsym(cp);
cp = skipcomment(cp);
if (*cp++ != ')')
return (LT_IF);
+ if (sym >= 0)
+ *valp = (value[sym] != NULL);
+ else {
+ *cpp = cp;
+ return (LT_IF);
+ }
keepthis = false;
} else if (!endsym(*cp)) {
debug("eval%d symbol", ops - eval_ops);
@@ -741,11 +746,11 @@
const struct op *op;
const char *cp;
int val;
+ Linetype lhs, rhs;
debug("eval%d", ops - eval_ops);
cp = *cpp;
- if (ops->inner(ops+1, valp, &cp) == LT_IF)
- return (LT_IF);
+ lhs = ops->inner(ops+1, valp, &cp);
for (;;) {
cp = skipcomment(cp);
for (op = ops->op; op->str != NULL; op++)
@@ -755,14 +760,32 @@
break;
cp += strlen(op->str);
debug("eval%d %s", ops - eval_ops, op->str);
- if (ops->inner(ops+1, &val, &cp) == LT_IF)
- return (LT_IF);
- *valp = op->fn(*valp, val);
+ rhs = ops->inner(ops+1, &val, &cp);
+ if (op->fn == op_and && (lhs == LT_FALSE || rhs == LT_FALSE)) {
+ debug("eval%d: and always false", ops - eval_ops);
+ if (lhs == LT_IF)
+ *valp = val;
+ lhs = LT_FALSE;
+ continue;
+ }
+ if (op->fn == op_or && (lhs == LT_TRUE || rhs == LT_TRUE)) {
+ debug("eval%d: or always true", ops - eval_ops);
+ if (lhs == LT_IF)
+ *valp = val;
+ lhs = LT_TRUE;
+ continue;
+ }
+ if (rhs == LT_IF)
+ lhs = LT_IF;
+ if (lhs != LT_IF)
+ *valp = op->fn(*valp, val);
}
*cpp = cp;
debug("eval%d = %d", ops - eval_ops, *valp);
- return (*valp ? LT_TRUE : LT_FALSE);
+ if (lhs != LT_IF)
+ lhs = (*valp ? LT_TRUE : LT_FALSE);
+ return lhs;
}
/*
@@ -773,12 +796,15 @@
static Linetype
ifeval(const char **cpp)
{
+ const char *cp = *cpp;
int ret;
int val;
debug("eval %s", *cpp);
keepthis = killconsts ? false : true;
- ret = eval_table(eval_ops, &val, cpp);
+ ret = eval_table(eval_ops, &val, &cp);
+ if (ret != LT_IF)
+ *cpp = cp;
debug("eval = %d", val);
return (keepthis ? LT_IF : ret);
}