c_g_spawn_async_with_fds

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
int function(char* workingDirectory, char** argv, char** envp, GSpawnFlags flags, GSpawnChildSetupFunc childSetup, void* userData, GPid* childPid, int stdinFd, int stdoutFd, int stderrFd, GError** err) c_g_spawn_async_with_fds;

Meta