Re: [PATCH] nss: Get rid of alloca usage in makedb's write_output.

[Joe Simmons-Talbott <josimmon@redhat.com>]

On Thu, Sep 28, 2023 at 01:16:00PM +0200, Andreas Schwab wrote:
> On Sep 26 2023, Joe Simmons-Talbott wrote:
> 
> > @@ -802,6 +812,7 @@ write_output (int fd)
> >    assert (iov_nelts <= INT_MAX);
> >    if (writev (fd, iov, iov_nelts) != keydataoffset)
> >      {
> > +      scratch_buffer_free (&sbuf);
> >        error (0, errno, gettext ("failed to write new database file"));
> >        return EXIT_FAILURE;
> 
> Does scratch_buffer_free guarantee that errno is not changed?

scratch_buffer_free doesn't do anything other than call free when the
buffer has been heap-allocated.  IIUC free preserves errno since 2.33 in
the default free.  So I guess if there is a non-default free that
doesn't preserve errno then there is no explicit guarantee.  Should I
adjust scratch_buffer_free to explicitly preserve errno (in a separate
patch) or just preserve errno around this one call to
scratch_buffer_free?

Thanks,
Joe