Add cygwin_internal CW_GET_MODULE_PATH_FOR_ADDR

Charles Wilson
Sat Oct 15 14:16:00 GMT 2011

On 10/15/2011 4:51 AM, Corinna Vinschen wrote:
> On Oct 15 01:00, Charles Wilson wrote:
 >> [stuff]
> Sorry, I meant localename.c.  Almost everything for Win32 is done
> for Cygwin as well.  Plus ignoring C.UTF-8 explicitly just on Cygwin.
> That's cruel.

My working patch #ifdefs-out removes almost all of the code in localename.c.

>> No.  Now that cygintl-8.dll has been published with an added
>> interface (libintl_setlocale) I can't remove that new symbol without
>> breaking any apps compiled in the meantime.
> libintl_setlocale is only defined if ENABLE_RELOCATABLE is defined?
> That's not immediately visble from ther sources.

That's what Bruno said, and I had no reason to doubt him and verify it 
in the sources.  I'll check later, but no time right now.

>> However, I had already come to the conclusion that simply applying
>> Bruno's "cheap vs. expensive" fix from CVS will do, for now.  This
>> doesn't require any new cygwin APIs.  The new API is only an attempt
>> to speed up "expensive" relocation (which cygwin's official packages
>> will never need to do) while staying at least somewhat
>> unixy/cygwiny, rather than calling the w32api.
> Cool!  That's the solution then.

Yep. Seems to solve the complaint.  Now if I can just figure out where 
the handful of new testsuite failures are coming from -- could be they 
are explicitly testing for the functionality I removed.  Need to 

Also, need to do a private build with the two different forms of 
relocation, and verify functionality but I can do that after uploading 
the official versions.

>> After we told Bruno to not use any windowsisms?  Sure, it's a lot
>> simpler -- but it violates our recommendations for cygwin clients.
> So in turn, there's no practical difference between
>    #ifdef __CYGWIN__
>      cygwin_internal (CW_GET_MODULE_PATH_FOR_ADDR,
> 		     addr, buf, sizeof (buf))
>      shared_library_fullname = strdup (buf);
>    #endif
> and
>    #ifdef __CYGWIN__
>      GetModuleFileNameW (module_handle, buf, sizeof (buf)))
>      shared_library_fullname = (char *) cygwin_create_path (CCP_WIN_W_TO_POSIX,
> 							   buf);
>    #endif
> In both cases you have to use a Cygwinism and you have to guard the
> code using #ifdef __CYGWIN__.


>> But making "expensive" relocation less expensive doesn't have to be
>> solved this very minute.
> Actually, since we have two types of relocation anyway, cheap and
> expensive, why isn't it enough to have an expensive relocation using the
> maps file?

Well, at the time I was thinking that if "expensive" could be made cheap 
*enough*, we could remove the distinction again.  The issue I have with 
Bruno's solution is that we now have three states, in the relocation 
code -- but only for cygwin.  And the states are controlled by two 
different mechanisms:
   --disable-relocation + -UENABLE_COSTLY_RELOCATABLE (default) [*]
   --enable-relocation + -UENABLE_COSTLY_RELOCATABLE
   --enable-relocation + -DENABLE_COSTLY_RELOCATABLE

[*] subverted in libintl's Makefile with its -DENABLE_RELOCATABLE

That's just ugly.

> Somehow I missed the numbers.  How slow is accessing the
> maps file in comparison?

10-20x slower than linux -- 3 5o 5 ms per call, vs. 0.3 ms for linux. 
(Those are Bruno's timing investigation numbers).

> I don't think it makes sense to add a cygwin_internal call for this
> functionality.

OK. We can take this back to the main cygwin list now, then.


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