[Geany-Devel] [geany/geany] a3664f: Fix spawning [synchronous] commands on Windows

[Dimitar Zhekov]

On Fri, 26 Oct 2012 18:44:04 +0100
Nick Treleaven <nick.treleaven at btinternet.com> wrote:

> On 26/10/2012 17:44, Dimitar Zhekov wrote:
> > I'm using Geany on win~1 recently, with gtk+2.16 and glib-2.22 (the
> > minimum versions). g_spawn_async_with_pipes() works fine for me, from a
> > plugin, for a console application, along with the helper.
> 
> So redirecting I/O works for stdout, stderr and it works for build 
> commands like gcc, make, grep, etc?

It works between a console program and the plugin that spawned it, with
{PeekNamedPipe() + read()} and {repeat write() on N ms} calls.

Note that instead of EAGAIN, read() may return EINVAL, and write() may
return ENOSPC. I have no idea how the higher level I/O functions
respond, and I'm doing async spawn, not sync (though it shoudn't
differ).

One more thing you must do:

HANDLE h = (HANDLE) _get_osfhandle(fd);
DWORD state;

if (h != INVALID_HANDLE_VALUE &&
	GetNamedPipeHandleState(h, &state, NULL, NULL, NULL, NULL, 0))
	{
		state |= PIPE_NOWAIT;
		if (SetNamedPipeHandleState(h, &state, NULL, NULL))
			return TRUE;
	}

return FALSE;

for all fd-s used, otherwise read() and write() will block.

> IME it sometimes works and sometimes doesn't, and it might depend on 
> which program is being spawned (e.g. which grep you use). I recently 
> checked the commits on the GLib gspawn-win32 code and there didn't seem 
> to be any relevant fixes.

The anonymous pipe I/O under Win~1 is not marked as deprecated, but all
documentation says to use overlapped I/O (which is no good for us),
and the named pipe functions work on anonymous pipes only "for
compatibility with MS-DOS LAN Manager" (sic!) IIRC, and may be killed
any time. So it's not much of a glib problem...

-- 
E-gards: Jimmy