[PATCH v2] Fix WOW64 process system DLL paths

[Hannes Domani]

 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?


Hannes