PR/2386 [2/2]: MinGW attach to process without an exec file

[Pedro Alves]

Joel Brobecker wrote:
> I have a couple of questions, out of curiosity...
> 

Which prompted me to google a bit more :-)

I guess I was trying too hard to not depend on psapi.dll.
psapi.dll is available as part of the platform SDK, from MSFT,
and since it is redistributable, as part of several
applications, which means the chances it isn't
there are slimm nowadays.  If it isn't there, like for
instance the user is still on an NT4, it can be downloaded
from MSFT.  "Platform SDK Redistributable: PSAPI for
Windows NT" gets you there.

>>   - looks in the Cygwin processes using cygwin_internal (CW_GETPINFO, ...).
>>     This is what's done currently, so Cygwin processes will be detected
>>     like before.
> 
> If we are going to have some code that does this natively as suggested
> below, why have some code that would work on cygwin only? Is the above
> going to cover more cases (windows versions?) than the approach below?
> 

It will cover Cygwin processes on 9x, and the cases where psapi.dll
isn't found.  I'll leave to Christopher to decide if it should
be removed.

>>   - If that fails, tries to get at the filename associated with the file
>>     handle that the debug api gives us in the CREATE_PROCESS_DEBUG_EVENT.
>>     Previously, it was just closed; we now store it in a global variable.
>>     This relies on the internal NT name of the HANDLE, and it may change
>>     in future releases, hence,
> 

I've stripped this part from the patch.

  > Do you know when it wouldn't work?
The name associated with the HANDLE is an internal, private NT detail
which which happens to work in practice, in XP at least, but subject to
change by MSFT.

> 
>>   - If that fails, GetModuleFileNameEx from psapi.dll is used.
> 
> Same here, if we know the conditions when this would or woudln't work,
> a comment would be very helpful for future contributors.
> 

The function will always work for a process we're already debugging,
provided dynamically loading psapi.dll works.


The patch is now certainly much less invasive.  Chris, do you think
it is on the right track now ?

-- 
Pedro Alves

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