On 2022-04-05, at 13:15:45 +0200, Florian Westphal wrote:
> Jeremy Sowden <jeremy@xxxxxxxxxx> wrote:
> > If the symbol-table passed to `ct_label2str` is `NULL`, return `NULL`.
>
> It would be nice to describe why, not what.
> Does this fix a crash when the label file is missing?
I've been putting debug logging in various places while developing and
testing things. Here's a function for dumping expressions to stderr:
static inline void
dbg_print_expr(const char *func, const char *name,
const struct expr *expr)
{
struct output_ctx *dbgctx = &(struct output_ctx) { .output_fp = stderr };
nft_print(dbgctx, "%s: %s = (%s, %u, %s, %s) { ",
func, name,
expr_ops(expr)->name,
expr->len,
expr->dtype ? expr->dtype->name : "",
byteorder_names[expr->byteorder]);
expr_print(expr, dbgctx);
nft_print(dbgctx, " }\n");
}
There are two problems with this. Firstly, the `byteorder_names` array
is defined in src/evaluate.c and so this function cannot be used
elsewhere. Secondly, the symbol-tables in the output context are not
initialized, which results in crashes when trying to print symbolic
constants and CT labels. Patch 3 fixes the former problem by moving the
`byteorder_names` array, and patches 4 & 5 fix the latter problem by
adding NULL checks before trying to dereference the symbol-tables. They
seemed like small, low-impact changes that could be upstreamed, so that
I didn't have to carry them.
J.
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