extern "C" int cygwin_attach_handle_to_fd char *name int fd HANDLE handle int bin int access This function can be used to turn a Win32 "handle" into a posix-style file handle. fd may be -1 to make cygwin allocate a handle; the actual handle is returned in all cases. Even after using function, Cygwin doesn't know anything about the underlying file or device. It just tries to supply the typical file functions on a "best-effort" basis. Use with care. Don't expect too much. extern "C" uintptr_t cygwin_internal cygwin_getinfo_types t ... This function gives you access to various internal data and functions. It takes two arguments. The first argument is a type from the 'cygwin_getinfo_types' enum. The second is an optional pointer. Stay away unless you know what you're doing. extern "C" void cygwin_stackdump Outputs a stackdump to stderr from the called location.