Message 159373 - Python tracker (original) (raw)

the errno codes (EAGAIN etc) are provided only as a compatibility for posix apps that test "errno". On windows, we use the WSA return values from the api functions and WsaGetLastError(). ... So, the proposed patch is not a change, it is merely reinforcing the previous practice of prefering the native error codes over the 'errno' emulation.

Except that Microsoft's C library also uses some of the non-WSA versions. For instance read() (or _read()) is documented to set errno to EBADF or EINVAL on error. So EBADF and EINVAL are just as "native" as WSAEBADF and WSAEINVAL.

It is also quite common for python's C code to do stuff like

errno = EINVAL;
PyErr_SetFromErrno(PyExc_OSError);

errnomap in Objects/exceptions.c is used to convert some OSError exceptions to subclasses like PermissionError. It shouldn't be hard to use it to also convert WSAEINVAL to EINVAL etc.