This patch replaces the use of shbufs for GUI::Window backing stores
with the new anonymous files mechanism.
Backing bitmaps are now built on memory allocated with anon_create().
They are passed across the IPC socket as IPC::File. This means that
WindowServer now pledges "recvfd" and graphical clients need to pledge
"sendfd" to work.
To support the cached bitmap swapping optimization on the WindowServer
side, each backing store is assigned an incrementing serial number on
the client side. (This allows us to re-use an already mapped file.)
Problem:
- `HttpProtocol::start_download` and `HttpsProtocol::start_download`
implementations are the same except for a few types.
Solution:
- Follow the "Don't Repeat Yourself" mantra and de-duplicate the code
using templates.
If you don't need a file descriptor after sending it to someone over
IPC, construct it with IPC::File(fd, IPC::File::CloseAfterSending)
and LibIPC will take care of it for you. :^)
This API was a mostly gratuitous deviation from POSIX that gave up some
portability in exchange for avoiding the occasional strlen().
I don't think that was actually achieving anything valuable, so let's
just chill out and have the same open() API as everyone else. :^)
