Re: [PATCH v2 1/2] posix: Add compat glob symbol to not follow dangling symbols

[Paul Eggert]

On 09/26/2017 10:24 AM, Adhemerval Zanella wrote:
> I see other possible issues that would
> need to be fixed as well:
>
>    * FLEXIBLE_ARRAY_MEMBER definition for !__LIBC.
>    * __glob_pattern_type duplicated prototype.
>    * __set_errno and mempcpy definition.

Thanks for reporting the duplicated prototype; that is a portability 
issue that I fixed in Gnulib by applying the attached patch to Gnulib 
master. Gnulib glob.c already handles FLEXIBLE_ARRAY_MEMBER, 
__set_errno, and mempcpy automatically, because its 'glob' module has 
the modules 'flexmember', 'libc-config', and 'mempcpy' as prerequisites, 
and these supply the necessary definitions.

You can test Gnulib glob.c's portabililty by running this shell command 
in Gnulib's top directory:

./gnulib-tool --create-testdir --dir foo glob

and then by copying the newly-created 'foo' directory to the platform of 
your choice and running './configure; make check' there.

Gnu Make does not use Gnulib. Instead, it ships an old version of 
glob.c, which it took directly from glibc in 1999; this all predates 
Gnulib. If GNU Make ever updates to a more-modern glob.c I suggest that 
it use the Gnulib glob module, along with that module's prerequisites. I 
could help do that, if the GNU Make maintainer wants to go that route. 
[I'll CC: this to bug-make to give its maintainer a heads-up about this 
libc-alpha discussion, which can be followed from here:

https://sourceware.org/ml/libc-alpha/2017-09/msg00972.html

]

> I could build gnumake with forced internal glob implementation
> (make_cv_sys_gnu_glob=no) with the patch following patch.  Looking
> gnulib I am not sure if the correct way to use mempcpy for !_LIBC.

Sorry, but I'm confused by that patch (quoted below). It is a patch to 
glibc, so at first I assumed that you applied it to a copy of the glibc 
source, built a new glibc with it, and then used the newly-built glibc 
to configure and build GNU Make 4.2.1.  But that assumption cannot be 
right, since the patch modifies only code that is unused when building 
glibc. And one cannot simply copy current or patched glibc posix/glob.c 
into make's lib/glob.c, as (among other things) glibc's posix/glob.c 
includes <flexmember.h> when compiled outside of glibc, and GNU Make 
does not have that include file. So how did you use this patch?

> diff --git a/posix/glob.c b/posix/glob.c
> index 98122dac88..31e3aba4dd 100644
> --- a/posix/glob.c
> +++ b/posix/glob.c
> @@ -65,11 +65,15 @@
>   # define __stat64(fname, buf)   stat (fname, buf)
>   # define __fxstatat64(_, d, f, st, flag) fstatat (d, f, st, flag)
>   # define struct_stat64          struct stat
> -# ifndef __MVS__
> -#  define __alloca              alloca
> -# endif
> +# define __alloca               alloca
>   # define __readdir              readdir
> +# define FLEXIBLE_ARRAY_MEMBER 0
>   # define COMPILE_GLOB64
> +static inline void *
> +mempcpy (void *dest, const void *src, size_t n)
> +{
> +  return memcpy (dest, src, n) + n;
> +}
>   #endif /* _LIBC */
>   
>   #include <fnmatch.h>
> @@ -230,8 +234,6 @@ glob_use_alloca (size_t alloca_used, size_t len)
>   static int glob_in_dir (const char *pattern, const char *directory,
>                          int flags, int (*errfunc) (const char *, int),
>                          glob_t *pglob, size_t alloca_used);
> -extern int __glob_pattern_type (const char *pattern, int quote)
> -    attribute_hidden;
>   
>   static int prefix_array (const char *prefix, char **array, size_t n) __THROWNL;
>   static int collated_compare (const void *, const void *) __THROWNL;

0001-glob-remove-bogus-extern-decl.patch
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