From: Jeff King <peff@peff.net>
Date: Tue, 03 Jul 2012 05:14:26 GMT
Subject: Re: bug: "fatal: cannot pread pack file", version 1.7.5.4
Message-ID: <20120703051426.GA12965@sigill.intra.peff.net>
In-Reply-To: <CACsJy8AmCo82YxHA_6+rkbuJOjOG-HqCgjoP2tz753SXH5w8_Q@mail.gmail.com>

On Tue, Jul 03, 2012 at 11:25:16AM +0700, Nguyen Thai Ngoc Duy wrote:

> On Tue, Jul 3, 2012 at 10:45 AM, Jeff King <peff@peff.net> wrote:
> > On Tue, Jul 03, 2012 at 12:43:42AM +0200, Andreas Schwab wrote:
> >
> >> Jeff King <peff@peff.net> writes:
> >>
> >> > It's very odd for pread to report ENOENT (since it is always operating
> >> > on an already-opened file descriptor).
> >>
> >> It doesn't, but gettext will clobber errno:
> >>
> >>               n = pread(pack_fd, inbuf, n, from);
> >>               if (n < 0)
> >>                       die_errno(_("cannot pread pack file"));
> >>
> >> There is nothing that saves errno.  This isn't limited to i18n though,
> >> any function call in the arguments may potentially clobber errno.
> >
> > That's horribly lame of gettext. I don't expect arbitrary functions to
> > save errno, but when the entire purpose of a function is to be a
> > non-intrusive wrapper to massage messages to the user, it seems kind of
> > evil to overwrite errno. Isn't the whole point of calling it "_" that
> > you don't want to or have to notice it?
> 
> Agreed.

Hmm. According to gettext(3):

  ERRORS
         errno is not modified.

And googling for "gettext" and "errno" reveals several bugfixes in GNU
gettext to make sure that gettext preserves errno. I wonder if there are
systems where that is not the case, though; I don't know what non-GNU
gettext implementations are in common use these days. I'd still be
curious to hear what platform the server is for this bug report.

-Peff