[Lldb-commits] [PATCH] D18459: Fix FILE * leak in Python API

Francis Ricci via lldb-commits lldb-commits at lists.llvm.org
Thu Mar 24 15:56:51 PDT 2016

fjricci added inline comments.

Comment at: scripts/Python/python-typemaps.swig:532
@@ -531,3 +524,1 @@
-         file.Clear();
-    }
zturner wrote:
> zturner wrote:
> > fjricci wrote:
> > > The problem is that here, we save the `FILE*` (`$1`) and let the `File` (`file`) go out of scope. So the `File` gets destructed (but it's after calling `file.Clear()`, so the close doesn't happen). But we still hold onto the `FILE*`, and we pass it, as `$1`, to the API call (not seen here, but it comes right after this block in the generated swig cpp code).
> > I think SWIG explicitly has a mechanism to handle this.  Let me find it.
> It's the `freearg` [[ http://www.swig.org/Doc1.3/Typemaps.html#Typemaps_nn33 | typemap ]].
> Basically you can put a rule that just calls `fclose()` on the argument, and it will generate this code after it's called the API.
> Would this work?
So the issue is that we don't want to `fclose()` after `SetImmediateOutputFile()`, we want it to `fclose()` when we're done writing to the `FILE*`, which happens when the `CommandReturnObject` is destructed.


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