On Fri, Oct 26, 2018 at 04:26:30PM +0100, Ben Dooks wrote:
> ---
> parse.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> symbol.h | 2 ++
> 2 files changed, 76 insertions(+), 1 deletion(-)
>
> @@ -1051,6 +1061,69 @@ static struct token *attribute_address_space(struct token *token, struct symbol
> return token;
> }
>
> +static struct token *attribute_format(struct token *token, struct symbol *attr, struct decl_state *ctx)
> +{
> + struct expression *args[3];
> + struct symbol *fmt_sym = NULL;
> + int argc = 0;
> +
> + /* expecting format ( type, start, va_args at) */
> +
> + token = expect(token, '(', "after format attribute");
> + while (!match_op(token, ')')) {
> + struct expression *expr = NULL;
> +
> + if (argc == 0) {
> + if (token_type(token) == TOKEN_IDENT)
> + fmt_sym = lookup_keyword(token->ident, NS_KEYWORD);
> +
> + if (!fmt_sym || !fmt_sym->op ||
> + fmt_sym->op != &attr_printf_op) {
> + sparse_error(token->pos,
> + "unknown format type '%s'\n",
> + show_ident(token->ident));
> + fmt_sym = NULL;
> + }
> + }
> +
> + token = conditional_expression(token, &expr);
> + if (!expr)
> + break;
> + if (argc < 3)
> + args[argc++] = expr;
> + if (!match_op(token, ','))
> + break;
> + token = token->next;
> + }
> +
> + if (argc != 3 || !fmt_sym)
> + warning(token->pos,
> + "expected format type and start/position values");
> + else {
> + struct symbol *base_type = ctx->ctype.base_type;
> + long long start, at;
> +
> + start = get_expression_value(args[2]);
> + at = get_expression_value(args[1]);
> +
> + if (start <= 0 || at <= 0)
> + warning(token->pos, "bad format positions");
> + else if (!base_type)
> + sparse_error(token->pos, "no base context for format");
> + else if (base_type->type != SYM_FN)
> + warning(token->pos, "attribute format can only be used on functions");
> + else if (!base_type->variadic)
> + warning(token->pos, "attribute format used on non variadic function");
> + else {
> + base_type->printf_va_start = start;
> + base_type->printf_msg = at;
> + }
Another reason why printf_va_start & printf_msg need to move (to ctx->ctype) is
that the attribute can be placed before the function. For example:
extern __attribute__((format(printf, 1, 2))) void printk(const char *, ...);
is legit but gives here the error "no base context for format".
-- Luc
