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 58 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 and a patch-set for Linux are available as well. This means that CloudABI binaries can be executed in 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 an fd to a listening socket, and an fd to the directory to serve files out of. The web server will then be unable to do anything other than reading files in that directory, and accept connections on the given socket.

So, unknown CloudABI binaries can safely be executed without the need for containers, virtual machines, or other sandboxing techonologies.

Watch Ed Schouten's Talk at 32C3 for more information about what capability-based security for UNIX means.

Cloudlibc

Cloudlibc is an implementation of the C standard library, without all CloudABI-incompatible functions. For example, Cloudlibc does not have open, but does have openat.

CloudABI-Ports

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:

Specification of the ABI

The entire ABI is specified in a a file called cloudabi.txt, from which all headers and documentation (including the one you're reading now) is generated.

Syscalls

`cloudabi_sys_clock_res_get`

Obtains the resolution of a clock.

Inputs:

cloudabi_clockid_t clock_id

The clock for which the resolution needs to be returned.

Outputs:

cloudabi_timestamp_t resolution

The resolution of the clock.

`cloudabi_sys_clock_time_get`

Obtains the time value of a clock.

Inputs:

cloudabi_clockid_t clock_id

The clock for which the time needs to be returned.
cloudabi_timestamp_t precision

The maximum lag (exclusive) that the returned time value may have, compared to its actual value.

Outputs:

cloudabi_timestamp_t time

The time value of the clock.

`cloudabi_sys_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 CLOUDABI_CONDVAR_HAS_NO_WAITERS. As long as the condition variable is set to this value, it is not needed to invoke this system call.

Inputs:

_Atomic(cloudabi_condvar_t) *condvar

The userspace condition variable that has waiting threads.
cloudabi_mflags_t scope

Possible values:
- CLOUDABI_MAP_PRIVATE
  
  The condition variable is stored in private memory.
- CLOUDABI_MAP_SHARED
  
  The condition variable is stored in shared memory.
cloudabi_nthreads_t nwaiters

The number of threads that need to be woken up. If it exceeds the number of waiting threads, all threads are woken up.

`cloudabi_sys_fd_close`

Closes a file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor that needs to be closed.

`cloudabi_sys_fd_create1`

Creates a file descriptor.

Inputs:

cloudabi_filetype_t type

Possible values:
- CLOUDABI_FILETYPE_POLL
  
  Creates a polling event queue.
- CLOUDABI_FILETYPE_SHARED_MEMORY
  
  Creates an anonymous shared memory object.
- CLOUDABI_FILETYPE_SOCKET_DGRAM
  
  Creates a UNIX datagram socket.
- CLOUDABI_FILETYPE_SOCKET_SEQPACKET
  
  Creates a UNIX sequenced-packet socket.
- CLOUDABI_FILETYPE_SOCKET_STREAM
  
  Creates a UNIX byte-stream socket.

Outputs:

cloudabi_fd_t fd

The file descriptor that has been created.

`cloudabi_sys_fd_create2`

Creates a pair of file descriptors.

Inputs:

cloudabi_filetype_t type

Possible values:
- CLOUDABI_FILETYPE_FIFO
  
  Creates a pipe.
- CLOUDABI_FILETYPE_SOCKET_DGRAM
  
  Creates a UNIX datagram socket pair.
- CLOUDABI_FILETYPE_SOCKET_SEQPACKET
  
  Creates a UNIX sequenced-packet socket pair.
- CLOUDABI_FILETYPE_SOCKET_STREAM
  
  Creates a UNIX byte-stream socket pair.

Outputs:

cloudabi_fd_t fd1

The first file descriptor of the pair. For pipes, this corresponds to the read end.
cloudabi_fd_t fd2

The second file descriptor of the pair. For pipes, this corresponds to the write end.

`cloudabi_sys_fd_datasync`

Synchronizes the data of a file to disk.

Inputs:

cloudabi_fd_t fd

The file descriptor of the file whose data needs to be synchronized to disk.

`cloudabi_sys_fd_dup`

Duplicates a file descriptor.

Inputs:

cloudabi_fd_t from

The file descriptor that needs to be duplicated.

Outputs:

cloudabi_fd_t fd

The new file descriptor.

`cloudabi_sys_fd_pread`

Reads from a file descriptor, without using and updating the file descriptor's offset.

Inputs:

cloudabi_fd_t fd

The file descriptor from which data should be read.
const cloudabi_iovec_t *iov and size_t iovcnt

List of scatter/gather vectors where data should be stored.
cloudabi_filesize_t offset

The offset within the file at which reading should start.

Outputs:

size_t nread

The number of bytes read.

`cloudabi_sys_fd_pwrite`

Writes to a file descriptor, without using and updating the file descriptor's offset.

Inputs:

cloudabi_fd_t fd

The file descriptor to which data should be written.
const cloudabi_ciovec_t *iov and size_t iovcnt

List of scatter/gather vectors where data should be retrieved.
cloudabi_filesize_t offset

The offset within the file at which writing should start.

Outputs:

size_t nwritten

The number of bytes written.

`cloudabi_sys_fd_read`

Reads from a file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor from which data should be read.
const cloudabi_iovec_t *iov and size_t iovcnt

List of scatter/gather vectors where data should be stored.

Outputs:

size_t nread

The number of bytes read.

`cloudabi_sys_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.

Inputs:

cloudabi_fd_t from

The file descriptor that needs to be copied.
cloudabi_fd_t to

The file descriptor that needs to be overwritten.

`cloudabi_sys_fd_seek`

Moves the offset of the file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor whose offset has to be moved.
cloudabi_filedelta_t offset

The number of bytes to move.
cloudabi_whence_t whence

Relative to which position the move should take place.

Outputs:

cloudabi_filesize_t newoffset

The new offset of the file descriptor, relative to the start of the file.

`cloudabi_sys_fd_stat_get`

Gets attributes of a file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor whose attributes have to be obtained.
cloudabi_fdstat_t *buf

The buffer where the file descriptor's attributes are stored.

`cloudabi_sys_fd_stat_put`

Adjusts attributes of a file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor whose attributes have to be adjusted.
const cloudabi_fdstat_t *buf

The desired values of the file descriptor attributes that are adjusted.
cloudabi_fdsflags_t flags

A bitmask indicating which attributes have to be adjusted.

`cloudabi_sys_fd_sync`

Synchronizes the data and metadata of a file to disk.

Inputs:

cloudabi_fd_t fd

The file descriptor of the file whose data and metadata needs to be synchronized to disk.

`cloudabi_sys_fd_write`

Writes to a file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor to which data should be written.
const cloudabi_ciovec_t *iov and size_t iovcnt

List of scatter/gather vectors where data should be retrieved.

Outputs:

size_t nwritten

The number of bytes written.

`cloudabi_sys_file_advise`

Provides file advisory information on a file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor for which to provide file advisory information.
cloudabi_filesize_t offset

The offset within the file to which the advisory applies.
cloudabi_filesize_t len

The length of the region to which the advisory applies.
cloudabi_advice_t advice

The advice.

`cloudabi_sys_file_allocate`

Forces the allocation of space in a file.

Inputs:

cloudabi_fd_t fd

The file in which the space should be allocated.
cloudabi_filesize_t offset

The offset at which the allocation should start.
cloudabi_filesize_t len

The length of the area that is allocated.

`cloudabi_sys_file_create`

Creates a file of a specified type.

Inputs:

cloudabi_fd_t fd

The working directory at which the resolution of the file to be created starts.
const char *path and size_t pathlen

The path at which the file should be created.
cloudabi_filetype_t type

Possible values:
- CLOUDABI_FILETYPE_DIRECTORY
  
  Creates a directory.
- CLOUDABI_FILETYPE_FIFO
  
  Creates a FIFO.

`cloudabi_sys_file_link`

Creates a hard link.

Inputs:

cloudabi_lookup_t fd1

The working directory at which the resolution of the source path starts.
const char *path1 and size_t path1len

The source path of the file that should be hard linked.
cloudabi_fd_t fd2

The working directory at which the resolution of the destination path starts.
const char *path2 and size_t path2len

The destination path at which the hard link should be created.

`cloudabi_sys_file_open`

Opens a file.

Inputs:

cloudabi_lookup_t dirfd

The working directory at which the resolution of the file to be opened starts.
const char *path and size_t pathlen

The path of the file that should be opened.
cloudabi_oflags_t oflags

The method at which the file should be opened.
const cloudabi_fdstat_t *fds

The initial attributes of the file descriptor that is returned by this system call.

Outputs:

cloudabi_fd_t fd

The file descriptor of the file that has been opened.

`cloudabi_sys_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 cloudabi_dirent_t object, followed by cloudabi_dirent_t::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.

Inputs:

cloudabi_fd_t fd

The directory from which to read the directory entries.
void *buf and size_t nbyte

The buffer where directory entries are stored.
cloudabi_dircookie_t cookie

The location within the directory to start reading.

Outputs:

size_t 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.

`cloudabi_sys_file_readlink`

Reads the contents of a symbolic link.

Inputs:

cloudabi_fd_t fd

The working directory at which the resolution of the path of the symbolic starts.
const char *path and size_t pathlen

The path of the symbolic link whose contents should be read.
char *buf and size_t bufsize

The buffer where the contents of the symbolic link should be stored.

Outputs:

size_t bufused

The number of bytes placed in the buffer.

`cloudabi_sys_file_rename`

Renames a file.

Inputs:

cloudabi_fd_t oldfd

The working directory at which the resolution of the source path starts.
const char *old and size_t oldlen

The source path of the file that should be renamed.
cloudabi_fd_t newfd

The working directory at which the resolution of the destination path starts.
const char *new and size_t newlen

The destination path to which the file should be renamed.

`cloudabi_sys_file_stat_fget`

Gets attributes of a file by file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor whose attributes have to be obtained.
cloudabi_filestat_t *buf

The buffer where the file's attributes are stored.

`cloudabi_sys_file_stat_fput`

Adjusts attributes of a file by file descriptor.

Inputs:

cloudabi_fd_t fd

The file descriptor whose attributes have to be adjusted.
const cloudabi_filestat_t *buf

The desired values of the file attributes that are adjusted.
cloudabi_fsflags_t flags

A bitmask indicating which attributes have to be adjusted.

`cloudabi_sys_file_stat_get`

Gets attributes of a file by path.

Inputs:

cloudabi_lookup_t fd

The working directory at which the resolution of the path whose attributes have to be obtained starts.
const char *path and size_t pathlen

The path of the file whose attributes have to be obtained.
cloudabi_filestat_t *buf

The buffer where the file's attributes are stored.

`cloudabi_sys_file_stat_put`

Adjusts attributes of a file by path.

Inputs:

cloudabi_lookup_t fd

The working directory at which the resolution of the path whose attributes have to be adjusted starts.
const char *path and size_t pathlen

The path of the file whose attributes have to be adjusted.
const cloudabi_filestat_t *buf

The desired values of the file attributes that are adjusted.
cloudabi_fsflags_t flags

A bitmask indicating which attributes have to be adjusted.

`cloudabi_sys_file_symlink`

Creates a symbolic link.

Inputs:

const char *path1 and size_t path1len

The contents of the symbolic link.
cloudabi_fd_t fd

The working directory at which the resolution of the destination path starts.
const char *path2 and size_t path2len

The destination path at which the symbolic link should be created.

`cloudabi_sys_file_unlink`

Unlinks a file, or removes a directory.

Inputs:

cloudabi_fd_t fd

The working directory at which the resolution of the path starts.
const char *path and size_t pathlen

The path that needs to be unlinked or removed.
cloudabi_ulflags_t flags

Possible values:
- CLOUDABI_UNLINK_REMOVEDIR
  
  If set, attempt to remove a directory. Otherwise, unlink a file.

`cloudabi_sys_lock_unlock`

Unlocks a write-locked userspace lock.

If a userspace lock is unlocked while having its CLOUDABI_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.

Inputs:

_Atomic(cloudabi_lock_t) *lock

The userspace lock that is locked for writing by the calling thread.
cloudabi_mflags_t scope

Possible values:
- CLOUDABI_MAP_PRIVATE
  
  The lock is stored in private memory.
- CLOUDABI_MAP_SHARED
  
  The lock is stored in shared memory.

`cloudabi_sys_mem_advise`

Provides memory advisory information on a region of memory.

Inputs:

void *addr and size_t len

The pages for which to provide memory advisory information.
cloudabi_advice_t advice

The advice.

`cloudabi_sys_mem_lock`

Increments the lock count on a region of memory, which prevents it from leaving system memory.

Inputs:

const void *addr and size_t len

The pages that need its lock count incremented.

`cloudabi_sys_mem_map`

Creates a memory mapping, making the contents of a file accessible through memory.

Inputs:

void *addr

If CLOUDABI_MAP_FIXED is set, specifies to which address the file region is mapped. Otherwise, the mapping is performed at an unused location.
size_t len

The length of the memory mapping to be created.
cloudabi_mprot_t prot

Initial memory protection options for the memory mapping.
cloudabi_mflags_t flags

Memory mapping flags.
cloudabi_fd_t fd

If CLOUDABI_MAP_ANON is set, this argument must be CLOUDABI_MAP_ANON_FD. Otherwise, this argument specifies the file whose contents need to be mapped.
cloudabi_filesize_t off

If CLOUDABI_MAP_ANON is set, this argument must be zero. Otherwise, this argument specifies the offset within the file at which the mapping starts.

Outputs:

void *mem

The starting address of the memory mapping.

`cloudabi_sys_mem_protect`

Change the protection of a memory mapping.

Inputs:

void *addr and size_t len

The pages that need their protection changed.
cloudabi_mprot_t prot

New protection options.

`cloudabi_sys_mem_sync`

Synchronize a region of memory with its physical storage.

Inputs:

void *addr and size_t len

The pages that need to be synchronized.
cloudabi_msflags_t flags

The method of synchronization.

`cloudabi_sys_mem_unlock`

Decrements the lock count on a region of memory, which prevents it from leaving system memory.

Inputs:

const void *addr and size_t len

The pages that need its lock count decremented.

`cloudabi_sys_mem_unmap`

Unmaps a region of memory.

Inputs:

void *addr and size_t len

The pages that needs to be unmapped.

`cloudabi_sys_poll`

Concurrently polls for the occurrence of a set of events.

Inputs:

const cloudabi_subscription_t *in

The events to which to subscribe.
cloudabi_event_t *out

The events that have occurred.
size_t nsubscriptions

Both the number of subscriptions and events.

Outputs:

size_t nevents

The number of events stored.

`cloudabi_sys_poll_fd`

Concurrently polls for the occurrence of a set of events, while retaining subscriptions across calls.

Inputs:

cloudabi_fd_t fd

The polling event queue.
const cloudabi_subscription_t *in and size_t nin

Changes that need to be made to the polling event queue.
cloudabi_event_t *out and size_t nout

The events that have occurred.
const cloudabi_subscription_t *timeout

Subscription of type CLOUDABI_EVENTTYPE_CLOCK to serve as a timeout for the system call. The subscription is local to this invocation of this system call and is automatically purged upon completion.

Outputs:

size_t nevents

The number of events stored.

`cloudabi_sys_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. A buffer with binary data is copied into the new executable instead. 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.

Inputs:

cloudabi_fd_t fd

A file descriptor of the new executable.
const void *data and size_t datalen

Binary argument data that is passed on to the new executable.
const cloudabi_fd_t *fds and size_t fdslen

The layout of the file descriptor table after execution.

`cloudabi_sys_proc_exit`

Terminates the process normally.

Inputs:

cloudabi_exitcode_t rval

The exit code returned by the process. The exit code can be obtained by other processes through cloudabi_event_t::proc_terminate.exitcode.

Does not return.

`cloudabi_sys_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 signalled with CLOUDABI_SIGKILL.

Outputs:

cloudabi_fd_t fd

In the parent process: the file descriptor number of the process descriptor.

In the child process: CLOUDABI_PROCESS_CHILD.
cloudabi_tid_t tid

In the parent process: undefined.

In the child process: the thread ID of the initial thread of the child process.

`cloudabi_sys_proc_raise`

Sends a signal to the process of the calling thread.

Inputs:

cloudabi_signal_t 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 cloudabi_event_t::proc_terminate.signal.

`cloudabi_sys_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.

Inputs:

void *buf and size_t nbyte

The buffer that needs to be filled with random data.

`cloudabi_sys_sock_accept`

Accepts an incoming connection on a listening socket.

Inputs:

cloudabi_fd_t sock

The file descriptor of the listening socket.
cloudabi_sockstat_t *buf

The attributes of the socket associated with the incoming connection.

Outputs:

cloudabi_fd_t conn

The socket associated with the incoming connection.

`cloudabi_sys_sock_bind`

Binds a UNIX socket to a path.

Inputs:

cloudabi_fd_t sock

The file descriptor of the socket to be bound.
cloudabi_fd_t fd

The working directory at which the resolution of the path to which to bind starts.
const char *path and size_t pathlen

The path to which the socket should bind.

`cloudabi_sys_sock_connect`

Connects a UNIX socket to another UNIX socket bound at a path.

Inputs:

cloudabi_fd_t sock

The file descriptor of the socket to connect.
cloudabi_fd_t fd

The working directory at which the resolution of the path to which to connect starts.
const char *path and size_t pathlen

The path to which the socket should onnect.

`cloudabi_sys_sock_listen`

Listens for incoming connections on a socket.

Inputs:

cloudabi_fd_t sock

The socket on which listening should be enabled.
cloudabi_backlog_t backlog

Number of incoming connections the socket is capable of keeping in its backlog.

`cloudabi_sys_sock_recv`

Receives a message on a socket.

Inputs:

cloudabi_fd_t sock

The socket on which a message should be received.
const cloudabi_recv_in_t *in

Input parameters.
cloudabi_recv_out_t *out

Output parameters.

`cloudabi_sys_sock_send`

Sends a message on a socket.

Inputs:

cloudabi_fd_t sock

The socket on which a message should be sent.
const cloudabi_send_in_t *in

Input parameters.
cloudabi_send_out_t *out

Output parameters.

`cloudabi_sys_sock_shutdown`

Shuts down socket send and receive channels.

Inputs:

cloudabi_fd_t sock

The socket that needs its channels shut down.
cloudabi_sdflags_t how

Which channels on the socket need to be shut down.

`cloudabi_sys_sock_stat_get`

Gets attributes of a socket.

Inputs:

cloudabi_fd_t sock

The socket whose attributes have to be obtained.
cloudabi_sockstat_t *buf

The buffer where the socket's attributes are stored.
cloudabi_ssflags_t flags

Flags indicating how the existing socket attributes need to be changed.

`cloudabi_sys_thread_create`

Creates a new thread within the current process.

Inputs:

cloudabi_threadattr_t *attr

The desired attributes of the new thread.

Outputs:

cloudabi_tid_t tid

The thread ID of the new thread.

`cloudabi_sys_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.

Inputs:

_Atomic(cloudabi_lock_t) *lock

Userspace lock that is locked for writing by the calling thread.
cloudabi_mflags_t scope

Possible values:
- CLOUDABI_MAP_PRIVATE
  
  The lock is stored in private memory.
- CLOUDABI_MAP_SHARED
  
  The lock is stored in shared memory.

Does not return.

`cloudabi_sys_thread_tcb_set`

Adjusts the machine-dependent TLS base address register.

On certain architectures, the TLS base address register can only be modified through privileged instructions (e.g., %fs on x86). This system call can be used on those architectures to adjust the contents of this register.

The results are undefined if this system call is invoked on architectures that do have writable TLS base address registers (e.g., aarch64).

Inputs:

void *tcb

The new register contents.

`cloudabi_sys_thread_yield`

Temporarily yields execution of the calling thread.

Types

`cloudabi_advice_t` (`uint8_t`)

File or memory access pattern advisory information.

Possible values:

CLOUDABI_ADVICE_DONTNEED

The application expects that it will not access the specified data in the near future.
CLOUDABI_ADVICE_NOREUSE

The application expects to access the specified data once and then not reuse it thereafter.
CLOUDABI_ADVICE_NORMAL

The application has no advice to give on its behavior with respect to the specified data.
CLOUDABI_ADVICE_RANDOM

The application expects to access the specified data in a random order.
CLOUDABI_ADVICE_SEQUENTIAL

The application expects to access the specified data sequentially from lower offsets to higher offsets.
CLOUDABI_ADVICE_WILLNEED

The application expects to access the specified data in the near future.

`cloudabi_auxtype_t` (`uint32_t`)

Enumeration describing the kind of value stored in cloudabi_auxv_t.

Possible values:

CLOUDABI_AT_ARGDATA

Base address of the binary argument data provided to cloudabi_sys_proc_exec.
CLOUDABI_AT_ARGDATALEN

Length of the binary argument data provided to cloudabi_sys_proc_exec.
CLOUDABI_AT_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.
CLOUDABI_AT_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.
CLOUDABI_AT_NCPUS

Number of CPUs that the system this process is running on has.
CLOUDABI_AT_NULL

Terminator of the auxiliary vector.
CLOUDABI_AT_PAGESZ

Smallest memory object size for which individual memory protection controls can be configured.
CLOUDABI_AT_PHDR

Address of the first ELF program header of the executable.
CLOUDABI_AT_PHNUM

Number of ELF program headers of the executable.
CLOUDABI_AT_TID

Thread ID of the initial thread of the process.

`cloudabi_auxv_t` (`struct`)

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 CLOUDABI_AT_NULL.

The auxiliary vector is part of the x86-64 ABI, but is used by this environment on all architectures.

Members:

cloudabi_auxtype_t a_type

The type of the auxiliary vector entry.
When a_type is one of: CLOUDABI_AT_ARGDATALEN, CLOUDABI_AT_CANARYLEN, CLOUDABI_AT_NCPUS, CLOUDABI_AT_PAGESZ, CLOUDABI_AT_PHNUM, CLOUDABI_AT_TID:
- size_t a_val
  
  A numerical value.
When a_type is one of: CLOUDABI_AT_ARGDATA, CLOUDABI_AT_CANARY, CLOUDABI_AT_PHDR:
- void *a_ptr
  
  A pointer value.

`cloudabi_backlog_t` (`uint32_t`)

Number of incoming connections a socket is capable of keeping in its backlog.

`cloudabi_ciovec_t` (`struct`)

A region of memory for scatter/gather writes.

Members:

const void *iov_base and size_t iov_len

The address and length of the buffer to be written.

`cloudabi_clockid_t` (`uint32_t`)

Identifiers for clocks.

Possible values:

CLOUDABI_CLOCK_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.
CLOUDABI_CLOCK_PROCESS_CPUTIME_ID

The CPU-time clock associated with the current process.
CLOUDABI_CLOCK_REALTIME

The system-wide clock measuring real time. Time value zero corresponds with 1970-01-01T00:00:00Z.
CLOUDABI_CLOCK_THREAD_CPUTIME_ID

The CPU-time clock associated with the current thread.

`cloudabi_condvar_t` (`uint32_t`)

A userspace condition variable.

Special values:

CLOUDABI_CONDVAR_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.

`cloudabi_device_t` (`uint64_t`)

Identifier for a device containing a file system. Can be used in combination with cloudabi_inode_t to uniquely identify a file on the local system.

`cloudabi_dircookie_t` (`uint64_t`)

A reference to the offset of a directory entry.

Special values:

CLOUDABI_DIRCOOKIE_START

Permanent reference to the first directory entry within a directory.

`cloudabi_dirent_t` (`struct`)

A directory entry.

Members:

cloudabi_dircookie_t d_next

The offset of the next directory entry stored in this directory.
cloudabi_inode_t d_ino

The serial number of the file referred to by this directory entry.
uint32_t d_namlen

The length of the name of the directory entry.
cloudabi_filetype_t d_type

The type of the file referred to by this directory entry.

`cloudabi_errno_t` (`uint16_t`)

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.

Possible values:

CLOUDABI_E2BIG

Argument list too long.
CLOUDABI_EACCES

Permission denied.
CLOUDABI_EADDRINUSE

Address in use.
CLOUDABI_EADDRNOTAVAIL

Address not available.
CLOUDABI_EAFNOSUPPORT

Address family not supported.
CLOUDABI_EAGAIN

Resource unavailable, or operation would block.
CLOUDABI_EALREADY

Connection already in progress.
CLOUDABI_EBADF

Bad file descriptor.
CLOUDABI_EBADMSG

Bad message.
CLOUDABI_EBUSY

Device or resource busy.
CLOUDABI_ECANCELED

Operation canceled.
CLOUDABI_ECHILD

No child processes.
CLOUDABI_ECONNABORTED

Connection aborted.
CLOUDABI_ECONNREFUSED

Connection refused.
CLOUDABI_ECONNRESET

Connection reset.
CLOUDABI_EDEADLK

Resource deadlock would occur.
CLOUDABI_EDESTADDRREQ

Destination address required.
CLOUDABI_EDOM

Mathematics argument out of domain of function.
CLOUDABI_EDQUOT

Reserved.
CLOUDABI_EEXIST

File exists.
CLOUDABI_EFAULT

Bad address.
CLOUDABI_EFBIG

File too large.
CLOUDABI_EHOSTUNREACH

Host is unreachable.
CLOUDABI_EIDRM

Identifier removed.
CLOUDABI_EILSEQ

Illegal byte sequence.
CLOUDABI_EINPROGRESS

Operation in progress.
CLOUDABI_EINTR

Interrupted function.
CLOUDABI_EINVAL

Invalid argument.
CLOUDABI_EIO

I/O error.
CLOUDABI_EISCONN

Socket is connected.
CLOUDABI_EISDIR

Is a directory.
CLOUDABI_ELOOP

Too many levels of symbolic links.
CLOUDABI_EMFILE

File descriptor value too large.
CLOUDABI_EMLINK

Too many links.
CLOUDABI_EMSGSIZE

Message too large.
CLOUDABI_EMULTIHOP

Reserved.
CLOUDABI_ENAMETOOLONG

Filename too long.
CLOUDABI_ENETDOWN

Network is down.
CLOUDABI_ENETRESET

Connection aborted by network.
CLOUDABI_ENETUNREACH

Network unreachable.
CLOUDABI_ENFILE

Too many files open in system.
CLOUDABI_ENOBUFS

No buffer space available.
CLOUDABI_ENODEV

No such device.
CLOUDABI_ENOENT

No such file or directory.
CLOUDABI_ENOEXEC

Executable file format error.
CLOUDABI_ENOLCK

No locks available.
CLOUDABI_ENOLINK

Reserved.
CLOUDABI_ENOMEM

Not enough space.
CLOUDABI_ENOMSG

No message of the desired type.
CLOUDABI_ENOPROTOOPT

Protocol not available.
CLOUDABI_ENOSPC

No space left on device.
CLOUDABI_ENOSYS

Function not supported.
CLOUDABI_ENOTCONN

The socket is not connected.
CLOUDABI_ENOTDIR

Not a directory or a symbolic link to a directory.
CLOUDABI_ENOTEMPTY

Directory not empty.
CLOUDABI_ENOTRECOVERABLE

State not recoverable.
CLOUDABI_ENOTSOCK

Not a socket.
CLOUDABI_ENOTSUP

Not supported, or operation not supported on socket.
CLOUDABI_ENOTTY

Inappropriate I/O control operation.
CLOUDABI_ENXIO

No such device or address.
CLOUDABI_EOVERFLOW

Value too large to be stored in data type.
CLOUDABI_EOWNERDEAD

Previous owner died.
CLOUDABI_EPERM

Operation not permitted.
CLOUDABI_EPIPE

Broken pipe.
CLOUDABI_EPROTO

Protocol error.
CLOUDABI_EPROTONOSUPPORT

Protocol not supported.
CLOUDABI_EPROTOTYPE

Protocol wrong type for socket.
CLOUDABI_ERANGE

Result too large.
CLOUDABI_EROFS

Read-only file system.
CLOUDABI_ESPIPE

Invalid seek.
CLOUDABI_ESRCH

No such process.
CLOUDABI_ESTALE

Reserved.
CLOUDABI_ETIMEDOUT

Connection timed out.
CLOUDABI_ETXTBSY

Text file busy.
CLOUDABI_EXDEV

Cross-device link.
CLOUDABI_ENOTCAPABLE

Extension: Capabilities insufficient.

`cloudabi_event_t` (`struct`)

An event that occurred.

Members:

cloudabi_userdata_t userdata

User-provided value that got attached to cloudabi_subscription_t::userdata.
cloudabi_errno_t error

If non-zero, an error that occurred while processing the subscription request.
cloudabi_eventtype_t type

The type of the event that occurred.
When type is CLOUDABI_EVENTTYPE_CLOCK:
- clock
  - cloudabi_userdata_t identifier
    
    The user-defined unique identifier of the clock.
When type is CLOUDABI_EVENTTYPE_CONDVAR:
- condvar
  - _Atomic(cloudabi_condvar_t) *condvar
    
    The condition variable that got woken up.
When type is one of: CLOUDABI_EVENTTYPE_FD_READ, CLOUDABI_EVENTTYPE_FD_WRITE:
- fd_readwrite
  - cloudabi_filesize_t nbytes
    
    The number of bytes available for reading or writing.
  - cloudabi_fd_t fd
    
    The file descriptor that has data available for reading or writing.
  - cloudabi_eventrwflags_t flags
    
    The state of the file descriptor.
When type is one of: CLOUDABI_EVENTTYPE_LOCK_RDLOCK, CLOUDABI_EVENTTYPE_LOCK_WRLOCK:
- lock
  - _Atomic(cloudabi_lock_t) *lock
    
    The lock that has been acquired for reading or writing.
When type is CLOUDABI_EVENTTYPE_PROC_TERMINATE:
- proc_terminate
  - cloudabi_fd_t fd
    
    The process descriptor of the process that has terminated.
  - cloudabi_signal_t signal
    
    If zero, the process has exited. Otherwise, the signal condition causing it to terminated.
  - cloudabi_exitcode_t exitcode
    
    If exited, the exit code of the process.

`cloudabi_eventrwflags_t` (`uint16_t` bitfield)

The state of the file descriptor subscribed to with CLOUDABI_EVENTTYPE_FD_READ or CLOUDABI_EVENTTYPE_FD_WRITE.

Possible values:

CLOUDABI_EVENT_FD_READWRITE_HANGUP

The peer of this FIFO or socket has closed or disconnected.

`cloudabi_eventtype_t` (`uint8_t`)

Type of a subscription to an event or its occurence.

Possible values:

CLOUDABI_EVENTTYPE_CLOCK

The time value of clock cloudabi_subscription_t::clock.clock_id has reached timestamp cloudabi_subscription_t::clock.timeout.
CLOUDABI_EVENTTYPE_CONDVAR

Condition variable cloudabi_subscription_t::condvar.condvar has been woken up.
CLOUDABI_EVENTTYPE_FD_READ

File descriptor cloudabi_subscription_t::fd_readwrite.fd has data available for reading.
CLOUDABI_EVENTTYPE_FD_WRITE

File descriptor cloudabi_subscription_t::fd_readwrite.fd has capacity available for writing.
CLOUDABI_EVENTTYPE_LOCK_RDLOCK

Lock cloudabi_subscription_t::lock.lock has been acquired for reading.
CLOUDABI_EVENTTYPE_LOCK_WRLOCK

Lock cloudabi_subscription_t::lock.lock has been acquired for writing.
CLOUDABI_EVENTTYPE_PROC_TERMINATE

The process associated with process descriptor cloudabi_subscription_t::proc_terminate.fd has terminated.

`cloudabi_exitcode_t` (`uint32_t`)

Exit code generated by a process when exiting.

`cloudabi_fd_t` (`uint32_t`)

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.

Special values:

CLOUDABI_PROCESS_CHILD

Returned to the child process by cloudabi_sys_proc_fork.
CLOUDABI_MAP_ANON_FD

Passed to cloudabi_sys_mem_map when creating a mapping to anonymous memory.

`cloudabi_fdflags_t` (`uint16_t` bitfield)

File descriptor flags.

Possible values:

CLOUDABI_FDFLAG_APPEND

Append mode: Data written to the file is always appended to the file's end.
CLOUDABI_FDFLAG_DSYNC

Write according to synchronized I/O data integrity completion. Only the data stored in the file is synchronized.
CLOUDABI_FDFLAG_NONBLOCK

Non-blocking mode.
CLOUDABI_FDFLAG_RSYNC

Synchronized read I/O operations.
CLOUDABI_FDFLAG_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.

`cloudabi_fdsflags_t` (`uint16_t` bitfield)

Which file descriptor attributes to adjust.

Possible values:

CLOUDABI_FDSTAT_FLAGS

Adjust the file descriptor flags stored in cloudabi_fdstat_t::fs_flags.
CLOUDABI_FDSTAT_RIGHTS

Restrict the rights of the file descriptor to the rights stored in cloudabi_fdstat_t::fs_rights_base and cloudabi_fdstat_t::fs_rights_inheriting.

`cloudabi_fdstat_t` (`struct`)

File descriptor attributes.

Members:

cloudabi_filetype_t fs_filetype

File type.
cloudabi_fdflags_t fs_flags

File descriptor flags.
cloudabi_rights_t fs_rights_base

Rights that apply to this file descriptor.
cloudabi_rights_t 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 cloudabi_sys_file_open.

`cloudabi_filedelta_t` (`int64_t`)

Relative offset within a file.

`cloudabi_filesize_t` (`uint64_t`)

Non-negative file size or length of a region within a file.

`cloudabi_filestat_t` (`struct`)

File attributes.

Members:

cloudabi_device_t st_dev

Device ID of device containing the file.
cloudabi_inode_t st_ino

File serial number.
cloudabi_filetype_t st_filetype

File type.
cloudabi_linkcount_t st_nlink

Number of hard links to the file.
cloudabi_filesize_t 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.
cloudabi_timestamp_t st_atim

Last data access timestamp.
cloudabi_timestamp_t st_mtim

Last data modification timestamp.
cloudabi_timestamp_t st_ctim

Last file status change timestamp.

`cloudabi_filetype_t` (`uint8_t`)

The type of a file descriptor or file.

Possible values:

CLOUDABI_FILETYPE_UNKNOWN

The type of the file descriptor or file is unknown or is different from any of the other types specified.
CLOUDABI_FILETYPE_BLOCK_DEVICE

The file descriptor or file refers to a block device inode.
CLOUDABI_FILETYPE_CHARACTER_DEVICE

The file descriptor or file refers to a character device inode.
CLOUDABI_FILETYPE_DIRECTORY

The file descriptor or file refers to a directory inode.
CLOUDABI_FILETYPE_FIFO

The file descriptor or file refers to a FIFO inode or one of the two endpoints of a pipe.
CLOUDABI_FILETYPE_POLL

The file descriptor refers to a polling event queue.
CLOUDABI_FILETYPE_PROCESS

The file descriptor refers to a process handle.
CLOUDABI_FILETYPE_REGULAR_FILE

The file descriptor or file refers to a regular file inode.
CLOUDABI_FILETYPE_SHARED_MEMORY

The file descriptor refers to a shared memory object.
CLOUDABI_FILETYPE_SOCKET_DGRAM

The file descriptor or file refers to a datagram socket.
CLOUDABI_FILETYPE_SOCKET_SEQPACKET

The file descriptor or file refers to a sequenced-packet socket.
CLOUDABI_FILETYPE_SOCKET_STREAM

The file descriptor or file refers to a byte-stream socket.
CLOUDABI_FILETYPE_SYMBOLIC_LINK

The file refers to a symbolic link inode.

`cloudabi_fsflags_t` (`uint16_t` bitfield)

Which file attributes to adjust.

Possible values:

CLOUDABI_FILESTAT_ATIM

Adjust the last data access timestamp to the value stored in cloudabi_filestat_t::st_atim.
CLOUDABI_FILESTAT_ATIM_NOW

Adjust the last data access timestamp to the time of clock CLOUDABI_CLOCK_REALTIME.
CLOUDABI_FILESTAT_MTIM

Adjust the last data modification timestamp to the value stored in cloudabi_filestat_t::st_mtim.
CLOUDABI_FILESTAT_MTIM_NOW

Adjust the last data modification timestamp to the time of clock CLOUDABI_CLOCK_REALTIME.
CLOUDABI_FILESTAT_SIZE

Truncate or extend the file to the size stored in cloudabi_filestat_t::st_size.

`cloudabi_inode_t` (`uint64_t`)

File serial number that is unique within its file system.

`cloudabi_iovec_t` (`struct`)

A region of memory for scatter/gather reads.

Members:

void *iov_base and size_t iov_len

The address and length of the buffer to be filled.

`cloudabi_linkcount_t` (`uint32_t`)

Number of hard links to an inode.

`cloudabi_lock_t` (`uint32_t`)

A userspace read-recursive readers-writer lock, similar to a Linux futex or a FreeBSD umtx.

Special values:

CLOUDABI_LOCK_UNLOCKED

Value indicating that the lock is in its initial unlocked state.
CLOUDABI_LOCK_WRLOCKED

Bitmask indicating that the lock is write-locked. The lower 30 bits of the lock contain the identifier of the thread that owns the write lock.
CLOUDABI_LOCK_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.
CLOUDABI_LOCK_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.

`cloudabi_lookup_t` (`struct`)

Path lookup properties.

Members:

cloudabi_fd_t fd

The working directory at which the resolution of the path starts.
cloudabi_lookupflags_t flags

Flags determining the method of how the path is resolved.

`cloudabi_lookupflags_t` (`uint32_t` bitfield)

Flags determining the method of how paths are resolved.

Possible values:

CLOUDABI_LOOKUP_SYMLINK_FOLLOW

As long as the resolved path corresponds to a symbolic link, it is expanded.

`cloudabi_mflags_t` (`uint8_t` bitfield)

Memory mapping flags.

Possible values:

CLOUDABI_MAP_ANON

Instead of mapping the contents of the file provided, create a mapping to anonymous memory. The file descriptor argument must be set to CLOUDABI_MAP_ANON_FD, and the offset must be set to zero.
CLOUDABI_MAP_FIXED

Require that the mapping is performed at the base address provided.
CLOUDABI_MAP_PRIVATE

Changes are private.
CLOUDABI_MAP_SHARED

Changes are shared.

`cloudabi_mprot_t` (`uint8_t` bitfield)

Memory page protection options.

This implementation enforces the W^X property: Pages cannot be mapped for execution while also mapped for writing.

Possible values:

CLOUDABI_PROT_EXEC

Page can be executed.
CLOUDABI_PROT_WRITE

Page can be written.
CLOUDABI_PROT_READ

Page can be read.

`cloudabi_msflags_t` (`uint8_t` bitfield)

Methods of synchronizing memory with physical storage.

Possible values:

CLOUDABI_MS_ASYNC

Perform asynchronous writes.
CLOUDABI_MS_INVALIDATE

Perform synchronous writes.
CLOUDABI_MS_SYNC

Invalidate cached data.

`cloudabi_msgflags_t` (`uint16_t` bitfield)

Flags provided to and returned by cloudabi_sys_sock_recv and cloudabi_sys_sock_send.

Possible values:

CLOUDABI_MSG_CTRUNC

Returned by cloudabi_sys_sock_recv: File descriptors truncated.
CLOUDABI_MSG_EOR

Provided to cloudabi_sys_sock_send: Terminates a record (if supported by the protocol).

Returned by cloudabi_sys_sock_recv: End-of-record was received (if supported by the protocol).
CLOUDABI_MSG_PEEK

Provided to cloudabi_sys_sock_recv: Returns the message without removing it from the socket's receive queue.
CLOUDABI_MSG_TRUNC

Returned by cloudabi_sys_sock_recv: Message data has been truncated.
CLOUDABI_MSG_WAITALL

Provided to cloudabi_sys_sock_recv: On byte-stream sockets, block until the full amount of data can be returned.

`cloudabi_nthreads_t` (`uint32_t`)

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

`cloudabi_oflags_t` (`uint16_t` bitfield)

Open flags used by cloudabi_sys_file_open.

Possible values:

CLOUDABI_O_CREAT

Create file if it does not exist.
CLOUDABI_O_DIRECTORY

Fail if not a directory.
CLOUDABI_O_EXCL

Fail if file already exists.
CLOUDABI_O_TRUNC

Truncate file to size 0.

`cloudabi_recv_in_t` (`struct`)

Arguments of cloudabi_sys_sock_recv.

Members:

const cloudabi_iovec_t *ri_data and size_t ri_datalen

List of scatter/gather vectors where message data should be stored.
cloudabi_fd_t *ri_fds and size_t ri_fdslen

Buffer where numbers of incoming file descriptors should be stored.
cloudabi_msgflags_t ri_flags

Message flags. Only CLOUDABI_MSG_PEEK and CLOUDABI_MSG_WAITALL are valid.

`cloudabi_recv_out_t` (`struct`)

Results of cloudabi_sys_sock_recv.

Members:

size_t ro_datalen

Number of bytes stored in cloudabi_recv_in_t::ri_data.
size_t ro_fdslen

Number of file descriptors stored in cloudabi_recv_in_t::ri_fds.
cloudabi_sockaddr_t ro_sockname

Address on which the message was received.
cloudabi_sockaddr_t ro_peername

Address of the peer sending the message.
cloudabi_msgflags_t ro_flags

Message flags. Only CLOUDABI_MSG_CTRUNC, CLOUDABI_MSG_EOR, and CLOUDABI_MSG_TRUNC are valid.

`cloudabi_rights_t` (`uint64_t` bitfield)

File descriptor rights, determining which actions may be performed.

Possible values:

CLOUDABI_RIGHT_FD_DATASYNC

The right to invoke cloudabi_sys_fd_datasync.

If CLOUDABI_RIGHT_FILE_OPEN is set, includes the right to invoke cloudabi_sys_file_open with CLOUDABI_FDFLAG_DSYNC.
CLOUDABI_RIGHT_FD_READ

The right to invoke cloudabi_sys_fd_read and cloudabi_sys_sock_recv.

If CLOUDABI_RIGHT_MEM_MAP is set, includes the right to invoke cloudabi_sys_mem_map with memory protection option CLOUDABI_PROT_READ.

If CLOUDABI_RIGHT_FD_SEEK is set, includes the right to invoke cloudabi_sys_fd_pread.
CLOUDABI_RIGHT_FD_SEEK

The right to invoke cloudabi_sys_fd_seek. This flag implies CLOUDABI_RIGHT_FD_TELL.
CLOUDABI_RIGHT_FD_STAT_PUT_FLAGS

The right to invoke cloudabi_sys_fd_stat_put with CLOUDABI_FDSTAT_FLAGS.
CLOUDABI_RIGHT_FD_SYNC

The right to invoke cloudabi_sys_fd_sync.

If CLOUDABI_RIGHT_FILE_OPEN is set, includes the right to invoke cloudabi_sys_file_open with CLOUDABI_FDFLAG_RSYNC and CLOUDABI_FDFLAG_DSYNC.
CLOUDABI_RIGHT_FD_TELL

The right to invoke cloudabi_sys_fd_seek in such a way that the file offset remains unaltered (i.e., CLOUDABI_WHENCE_CUR with offset zero).
CLOUDABI_RIGHT_FD_WRITE

The right to invoke cloudabi_sys_fd_write and cloudabi_sys_sock_send.

If CLOUDABI_RIGHT_MEM_MAP is set, includes the right to invoke cloudabi_sys_mem_map with memory protection option CLOUDABI_PROT_WRITE.

If CLOUDABI_RIGHT_FD_SEEK is set, includes the right to invoke cloudabi_sys_fd_pwrite.
CLOUDABI_RIGHT_FILE_ADVISE

The right to invoke cloudabi_sys_file_advise.
CLOUDABI_RIGHT_FILE_ALLOCATE

The right to invoke cloudabi_sys_file_allocate.
CLOUDABI_RIGHT_FILE_CREATE_DIRECTORY

The right to invoke cloudabi_sys_file_create with CLOUDABI_FILETYPE_DIRECTORY.
CLOUDABI_RIGHT_FILE_CREATE_FILE

If CLOUDABI_RIGHT_FILE_OPEN is set, the right to invoke cloudabi_sys_file_open with CLOUDABI_O_CREAT.
CLOUDABI_RIGHT_FILE_CREATE_FIFO

The right to invoke cloudabi_sys_file_create with CLOUDABI_FILETYPE_FIFO.
CLOUDABI_RIGHT_FILE_LINK_SOURCE

The right to invoke cloudabi_sys_file_link with the file descriptor as the source directory.
CLOUDABI_RIGHT_FILE_LINK_TARGET

The right to invoke cloudabi_sys_file_link with the file descriptor as the target directory.
CLOUDABI_RIGHT_FILE_OPEN

The right to invoke cloudabi_sys_file_open.
CLOUDABI_RIGHT_FILE_READDIR

The right to invoke cloudabi_sys_file_readdir.
CLOUDABI_RIGHT_FILE_READLINK

The right to invoke cloudabi_sys_file_readlink.
CLOUDABI_RIGHT_FILE_RENAME_SOURCE

The right to invoke cloudabi_sys_file_rename with the file descriptor as the source directory.
CLOUDABI_RIGHT_FILE_RENAME_TARGET

The right to invoke cloudabi_sys_file_rename with the file descriptor as the target directory.
CLOUDABI_RIGHT_FILE_STAT_FGET

The right to invoke cloudabi_sys_file_stat_fget.
CLOUDABI_RIGHT_FILE_STAT_FPUT_SIZE

The right to invoke cloudabi_sys_file_stat_fput with CLOUDABI_FILESTAT_SIZE.

If CLOUDABI_RIGHT_FILE_OPEN is set, includes the right to invoke cloudabi_sys_file_open with CLOUDABI_O_TRUNC.
CLOUDABI_RIGHT_FILE_STAT_FPUT_TIMES

The right to invoke cloudabi_sys_file_stat_fput with CLOUDABI_FILESTAT_ATIM, CLOUDABI_FILESTAT_ATIM_NOW, CLOUDABI_FILESTAT_MTIM, and CLOUDABI_FILESTAT_MTIM_NOW.
CLOUDABI_RIGHT_FILE_STAT_GET

The right to invoke cloudabi_sys_file_stat_get.
CLOUDABI_RIGHT_FILE_STAT_PUT_TIMES

The right to invoke cloudabi_sys_file_stat_put with CLOUDABI_FILESTAT_ATIM, CLOUDABI_FILESTAT_ATIM_NOW, CLOUDABI_FILESTAT_MTIM, and CLOUDABI_FILESTAT_MTIM_NOW.
CLOUDABI_RIGHT_FILE_SYMLINK

The right to invoke cloudabi_sys_file_symlink.
CLOUDABI_RIGHT_FILE_UNLINK

The right to invoke cloudabi_sys_file_unlink.
CLOUDABI_RIGHT_MEM_MAP

The right to invoke cloudabi_sys_mem_map with cloudabi_mprot_t set to zero.
CLOUDABI_RIGHT_MEM_MAP_EXEC

If CLOUDABI_RIGHT_MEM_MAP is set, the right to invoke cloudabi_sys_mem_map with CLOUDABI_PROT_EXEC.
CLOUDABI_RIGHT_POLL_FD_READWRITE

If CLOUDABI_RIGHT_FD_READ is set, includes the right to invoke cloudabi_sys_poll and cloudabi_sys_poll_fd to subscribe to CLOUDABI_EVENTTYPE_FD_READ.

If CLOUDABI_RIGHT_FD_WRITE is set, includes the right to invoke cloudabi_sys_poll and cloudabi_sys_poll_fd to subscribe to CLOUDABI_EVENTTYPE_FD_WRITE.
CLOUDABI_RIGHT_POLL_MODIFY

The right to modify the events a polling event queue is subscribed to.
CLOUDABI_RIGHT_POLL_PROC_TERMINATE

The right to invoke cloudabi_sys_poll and cloudabi_sys_poll_fd to subscribe to CLOUDABI_EVENTTYPE_PROC_TERMINATE.
CLOUDABI_RIGHT_POLL_WAIT

The right to wait for events on a polling event queue and extract them.
CLOUDABI_RIGHT_PROC_EXEC

The right to invoke cloudabi_sys_proc_exec.
CLOUDABI_RIGHT_SOCK_ACCEPT

The right to invoke cloudabi_sys_sock_accept.
CLOUDABI_RIGHT_SOCK_BIND_DIRECTORY

The right to invoke cloudabi_sys_sock_bind with the file descriptor as the directory.
CLOUDABI_RIGHT_SOCK_BIND_SOCKET

The right to invoke cloudabi_sys_sock_bind with the file descriptor as the socket.
CLOUDABI_RIGHT_SOCK_CONNECT_DIRECTORY

The right to invoke cloudabi_sys_sock_connect with the file descriptor as the directory.
CLOUDABI_RIGHT_SOCK_CONNECT_SOCKET

The right to invoke cloudabi_sys_sock_connect with the file descriptor as the socket.
CLOUDABI_RIGHT_SOCK_LISTEN

The right to invoke cloudabi_sys_sock_listen.
CLOUDABI_RIGHT_SOCK_SHUTDOWN

The right to invoke cloudabi_sys_sock_shutdown.
CLOUDABI_RIGHT_SOCK_STAT_GET

The right to invoke cloudabi_sys_sock_stat_get.

`cloudabi_sa_family_t` (`uint8_t`)

Socket address family.

Possible values:

CLOUDABI_AF_UNSPEC

The socket address family is unknown or is different from any of the other address families specified.
CLOUDABI_AF_INET

An IPv4 address.
CLOUDABI_AF_INET6

An IPv6 address.
CLOUDABI_AF_UNIX

The socket is local to the system, and may be bound to the file system.

`cloudabi_sdflags_t` (`uint8_t` bitfield)

Which channels on a socket need to be shut down.

Possible values:

CLOUDABI_SHUT_RD

Disables further receive operations.
CLOUDABI_SHUT_WR

Disables further send operations.

`cloudabi_send_in_t` (`struct`)

Arguments of cloudabi_sys_sock_send.

Members:

const cloudabi_ciovec_t *si_data and size_t si_datalen

List of scatter/gather vectors where message data should be retrieved.
const cloudabi_fd_t *si_fds and size_t si_fdslen

File descriptors that need to be attached to the message.
cloudabi_msgflags_t si_flags

Message flags. Only CLOUDABI_MSG_EOR is valid.

`cloudabi_send_out_t` (`struct`)

Results of cloudabi_sys_sock_send.

Members:

size_t so_datalen

Number of bytes transmitted.

`cloudabi_signal_t` (`uint8_t`)

Signal condition.

Possible values:

CLOUDABI_SIGABRT

Process abort signal.

Action: Terminates the process.
CLOUDABI_SIGALRM

Alarm clock.

Action: Terminates the process.
CLOUDABI_SIGBUS

Access to an undefined portion of a memory object.

Action: Terminates the process.
CLOUDABI_SIGCHLD

Child process terminated, stopped, or continued.

Action: Ignored.
CLOUDABI_SIGCONT

Continue executing, if stopped.

Action: Continues executing, if stopped.
CLOUDABI_SIGFPE

Erroneous arithmetic operation.

Action: Terminates the process.
CLOUDABI_SIGHUP

Hangup.

Action: Terminates the process.
CLOUDABI_SIGILL

Illegal instruction.

Action: Terminates the process.
CLOUDABI_SIGINT

Terminale interrupt signal.

Action: Terminates the process.
CLOUDABI_SIGKILL

Kill.

Action: Terminates the process.
CLOUDABI_SIGPIPE

Write on a pipe with no one to read it.

Action: Ignored.
CLOUDABI_SIGQUIT

Terminal quit signal.

Action: Terminates the process.
CLOUDABI_SIGSEGV

Invalid memory reference.

Action: Terminates the process.
CLOUDABI_SIGSTOP

Stop executing.

Action: Stops executing.
CLOUDABI_SIGSYS

Bad system call.

Action: Terminates the process.
CLOUDABI_SIGTERM

Termination signal.

Action: Terminates the process.
CLOUDABI_SIGTRAP

Trace/breakpoint trap.

Action: Terminates the process.
CLOUDABI_SIGTSTP

Terminal stop signal.

Action: Stops executing.
CLOUDABI_SIGTTIN

Background process attempting read.

Action: Stops executing.
CLOUDABI_SIGTTOU

Background process attempting write.

Action: Stops executing.
CLOUDABI_SIGURG

High bandwidth data is available at a socket.

Action: Ignored.
CLOUDABI_SIGUSR1

User-defined signal 1.

Action: Terminates the process.
CLOUDABI_SIGUSR2

User-defined signal 2.

Action: Terminates the process.
CLOUDABI_SIGVTALRM

Virtual timer expired.

Action: Terminates the process.
CLOUDABI_SIGXCPU

CPU time limit exceeded.

Action: Terminates the process.
CLOUDABI_SIGXFSZ

File size limit exceeded.

Action: Terminates the process.

`cloudabi_sockaddr_t` (`struct`)

Network address of a bound socket or its peer.

Members:

cloudabi_sa_family_t sa_family

Address family.
When sa_family is CLOUDABI_AF_INET:
- sa_inet
  - uint8_t addr[4]
    
    IPv4 address.
  - uint16_t port
    
    IPv4 port number.
When sa_family is CLOUDABI_AF_INET6:
- sa_inet6
  - uint8_t addr[16]
    
    IPv6 address.
  - uint16_t port
    
    IPv6 port number.

`cloudabi_sockstat_t` (`struct`)

Socket attributes.

Members:

cloudabi_sockaddr_t ss_sockname

The address to which this socket is bound.
cloudabi_sockaddr_t ss_peername

The address to which this socket is connected.
cloudabi_errno_t ss_error

Error code of the last completed asynchronous operation performed on this socket.
cloudabi_sstate_t ss_state

Flags describing the state of the socket.

`cloudabi_ssflags_t` (`uint8_t` bitfield)

Specifies which socket attributes need to be altered when calling cloudabi_sys_sock_stat_get.

Possible values:

CLOUDABI_SOCKSTAT_CLEAR_ERROR

Clear cloudabi_sockstat_t::ss_error.

`cloudabi_sstate_t` (`uint32_t` bitfield)

State of the socket.

Possible values:

CLOUDABI_SOCKSTATE_ACCEPTCONN

cloudabi_sys_sock_listen has been called on the socket. The socket is accepting incoming connections.

`cloudabi_subclockflags_t` (`uint16_t` bitfield)

Flags determining how the timestamp provided in cloudabi_subscription_t::clock.timeout should be interpreted.

Possible values:

CLOUDABI_SUBSCRIPTION_CLOCK_ABSTIME

If set, treat the timestamp provided in cloudabi_subscription_t::clock.timeout as an absolute timestamp of clock cloudabi_subscription_t::clock.clock_id.

If clear, treat the timestamp provided in cloudabi_subscription_t::clock.timeout relative to the current time value of clock cloudabi_subscription_t::clock.clock_id.

`cloudabi_subflags_t` (`uint16_t` bitfield)

Flags for cloudabi_sys_poll_fd to determine how to process a subscription request. These flags are ignored by cloudabi_sys_poll.

Possible values:

CLOUDABI_SUBSCRIPTION_ADD

Adds and enables the subscription. Implies CLOUDABI_SUBSCRIPTION_ENABLE, unless CLOUDABI_SUBSCRIPTION_DISABLE is specified.
CLOUDABI_SUBSCRIPTION_CLEAR

Sets the event back to the initial state, so that it no longer triggers.
CLOUDABI_SUBSCRIPTION_DELETE

Deletes the subscription.
CLOUDABI_SUBSCRIPTION_DISABLE

Disables the subscription so that it does not trigger, but does not delete it.
CLOUDABI_SUBSCRIPTION_ENABLE

Enables the subscription so that it can trigger.
CLOUDABI_SUBSCRIPTION_ONESHOT

Automatically deletes the subscription once triggered.

`cloudabi_subrwflags_t` (`uint16_t` bitfield)

Flags influencing the method of polling for read or writing on a file descriptor.

Possible values:

CLOUDABI_SUBSCRIPTION_FD_READWRITE_POLL

If set, trigger immediately when polling for reading on a regular file, just like the POSIX poll function. Otherwise, only trigger when not at the end-of-file.

`cloudabi_subscription_t` (`struct`)

Subscription to an event.

Members:

cloudabi_userdata_t userdata

User-provided value that is attached to the subscription in the kernel and returned through cloudabi_event_t::userdata.
cloudabi_subflags_t flags

Subscription adjustment flags used by cloudabi_sys_poll_fd. Ignored by cloudabi_sys_poll.
cloudabi_eventtype_t type

The type of the event to which to subscribe.
When type is CLOUDABI_EVENTTYPE_CLOCK:
- clock
  - cloudabi_userdata_t identifier
    
    The user-defined unique identifier of the clock.
  - cloudabi_clockid_t clock_id
    
    The clock against which the timestamp should be compared.
  - cloudabi_timestamp_t timeout
    
    The absolute or relative timestamp.
  - cloudabi_timestamp_t precision
    
    The amount of time that the kernel may wait additionally to coalesce with other events.
  - cloudabi_subclockflags_t flags
    
    Flags specifying whether the timeout is absolute or relative.
When type is CLOUDABI_EVENTTYPE_CONDVAR:
- condvar
  - _Atomic(cloudabi_condvar_t) *condvar
    
    The condition variable on which to wait to be woken up.
  - _Atomic(cloudabi_lock_t) *lock
    
    The lock that should be released while waiting.
  - cloudabi_mflags_t condvar_scope
    
    CLOUDABI_MAP_PRIVATE if the condition variable is stored in private memory. CLOUDABI_MAP_SHARED if the condition variable is stored in shared memory.
  - cloudabi_mflags_t lock_scope
    
    CLOUDABI_MAP_PRIVATE if the lock is stored in private memory. CLOUDABI_MAP_SHARED if the lock is stored in shared memory.
When type is one of: CLOUDABI_EVENTTYPE_FD_READ, CLOUDABI_EVENTTYPE_FD_WRITE:
- fd_readwrite
  - cloudabi_fd_t fd
    
    The file descriptor on which to wait for it to become ready for reading or writing.
  - cloudabi_subrwflags_t flags
    
    Under which conditions to trigger.
When type is one of: CLOUDABI_EVENTTYPE_LOCK_RDLOCK, CLOUDABI_EVENTTYPE_LOCK_WRLOCK:
- lock
  - _Atomic(cloudabi_lock_t) *lock
    
    The lock that should be acquired for reading or writing.
  - cloudabi_mflags_t lock_scope
    
    CLOUDABI_MAP_PRIVATE if the lock is stored in private memory. CLOUDABI_MAP_SHARED if the lock is stored in shared memory.
When type is CLOUDABI_EVENTTYPE_PROC_TERMINATE:
- proc_terminate
  - cloudabi_fd_t fd
    
    The process descriptor on which to wait for process termination.

`cloudabi_threadattr_t` (`struct`)

Attributes for thread creation.

Members:

cloudabi_threadentry_t *entry_point

Initial program counter value.
void *stack and size_t stack_size

Region allocated to serve as stack space.
void *argument

Argument to be forwarded to the entry point function.

`cloudabi_threadentry_t` (function type)

Entry point for additionally created threads.

Parameters:

cloudabi_tid_t tid

Thread ID of the current thread.
void *aux

Copy of the value stored in cloudabi_threadattr_t::argument.

`cloudabi_tid_t` (`uint32_t`)

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.

`cloudabi_timestamp_t` (`uint64_t`)

Timestamp in nanoseconds.

`cloudabi_ulflags_t` (`uint8_t` bitfield)

Specifies whether files are unlinked or directories are removed.

Possible values:

CLOUDABI_UNLINK_REMOVEDIR

If set, removes a directory. Otherwise, unlinks any non-directory file.

`cloudabi_userdata_t` (`uint64_t`)

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

`cloudabi_whence_t` (`uint8_t`)

Relative to which position the offset of the file descriptor should be set.

Possible values:

CLOUDABI_WHENCE_CUR

Seek relative to current position.
CLOUDABI_WHENCE_END

Seek relative to end-of-file.
CLOUDABI_WHENCE_SET

Seek relative to start-of-file.

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LICENSE		LICENSE
README.md		README.md
cloudabi.txt		cloudabi.txt
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Nuxi CloudABI

Capability-Based Security

Cloudlibc

CloudABI-Ports

Using CloudABI

Specification of the ABI

Syscalls

cloudabi_sys_clock_res_get

cloudabi_sys_clock_time_get

cloudabi_sys_condvar_signal

cloudabi_sys_fd_close

cloudabi_sys_fd_create1

cloudabi_sys_fd_create2

cloudabi_sys_fd_datasync

cloudabi_sys_fd_dup

cloudabi_sys_fd_pread

cloudabi_sys_fd_pwrite

cloudabi_sys_fd_read

cloudabi_sys_fd_replace

cloudabi_sys_fd_seek

cloudabi_sys_fd_stat_get

cloudabi_sys_fd_stat_put

cloudabi_sys_fd_sync

cloudabi_sys_fd_write

cloudabi_sys_file_advise

cloudabi_sys_file_allocate

cloudabi_sys_file_create

cloudabi_sys_file_link

cloudabi_sys_file_open

cloudabi_sys_file_readdir

cloudabi_sys_file_readlink

cloudabi_sys_file_rename

cloudabi_sys_file_stat_fget

cloudabi_sys_file_stat_fput

cloudabi_sys_file_stat_get

cloudabi_sys_file_stat_put

cloudabi_sys_file_symlink

cloudabi_sys_file_unlink

cloudabi_sys_lock_unlock

cloudabi_sys_mem_advise

cloudabi_sys_mem_lock

cloudabi_sys_mem_map

cloudabi_sys_mem_protect

cloudabi_sys_mem_sync

cloudabi_sys_mem_unlock

cloudabi_sys_mem_unmap

cloudabi_sys_poll

cloudabi_sys_poll_fd

cloudabi_sys_proc_exec

cloudabi_sys_proc_exit

cloudabi_sys_proc_fork

cloudabi_sys_proc_raise

cloudabi_sys_random_get

cloudabi_sys_sock_accept

cloudabi_sys_sock_bind

cloudabi_sys_sock_connect

cloudabi_sys_sock_listen

cloudabi_sys_sock_recv

cloudabi_sys_sock_send

cloudabi_sys_sock_shutdown

cloudabi_sys_sock_stat_get

cloudabi_sys_thread_create

cloudabi_sys_thread_exit

cloudabi_sys_thread_tcb_set

cloudabi_sys_thread_yield

Types

cloudabi_advice_t (uint8_t)

cloudabi_auxtype_t (uint32_t)

cloudabi_auxv_t (struct)

cloudabi_backlog_t (uint32_t)

cloudabi_ciovec_t (struct)

cloudabi_clockid_t (uint32_t)

cloudabi_condvar_t (uint32_t)

cloudabi_device_t (uint64_t)

`cloudabi_sys_clock_res_get`

`cloudabi_sys_clock_time_get`

`cloudabi_sys_condvar_signal`

`cloudabi_sys_fd_close`

`cloudabi_sys_fd_create1`

`cloudabi_sys_fd_create2`

`cloudabi_sys_fd_datasync`

`cloudabi_sys_fd_dup`

`cloudabi_sys_fd_pread`

`cloudabi_sys_fd_pwrite`

`cloudabi_sys_fd_read`

`cloudabi_sys_fd_replace`

`cloudabi_sys_fd_seek`

`cloudabi_sys_fd_stat_get`

`cloudabi_sys_fd_stat_put`

`cloudabi_sys_fd_sync`

`cloudabi_sys_fd_write`

`cloudabi_sys_file_advise`

`cloudabi_sys_file_allocate`

`cloudabi_sys_file_create`

`cloudabi_sys_file_link`

`cloudabi_sys_file_open`

`cloudabi_sys_file_readdir`

`cloudabi_sys_file_readlink`

`cloudabi_sys_file_rename`

`cloudabi_sys_file_stat_fget`

`cloudabi_sys_file_stat_fput`

`cloudabi_sys_file_stat_get`

`cloudabi_sys_file_stat_put`

`cloudabi_sys_file_symlink`

`cloudabi_sys_file_unlink`

`cloudabi_sys_lock_unlock`

`cloudabi_sys_mem_advise`

`cloudabi_sys_mem_lock`

`cloudabi_sys_mem_map`

`cloudabi_sys_mem_protect`

`cloudabi_sys_mem_sync`

`cloudabi_sys_mem_unlock`

`cloudabi_sys_mem_unmap`

`cloudabi_sys_poll`

`cloudabi_sys_poll_fd`

`cloudabi_sys_proc_exec`

`cloudabi_sys_proc_exit`

`cloudabi_sys_proc_fork`

`cloudabi_sys_proc_raise`

`cloudabi_sys_random_get`

`cloudabi_sys_sock_accept`

`cloudabi_sys_sock_bind`

`cloudabi_sys_sock_connect`

`cloudabi_sys_sock_listen`

`cloudabi_sys_sock_recv`

`cloudabi_sys_sock_send`

`cloudabi_sys_sock_shutdown`

`cloudabi_sys_sock_stat_get`

`cloudabi_sys_thread_create`

`cloudabi_sys_thread_exit`

`cloudabi_sys_thread_tcb_set`

`cloudabi_sys_thread_yield`

`cloudabi_advice_t` (`uint8_t`)

`cloudabi_auxtype_t` (`uint32_t`)

`cloudabi_auxv_t` (`struct`)

`cloudabi_backlog_t` (`uint32_t`)

`cloudabi_ciovec_t` (`struct`)

`cloudabi_clockid_t` (`uint32_t`)

`cloudabi_condvar_t` (`uint32_t`)

`cloudabi_device_t` (`uint64_t`)

`cloudabi_dircookie_t` (`uint64_t`)

`cloudabi_dirent_t` (`struct`)

`cloudabi_errno_t` (`uint16_t`)

`cloudabi_event_t` (`struct`)

`cloudabi_eventrwflags_t` (`uint16_t` bitfield)

`cloudabi_eventtype_t` (`uint8_t`)

`cloudabi_exitcode_t` (`uint32_t`)

`cloudabi_fd_t` (`uint32_t`)

`cloudabi_fdflags_t` (`uint16_t` bitfield)

`cloudabi_fdsflags_t` (`uint16_t` bitfield)

`cloudabi_fdstat_t` (`struct`)

`cloudabi_filedelta_t` (`int64_t`)

`cloudabi_filesize_t` (`uint64_t`)

`cloudabi_filestat_t` (`struct`)