cloudabi.txt

# Copyright (c) 2016 Nuxi (https://nuxi.nl/) and contributors.
#
# SPDX-License-Identifier: BSD-2-Clause

| # Nuxi CloudABI
|
| CloudABI is what you get if you take POSIX, add capability-based
| security, and remove everything that's incompatible with that. The
| result is a minimal ABI consisting of only 49 syscalls.
|
| CloudABI doesn't have its own kernel, but instead is implemented in existing
| kernels: FreeBSD has CloudABI support for x86-64 and arm64, and [a patch-set
| for NetBSD](https://github.com/NuxiNL/netbsd) and [a patch-set for
| Linux](https://github.com/NuxiNL/linux) are available as well. This means that
| CloudABI binaries can be executed on different operating systems, without any
| modification.
|
| ## Capability-Based Security
|
| Capability-based security means that processes can only perform
| actions that have no global impact. Processes cannot open files by
| their absolute path, cannot open network connections, and cannot
| observe global system state such as the process table.
|
| The capabilities of a process are fully determined by its set of open
| file descriptors (fds). For example, files can only be opened if the
| process already has a file descriptor to a directory the file is in.
|
| Unlike in POSIX, where processes are normally started with file
| descriptors 0, 1, and 2 reserved for standard input, output, and
| error, CloudABI does not reserve any file descriptor numbers for
| specific purposes.
|
| In CloudABI, a process depends on its parent process to launch it with
| the right set of resources, since the process will not be able to open
| any new resources. For example, a simple static web server would need
| to be started with a file descriptor to a [TCP
| listener](https://github.com/NuxiNL/flower), and a file descriptor to
| the directory for which to serve files. The web server will then be
| unable to do anything other than reading files in that directory, and
| process incoming network connections.
|
| So, unknown CloudABI binaries can safely be executed without the need
| for containers, virtual machines, or other sandboxing technologies.
|
| Watch [Ed Schouten's Talk at
| 32C3](https://www.youtube.com/watch?v=3N29vrPoDv8) for more
| information about what capability-based security for UNIX means.
|
| ## Cloudlibc
|
| [Cloudlibc](https://github.com/NuxiNL/cloudlibc) is an implementation
| of the C standard library, without all CloudABI-incompatible
| functions. For example, Cloudlibc does not have `printf`, but does
| have `fprintf`. It does not have `open`, but does have `openat`.
|
| ## CloudABI-Ports
|
| [CloudABI-Ports](https://github.com/NuxiNL/cloudabi-ports) is a
| collection of ports of commonly used libraries and applications to
| CloudABI. It contains software such as `zlib`, `libpng`, `boost`,
| `memcached`, and much more. The software is patched to not depend on
| any global state, such as files in `/etc` or `/dev`, using `open()`,
| etc.
|
| ## Using CloudABI
|
| Instructions for using CloudABI (including kernel modules/patches,
| toolchain, and ports) are available for several operating systems:
|
| - [FreeBSD](https://cloudabi.org/run/freebsd/)
| - [Linux](https://cloudabi.org/run/linux/)
| - [macOS](https://cloudabi.org/run/macos/)
|
| ## Specification of the ABI
|
| The entire ABI is specified in a file called
| [`cloudabi.txt`](https://github.com/NuxiNL/cloudabi/blob/master/cloudabi.txt),
| from which all
| [headers](https://github.com/NuxiNL/cloudabi/tree/master/headers)
| and documentation (including the one you're reading now) is generated.

enum uint8 advice
	| File or memory access pattern advisory information.
	1 dontneed
		| The application expects that it will not access the
		| specified data in the near future.
	2 noreuse
		| The application expects to access the specified data
		| once and then not reuse it thereafter.
	3 normal
		| The application has no advice to give on its behavior
		| with respect to the specified data.
	4 random
		| The application expects to access the specified data
		| in a random order.
	5 sequential
		| The application expects to access the specified data
		| sequentially from lower offsets to higher offsets.
	6 willneed
		| The application expects to access the specified data
		| in the near future.

enum uint32 auxtype
	| Enumeration describing the kind of value stored in [auxv].
	@cprefix AT_
	256 argdata
		| Base address of the binary argument data provided to
		| [proc_exec].
	257 argdatalen
		| Length of the binary argument data provided to
		| [proc_exec].
	7 base
		| Base address at which the executable is placed in
		| memory.
	258 canary
		| Base address of a buffer of random data that may be
		| used for non-cryptographic purposes, for example as a
		| canary for stack smashing protection.
	259 canarylen
		| Length of a buffer of random data that may be used
		| for non-cryptographic purposes, for example as a
		| canary for stack smashing protection.
	260 ncpus
		| Number of CPUs that the system this process is running
		| on has.
	0   null
		| Terminator of the auxiliary vector.
	6   pagesz
		| Smallest memory object size for which individual
		| memory protection controls can be configured.
	3   phdr
		| Address of the first ELF program header of the
		| executable.
	4   phnum
		| Number of ELF program headers of the executable.
	263 pid
		| Identifier of the process.
		|
		| This environment does not provide any simple numerical
		| process identifiers, for the reason that these are not
		| useful in distributed contexts. Instead, processes are
		| identified by a UUID.
		|
		| This record should point to sixteen bytes of binary
		| data, containing a version 4 UUID (fully random).
	262 sysinfo_ehdr
		| Address of the ELF header of the vDSO.
		|
		| The vDSO is a shared library that is mapped in the
		| address space of the process. It provides entry points
		| for every system call supported by the environment,
		| all having a corresponding symbol that is prefixed
		| with `cloudabi_sys_`. System calls should be invoked
		| through these entry points.
		|
		| The first advantage of letting processes call into a
		| vDSO to perform system calls instead of raising
		| hardware traps is that it allows for easy emulation of
		| executables on top of existing operating systems. The
		| second advantage is that in cases where an operating
		| system provides native support for CloudABI executables,
		| it may still implement partial userspace
		| implementations of these system calls to improve
		| performance (e.g., [clock_time_get]). It also provides
		| a more dynamic way of adding, removing or replacing
		| system calls.
	261 tid
		| Thread ID of the initial thread of the process.

enum uint32 clockid
	| Identifiers for clocks.
	@cprefix CLOCK_
	1 monotonic
		| The system-wide monotonic clock, which is defined as a
		| clock measuring real time, whose value cannot be
		| adjusted and which cannot have negative clock jumps.
		|
		| The epoch of this clock is undefined. The absolute
		| time value of this clock therefore has no meaning.
	2 process_cputime_id
		| The CPU-time clock associated with the current
		| process.
	3 realtime
		| The system-wide clock measuring real time. Time value
		| zero corresponds with 1970-01-01T00:00:00Z.
	4 thread_cputime_id
		| The CPU-time clock associated with the current thread.

opaque uint32 condvar
	| A userspace condition variable.
	0 has_no_waiters
		| The condition variable is in its initial state. There
		| are no threads waiting to be woken up. If the
		| condition variable has any other value, the kernel
		| must be called to wake up any sleeping threads.

opaque uint64 device
	| Identifier for a device containing a file system. Can be used
	| in combination with [inode] to uniquely identify a file on the
	| local system.

opaque uint64 dircookie
	| A reference to the offset of a directory entry.
	0 start
		| Permanent reference to the first directory entry
		| within a directory.

enum uint16 errno
	| Error codes returned by system calls.
	|
	| Not all of these error codes are returned by the system calls
	| provided by this environment, but are either used in userspace
	| exclusively or merely provided for alignment with POSIX.
	@cprefix E
	0  success
		| No error occurred. System call completed successfully.
	1  2big
		| Argument list too long.
	2  acces
		| Permission denied.
	3  addrinuse
		| Address in use.
	4  addrnotavail
		| Address not available.
	5  afnosupport
		| Address family not supported.
	6  again
		| Resource unavailable, or operation would block.
	7  already
		| Connection already in progress.
	8  badf
		| Bad file descriptor.
	9  badmsg
		| Bad message.
	10 busy
		| Device or resource busy.
	11 canceled
		| Operation canceled.
	12 child
		| No child processes.
	13 connaborted
		| Connection aborted.
	14 connrefused
		| Connection refused.
	15 connreset
		| Connection reset.
	16 deadlk
		| Resource deadlock would occur.
	17 destaddrreq
		| Destination address required.
	18 dom
		| Mathematics argument out of domain of function.
	19 dquot
		| Reserved.
	20 exist
		| File exists.
	21 fault
		| Bad address.
	22 fbig
		| File too large.
	23 hostunreach
		| Host is unreachable.
	24 idrm
		| Identifier removed.
	25 ilseq
		| Illegal byte sequence.
	26 inprogress
		| Operation in progress.
	27 intr
		| Interrupted function.
	28 inval
		| Invalid argument.
	29 io
		| I/O error.
	30 isconn
		| Socket is connected.
	31 isdir
		| Is a directory.
	32 loop
		| Too many levels of symbolic links.
	33 mfile
		| File descriptor value too large.
	34 mlink
		| Too many links.
	35 msgsize
		| Message too large.
	36 multihop
		| Reserved.
	37 nametoolong
		| Filename too long.
	38 netdown
		| Network is down.
	39 netreset
		| Connection aborted by network.
	40 netunreach
		| Network unreachable.
	41 nfile
		| Too many files open in system.
	42 nobufs
		| No buffer space available.
	43 nodev
		| No such device.
	44 noent
		| No such file or directory.
	45 noexec
		| Executable file format error.
	46 nolck
		| No locks available.
	47 nolink
		| Reserved.
	48 nomem
		| Not enough space.
	49 nomsg
		| No message of the desired type.
	50 noprotoopt
		| Protocol not available.
	51 nospc
		| No space left on device.
	52 nosys
		| Function not supported.
	53 notconn
		| The socket is not connected.
	54 notdir
		| Not a directory or a symbolic link to a directory.
	55 notempty
		| Directory not empty.
	56 notrecoverable
		| State not recoverable.
	57 notsock
		| Not a socket.
	58 notsup
		| Not supported, or operation not supported on socket.
	59 notty
		| Inappropriate I/O control operation.
	60 nxio
		| No such device or address.
	61 overflow
		| Value too large to be stored in data type.
	62 ownerdead
		| Previous owner died.
	63 perm
		| Operation not permitted.
	64 pipe
		| Broken pipe.
	65 proto
		| Protocol error.
	66 protonosupport
		| Protocol not supported.
	67 prototype
		| Protocol wrong type for socket.
	68 range
		| Result too large.
	69 rofs
		| Read-only file system.
	70 spipe
		| Invalid seek.
	71 srch
		| No such process.
	72 stale
		| Reserved.
	73 timedout
		| Connection timed out.
	74 txtbsy
		| Text file busy.
	75 xdev
		| Cross-device link.
	76 notcapable
		| Extension: Capabilities insufficient.

flags uint16 eventrwflags
	| The state of the file descriptor subscribed to with
	| [eventtype.fd_read] or [eventtype.fd_write].
	@cprefix EVENT_FD_READWRITE_
	0x01 hangup
		| The peer of this socket has closed or disconnected.

enum uint8 eventtype
	| Type of a subscription to an event or its occurrence.
	1 clock
		| The time value of clock [subscription.clock.clock_id]
		| has reached timestamp [subscription.clock.timeout].
	2 condvar
		| Condition variable [subscription.condvar.condvar] has
		| been woken up and [subscription.condvar.lock] has been
		| acquired for writing.
	3 fd_read
		| File descriptor [subscription.fd_readwrite.fd] has
		| data available for reading. This event always triggers
		| for regular files.
	4 fd_write
		| File descriptor [subscription.fd_readwrite.fd] has
		| capacity available for writing. This event always
		| triggers for regular files.
	5 lock_rdlock
		| Lock [subscription.lock.lock] has been acquired for
		| reading.
	6 lock_wrlock
		| Lock [subscription.lock.lock] has been acquired for
		| writing.
	7 proc_terminate
		| The process associated with process descriptor
		| [subscription.proc_terminate.fd] has terminated.

alias uint32 exitcode
	| Exit code generated by a process when exiting.

opaque uint32 fd
	| A file descriptor number.
	|
	| Unlike on POSIX-compliant systems, none of the file descriptor
	| numbers are reserved for a purpose (e.g., stdin, stdout,
	| stderr). Operating systems are not required to allocate new
	| file descriptors in ascending order.
	@cprefix
	0xffffffff process_child
		| Returned to the child process by [proc_fork].
	0xffffffff map_anon_fd
		| Passed to [mem_map] when creating a mapping to
		| anonymous memory.

flags uint16 fdflags
	| File descriptor flags.
	@cprefix FDFLAG_
	0x01 append
		| Append mode: Data written to the file is always
		| appended to the file's end.
	0x02 dsync
		| Write according to synchronized I/O data integrity
		| completion. Only the data stored in the file is
		| synchronized.
	0x04 nonblock
		| Non-blocking mode.
	0x08 rsync
		| Synchronized read I/O operations.
	0x10 sync
		| Write according to synchronized I/O file integrity
		| completion. In addition to synchronizing the data
		| stored in the file, the system may also synchronously
		| update the file's metadata.

flags uint16 fdsflags
	| Which file descriptor attributes to adjust.
	@cprefix FDSTAT_
	0x01 flags
		| Adjust the file descriptor flags stored in
		| [fdstat.fs_flags].
	0x02 rights
		| Restrict the rights of the file descriptor to the
		| rights stored in [fdstat.fs_rights_base] and
		| [fdstat.fs_rights_inheriting].

alias int64 filedelta
	| Relative offset within a file.

alias uint64 filesize
	| Non-negative file size or length of a region within a file.

flags uint16 fsflags
	| Which file attributes to adjust.
	@cprefix FILESTAT_
	0x01 atim
		| Adjust the last data access timestamp to the value
		| stored in [filestat.st_atim].
	0x02 atim_now
		| Adjust the last data access timestamp to the time
		| of clock [clockid.realtime].
	0x04 mtim
		| Adjust the last data modification timestamp to the
		| value stored in [filestat.st_mtim].
	0x08 mtim_now
		| Adjust the last data modification timestamp to the
		| time of clock [clockid.realtime].
	0x10 size
		| Truncate or extend the file to the size stored in
		| [filestat.st_size].

enum uint8 filetype
	| The type of a file descriptor or file.
	0x00 unknown
		| The type of the file descriptor or file is unknown or
		| is different from any of the other types specified.
	0x10 block_device
		| The file descriptor or file refers to a block device
		| inode.
	0x11 character_device
		| The file descriptor or file refers to a character
		| device inode.
	0x20 directory
		| The file descriptor or file refers to a directory
		| inode.
	0x50 process
		| The file descriptor refers to a process handle.
	0x60 regular_file
		| The file descriptor or file refers to a regular file
		| inode.
	0x70 shared_memory
		| The file descriptor refers to a shared memory object.
	0x80 socket_dgram
		| The file descriptor or file refers to a datagram
		| socket.
	0x82 socket_stream
		| The file descriptor or file refers to a byte-stream
		| socket.
	0x90 symbolic_link
		| The file refers to a symbolic link inode.

opaque uint64 inode
	| File serial number that is unique within its file system.

alias uint32 linkcount
	| Number of hard links to an inode.

opaque uint32 lock
	| A userspace read-recursive readers-writer lock, similar to a
	| Linux futex or a FreeBSD umtx.
	0          unlocked
		| Value indicating that the lock is in its initial
		| unlocked state.
	0x40000000 wrlocked
		| Bitmask indicating that the lock is write-locked. If
		| set, the lower 30 bits of the lock contain the
		| identifier of the thread that owns the write lock.
		| Otherwise, the lower 30 bits of the lock contain the
		| number of acquired read locks.
	0x80000000 kernel_managed
		| Bitmask indicating that the lock is either read locked
		| or write locked, and that one or more threads have
		| their execution suspended, waiting to acquire the
		| lock. The last owner of the lock must call the
		| kernel to unlock.
		|
		| When the lock is acquired for reading and this bit is
		| set, it means that one or more threads are attempting
		| to acquire this lock for writing. In that case, other
		| threads should only acquire additional read locks if
		| suspending execution would cause a deadlock. It is
		| preferred to suspend execution, as this prevents
		| starvation of writers.
	0x80000000 bogus
		| Value indicating that the lock is in an incorrect
		| state. A lock cannot be in its initial unlocked state,
		| while also managed by the kernel.

flags uint32 lookupflags
	| Flags determining the method of how paths are resolved.
	@cprefix LOOKUP_
	1 symlink_follow
		| As long as the resolved path corresponds to a symbolic
		| link, it is expanded.

flags uint8 mflags
	| Memory mapping flags.
	@cprefix MAP_
	0x01 anon
		| Instead of mapping the contents of the file provided,
		| create a mapping to anonymous memory. The file
		| descriptor argument must be set to [fd.map_anon_fd],
		| and the offset must be set to zero.
	0x02 fixed
		| Require that the mapping is performed at the base
		| address provided.
	0x04 private
		| Changes are private.
	0x08 shared
		| Changes are shared.

enum uint8 scope
	| Indicates whether an object is stored in private or shared
	| memory.
	0x04 private
		| The object is stored in private memory.
	0x08 shared
		| The object is stored in shared memory.

flags uint8 mprot
	| Memory page protection options.
	|
	| This implementation enforces the `W^X` property: Pages cannot be
	| mapped for execution while also mapped for writing.
	@cprefix PROT_
	0x01 exec
		| Page can be executed.
	0x02 write
		| Page can be written.
	0x04 read
		| Page can be read.

flags uint8 msflags
	| Methods of synchronizing memory with physical storage.
	@cprefix MS_
	0x01 async
		| Perform asynchronous writes.
	0x02 invalidate
		| Invalidate cached data.
	0x04 sync
		| Perform synchronous writes.

alias uint32 nthreads
	| Specifies the number of threads sleeping on a condition
	| variable that should be woken up.

flags uint16 oflags
	| Open flags used by [file_open].
	@cprefix O_
	0x01 creat
		| Create file if it does not exist.
	0x02 directory
		| Fail if not a directory.
	0x04 excl
		| Fail if file already exists.
	0x08 trunc
		| Truncate file to size 0.

flags uint64 rights
	| File descriptor rights, determining which actions may be
	| performed.
	@cprefix RIGHT_
	0x0000000000000001 fd_datasync
		| The right to invoke [fd_datasync].
		|
		| If [rights.file_open] is set, includes the right to
		| invoke [file_open] with [fdflags.dsync].
	0x0000000000000002 fd_read
		| The right to invoke [fd_read] and [sock_recv].
		|
		| If [rights.mem_map] is set, includes the right to
		| invoke [mem_map] with memory protection option
		| [mprot.read].
		|
		| If [rights.fd_seek] is set, includes the right to invoke
		| [fd_pread].
	0x0000000000000004 fd_seek
		| The right to invoke [fd_seek]. This flag implies
		| [rights.fd_tell].
	0x0000000000000008 fd_stat_put_flags
		| The right to invoke [fd_stat_put] with
		| [fdsflags.flags].
	0x0000000000000010 fd_sync
		| The right to invoke [fd_sync].
		|
		| If [rights.file_open] is set, includes the right to
		| invoke [file_open] with [fdflags.rsync] and
		| [fdflags.dsync].
	0x0000000000000020 fd_tell
		| The right to invoke [fd_seek] in such a way that the
		| file offset remains unaltered (i.e., [whence.cur] with
		| offset zero).
	0x0000000000000040 fd_write
		| The right to invoke [fd_write] and [sock_send].
		|
		| If [rights.mem_map] is set, includes the right to
		| invoke [mem_map] with memory protection option
		| [mprot.write].
		|
		| If [rights.fd_seek] is set, includes the right to
		| invoke [fd_pwrite].
	0x0000000000000080 file_advise
		| The right to invoke [file_advise].
	0x0000000000000100 file_allocate
		| The right to invoke [file_allocate].
	0x0000000000000200 file_create_directory
		| The right to invoke [file_create] with
		| [filetype.directory].
	0x0000000000000400 file_create_file
		| If [rights.file_open] is set, the right to invoke
		| [file_open] with [oflags.creat].
	0x0000000000001000 file_link_source
		| The right to invoke [file_link] with the file
		| descriptor as the source directory.
	0x0000000000002000 file_link_target
		| The right to invoke [file_link] with the file
		| descriptor as the target directory.
	0x0000000000004000 file_open
		| The right to invoke [file_open].
		# Does not include file_open with oflags.creat and
		# oflags.trunc?
	0x0000000000008000 file_readdir
		| The right to invoke [file_readdir].
	0x0000000000010000 file_readlink
		| The right to invoke [file_readlink].
	0x0000000000020000 file_rename_source
		| The right to invoke [file_rename] with the file
		| descriptor as the source directory.
	0x0000000000040000 file_rename_target
		| The right to invoke [file_rename] with the file
		| descriptor as the target directory.
	0x0000000000080000 file_stat_fget
		| The right to invoke [file_stat_fget].
	0x0000000000100000 file_stat_fput_size
		| The right to invoke [file_stat_fput] with
		| [fsflags.size].
		|
		| If [rights.file_open] is set, includes the right to
		| invoke [file_open] with [oflags.trunc].
	0x0000000000200000 file_stat_fput_times
		| The right to invoke [file_stat_fput] with
		| [fsflags.atim], [fsflags.atim_now], [fsflags.mtim],
		| and [fsflags.mtim_now].
	0x0000000000400000 file_stat_get
		| The right to invoke [file_stat_get].
	0x0000000000800000 file_stat_put_times
		| The right to invoke [file_stat_put] with
		| [fsflags.atim], [fsflags.atim_now], [fsflags.mtim],
		| and [fsflags.mtim_now].
	0x0000000001000000 file_symlink
		| The right to invoke [file_symlink].
	0x0000000002000000 file_unlink
		| The right to invoke [file_unlink].
	0x0000000004000000 mem_map
		| The right to invoke [mem_map] with [mprot] set to
		| zero.
	0x0000000008000000 mem_map_exec
		| If [rights.mem_map] is set, the right to invoke
		| [mem_map] with [mprot.exec].
	0x0000000010000000 poll_fd_readwrite
		| If [rights.fd_read] is set, includes the right to
		| invoke [poll] to subscribe to [eventtype.fd_read].
		|
		| If [rights.fd_write] is set, includes the right to
		| invoke [poll] to subscribe to [eventtype.fd_write].
	0x0000000040000000 poll_proc_terminate
		| The right to invoke [poll] to subscribe to
		| [eventtype.proc_terminate].
	0x0000000100000000 proc_exec
		| The right to invoke [proc_exec].
	0x0000008000000000 sock_shutdown
		| The right to invoke [sock_shutdown].

flags uint8 sdflags
	| Which channels on a socket need to be shut down.
	@cprefix SHUT_
	0x01 rd
		| Disables further receive operations.
	0x02 wr
		| Disables further send operations.

flags uint16 siflags
	| Flags provided to [sock_send]. As there are currently no flags
	| defined, it must be set to zero.

enum uint8 signal
	| Signal condition.
	@cprefix SIG
	1  abrt
		| Process abort signal.
		|
		| Action: Terminates the process.
	2  alrm
		| Alarm clock.
		|
		| Action: Terminates the process.
	3  bus
		| Access to an undefined portion of a memory object.
		|
		| Action: Terminates the process.
	4  chld
		| Child process terminated, stopped, or continued.
		|
		| Action: Ignored.
	5  cont
		| Continue executing, if stopped.
		|
		| Action: Continues executing, if stopped.
	6  fpe
		| Erroneous arithmetic operation.
		|
		| Action: Terminates the process.
	7  hup
		| Hangup.
		|
		| Action: Terminates the process.
	8  ill
		| Illegal instruction.
		|
		| Action: Terminates the process.
	9  int
		| Terminate interrupt signal.
		|
		| Action: Terminates the process.
	10 kill
		| Kill.
		|
		| Action: Terminates the process.
	11 pipe
		| Write on a pipe with no one to read it.
		|
		| Action: Ignored.
	12 quit
		| Terminal quit signal.
		|
		| Action: Terminates the process.
	13 segv
		| Invalid memory reference.
		|
		| Action: Terminates the process.
	14 stop
		| Stop executing.
		|
		| Action: Stops executing.
	15 sys
		| Bad system call.
		|
		| Action: Terminates the process.
	16 term
		| Termination signal.
		|
		| Action: Terminates the process.
	17 trap
		| Trace/breakpoint trap.
		|
		| Action: Terminates the process.
	18 tstp
		| Terminal stop signal.
		|
		| Action: Stops executing.
	19 ttin
		| Background process attempting read.
		|
		| Action: Stops executing.
	20 ttou
		| Background process attempting write.
		|
		| Action: Stops executing.
	21 urg
		| High bandwidth data is available at a socket.
		|
		| Action: Ignored.
	22 usr1
		| User-defined signal 1.
		|
		| Action: Terminates the process.
	23 usr2
		| User-defined signal 2.
		|
		| Action: Terminates the process.
	24 vtalrm
		| Virtual timer expired.
		|
		| Action: Terminates the process.
	25 xcpu
		| CPU time limit exceeded.
		|
		| Action: Terminates the process.
	26 xfsz
		| File size limit exceeded.
		|
		| Action: Terminates the process.

flags uint16 subclockflags
	| Flags determining how the timestamp provided in
	| [subscription.clock.timeout] should be interpreted.
	@cprefix SUBSCRIPTION_CLOCK_
	0x01 abstime
		| If set, treat the timestamp provided in
		| [subscription.clock.timeout] as an absolute timestamp
		| of clock [subscription.clock.clock_id].
		|
		| If clear, treat the timestamp provided in
		| [subscription.clock.timeout] relative to the current
		| time value of clock [subscription.clock.clock_id].

flags uint16 subrwflags
	| Flags influencing the method of polling for read or writing on
	| a file descriptor.
	@cprefix SUBSCRIPTION_FD_READWRITE_
	0x01 poll
		| Deprecated. Must be set by callers and ignored by
		| implementations.

flags uint16 riflags
	| Flags provided to [sock_recv].
	@cprefix SOCK_RECV_
	0x04 peek
		| Returns the message without removing it from the
		| socket's receive queue.
	0x10 waitall
		| On byte-stream sockets, block until the full amount
		| of data can be returned.

flags uint16 roflags
	| Flags returned by [sock_recv].
	@cprefix SOCK_RECV_
	0x01 fds_truncated
		| Returned by [sock_recv]: List of file descriptors
		| has been truncated.
	0x08 data_truncated
		| Returned by [sock_recv]: Message data has been
		| truncated.

opaque uint32 tid
	| Unique system-local identifier of a thread. This identifier is
	| only valid during the lifetime of the thread.
	|
	| Threads must be aware of their thread identifier, as it is
	| written it into locks when acquiring them for writing. It is
	| not advised to use these identifiers for any other purpose.
	|
	| As the thread identifier is also stored in [lock] when
	| [lock.wrlocked] is set, the top two bits of the thread
	| must always be set to zero.

alias uint64 timestamp
	| Timestamp in nanoseconds.

flags uint8 ulflags
	| Specifies whether files are unlinked or directories are
	| removed.
	@cprefix UNLINK_
	0x01 removedir
		| If set, removes a directory. Otherwise, unlinks any
		| non-directory file.

alias uint64 userdata
	| User-provided value that can be attached to objects that is
	| retained when extracted from the kernel.

enum uint8 whence
	| Relative to which position the offset of the file descriptor
	| should be set.
	1 cur
		| Seek relative to current position.
	2 end
		| Seek relative to end-of-file.
	3 set
		| Seek relative to start-of-file.

function threadentry
	| Entry point for additionally created threads.
	in
		tid      tid
			| Thread ID of the current thread.
		ptr void aux
			| Copy of the value stored in
			| [threadattr.argument].

struct auxv
	| Auxiliary vector entry.
	|
	| The auxiliary vector is a list of key-value pairs that is
	| provided to the process on startup. Unlike structures, it is
	| extensible, as it is possible to add new records later on.
	| The auxiliary vector is always terminated by an entry having
	| type [auxtype.null].
	|
	| The auxiliary vector is part of the x86-64 ABI, but is used by
	| this environment on all architectures.
	auxtype a_type
		| The type of the auxiliary vector entry.
	variant a_type
		argdatalen canarylen ncpus pagesz phnum tid
			size a_val
				| A numerical value.
		argdata base canary phdr pid sysinfo_ehdr
			ptr void a_ptr
				| A pointer value.

function processentry
	| Entry point for a process (`_start`).
	in
		cptr auxv auxv
			| The auxiliary vector. See [auxv].

struct ciovec
	| A region of memory for scatter/gather writes.
	crange void buf
		| The address and length of the buffer to be written.

struct dirent
	| A directory entry.
	dircookie d_next
		| The offset of the next directory entry stored in this
		| directory.
	inode     d_ino
		| The serial number of the file referred to by this
		| directory entry.
	uint32    d_namlen
		| The length of the name of the directory entry.
	filetype  d_type
		| The type of the file referred to by this directory
		| entry.

struct event
	| An event that occurred.
	userdata  userdata
		| User-provided value that got attached to
		| [subscription.userdata].
	errno     error
		| If non-zero, an error that occurred while processing
		| the subscription request.
	eventtype type
		| The type of the event that occurred.
	variant type
		fd_read fd_write
			struct fd_readwrite
				filesize     nbytes
					| The number of bytes available
					| for reading or writing.
				array 4 char unused
					| Obsolete.
				eventrwflags flags
					| The state of the file
					| descriptor.
		proc_terminate
			struct proc_terminate
				array 4 char unused
					| Obsolete.
				signal       signal
					| If zero, the process has
					| exited.
					| Otherwise, the signal
					| condition causing it to
					| terminated.
				exitcode     exitcode
					| If exited, the exit code of
					| the process.

struct fdstat
	| File descriptor attributes.
	filetype fs_filetype
		| File type.
	fdflags  fs_flags
		| File descriptor flags.
	rights   fs_rights_base
		| Rights that apply to this file descriptor.
	rights   fs_rights_inheriting
		| Maximum set of rights that can be installed on new
		| file descriptors that are created through this file
		| descriptor, e.g., through [file_open].

struct filestat
	| File attributes.
	device    st_dev
		| Device ID of device containing the file.
	inode     st_ino
		| File serial number.
	filetype  st_filetype
		| File type.
	linkcount st_nlink
		| Number of hard links to the file.
	filesize  st_size
		| For regular files, the file size in bytes. For
		| symbolic links, the length in bytes of the pathname
		| contained in the symbolic link.
	timestamp st_atim
		| Last data access timestamp.
	timestamp st_mtim
		| Last data modification timestamp.
	timestamp st_ctim
		| Last file status change timestamp.

struct iovec
	| A region of memory for scatter/gather reads.
	range void buf
		| The address and length of the buffer to be filled.

struct lookup
	| Path lookup properties.
	fd          fd
		| The working directory at which the resolution of the
		| path starts.
	lookupflags flags
		| Flags determining the method of how the path is
		| resolved.

struct recv_in
	| Arguments of [sock_recv].
	crange iovec ri_data
		| List of scatter/gather vectors where message data
		| should be stored.
	range fd     ri_fds
		| Buffer where numbers of incoming file descriptors
		| should be stored.
	riflags      ri_flags
		| Message flags.

struct send_in
	| Arguments of [sock_send].
	crange ciovec si_data
		| List of scatter/gather vectors where message data
		| should be retrieved.
	crange fd     si_fds
		| File descriptors that need to be attached to the
		| message.
	siflags       si_flags
		| Message flags.

struct send_out
	| Results of [sock_send].
	size so_datalen
		| Number of bytes transmitted.

struct recv_out
	| Results of [sock_recv].
	size     ro_datalen
		| Number of bytes stored in [recv_in.ri_data].
	size     ro_fdslen
		| Number of file descriptors stored in [recv_in.ri_fds].
	array 40 char ro_unused
		| Fields that were used by previous implementations.
	roflags  ro_flags
		| Message flags.

struct subscription
	| Subscription to an event.
	userdata  userdata
		| User-provided value that is attached to the
		| subscription in the kernel and returned through
		| [event.userdata].
	uint16    unused
		| Used by previous implementations. Ignored.
	eventtype type
		| The type of the event to which to subscribe.
		|
		| Currently, [eventtype.condvar],
		| [eventtype.lock_rdlock], and [eventtype.lock_wrlock]
		| must be provided as the first subscription and may
		| only be followed by up to one other subscription,
		| having type [eventtype.clock].
	variant type
		clock
			struct clock
				userdata identifier
					| The user-defined unique
					| identifier of the clock.
				clockid  clock_id
					| The clock against which the
					| timestamp should be compared.
		# What happens when waiting for thread_cputime_id?
		# UB? Wait forever? Actually uses monotonic instead?
		# And how about realtime? Can I wait for a specific
		# date/time?
				timestamp timeout
					| The absolute or relative
					| timestamp.
				timestamp precision
					| The amount of time that the
					| kernel may wait additionally
					| to coalesce with other events.
				subclockflags flags
					| Flags specifying whether the
					| timeout is absolute or
					| relative.
		condvar
			struct condvar
				ptr atomic condvar condvar
					| The condition variable on
					| which to wait to be woken up.
				ptr atomic lock    lock
					| The lock that will be
					| released while waiting.
					|
					| The lock will be reacquired
					| for writing when the condition
					| variable triggers.
				scope              condvar_scope
					| Whether the condition variable
					| is stored in private or shared
					| memory.
				scope              lock_scope
					| Whether the lock is stored in
					| private or shared memory.
		fd_read fd_write
			struct fd_readwrite
				fd         fd
					| The file descriptor on which
					| to wait for it to become ready
					| for reading or writing.
				subrwflags flags
					| Under which conditions to
					| trigger.
		lock_rdlock lock_wrlock
			struct lock
				ptr atomic lock lock
					| The lock that will be acquired
					| for reading or writing.
				scope           lock_scope
					| Whether the lock is stored in
					| private or shared memory.
		proc_terminate
			struct proc_terminate
				fd       fd
					| The process descriptor on
					| which to wait for process
					| termination.

struct tcb
	| The Thread Control Block (TCB).
	|
	| After a thread begins execution (at program startup or when
	| created through [thread_create]), the CPU's registers
	| controlling Thread-Local Storage (TLS) will already be
	| initialized. They will point to an area only containing the
	| TCB.
	|
	| If the thread needs space for storing thread-specific
	| variables, the thread may allocate a larger area and adjust
	| the CPU's registers to point to that area instead. However, it
	| does need to make sure that the TCB is copied over to the new
	| TLS area.
	|
	| The purpose of the TCB is that it allows light-weight
	| emulators to store information related to individual threads.
	| For example, it may be used to store a copy of the CPU
	| registers prior emulation, so that TLS for the host system
	| can be restored if needed.
	ptr void parent
		| Pointer that may be freely assigned by the system. Its
		| value cannot be interpreted by the application.

struct threadattr
	| Attributes for thread creation.
	ptr threadentry entry_point
		| Initial program counter value.
	range void      stack
		| Region allocated to serve as stack space.
	ptr void        argument
		| Argument to be forwarded to the entry point function.

syscall clock_res_get
	| Obtains the resolution of a clock.
	in
		clockid   clock_id
			| The clock for which the resolution needs to be
			| returned.
	out
		timestamp resolution
			| The resolution of the clock.

syscall clock_time_get
	| Obtains the time value of a clock.
	in
		clockid   clock_id
			| The clock for which the time needs to be
			| returned.
		timestamp precision
			| The maximum lag (exclusive) that the returned
			| time value may have, compared to its actual
			| value.
	out
		timestamp time
			| The time value of the clock.

syscall condvar_signal
	| Wakes up threads waiting on a userspace condition variable.
	|
	| If an invocation of this system call causes all waiting
	| threads to be woken up, the value of the condition variable
	| is set to [condvar.has_no_waiters]. As long as the condition
	| variable is set to this value, it is not needed to invoke this
	| system call.
	in
		ptr atomic condvar condvar
			| The userspace condition variable that has
			| waiting threads.
		scope              scope
			| Whether the condition variable is stored in
			| private or shared memory.
		nthreads           nwaiters
			| The number of threads that need to be woken
			| up. If it exceeds the number of waiting
			| threads, all threads are woken up.

syscall fd_close
	| Closes a file descriptor.
	in
		fd fd
			| The file descriptor that needs to be closed.

syscall fd_create1
	| Creates a file descriptor.
	in
		filetype type
			shared_memory
				| Creates an anonymous shared memory
				| object.
	out
		fd       fd
			| The file descriptor that has been created.

syscall fd_create2
	| Creates a pair of file descriptors.
	in
		filetype type
			socket_dgram
				| Creates a UNIX datagram socket pair.
			socket_stream
				| Creates a UNIX byte-stream socket
				| pair.
	out
		fd       fd1
			| The first file descriptor of the pair.
		fd       fd2
			| The second file descriptor of the pair.

syscall fd_datasync
	| Synchronizes the data of a file to disk.
	in
		fd fd
			| The file descriptor of the file whose data
			| needs to be synchronized to disk.

syscall fd_dup
	| Duplicates a file descriptor.
	in
		fd from
			| The file descriptor that needs to be
			| duplicated.
	out
		fd fd
			| The new file descriptor.

syscall fd_pread
	| Reads from a file descriptor, without using and updating the
	| file descriptor's offset.
	in
		fd           fd
			| The file descriptor from which data should be
			| read.
		crange iovec iovs
			| List of scatter/gather vectors where data
			| should be stored.
		filesize     offset
			| The offset within the file at which reading
			| should start.
	out
		size         nread
			| The number of bytes read.

syscall fd_pwrite
	| Writes to a file descriptor, without using and updating the
	| file descriptor's offset.
	in
		fd            fd
			| The file descriptor to which data should be
			| written.
		crange ciovec iovs
			| List of scatter/gather vectors where data
			| should be retrieved.
		filesize      offset
			| The offset within the file at which writing
			| should start.
	out
		size          nwritten
			| The number of bytes written.

syscall fd_read
	| Reads from a file descriptor.
	in
		fd           fd
			| The file descriptor from which data should be
			| read.
		crange iovec iovs
			| List of scatter/gather vectors where data
			| should be stored.
	out
		size         nread
			| The number of bytes read.

syscall fd_replace
	| Atomically replaces a file descriptor by a copy of another
	| file descriptor.
	|
	| Due to the strong focus on thread safety, this environment
	| does not provide a mechanism to duplicate a file descriptor to
	| an arbitrary number, like dup2(). This would be prone to race
	| conditions, as an actual file descriptor with the same number
	| could be allocated by a different thread at the same time.
	|
	| This system call provides a way to atomically replace file
	| descriptors, which would disappear if dup2() were to be
	| removed entirely.
	in
		fd from
			| The file descriptor that needs to be copied.
		fd to
			| The file descriptor that needs to be
			| overwritten.

syscall fd_seek
	| Moves the offset of the file descriptor.
	in
		fd        fd
			| The file descriptor whose offset has to be
			| moved.
		filedelta offset
			| The number of bytes to move.
		whence    whence
			| Relative to which position the move should
			| take place.
	out
		filesize newoffset
			| The new offset of the file descriptor,
			| relative to the start of the file.

syscall fd_stat_get
	| Gets attributes of a file descriptor.
	in
		fd         fd
			| The file descriptor whose attributes have to
			| be obtained.
		ptr fdstat buf
			| The buffer where the file descriptor's
			| attributes are stored.

syscall fd_stat_put
	| Adjusts attributes of a file descriptor.
	in
		fd          fd
			| The file descriptor whose attributes have to
			| be adjusted.
		cptr fdstat buf
			| The desired values of the file descriptor
			| attributes that are adjusted.
		fdsflags    flags
			| A bitmask indicating which attributes have to
			| be adjusted.

syscall fd_sync
	| Synchronizes the data and metadata of a file to disk.
	in
		fd fd
			| The file descriptor of the file whose data
			| and metadata needs to be synchronized to disk.

syscall fd_write
	| Writes to a file descriptor.
	in
		fd            fd
			| The file descriptor to which data should be
			| written.
		crange ciovec iovs
			| List of scatter/gather vectors where data
			| should be retrieved.
	out
		size nwritten
			| The number of bytes written.

syscall file_advise
	| Provides file advisory information on a file descriptor.
	in
		fd       fd
			| The file descriptor for which to provide file
			| advisory information.
		filesize offset
			| The offset within the file to which the
			| advisory applies.
		filesize len
			| The length of the region to which the advisory
			| applies.
		advice   advice
			| The advice.

syscall file_allocate
	| Forces the allocation of space in a file.
	in
		fd       fd
			| The file in which the space should be
			| allocated.
		filesize offset
			| The offset at which the allocation should
			| start.
		filesize len
			| The length of the area that is allocated.

syscall file_create
	| Creates a file of a specified type.
	in
		fd          fd
			| The working directory at which the resolution
			| of the file to be created starts.
		crange char path
			| The path at which the file should be created.
		filetype    type
			directory
				| Creates a directory.

syscall file_link
	| Creates a hard link.
	in
		lookup      fd1
			| The working directory at which the resolution
			| of the source path starts.
		crange char path1
			| The source path of the file that should be
			| hard linked.
		fd          fd2
			| The working directory at which the resolution
			| of the destination path starts.
		crange char path2
			| The destination path at which the hard link
			| should be created.

syscall file_open
	| Opens a file.
	in
		lookup      dirfd
			| The working directory at which the resolution
			| of the file to be opened starts.
		crange char path
			| The path of the file that should be opened.
		oflags      oflags
			| The method at which the file should be opened.
		cptr fdstat fds
			| [fdstat.fs_rights_base] and
			| [fdstat.fs_rights_inheriting] specify the
			| initial rights of the newly created file
			| descriptor. The operating system is allowed to
			| return a file descriptor with fewer rights
			| than specified, if and only if those rights do
			| not apply to the type of file being opened.
			|
			| [fdstat.fs_flags] specifies the initial flags
			| of the file descriptor.
			|
			| [fdstat.fs_filetype] is ignored.
	out
		fd fd
			| The file descriptor of the file that has been
			| opened.

syscall file_readdir
	| Reads directory entries from a directory.
	|
	| When successful, the contents of the output buffer consist of
	| a sequence of directory entries. Each directory entry consists
	| of a [dirent] object, followed by [dirent.d_namlen] bytes
	| holding the name of the directory entry.
	|
	| This system call fills the output buffer as much as possible,
	| potentially truncating the last directory entry. This allows
	| the caller to grow its read buffer size in case it's too small
	| to fit a single large directory entry, or skip the oversized
	| directory entry.
	in
		fd         fd
			| The directory from which to read the directory
			| entries.
		range void buf
			| The buffer where directory entries are stored.
		dircookie  cookie
			| The location within the directory to start
			| reading.
	out
		size bufused
			| The number of bytes stored in the read buffer.
			| If less than the size of the read buffer, the
			| end of the directory has been reached.

syscall file_readlink
	| Reads the contents of a symbolic link.
	in
		fd          fd
			| The working directory at which the resolution
			| of the path of the symbolic starts.
		crange char path
			| The path of the symbolic link whose contents
			| should be read.
		range char  buf
			| The buffer where the contents of the symbolic
			| link should be stored.
	out
		size bufused
			| The number of bytes placed in the buffer.

syscall file_rename
	| Renames a file.
	in
		fd          fd1
			| The working directory at which the resolution
			| of the source path starts.
		crange char path1
			| The source path of the file that should be
			| renamed.
		fd          fd2
			| The working directory at which the resolution
			| of the destination path starts.
		crange char path2
			| The destination path to which the file should
			| be renamed.

syscall file_stat_fget
	| Gets attributes of a file by file descriptor.
	in
		fd           fd
			| The file descriptor whose attributes have to
			| be obtained.
		ptr filestat buf
			| The buffer where the file's attributes are
			| stored.

syscall file_stat_fput
	| Adjusts attributes of a file by file descriptor.
	in
		fd            fd
			| The file descriptor whose attributes have to
			| be adjusted.
		cptr filestat buf
			| The desired values of the file attributes that
			| are adjusted.
		fsflags       flags
			| A bitmask indicating which attributes have to
			| be adjusted.

syscall file_stat_get
	| Gets attributes of a file by path.
	in
		lookup       fd
			| The working directory at which the resolution
			| of the path whose attributes have to be
			| obtained starts.
		crange char  path
			| The path of the file whose attributes have to
			| be obtained.
		ptr filestat buf
			| The buffer where the file's attributes are
			| stored.

syscall file_stat_put
	| Adjusts attributes of a file by path.
	in
		lookup        fd
			| The working directory at which the resolution
			| of the path whose attributes have to be
			| adjusted starts.
		crange char   path
			| The path of the file whose attributes have to
			| be adjusted.
		cptr filestat buf
			| The desired values of the file attributes that
			| are adjusted.
		fsflags       flags
			| A bitmask indicating which attributes have to
			| be adjusted.

syscall file_symlink
	| Creates a symbolic link.
	in
		crange char path1
			| The contents of the symbolic link.
		fd          fd
			| The working directory at which the resolution
			| of the destination path starts.
		crange char path2
			| The destination path at which the symbolic
			| link should be created.

syscall file_unlink
	| Unlinks a file, or removes a directory.
	in
		fd          fd
			| The working directory at which the resolution
			| of the path starts.
		crange char path
			| The path that needs to be unlinked or removed.
		ulflags     flags
			removedir
				| If set, attempt to remove a directory.
				| Otherwise, unlink a file.

syscall lock_unlock
	| Unlocks a write-locked userspace lock.
	|
	| If a userspace lock is unlocked while having its
	| [lock.kernel_managed] flag set, the lock cannot be unlocked in
	| userspace directly. This system call needs to be performed
	| instead, so that any waiting threads can be woken up.
	|
	| To prevent spurious invocations of this system call, the lock
	| must be locked for writing. This prevents other threads from
	| acquiring additional read locks while the system call is in
	| progress. If the lock is acquired for reading, it must first
	| be upgraded to a write lock.
	in
		ptr atomic lock lock
			| The userspace lock that is locked for writing
			| by the calling thread.
		scope           scope
			| Whether the lock is stored in private or
			| shared memory.

syscall mem_advise
	| Provides memory advisory information on a region of memory.
	in
		range void mapping
			| The pages for which to provide memory advisory
			| information.
		advice     advice
			| The advice.

syscall mem_map
	| Creates a memory mapping, making the contents of a file
	| accessible through memory.
	in
		ptr void addr
			| If [mflags.fixed] is set, specifies to which
			| address the file region is mapped. Otherwise,
			| the mapping is performed at an unused
			| location.
		size len
			| The length of the memory mapping to be
			| created.
		mprot      prot
			| Initial memory protection options for the
			| memory mapping.
		mflags     flags
			| Memory mapping flags.
		fd         fd
			| If [mflags.anon] is set, this argument must be
			| [fd.map_anon_fd]. Otherwise, this argument
			| specifies the file whose contents need to be
			| mapped.
		filesize   off
			| If [mflags.anon] is set, this argument must be
			| zero. Otherwise, this argument specifies the
			| offset within the file at which the mapping
			| starts.
	out
		ptr void   mem
			| The starting address of the memory mapping.

syscall mem_protect
	| Change the protection of a memory mapping.
	in
		range void mapping
			| The pages that need their protection changed.
		mprot      prot
			| New protection options.

syscall mem_sync
	| Synchronize a region of memory with its physical storage.
	in
		range void mapping
			| The pages that need to be synchronized.
		msflags    flags
			| The method of synchronization.

syscall mem_unmap
	| Unmaps a region of memory.
	in
		range void mapping
			| The pages that needs to be unmapped.

syscall poll
	| Concurrently polls for the occurrence of a set of events.
	in
		cptr subscription in
			| The events to which to subscribe.
		ptr event         out
			| The events that have occurred.
		size              nsubscriptions
			| Both the number of subscriptions and events.
	out
		size nevents
			| The number of events stored.

syscall proc_exec
	| Replaces the process by a new executable.
	|
	| Process execution in CloudABI differs from POSIX in two ways:
	| handling of arguments and inheritance of file descriptors.
	|
	| CloudABI does not use string command line arguments. Instead,
	| a buffer with binary data is copied into the address space of
	| the new executable. The kernel does not enforce any specific
	| structure to this data, although CloudABI's C library uses it
	| to store a tree structure that is semantically identical to
	| YAML.
	|
	| Due to the strong focus on thread safety, file descriptors
	| aren't inherited through close-on-exec flags. An explicit
	| list of file descriptors that need to be retained needs to be
	| provided. After execution, file descriptors are placed in the
	| order in which they are stored in the array. This not only
	| makes the execution process deterministic. It also prevents
	| potential information disclosures about the layout of the
	| original process.
	in
		fd          fd
			| A file descriptor of the new executable.
		crange void data
			| Binary argument data that is passed on to the
			| new executable.
		crange fd   fds
			| The layout of the file descriptor table after
			| execution.

syscall proc_exit
	| Terminates the process normally.
	in
		exitcode rval
			| The exit code returned by the process. The
			| exit code can be obtained by other processes
			| through [event.proc_terminate.exitcode].
	noreturn

syscall proc_fork
	| Forks the process of the calling thread.
	|
	| After forking, a new process shall be created, having only a
	| copy of the calling thread. The parent process will obtain a
	| process descriptor. When closed, the child process is
	| automatically signaled with [signal.kill].
	out
		fd  fd
			| In the parent process: the file descriptor
			| number of the process descriptor.
			|
			| In the child process: [fd.process_child].
		tid tid
			| In the parent process: undefined.
			|
			| In the child process: the thread ID of the
			| initial thread of the child process.

syscall proc_raise
	| Sends a signal to the process of the calling thread.
	in
		signal sig
			| The signal condition that should be triggered.
			| If the signal causes the process to terminate,
			| its condition can be obtained by other
			| processes through
			| [event.proc_terminate.signal].

syscall random_get
	| Obtains random data from the kernel random number generator.
	|
	| As this interface is not guaranteed to be fast, it is advised
	| that the random data obtained through this system call is used
	| as the seed for a userspace pseudo-random number generator.
	in
		range void buf
			| The buffer that needs to be filled with random
			| data.

syscall sock_recv
	| Receives a message on a socket.
	in
		fd           sock
			| The socket on which a message should be
			| received.
		cptr recv_in in
			| Input parameters.
		ptr recv_out out
			| Output parameters.

syscall sock_send
	| Sends a message on a socket.
	in
		fd           sock
			| The socket on which a message should be sent.
		cptr send_in in
			| Input parameters.
		ptr send_out out
			| Output parameters.

syscall sock_shutdown
	| Shuts down socket send and receive channels.
	in
		fd      sock
			| The socket that needs its channels shut down.
		sdflags how
			| Which channels on the socket need to be shut
			| down.

syscall thread_create
	| Creates a new thread within the current process.
	in
		ptr threadattr attr
			| The desired attributes of the new thread.
	out
		tid tid
			| The thread ID of the new thread.

syscall thread_exit
	| Terminates the calling thread.
	|
	| This system call can also unlock a single userspace lock
	| after termination, which can be used to implement thread
	| joining.
	in
		ptr atomic lock lock
			| Userspace lock that is locked for writing by
			| the calling thread.
		scope           scope
			| Whether the lock is stored in private or
			| shared memory.
	noreturn

syscall thread_yield
	| Temporarily yields execution of the calling thread.