On 03/13/2015 07:54 AM, Eli Zaretskii wrote:
> file handles (which are
> actually pointers in disguise).

Only to the extent that file descriptors are also pointers in disguise.

> Handles to kernel objects are
> system-global on Windows,

They work like file descriptors.

> so you can make a handle inheritable, and
> then pass its value to the subprocess as a command-line argument; the
> subprocess then should convert it to a Posix-style file descriptor by
> calling a function.
> 
> But for this to work vis-à-vis gpg, the Windows port of gpg should
> perform its part of this dance: it should know it accepts handles
> (which could be 64-bit wide in 64-bit builds)

Even on 64-bit builds of Windows, HANDLEs only have 32 significant bits:
see

https://msdn.microsoft.com/en-us/library/windows/desktop/aa384203%28v=vs.85%29.aspx

https://msdn.microsoft.com/en-us/library/windows/desktop/aa384249%28v=vs.85%29.aspx

(Note that we can't know in advance whether a HANDLE will be shared with
a 32-bit application.)