Re: [PATCH] Add variadic-style alternative function for avc logging
On Sun, 2006-09-17 at 10:19 -0400, Steve Grubb wrote:
On Friday 08 September 2006 22:33, Eamon Walsh wrote:
> The attached patch adds a new function audit_log_user_avc_message_fmt
> that behaves just like audit_log_user_avc_message, but takes a format
> string and argument list instead of a fixed message string.
Do you have examples of its use in real upstream code? I'm not opposed to
this, but I've been able to add audit messages all over the place without
duplicating the API with variadic functions.
Since we're already discussing changing the libselinux userspace avc API
for logging, I guess just hold off on this patch for now.
But here's the pitch: I think it's reasonable to expect that people are
going to be calling the libaudit logging functions from within
printf-style functions that take a format string and argument list.
This is true of the current userspace avc logging callback, and the X
server, where the logging functions look like ErrorF(fmt, ...). I think
it's fairly common to have logging subsystems that behave like this.
Currently, something like the following is required:
va_list ap;
char buf[MAX_AUDIT_MESSAGE_LENGTH];
va_start(ap, fmt);
vsnprintf(buf, MAX_AUDIT_MESSAGE_LENGTH, fmt, ap);
audit_log_user_avc_message(..., buf, ...);
va_end(ap);
Which could be reduced to (with the duplicate API):
va_list ap;
va_start(ap, fmt);
audit_log_user_avc_message(..., fmt, ap, ...);
va_end(ap);
Which avoids the library call and doesn't care about the max_length
constant. Not terribly much, but why not have a convenience function
for it?
--
Eamon Walsh <ewalsh(a)tycho.nsa.gov>
National Security Agency