[lldb-dev] Process::GetSTDOUT and PutSTDIN

[Zachary Turner]

Looks like I sent this to the wrong mailing list, and during the holiday
season to boot.  Posting it to the right mailing list this time.

To add a little bit to my original post, I did end up finding a few more
places where this is called.  In particular, in addition to the
aforementioned tests, it also seems to be called in order to get the
process's as a way to embed the application's input/output in the LLDB
terminal.

With that said, I also want to add a 3rd question to my original list.

3) Can we satisfy every use case of GetSTDOUT, GetSTDERR, and PutSTDIN with
a different mechanism?  For example, stdio redirection of the target
process.  Unless there is some use case of these functions that require
LLDB to be able to manipulate a target's stdio *without* re-directing them
(so that they are still hooked up to the standard terminal), then it seems
like we should be ok in principle with just repurposing stdio redirection
for this.

The reason I ask is that it is almost impossible (at the very least, it is
extremely difficult) to implement this on Windows in such a way that LLDB
can read / write to these streams without creating a pipe between LLDB and
the target.  If there's a way to satisfy every platform that would be
preferable.  If not, what feature set am I missing out on?

On Fri Nov 21 2014 at 5:46:46 PM Zachary Turner <zturner at google.com> wrote:

> I only see these functions being called from a couple of tests so I wasn't
> able to figure out from the documentation all the preconditions and
> assumptions that these functions make.    So I have a few questions:
>
> 1) Does the use of these functions require or assume that the process is
> stopped at a breakpoint, or should they work even if the process is running?
>
> 2) When you call GetSTDOUT or GetSTDERR and they return successfully, does
> it matter whether this eats the output from the actual STDOUT / STDERR?
>
> For example, let's say we are using the public API and we launch a process
> with STDOUT re-directed to a file.  Later, we call Process.GetSTDOUT using
> the public API, and the value is returned to our script.  Does the output
> that we read still need to go to the file?
>
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