Home page logo

wireshark logo Wireshark mailing list archives

Re: Val_to_str as a macro
From: Jakub Zawadzki <darkjames-ws () darkjames pl>
Date: Wed, 11 Dec 2013 23:40:16 +0100


On Wed, Dec 11, 2013 at 05:22:31PM -0500, Evan Huus wrote:
I've been exploring a few options for the val_to_str function and
wmem. One of the tangential things I've been trying to achieve is to
make it into a macro so that the compiler will catch format-string
mismatches (which have been a source of bugs in the past). This is
easy to do inefficiently:

#define val_to_str(VAL, VS, POOL, FMT) (try_val_to_str(VAL, VS) ?
try_val_to_str(VAL, VS) : wmem_strdup_printf(POOL, FMT, VAL))

but I've been unable to find a nice way to avoid the second call to
try_val_to_str(). I can wrap it in a block and use a temporary
variable, but then it can't return a value and no longer behaves like
the original function.

We could use GCC extension: http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
(MSVC can't check format types anyway).

Can anybody else think of a nice way to do this, or is it just one of
those things that's impossible in C?

Or more portable: I'd try moving val_to_str() as inline function to value_string.h

and later just to test with something like: val_to_str(0, NULL, "%s");

Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
Archives:    http://www.wireshark.org/lists/wireshark-dev
Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
             mailto:wireshark-dev-request () wireshark org?subject=unsubscribe

  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]