Re: [PATCH] iptables: set errno correctly in iptcc_chain_index_alloc

[Phil Oester <kernel@linuxace.com>]

On Thu, Jul 04, 2013 at 09:42:22AM +0200, Florian Westphal wrote:
> Personally I think libraries should not change errno at all.

OK, but then we output misleading error messages.

> I don't understand how this changes anything?

Simulate an out of memory condition with this patch

@@ -500,9 +500,11 @@ static int iptcc_chain_index_alloc(struct xtc_handle *h)
              array_elems, array_mem);

        h->chain_index = malloc(array_mem);
-       if (h->chain_index == NULL && array_mem > 0) {
+       //if (h->chain_index == NULL && array_mem > 0) {
+       if (1) {
                h->chain_index_sz = 0;

With the patch, the error message returned to user:

   ...can't initialize iptables table `filter': Memory allocation problem

without the patch:

   ...can't initialize iptables table `filter': Incompatible with this kernel

The former seems better, no?

Phil