[Sbcl-devel] win32 patch: first round of i/o fixes

[James B. <ja...@ja...>]

Hi,

The attached patch, along with the new file src/code/win32.lisp,
replaces the calls to select in fd-streams with Win32 API calls (and
creates an SB-WIN32 package for them to live in).  It also depends on
Lu=C3=ADs's stdcall patch from a few days ago.

(Apologies if this doesn't apply cleanly to HEAD---I tried to keep it
updated, but due to the need to use -kb with CVS on Windows, none of
the source files are mergeable...)

The select wrapper in the Win32 runtime cannot work for all possible
file handles.  Currently, it will immediately return indicating
available input regardless of whether a read will block, for all file
descriptors except console handles.

The patch replaces the simple cases where code uses unix-select to
check for input on a single file descriptor without blocking.  This
fixes problems with CLEAR-INPUT and READ-CHAR-NO-HANG going into
infinite loops when stdin was a pipe and select was lying to them.

Even once a proper wrapper for select/poll is ready, it's going to be
pretty heavyweight compared to a UNIX select---we'll want to avoid
using it unless we really need to block on multiple fds.

It's now possible to run SBCL/Win32 inside Emacs with M-x run-lisp,
which gets things closer to feeling like home... ;-)