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Re: [PATCH][BZ #12847] dprintf/vdprintf can cause fork to fail (child process crash)
- From: Rich Felker <dalias at aerifal dot cx>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: Roland McGrath <roland at hack dot frob dot com>, OndÅej BÃlka <neleai at seznam dot cz>, libc-alpha at sourceware dot org
- Date: Wed, 25 Sep 2013 17:29:55 -0400
- Subject: Re: [PATCH][BZ #12847] dprintf/vdprintf can cause fork to fail (child process crash)
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On Wed, Sep 25, 2013 at 07:38:40PM +0000, Joseph S. Myers wrote:
> On Wed, 25 Sep 2013, Roland McGrath wrote:
>
> > > If so, since dprintf is not required to be AS-safe,
> > > should it just be filed like a wishlist item?
> >
> > Sure. Though, as the sole inventor of dprintf many years before it was
> > standardized, I can say authoritatively that it was always the intent that
> > it not have any more entanglements (i.e. potential failure modes) than
> > stack use and calling write. (That was never exactly true in the face of
> > user-defined printf extensions, but close enough.)
>
> There are plenty of cases where the underlying printf code uses malloc if
> it needs an allocation too large for alloca (and the cut-off, or how such
> allocations relate to the arguments passed to dprintf, is not as far as I
> know considered a public interface to glibc).
Indeed, I was going to say the same thing. So I'm not clear on whether
the bug report should be "dprintf fails to be AS-safe" or "dprintf
unnecessarily takes open file list lock and adds/removes temporary
FILE objects to it". In the former case, fixing the "bug" will be a
lot more work. In the latter case, I don't think it's really
user-visible.
Rich