labath added inline comments.
================
Comment at:
lldb/trunk/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp:1075-1096
+static int readfn(void *ctx, char *buffer, int n)
+{
+ auto state = PyGILState_Ensure();
+ auto *file = (PyObject *) ctx;
+ int result = -1;
+ auto pybuffer = PyBuffer_FromMemory(buffer, n);
+ PyObject *pyresult = NULL;
----------------
zturner wrote:
> zturner wrote:
> > labath wrote:
> > > lawrence_danna wrote:
> > > > zturner wrote:
> > > > > I am still pretty unhappy about these functions, and passing function
> > > > > pointers into the `File` class.
> > > > >
> > > > > I think another approach would be this:
> > > > >
> > > > > 1) Make the `File` class contain a member `std::unique_ptr<IOObject>
> > > > > LowLevelIo;`
> > > > >
> > > > > 2) In `File.cpp`, define something called `class DefaultLowLevelIo :
> > > > > public IOObject` that implements the virtual methods against an fd.
> > > > >
> > > > > 3) In `PythonDataObjects`, define `PythonFileIo : public IOObject`
> > > > > and implement the virtual methods against a `PyObject`.
> > > > >
> > > > > 4) Add an additional constructor to `File` which takes a
> > > > > `std::unique_ptr<IOObject> LowLevelIo`, which we can use when
> > > > > creating one of these from a python file.
> > > > >
> > > > > One advantage of this method is that it allows the `PythonFileIo`
> > > > > class to be easily tested.
> > > > >
> > > > > (Also, sorry for not getting back to reviewing this several weeks ago)
> > > > I don't see how this approach gets around the problem that the
> > > > interfaces in SBDebugger use FILE *, not IOObject
> > > >
> > > > The only way I can see to do it the way you are saying is to also add a
> > > > SBIOObject, with swig wrappers to that, and variants of the SBDebugger
> > > > interfaces that take IOObject instead of FILE *
> > > >
> > > > Do you want to do it that way?
> > > What's the final use case here. In the patch itself I don't see anything
> > > that would necessitate a FILE * conversion, but I don't know what do you
> > > actually intend to use this for. We can always return a null FILE * if
> > > the File object is backed by a a python file (we do the same for file
> > > descriptors, as there is no way to convert those into FILE*, not without
> > > going the fopencookie way).
> > Alright, I re-read this more closely. This is actually something I wanted
> > to fix for a long time. Specifically, I don't believe LLDB should be
> > using `FILE*` anywhere. I would prefer to mark this method dangerous in
> > big letters in the SB API, and add new versions that take an fd. A `FILE*`
> > doesn't even mean anything in Python. It's specifically a native
> > construct.
> >
> > I see it being used in two places currently. 1) Setting to `None`, and 2)
> > setting to the result of `open("/dev/null")`. The open method
> > documentation says "Open a file, returning an object of the file type
> > described in section File Objects".
> >
> > So when this method is being called from Python, it is not even a real
> > `FILE*`, it's a pointer to some python object. I think this is just a bug
> > in the design of the SB API, and we should fix it there.
> >
> > I don't often propose adding new SB APIs, but I think we need an entirely
> > different API here. There should be methods:
> >
> > ```
> > SetOutputFileHandle(SBFile F);
> > SetInputFileHandle(SBFile F);
> > SetErrorFileHandle(SBFile F);
> > ```
> >
> > And we should be passing those. This will in turn necessitate a lot of
> > trickle down changes in the native side too. We can mark the older
> > functions deprecated to indicate that people should no longer be using them.
> >
> > Thoughts?
> Sorry, s/add a new version that takes an fd/add a new version that takes an
> SBFile/
>I don't often propose adding new SB APIs, but I think we need an entirely
>different API here. There should be methods:
>SetOutputFileHandle(SBFile F);
>SetInputFileHandle(SBFile F);
>SetErrorFileHandle(SBFile F);
>And we should be passing those. This will in turn necessitate a lot of trickle
>down changes in the native side too. We can mark the older functions
>deprecated to indicate that people should no longer be using them.
Note that these file handles eventually trickle down into libedit, which
expects to see a FILE *. These could probably be synthesized(*) for libedit's
usage alone, and leave the rest of the world oblivious to FILE*, but it will
need to be done very carefully.
(*) Windows does not have a fopencookie/funopen equivalent afaik, but then
again, it also does not have libedit...
Repository:
rL LLVM
https://reviews.llvm.org/D38829
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