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Re: [COMMITTERS] pgsql: Add comments about why errno is set to zero.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: [COMMITTERS] pgsql: Add comments about why errno is set to zero.
Date: 2005-12-01 21:06:20
Message-ID: 17114.1133471180@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-committerspgsql-hackers
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Should I just change them all to:

> 	errno = 0;  /* avoid checking result for failure */

No, that's still a completely inaccurate description of the reason
for having the statement.

> or should I add a macro to c.h as:

> 	/* Sometimes we need to clear errno so we can check errno
> 	 * without having to check for a failure value from the function
> 	 * call.
> 	 */	
> 	#define CLEAR_ERRNO \\
> 	do { \
> 		errno = 0; \\
> 	while (0);

I vote "neither".  Anyone who doesn't understand what this is for will
need to go read the C library man pages for a bit anyway.  Nor do I find
"CLEAR_ERRNO" an improvement over "errno = 0".

			regards, tom lane

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