[llvm] r339027 - Fix raw_fd_ostream::write_impl hang due to an infinite loop with large output

[David Blaikie via llvm-commits]

Any chance of a test case?

On Mon, Aug 6, 2018 at 9:22 AM Owen Reynolds via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: gbreynoo
> Date: Mon Aug  6 09:21:41 2018
> New Revision: 339027
>
> URL: http://llvm.org/viewvc/llvm-project?rev=339027&view=rev
> Log:
> Fix raw_fd_ostream::write_impl hang due to an infinite loop with large
> output
>
> On windows when raw_fd_ostream::write_impl calls write, a 32 bit input is
> required for character count. As a variable with size_t is used for this
> argument, on x64 integral demotion occurs. In the case of large files an
> infinite loop follows.
> See: https://bugs.llvm.org/show_bug.cgi?id=37926
> This fix allows the output of files larger than the previous int32 limit.
>
> Differential Revision: https://reviews.llvm.org/D48948
>
> Modified:
>     llvm/trunk/lib/Support/raw_ostream.cpp
>
> Modified: llvm/trunk/lib/Support/raw_ostream.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=339027&r1=339026&r2=339027&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Support/raw_ostream.cpp (original)
> +++ llvm/trunk/lib/Support/raw_ostream.cpp Mon Aug  6 09:21:41 2018
> @@ -613,10 +613,10 @@ void raw_fd_ostream::write_impl(const ch
>    assert(FD >= 0 && "File already closed.");
>    pos += Size;
>
> -  // The maximum write size is limited to SSIZE_MAX because a write
> -  // greater than SSIZE_MAX is implementation-defined in POSIX.
> -  // Since SSIZE_MAX is not portable, we use SIZE_MAX >> 1 instead.
> -  size_t MaxWriteSize = SIZE_MAX >> 1;
> +  // The maximum write size is limited to INT32_MAX. A write
> +  // greater than SSIZE_MAX is implementation-defined in POSIX,
> +  // and Windows _write requires 32 bit input.
> +  size_t MaxWriteSize = INT32_MAX;
>
>  #if defined(__linux__)
>    // It is observed that Linux returns EINVAL for a very large write
> (>2G).
>
>
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