The most important change in this release is the removal of the
poll_fd() system call; CloudABI's equivalent of kevent(). Though I think
that kqueue is a lot saner than many of its alternatives, our
experience is that emulating this system call on other systems
accurately isn't easy. It has become a complex API, even though I'm not
convinced this complexity is needed. This is why we've decided to take a
different approach, by looking one layer up.
We're currently adding an event loop to CloudABI's C library that is API
compatible with libuv (except when incompatible with Capsicum).
Initially, this event loop will be built on top of plain inefficient
poll() calls. Only after this is finished, we'll work our way backwards
and design a new set of system calls to optimize it.
Interesting challenges will include integrating asynchronous I/O into
such a system call API. libuv currently doesn't aio(4) on Linux/BSD, due
to it being unreliable and having undesired semantics.
Obtained from: https://github.com/NuxiNL/cloudabi
Now that all of the packaged software has been adjusted to either use
Flower (https://github.com/NuxiNL/flower) for making incoming/outgoing
network connections or can have connections injected, there is no longer
need to keep accept() around. It is now a lot easier to write networked
services that are address family independent, dual-stack, testable, etc.
Remove all of the bits related to accept(), but also to
getsockopt(SO_ACCEPTCONN).
With Flower (CloudABI's network connection daemon) becoming more
complete, there is no longer any need for creating any unconnected
sockets. Socket pairs in combination with file descriptor passing is all
that is necessary, as that is what is used by Flower to pass network
connections from the public internet to listening processes.
Remove all of the kernel bits that were used to implement socket(),
listen(), bindat() and connectat(). In principle, accept() and
SO_ACCEPTCONN may also be removed, but there are still some consumers
left.
Obtained from: https://github.com/NuxiNL/cloudabi
MFC after: 1 month
The CloudABI specification has had some minor changes over the last half
year. No substantial features have been added, but some features that
are deemed unnecessary in retrospect have been removed:
- mlock()/munlock():
These calls tend to be used for two different purposes: real-time
support and handling of sensitive (cryptographic) material that
shouldn't end up in swap. The former use case is out of scope for
CloudABI. The latter may also be handled by encrypting swap.
Removing this has the advantage that we no longer need to worry about
having resource limits put in place.
- SOCK_SEQPACKET:
Support for SOCK_SEQPACKET is rather inconsistent across various
operating systems. Some operating systems supported by CloudABI (e.g.,
macOS) don't support it at all. Considering that they are rarely used,
remove support for the time being.
- getsockname(), getpeername(), etc.:
A shortcoming of the sockets API is that it doesn't allow you to
create socket(pair)s, having fake socket addresses associated with
them. This makes it harder to test applications or transparently
forward (proxy) connections to them.
With CloudABI, we're slowly moving networking connectivity into a
separate daemon called Flower. In addition to passing around socket
file descriptors, this daemon provides address information in the form
of arbitrary string labels. There is thus no longer any need for
requesting socket address information from the kernel itself.
This change also updates consumers of the generated code accordingly.
Even though system calls end up getting renumbered, this won't cause any
problems in practice. CloudABI programs always call into the kernel
through a kernel-supplied vDSO that has the numbers updated as well.
Obtained from: https://github.com/NuxiNL/cloudabi
A nice thing about requiring a vDSO is that it makes it incredibly easy
to provide full support for running 32-bit processes on 64-bit systems.
Instead of letting the kernel be responsible for composing/decomposing
64-bit arguments across multiple registers/stack slots, all of this can
now be done in the vDSO. This means that there is no need to provide
duplicate copies of certain system calls, like the sys_lseek() and
freebsd32_lseek() we have for COMPAT_FREEBSD32.
This change imports a new vDSO from the CloudABI repository that has
automatically generated code in it that copies system call arguments
into a buffer, padding them to eight bytes and zero-extending any
pointers/size_t arguments. After returning from the kernel, it does the
inverse: extracting return values, in the process truncating
pointers/size_t values to 32 bits.
Obtained from: https://github.com/NuxiNL/cloudabi
