[patch bfd]: Fix PR ld/12742 for windows targets

[Kai Tietz]

2012/3/10 Jeffrey Walton <noloader@gmail.com>:
> On Sat, Mar 10, 2012 at 3:58 AM, Jeffrey Walton <noloader@gmail.com> wrote:
>> On Fri, Mar 9, 2012 at 2:54 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
>>> Hi,
>>>
>>> this patch adds compatible implementation of dlfcn API on Windows
>>> targets, if this header/API isn't present.
>>>
>>> ChangeLog
>>>
>>> 2012-03-09  Kai Tietz  <ktietz@redhat.com>
>>>
>>>        PR ld/12742
>>>        * configure.in (AC_CHECK_HEADERS): Test for windows.h and dlfcn.h.
>>>        * plugin.c: Guard include of dlfcn.h if HAVE_DLFCN_H is defined.
>>>        Add windows.h header include if HAVE_WINDOWS_H is defined.
>>>        (dlerror): New static function if windows variant is used instead
>>>        of dlfcn.h.
>>>        (dlclose): Likewise.
>>>        (dlopen): Likewise.
>>>        (dlsym): Likewise.
>>>        * configure: Regenerated.
>>>        * config.in: Regenerated.
>>>
>>> Tested for i686-w64-mingw32 and x86_64-w64-mingw32.  Ok for apply?
>>>
>>> Regards,
>>> Kai
>>>
>>> [SNIP]
>>
>> If filename is NULL, I believe LoadLibrary will treat the filename as
>> an ordinal. Perhaps you should explicitly test the char* against NULL
>> (unless, of course, you want to return the function at ordinal 0):
>>
>>> +dlopen (const char *file, int mode ATTRIBUTE_UNUSED)
>>> +{
>>> +  return LoadLibrary (file);
>>> +}
>>
>> I think you wil get expected behavior if there are no ordinals, which
>> means you might have an intermittent problem.
> My bad - I meant function name:
>
> +static void *
> +dlsym (void *handle, const char *name)
> +{
> +  return GetProcAddress (handle, name);

GetProcAddress with name of NULL is simply invalid.  Any ordinal has
to start at 1 AFAIK.  Ordinal 0 doesn't exists.
See http://msdn.microsoft.com/en-us/library/windows/desktop/ms683212%28v=vs.85%29.aspx
for more details.

Regards,
Kai