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Re: Customizing printf

Cross-posted to 2 groups.

Followups directed to: comp.lang.c

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On 2011-11-21, Joe keane <jgk@panix.com> wrote:
> That makes it worse!
>
> At least if the format string is compile-time constant, the compiler
> -could- help you out.  It's not obligated to do this check, and C offers

Indeed. A C format string is a form of code, so if you have translators writing
format strings, they are coding.

> If the format string is read from a file, then God help you...

Suppose you had a translations file with records containing the original format
strings, and translated ones. A checker, invoked at build time, could validate
that every record in the file contains only equivalent format strings (that
differ only in their template text, not in the conversion specifiers).

Furthermore, the checker would generate, from this file, a C header file which
contains #define for nominal format strings (untranslated entries in English or
whatever your development team's common language is).

These #defines are used for writing the printf statements; they supply
real string-literal format strings. Except these go to a printf wrapper which
substitutes the translated text. The printf wrapper is endowed with the special
GCC annotation so that the printf argument checking is applied to it at compile
time.

The translated text is pulled from some data structure which is also generated
by the checker, in addition to that header file.

> [core dump]

That's the good case. The bad case is someone turns it into an exploitable
security hole.

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Thread

Customizing printf jacob navia <jacob@spamsink.net> - 2011-11-15 14:36 +0100
  Re: Customizing printf "Joel C. Salomon" <joelcsalomon@gmail.com> - 2011-11-15 13:07 -0500
  Re: Customizing printf Ben Pfaff <blp@cs.stanford.edu> - 2011-11-15 10:10 -0800
    Re: Customizing printf jacob navia <jacob@spamsink.net> - 2011-11-15 21:36 +0100
      Re: Customizing printf blp@cs.stanford.edu (Ben Pfaff) - 2011-11-15 12:51 -0800
        Re: Customizing printf "Joel C. Salomon" <joelcsalomon@gmail.com> - 2011-11-15 18:03 -0500
    Re: Customizing printf jgk@panix.com (Joe keane) - 2011-11-20 15:14 +0000
      Re: Customizing printf blp@cs.stanford.edu (Ben Pfaff) - 2011-11-20 10:43 -0800
        Re: Customizing printf Lauri Alanko <la@iki.fi> - 2011-11-20 19:01 +0000
          Re: Customizing printf blp@cs.stanford.edu (Ben Pfaff) - 2011-11-20 11:05 -0800
            Re: Customizing printf Dag-Erling Smørgrav <des@des.no> - 2011-11-20 20:38 +0100
              Re: Customizing printf blp@cs.stanford.edu (Ben Pfaff) - 2011-11-20 11:37 -0800
        Re: Customizing printf jgk@panix.com (Joe keane) - 2011-11-21 22:23 +0000
          Re: Customizing printf Ian Collins <ian-news@hotmail.com> - 2011-11-22 11:26 +1300
          Re: Customizing printf blp@cs.stanford.edu (Ben Pfaff) - 2011-11-21 14:23 -0800
          Re: Customizing printf Kaz Kylheku <kaz@kylheku.com> - 2011-11-21 23:06 +0000
            Re: Customizing printf jgk@panix.com (Joe keane) - 2011-11-23 00:09 +0000
              Re: Customizing printf blp@cs.stanford.edu (Ben Pfaff) - 2011-11-22 16:16 -0800
      Re: Customizing printf Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-21 05:29 -0800
        Re: Customizing printf jgk@panix.com (Joe keane) - 2011-11-21 22:50 +0000
  Re: Customizing printf Lowell Gilbert <lgusenet@be-well.ilk.org> - 2011-11-15 13:13 -0500
  Re: Customizing printf "-.-" <none@none.none> - 2011-11-16 14:06 +0100
    Re: Customizing printf gazelle@shell.xmission.com (Kenny McCormack) - 2011-11-16 13:40 +0000
    Re: Customizing printf Seebs <usenet-nospam@seebs.net> - 2011-11-16 20:18 +0000
      Re: Customizing printf Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-17 07:54 +0200

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