nit picking daemons/irrecord.c

[D. H. R. <hug...@mi...>]

This post is in the spirit of David Jones' keynote at OLS this year.
In particular, strace reveals funny/surprising things about programs.

I was doing an strace on lircd and I happened upon a sequence that appears 
silly and is repeated fairly often:

time(NULL)                              = 1160202828
stat64("/etc/localtime", {st_mode=S_IFREG|0644, st_size=1252, ...}) = 0
stat64("/etc/localtime", {st_mode=S_IFREG|0644, st_size=1252, ...}) = 0
stat64("/etc/localtime", {st_mode=S_IFREG|0644, st_size=1252, ...}) = 0
writev(2, [{"lircd-0.8.1-CVS[32693]: accepted"..., 57}, {"\n", 1}], 2) = 58
send(5, "<29>Oct  7 02:33:48 lircd-0.8.1-"..., 77, MSG_NOSIGNAL) = 77

Well, I looked the wrong place (I think), but did find some code that
could be improved.  In daemons/irrecord.c, routine logprintf looks
like this:

void logprintf(int prio,char *format_str, ...)
{
	time_t current;
	char *currents;
	va_list ap;  
	
	current=time(&current);
	currents=ctime(&current);
	
	if(lf) fprintf(lf,"%15.15s %s %s: ",currents+4,hostname,progname);
	if(!daemonized) fprintf(stderr,"%s: ",progname);
	if(lf)
	{
		va_start(ap,format_str);
		if(prio==LOG_WARNING) fprintf(lf,"WARNING: ");
		vfprintf(lf,format_str,ap);
		fputc('\n',lf);fflush(lf);
		va_end(ap);
	}
	if(!daemonized)
	{
		va_start(ap,format_str);
		if(prio==LOG_WARNING) fprintf(stderr,"WARNING: ");
		vfprintf(stderr,format_str,ap);
		fputc('\n',stderr);fflush(stderr);
		va_end(ap);
	}
}

I think two transformations would improve it:
- only test lf and !daemonized once
- only do the time stuff if it will be used (if lf is non-null)

UNTESTED!  (I haven't managed to build the vanilla version, let alone
a modified one.)

void logprintf(int prio,char *format_str, ...)
{
	va_list ap;  
	
	if(lf)
	{
		time_t current;
		char *currents;

		current=time(&current);
		currents=ctime(&current);
		fprintf(lf,"%15.15s %s %s: ",currents+4,hostname,progname);
		va_start(ap,format_str);
		if(prio==LOG_WARNING) fprintf(lf,"WARNING: ");
		vfprintf(lf,format_str,ap);
		fputc('\n',lf);fflush(lf);
		va_end(ap);
	}
	if(!daemonized)
	{
		fprintf(stderr,"%s: ",progname);
		va_start(ap,format_str);
		if(prio==LOG_WARNING) fprintf(stderr,"WARNING: ");
		vfprintf(stderr,format_str,ap);
		fputc('\n',stderr);fflush(stderr);
		va_end(ap);
	}
}

Well, I've got to go to bed, so I'm not going to look for the real
reason for the redundant stat64 syscalls.  I hope that you found this
interesting.

PS:
It might be that the bad guy is syslog(3) since lircd.h contains the
definition:
  #define logprintf syslog