[PATCH v2 2/2] mfplat: Return HRESULT_FROM_WIN32(ERROR_HANDLE_EOF) when reading past the end of a file stream.

[Nikolay Sivov]

On 10/8/21 7:06 AM, Zebediah Figura wrote:
> Signed-off-by: Zebediah Figura <zfigura at codeweavers.com>
> ---
>  dlls/mfplat/main.c         | 15 ++++++++++++++-
>  dlls/mfplat/tests/mfplat.c |  2 +-
>  2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/dlls/mfplat/main.c b/dlls/mfplat/main.c
> index 7fd713261fc..fb55a8afb21 100644
> --- a/dlls/mfplat/main.c
> +++ b/dlls/mfplat/main.c
> @@ -3843,7 +3843,7 @@ static HRESULT WINAPI bytestream_file_IsEndOfStream(IMFByteStream *iface, BOOL *
>  static HRESULT WINAPI bytestream_file_Read(IMFByteStream *iface, BYTE *buffer, ULONG size, ULONG *read_len)
>  {
>      struct bytestream *stream = impl_from_IMFByteStream(iface);
> -    LARGE_INTEGER position;
> +    LARGE_INTEGER position, file_size;
>      HRESULT hr = S_OK;
>      BOOL ret;
>  
> @@ -3851,6 +3851,19 @@ static HRESULT WINAPI bytestream_file_Read(IMFByteStream *iface, BYTE *buffer, U
>  
>      EnterCriticalSection(&stream->cs);
>  
> +    if (!GetFileSizeEx(stream->hfile, &file_size))
> +    {
> +        LeaveCriticalSection(&stream->cs);
> +        return HRESULT_FROM_WIN32(GetLastError());
> +    }
> +
> +    if (stream->position > file_size.QuadPart)
> +    {
> +        LeaveCriticalSection(&stream->cs);
> +        *read_len = 0;
> +        return HRESULT_FROM_WIN32(ERROR_HANDLE_EOF);
> +    }
> +

I think this is too explicit. Can we rely on read length that ReadFile
returns? Doing (ret && size && !*read_len) -> EOF. Depending on how 0
reads work, when EOF is already reached.