The Serenity Stream API is the name for the new set of classes intended
to replace IODevice and its descendants. It provides more flexibility
for subclasses by allowing each subclass to override all the possible
functionalities according to their wishes.
Stream is the base class which implements majority of the functionality
expected from a readable and writable stream. SeekableStream adds
seeking on top, and provides a couple utility methods which derive from
seek. Socket adds a couple of BSD socket utility functions such as
checking whether there is data available to read and checking the
pending bytes on the socket.
As for the concrete classes, there is File which is a SeekableStream and
is intended to operate on file-like objects; and TCPSocket, UDPSocket
and LocalSocket, which handle TCP, UDP and UNIX sockets respectively.
The concrete classes do not do buffering by default. For buffering
functionality, a set of augmentative classes named BufferedSeekable and
BufferedSocket have been implemented, intended to wrap a SeekableStream
and a Socket, respectively.
Everyone used this hook in the same way: immediately accept() on the
socket and then do something with the newly accepted fd.
This patch simplifies the hook by having LocalServer do the accepting
automatically.
It appears that we don't have almost no cases of a callers passing
exec promises when they call `pledge()`. To simplify the code a bit we
add a default parameter that will pass nullptr for us to `pledge()`.
In the spirit of the Core::System name space having "modern" facades
for classically C functions / Kernel interfaces, it seems appropriate
that we should take Span's of data instead of raw pointer + length
arguments.
This is a fallible version of add<T>(...) that returns ErrorOr<T>.
It can be used together with TRY() to handle allocation failures when
instantiating new Core::Objects.
An explicit move constructor is required to null-out the moved-from
directory descriptor. Otherwise, we would call closedir() twice when
using ErrorOr<DirIterator>::release_value().
