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

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [COMMITTERS] pgsql: Add comments about why errno is set
Date: 2005-12-02 02:49:21
Message-ID: 200512020249.jB22nLd10985@candle.pha.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-committers pgsql-hackers


OK, comments removed, and comment added to port/strtol.c.

---------------------------------------------------------------------------

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > I modified it to:
> > errno = 0; /* avoid having to check the result for failure */
>
> Just for the record, that's *still* wrong. It implies that if we
> tested (result == LONG_MAX && errno == ERANGE), without zeroing
> errno beforehand, the code would be correct. But it would not,
> because the errno value could still be leftover. The plain fact
> of the matter is that if you're going to check for strtol overflow at
> all, you have to zero errno beforehand. This is perfectly well
> explained in the strtol spec page, and I see no need to duplicate it:
>
> Because 0, LONG_MIN and LONG_MAX are returned on error and are
> also valid returns on success, an application wishing to check
> for error situations should set errno to 0, then call strtol(),
> then check errno.
>
> regards, tom lane
>

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

In response to

Browse pgsql-committers by date

  From Date Subject
Next Message Bruce Momjian 2005-12-02 04:28:27 pgsql: Add calcluation of bitmap storage capacity.
Previous Message Bruce Momjian 2005-12-02 02:49:12 pgsql: Remove comment on errno=0 lines, but add mention to port/strtol.c

Browse pgsql-hackers by date

  From Date Subject
Next Message Greg Sabino Mullane 2005-12-02 02:56:45 Re: Windows installation notes
Previous Message Christopher Kings-Lynne 2005-12-02 02:45:02 Re: Reducing relation locking overhead