[cfe-dev] libclang locking files for write/delete on windows

[Kim Gräsman]

Hi Yaron,

On Wed, Dec 10, 2014 at 11:34 PM, Yaron Keren <yaron.keren at gmail.com> wrote:
> Before this bug report gets lost, Kim is correct about the error code EC,
> it's an output argument for MemoryBufferMMapFile::MemoryBufferMMapFile and
> must be passed by reference, like:
>
>
> Index: lib/Support/MemoryBuffer.cpp
> ===================================================================
> --- lib/Support/MemoryBuffer.cpp        (revision 223970)
> +++ lib/Support/MemoryBuffer.cpp        (working copy)
> @@ -203,7 +203,7 @@
>
>  public:
>    MemoryBufferMMapFile(bool RequiresNullTerminator, int FD, uint64_t Len,
> -                       uint64_t Offset, std::error_code EC)
> +                       uint64_t Offset, std::error_code &EC)
>        : MFR(FD, false, sys::fs::mapped_file_region::readonly,
>              getLegalMapSize(Len, Offset), getLegalMapOffset(Offset), EC) {
>      if (!EC) {
>
> This passes regression tests.

I started trying to create a unit test in
llvm/unittests/Support/MemoryBufferTest.cpp yesterday that proves this
change, but I think I started at the wrong level. I went at trying to
prove that MemoryBuffer::getOpenFile returned an invalid object on
error, but that would mean having to force mapping to fail
(consistently on all platforms).

Maybe it's better to add a test that MemoryBufferMMapFile's
constructor returns the error code through an out arg? Then It should
be trivial to test with an invalid FD or something.

Let me know if you have other ideas, I can try and put a patch together today.

- Kim