[lldb-dev] Native windows debugging support

[jingham at apple.com]

And really, this is more a feature of the Platform than the Target, since you might want it to do things like properly display process info when doing "platform process list".

It does look like the UserID is exposed through the SB API's.  We can't really remove SB API's - at least not till we do a grand review and declare SB API version 2 - since we don't know who is using them (though in this case I am pretty sure Xcode IS using this API...)  It is probably okay to have this return an error on Windows, and then add a better API using your new class.

BTW, ProcessUserID isn't a great name, since it makes it sound like it doesn't also include the GroupID.  Isn't the joke "There are only two hard things in CS, cache invalidation, naming things and off by one errors?"

Jim

> On Jul 2, 2014, at 3:26 PM, jingham at apple.com wrote:
> 
> The way to think about this distinction is to ask yourself whether you would need this feature to do remote debugging from one OS to a different OS.  In principle, lldb should be able to cross-debug from any OS to any other.
> 
> In this case, the way users & groups is represented is a feature of a process controlled by the debugger.  So the knowledge of how that works can't live in Host, it has to live in Target.  Note also that while Host code is only required to build on the platform that you are running lldb on, features of a process have to build on all architectures, again to support cross debugging.
> 
> Jim
> 
> 
>> On Jul 2, 2014, at 2:52 PM, Zachary Turner <zturner at google.com> wrote:
>> 
>> I've started experimenting with adding support to LLDB for debugging native Windows executables on Windows.  So windows host, windows target.  I've done a few little cleanup tasks here and there and fixed some low-hanging fruit, and I'd like to move onto something more meaty.
>> 
>> I took a look at what it would take to get "platform process list" to work.  The first thing I notice is that all of the Process info objects contain the notion of a UID and GID, a concept which doesn't really exist on Windows.  An analagous concept exists, but it's represented completely differently.
>> 
>> My question is: How best to abstract out this functionality?  I'm still not totally clear on where I'm allowed to use platform specific types / APIs and where it needs to be platform agnostic.  My first thought is to remove UID and GID from the ProcessInfo class, and replace them with a instance a "ProcessUserId" class, then provide a PosixProcessUserId and a WindowsProcessUserId, which abstracts away the differences.  
>> 
>> Assuming this approach is logical, where is the best place for this code to go?  Host or Target?
>> 
>> Anything else I should be aware of?
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