[patch] basename vs. __gnu_basename fix

[Corinna Vinschen]

On Apr 21 17:07, Craig Howland wrote:
> On 04/21/2015 11:50 AM, Corinna Vinschen wrote:
> >[...]
> >+/* There are two common basename variants.  If you #include <libgen.h> you get
> >+   the POSIX version; otherwise, if you define _GNU_SOURCE, you get the GNU
> >+   version via <string.h>.  POSIX requires that #undef basename will still let
> >+   you invoke the underlying function.  However, this also implies that the
> >+   POSIX version is used in this case.  That's made sure here. */
> >+#if __GNU_VISIBLE && !defined(basename)
> >  char	*_EXFUN(__gnu_basename,(const char *));
> >  # define basename __gnu_basename
> >-# endif
> >  #endif
> The prototype should not be skipped if basename is defined (which I'm
> guessing is an unintended change).

Hang on, the prototype *must* be skipped if basename is defined.  If you
don't do that you end up with the exact problem my patch is trying to
fix:  You'll get two contradicting prototypes for basename, one from
libgen.h, one from string.h.  If basename is defined, it's from
libgen.h, so basename is already prototyped.  Have a look into the glibc
headers.

> In addition, to help make use more clear
> (particularly for users--maintainers too, but not so much) the comment and
> #if condition should perhaps be changed a little.  I suggest it should end
> up being more like the following. (Comment same in both files, as you have
> it, but only shown once in the context of string.h.)
> 
> I also added the nonnull attribute to the prototype, to avoid a possible
> change in compiler warnings due to the GNUC part being dropped.
> 
> /* There are two common basename variants.  If you do NOT #include <libgen.h>
>  * and you do
>  * 	#define _GNU_SOURCE
>  * 	#include <string.h>
>  * you get the GNU version.  Otherwise, you get the POSIX version, for which
>  * you should #include <libgen.h> for the function prototype.  POSIX requires
>  * that #undef basename will still let you invoke the underlying function.
>  * However, this also implies that the POSIX version is used in this case.
>  * That's made sure here. */
> #if defined(_GNU_SOURCE)
> char	*_EXFUN(__nonnull(1) __gnu_basename,(const char *));
> # if !defined(basename)
> #  define basename __gnu_basename
> # endif
> #endif

Thanks, I changed that.


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat
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