itchio/shoom

:motorway: Cross-platform shared memory access for C++11

shoom

shoom is a small C++11 library for creating & opening shared memory on Windows, Linux and macOS.

License

shoom is released under the MIT license, see the LICENSE file.

shoom's Issues

Get rid of exceptions

They don't conform to the Google C++ style guide, and are hard to handle correctly.

how use this?

i mean including it in project.
how can i do so?

Great lib! :) Why not publish the pre-build binary libs?

I'm just thinking about a nice release with the binaries... would be simple to do and quite cool, no? :)

Thanks for the impl anyway!

I'll soon build a bridge to allow arbitrary data communication between Node.js and native C/C++ apps based on this :)

Cast away error in return from mmap in Unix code

Issue

In shoom_unix_darwin.cc:55:

data_ = static_cast<uint8_t *>(mmap(nullptr,     // addr
                                      size_,       // length
                                      prot,        // prot
                                      MAP_SHARED,  // flags
                                      fd_,         // fd
                                      0            // offset
                                      ));

mmap's return is always cast to a positive number. Which means the code to check that mmap worked always returns true.

Solution

Should explicitly test for MAP_FAILED before the cast.

auto memory = mmap(nullptr,     // addr
                    size_,       // length
                    prot,        // prot
                    MAP_SHARED,  // flags
                    fd_,         // fd
                    0            // offset
                    );

  if (memory == MAP_FAILED) {
    return kErrorMappingFailed;
  }
  
  data_ = static_cast<uint8_t *>(memory);