Add comments and another error message.

catkit_core/SharedMemory.cpp

@@ -42,15 +42,24 @@ SharedMemory::~SharedMemory()
  if (m_Buffer)
  {
 #ifdef _WIN32
+ // Unmap the buffer.
  UnmapViewOfFile(m_Buffer);
+
+ // Close the file.
+ // If all handles to the file are closed, the file is automatically removed. In Windows
+ // there is no manual remove as for Linux/MacOS.
  CloseHandle(m_File);
 #else
+ // Remove the shared memory if we are the owner. After this, the shared memory cannot
+ // be opened again.
  if (m_IsOwner)
  shm_unlink((m_Id + ".mem").c_str());
 
+ // Get size in bytes.
  struct stat stat_buf;
  fstat(m_File, &stat_buf);
 
+ // Unmap buffer and close the file.
  munmap(m_Buffer, stat_buf.st_size);
  close(m_File);
 #endif
@@ -81,7 +90,12 @@ std::shared_ptr<SharedMemory> SharedMemory::Create(const std::string &id, size_t
  FileObject file = shm_open((id + ".mem").c_str(), O_CREAT | O_RDWR | O_EXCL, 0666);
 
  if (file < 0)
- throw std::runtime_error("Something went wrong while creating shared memory.");
+ {
+ // Throw an error containing the error message.
+ std::string error_message = ErrnoAsString(errno);
+
+ throw std::runtime_error("Something went wrong while creating shared memory: " + error_message);
+ }
 
  int res = ftruncate(file, num_bytes_in_buffer);