All users of this mechanism have been switched to anonymous files and
passing file descriptors with sendfd()/recvfd().
Shbufs got us where we are today, but it's time we say good-bye to them
and welcome a much more idiomatic replacement. :^)
This 'data loss' was introduced in 809a8ee693, because
I hoped we could eventually outlaw overlong paths entirely. This sparked some discussion:
https://github.com/SerenityOS/serenity/discussions/4357
Among other things, we agree that yeah, the Kernel can and should be able to return
paths of arbitrary length. This means that the 'arbitrary' maximum of PATH_MAX in
UserspaceEmulator should be considered to be unnecessary data loss, and as such, needs to
be fixed.
Now that WindowServer broadcasts the system theme using an anonymous
file, we need clients to pledge "recvfd" so they can receive it.
Some programs keep the "shared_buffer" pledge since it's still used for
a handful of things.
When receiving a file descriptor over IPC, the receiver must now call
take_fd() on the IPC::File to take over the descriptor. Otherwise,
IPC::File will close the file on destruction.
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. :^)
