Re: [PATCH v2] Fix WOW64 process system DLL paths

[Simon Marchi <simark@simark.ca>]

On 2020-03-25 10:22 a.m., Hannes Domani via Gdb-patches wrote:
>  Am Mittwoch, 25. März 2020, 15:04:44 MEZ hat Simon Marchi <simark@simark.ca> Folgendes geschrieben:
> 
>> On 2020-03-24 3:23 p.m., Hannes Domani via Gdb-patches wrote:
>>
>>> GetModuleFileNameEx returns for some DLLs of WOW64 processes
>>> the path inside the 64bit system directory instead of the 32bit
>>> syswow64 directory.
>>>
>>> Problem happens e.g. with dbghelp.dll:
>>>
>>> (gdb) start
>>> Temporary breakpoint 1 at 0x415a00: file fiber.cpp, line 430.
>>> Starting program: C:\src\tests\fiber.exe
>>> warning: `C:\Windows\system32\dbghelp.dll': Shared library architecture i386:x86-64 is not compatible with target architecture i386.
>>>
>>> Temporary breakpoint 1, main () at fiber.cpp:430
>>> 430    {
>>> (gdb) info sharedlibrary
>>> From        To          Syms Read  Shared Object Library
>>> 0x77070000  0x771d4d20  Yes (*)    C:\Windows\SysWOW64\ntdll.dll
>>> 0x74dc0000  0x74ebad9c  Yes (*)    C:\Windows\syswow64\kernel32.dll
>>> 0x75341000  0x75386a18  Yes (*)    C:\Windows\syswow64\KernelBase.dll
>>> 0x6f6a1000  0x6f7c48fc  Yes (*)    C:\Windows\system32\dbghelp.dll
>>> 0x74d01000  0x74dab2c4  Yes (*)    C:\Windows\syswow64\msvcrt.dll
>>> (*): Shared library is missing debugging information.
>>>
>>> This detects this situation and converts the DLL path to the
>>> syswow64 equivalent.
>>>
>>> gdb/ChangeLog:
>>>
>>> 2020-03-24  Hannes Domani  <ssbssa@yahoo.de>
>>>
>>>      * windows-nat.c (windows_add_all_dlls): Fix system dll paths.
>>> ---
>>> v2:
>>> - added error check with gdb_assert's
>>> - use std::string for newly assembled dll path
>>
>>
>> Btw, I found this Stack Overflow question that seems to be about this exact
>> problem (which you may have already found too if you researched the topic),
>> but honestly I don't understand a thing from the answer.
>>
>>    https://stackoverflow.com/questions/46403532/getmodulefilenameex-on-32bit-process-from-64bit-process-on-windows-10
> 
> Yes, I did see this when I googled this problem.
> Basically, if you use GetMappedFileName instead of GetModuleFileNameEx, you
> get the correct path (I tested this also), but it's returned in the nt-path
> format:
> \Device\HarddiskVolume9\Windows\SysWOW64\dbghelp.dll
> 
> Which you then have to convert to the "normal" path every one else expects.
> But I figured my way with GetSystemWow64Directory is simpler.
> 
> 
> Is the v2 OK to commit?

Yes, thanks.

Simon