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Re: [PATCH v2 1/3] Introduce die_errno() that appends strerror(errno) to die()

From
Jeff King <peff@peff.net>
Date
Jun 8, 2009, 12:36 UTC
Message-ID
<20090608123608.GG13775@coredump.intra.peff.net>
In-Reply-To
<7vzlck9e3j.fsf@alter.siamese.dyndns.org>
On Sun, Jun 07, 2009 at 09:57:04AM -0700, Junio C Hamano wrote:
Show 14 quoted lines
> > This breaks theoretical usage of custom format string in custom die
> > routines:
> >         1. A custom die routine might not support %s.
> >         2. If the die routine adds a custom format specifier, vsnprintf
> >                 will fail.
> 
> I do not think that flies even as a theory.  The "custom" 39a3f5ea talks
> about is more about "Instead of sending it to stderr, let's pop up an info
> window and give the message there" kind of customization.
> 
> Existing die() that prints errno does so by giving strerror() to "%s", so
> no matter how custom your die routine is, you must support '%s' for its
> output to make sense to humans.  If you "not support %s", then you will
> ignore (or choke at) such strerror() result without this patch anyway.

More than that, you must support arbitrary printf format strings, because the die routine is passed whatever goes to die() (a quick grep revealed that we use at least %u and %c at various points). So it is an undocumented requirement that the die routine process its parameters as if it were from the printf family.

I think what Thomas posted is fine.
-Peff
Previous: Junio C HamanoNext: Alexander Potashev
Message 24 of 28 in “add strerror(errno) to die() calls where applicable”
  1. add strerror(errno) to die() calls where applicableThomas Rast, Jun 2, 2009
  2. Jeff KingJun 3, 2009
  3. diesys calls die and also reports strerror(errno)Alexander Potashev, Jun 4, 2009
  4. Jeff KingJun 4, 2009
  5. Junio C HamanoJun 4, 2009
  6. Johannes SixtJun 5, 2009
  7. Junio C HamanoJun 5, 2009
  8. Jeff KingJun 6, 2009
  9. Thomas RastJun 6, 2009
  10. 0/3 Thomas Rast <trast@student.ethz.ch>Thomas Rast, Jun 6, 2009
  11. 1/3 Introduce die_errno() that appends strerror(errno) to die()Thomas Rast, Jun 6, 2009
  12. 2/3 Convert existing die(..., strerror(errno)) to die_errno()Thomas Rast, Jun 6, 2009
  13. 3/3 Use die_errno() instead of die() when checking syscallsThomas Rast, Jun 6, 2009
  14. Johannes SixtJun 6, 2009
  15. Thomas RastJun 6, 2009
  16. Johannes SixtJun 6, 2009
  17. Johannes SixtJun 6, 2009
  18. Thomas RastJun 6, 2009
  19. Johannes SixtJun 6, 2009
  20. Jeff KingJun 6, 2009
  21. Jeff KingJun 6, 2009
  22. Alexander PotashevJun 7, 2009
  23. Junio C HamanoJun 7, 2009
  24. Jeff KingJun 8, 2009
  25. Alexander PotashevJun 8, 2009
  26. Jeff KingJun 8, 2009
  27. Alexander PotashevJun 4, 2009
  28. Jeff KingJun 4, 2009

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