Re: stdio: don't require ignore_value around fwrite

[Bruno Haible]

Hi Paul,

> +     This patch works around libc bug 11959
> +     <http://sources.redhat.com/bugzilla/show_bug.cgi?id=11959>.

This glibc bug is in status "NEW". I think before adding a workaround in
gnulib, the first action should be to ping the glibc maintainers about it.
If they close it as rejected / invalid / won't fix, then IMO we can consider
to do something in gnulib about it.

Three technical points about the patch:

- For legibility,

  > +#if (0 < __USE_FORTIFY_LEVEL                                            \
  > +     && ! (@GNULIB_FWRITE@                                              \
  > +           && @REPLACE_STDIO_WRITE_FUNCS@ && @GNULIB_STDIO_H_SIGPIPE@))
  > +# define GNULIB_inline_rpl_fwrite 1
  > +static inline size_t _GL_ARG_NONNULL ((1, 4))
  > +rpl_fwrite (const void *ptr, size_t s, size_t n, FILE *stream)
  > +{
  > +  size_t r = fwrite (ptr, s, n, stream);
  > +  (void) r;
  > +  return r;
  > +}
  > +#endif
  >  
  > -#if @GNULIB_FWRITE@
  > -# if @REPLACE_STDIO_WRITE_FUNCS@ && @GNULIB_STDIO_H_SIGPIPE@
  > +#if @GNULIB_FWRITE@ || GNULIB_inline_rpl_fwrite
  > +# if ((@REPLACE_STDIO_WRITE_FUNCS@ && @GNULIB_STDIO_H_SIGPIPE@) \

  could you please keep both parts in a single
    #if @GNULIB_FWRITE@
    #endif
  block?
  Since GNULIB_FWRITE is always 1 in practice (see m4/stdio_h.m4), you don't
  need to care about the case when GNULIB_FWRITE is 0.

- The workaround ought also to be documented in doc/posix-functions/fwrite.texi.

- You ask:
  > However, I'm no expert with C++ and the C++ parts of it
  > need another pair of eyes to look at.

  You can test C++ compatibility by doing
    $ ./gnulib-tool --test --with-tests --with-c++-tests stdio

  But I can tell you in advance that the C++ idioms just don't work with
  'static inline' replacements, as seen in
  <http://lists.gnu.org/archive/html/bug-gnulib/2010-12/msg00128.html>.
  The workaround is to provide the wrapper function in lib/stdio-write.c
  instead of as an inline function.

Bruno
-- 
In memoriam Jan Nepomucký <http://en.wikipedia.org/wiki/John_of_Nepomuk>