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

[Simon Marchi <simark@simark.ca>]

On 2020-03-26 4:48 p.m., Hannes Domani via Gdb-patches wrote:
>  Am Donnerstag, 26. März 2020, 21:39:27 MEZ hat Christian Biesinger <cbiesinger@google.com> Folgendes geschrieben:
> 
>> On Thu, Mar 26, 2020 at 3:35 PM Hannes Domani via Gdb-patches
>>
>> <gdb-patches@sourceware.org> wrote:
>>>
>>>   Am Donnerstag, 26. März 2020, 20:26:14 MEZ hat Eli Zaretskii <eliz@gnu.org> Folgendes geschrieben:
>>>
>>>>> Date: Wed, 25 Mar 2020 14:35:51 +0000 (UTC)
>>>>
>>>>> From: Hannes Domani via Gdb-patches <gdb-patches@sourceware.org>
>>>>>
>>>>>>> But I figured my way with GetSystemWow64Directory is simpler.
>>>>>>>
>>>>>>>
>>>>>>> Is the v2 OK to commit?
>>>>>>
>>>>>> Yes, thanks.
>>>>>
>>>>> Pushed, thanks.
>>>>
>>>>
>>>> It looks like the same problem exists in the 32-bit Windows build of
>>>> GDB, when it runs on 64-bit Windows 10: "info sharedlibrary" shows
>>>> C:\Windows\system32 instead of C:\Windows\SysWOW64 (it doesn't happen
>>>> on 64-bit Windows 7, for example).  So I guess the code which replaces
>>>> the former with the latter should also be in the 32-bit build, not
>>>> just "#ifdef __x86_64__".
>>>
>>> Yes, for me (on Win7) it also happens with the same dlls in the 32-bit gdb
>>> as with the 64-bit gdb.
>>> But it shouldn't matter, since for 32-bit gdb all C:\Windows\system32 paths
>>> are automatically redirected[1] to C:\Windows\SysWOW64 anyways.
>>>
>>> [1] https://docs.microsoft.com/en-us/windows/win32/winprog64/file-system-redirector
>>
>>
>> Even so, it's probably less confusing for the user if what GDB
>> displays actually matches reality?
> 
> I guess you are right.
> I will prepare a patch for this.

Let's say a 32 bit GDB is debugging a 64 bit program.  GDB gets the list of loaded libraries, which
contains c:\windows\system32\foo.dll.  When GDB opens it, to read the contents of the library, will
it open and read c:\windows\system32\foo.dll (which is the one really loaded in the 64-bit process)
or will it open and read c:\windows\syswow64\foo.dll?

Simon