Import the CloudABI datatypes and create a system call table.

CloudABI is a pure capability-based runtime environment for UNIX. It
works similar to Capsicum, except that processes already run in
capabilities mode on startup. All functionality that conflicts with this
model has been omitted, making it a compact binary interface that can be
supported by other operating systems without too much effort.

CloudABI is 'secure by default'; the idea is that it should be safe to
run arbitrary third-party binaries without requiring any explicit
hardware virtualization (Bhyve) or namespace virtualization (Jails). The
rights of an application are purely determined by the set of file
descriptors that you grant it on startup.

The datatypes and constants used by CloudABI's C library (cloudlibc) are
defined in separate files called syscalldefs_mi.h (pointer size
independent) and syscalldefs_md.h (pointer size dependent). We import
these files in sys/contrib/cloudabi and wrap around them in
cloudabi*_syscalldefs.h.

We then add stubs for all of the system calls in sys/compat/cloudabi or
sys/compat/cloudabi64, depending on whether the system call depends on
the pointer size. We only have nine system calls that depend on the
pointer size. If we ever want to support 32-bit binaries, we can simply
add sys/compat/cloudabi32 and implement these nine system calls again.

The next step is to send in code reviews for the individual system call
implementations, but also add a sysentvec, to allow CloudABI executabled
to be started through execve().

More information about CloudABI:
- GitHub: https://github.com/NuxiNL/cloudlibc
- Talk at BSDCan: https://www.youtube.com/watch?v=SVdF84x1EdA

Differential Revision:	https://reviews.freebsd.org/D2848
Reviewed by:	emaste, brooks
Obtained from:	https://github.com/NuxiNL/freebsd

2 files changed, 712 insertions, 0 deletions

diff --git a/sys/contrib/cloudabi/syscalldefs_md.h b/sys/contrib/cloudabi/syscalldefs_md.h
new file mode 100644
index 0000000..95dd129
--- /dev/null
+++ b/sys/contrib/cloudabi/syscalldefs_md.h
@@ -0,0 +1,255 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in the
+//    documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+// SUCH DAMAGE.
+
+// Machine dependent definitions.
+
+// Macro to force sane alignment rules.
+//
+// On x86-32 it is the case that 64-bit integers are 4-byte aligned when
+// embedded in structs, even though they are 8-byte aligned when not
+// embedded. Force 8-byte alignment explicitly.
+#define MEMBER(type) alignas(alignof(type)) type
+#define ASSERT_OFFSET(type, field, offset32, offset64)            \
+  static_assert((sizeof(PTR(void)) == 4 &&                        \
+                 offsetof(IDENT(type), field) == (offset32)) ||   \
+                    (sizeof(PTR(void)) == 8 &&                    \
+                     offsetof(IDENT(type), field) == (offset64)), \
+                "Offset incorrect")
+#define ASSERT_SIZE(type, size32, size64)                              \
+  static_assert(                                                       \
+      (sizeof(PTR(void)) == 4 && sizeof(IDENT(type)) == (size32)) ||   \
+          (sizeof(PTR(void)) == 8 && sizeof(IDENT(type)) == (size64)), \
+      "Size incorrect")
+
+typedef void IDENT(threadentry_t)(cloudabi_tid_t, PTR(void));
+
+typedef struct {
+  MEMBER(PTR(const void)) iov_base;
+  MEMBER(IDENT(size_t)) iov_len;
+} IDENT(ciovec_t);
+ASSERT_OFFSET(ciovec_t, iov_base, 0, 0);
+ASSERT_OFFSET(ciovec_t, iov_len, 4, 8);
+ASSERT_SIZE(ciovec_t, 8, 16);
+
+typedef struct {
+  MEMBER(cloudabi_userdata_t) userdata;
+  MEMBER(cloudabi_errno_t) error;
+  MEMBER(cloudabi_eventtype_t) type;
+  union {
+    // CLOUDABI_EVENTTYPE_CLOCK: Wait until the value of a clock
+    // exceeds a value.
+    struct {
+      MEMBER(cloudabi_userdata_t) identifier;
+    } clock;
+
+    // CLOUDABI_EVENTTYPE_CONDVAR: Release a lock and wait on a
+    // condition variable.
+    struct {
+      MEMBER(PTR(_Atomic(cloudabi_condvar_t))) condvar;
+    } condvar;
+
+    // CLOUDABI_EVENTTYPE_FD_READ and CLOUDABI_EVENTTYPE_FD_WRITE:
+    // Wait for a file descriptor to allow read() and write() to be
+    // called without blocking.
+    struct {
+      MEMBER(cloudabi_filesize_t) nbytes;
+      MEMBER(cloudabi_fd_t) fd;
+      MEMBER(uint16_t) flags;
+    } fd_readwrite;
+
+    // CLOUDABI_EVENT_LOCK_RDLOCK and CLOUDABI_EVENT_LOCK_WRLOCK: Wait
+    // and acquire a read or write lock.
+    struct {
+      MEMBER(PTR(_Atomic(cloudabi_lock_t))) lock;
+    } lock;
+
+    // CLOUDABI_EVENTTYPE_PROC_TERMINATE: Wait for a process to terminate.
+    struct {
+      MEMBER(cloudabi_fd_t) fd;
+      MEMBER(cloudabi_signal_t) signal;      // Non-zero if process got killed.
+      MEMBER(cloudabi_exitcode_t) exitcode;  // Exit code.
+    } proc_terminate;
+  };
+} IDENT(event_t);
+ASSERT_OFFSET(event_t, userdata, 0, 0);
+ASSERT_OFFSET(event_t, error, 8, 8);
+ASSERT_OFFSET(event_t, type, 10, 10);
+ASSERT_OFFSET(event_t, clock.identifier, 16, 16);
+ASSERT_OFFSET(event_t, condvar.condvar, 16, 16);
+ASSERT_OFFSET(event_t, fd_readwrite.nbytes, 16, 16);
+ASSERT_OFFSET(event_t, fd_readwrite.fd, 24, 24);
+ASSERT_OFFSET(event_t, fd_readwrite.flags, 28, 28);
+ASSERT_OFFSET(event_t, lock.lock, 16, 16);
+ASSERT_OFFSET(event_t, proc_terminate.fd, 16, 16);
+ASSERT_OFFSET(event_t, proc_terminate.signal, 20, 20);
+ASSERT_OFFSET(event_t, proc_terminate.exitcode, 24, 24);
+ASSERT_SIZE(event_t, 32, 32);
+
+typedef struct {
+  MEMBER(PTR(void)) iov_base;
+  MEMBER(IDENT(size_t)) iov_len;
+} IDENT(iovec_t);
+ASSERT_OFFSET(iovec_t, iov_base, 0, 0);
+ASSERT_OFFSET(iovec_t, iov_len, 4, 8);
+ASSERT_SIZE(iovec_t, 8, 16);
+
+typedef struct {
+  MEMBER(PTR(const IDENT(iovec_t))) ri_data;  // Data I/O vectors.
+  MEMBER(IDENT(size_t)) ri_datalen;           // Number of data I/O vectors.
+  MEMBER(PTR(cloudabi_fd_t)) ri_fds;          // File descriptors.
+  MEMBER(IDENT(size_t)) ri_fdslen;            // Number of file descriptors.
+  MEMBER(cloudabi_msgflags_t) ri_flags;       // Input flags.
+} IDENT(recv_in_t);
+ASSERT_OFFSET(recv_in_t, ri_data, 0, 0);
+ASSERT_OFFSET(recv_in_t, ri_datalen, 4, 8);
+ASSERT_OFFSET(recv_in_t, ri_fds, 8, 16);
+ASSERT_OFFSET(recv_in_t, ri_fdslen, 12, 24);
+ASSERT_OFFSET(recv_in_t, ri_flags, 16, 32);
+ASSERT_SIZE(recv_in_t, 20, 40);
+
+typedef struct {
+  MEMBER(IDENT(size_t)) ro_datalen;  // Bytes of data received.
+  MEMBER(IDENT(size_t)) ro_fdslen;   // Number of file descriptors received.
+  MEMBER(cloudabi_sockaddr_t) ro_sockname;  // Address of receiver.
+  MEMBER(cloudabi_sockaddr_t) ro_peername;  // Address of sender.
+  MEMBER(cloudabi_msgflags_t) ro_flags;     // Output flags.
+} IDENT(recv_out_t);
+ASSERT_OFFSET(recv_out_t, ro_datalen, 0, 0);
+ASSERT_OFFSET(recv_out_t, ro_fdslen, 4, 8);
+ASSERT_OFFSET(recv_out_t, ro_sockname, 8, 16);
+ASSERT_OFFSET(recv_out_t, ro_peername, 28, 36);
+ASSERT_OFFSET(recv_out_t, ro_flags, 48, 56);
+ASSERT_SIZE(recv_out_t, 52, 64);
+
+typedef struct {
+  MEMBER(PTR(const IDENT(ciovec_t))) si_data;  // Data I/O vectors.
+  MEMBER(IDENT(size_t)) si_datalen;            // Number of data I/O vectors.
+  MEMBER(PTR(const cloudabi_fd_t)) si_fds;     // File descriptors.
+  MEMBER(IDENT(size_t)) si_fdslen;             // Number of file descriptors.
+  MEMBER(cloudabi_msgflags_t) si_flags;        // Input flags.
+} IDENT(send_in_t);
+ASSERT_OFFSET(send_in_t, si_data, 0, 0);
+ASSERT_OFFSET(send_in_t, si_datalen, 4, 8);
+ASSERT_OFFSET(send_in_t, si_fds, 8, 16);
+ASSERT_OFFSET(send_in_t, si_fdslen, 12, 24);
+ASSERT_OFFSET(send_in_t, si_flags, 16, 32);
+ASSERT_SIZE(send_in_t, 20, 40);
+
+typedef struct {
+  MEMBER(IDENT(size_t)) so_datalen;  // Bytes of data sent.
+} IDENT(send_out_t);
+ASSERT_OFFSET(send_out_t, so_datalen, 0, 0);
+ASSERT_SIZE(send_out_t, 4, 8);
+
+typedef struct {
+  MEMBER(PTR(const void)) sd_arg;   // Program argument data.
+  MEMBER(IDENT(size_t)) sd_arglen;  // Program argument data size.
+
+  MEMBER(PTR(void)) sd_elf_phdr;         // ELF program header.
+  MEMBER(IDENT(size_t)) sd_elf_phdrlen;  // ELF program header length.
+
+  MEMBER(cloudabi_tid_t) sd_thread_id;  // Thread ID.
+  MEMBER(uint64_t) sd_random_seed;      // Random seed, used for SSP.
+
+  MEMBER(uint32_t) sd_ncpus;     // Number of CPUs.
+  MEMBER(uint32_t) sd_pagesize;  // Page size.
+} IDENT(startup_data_t);
+ASSERT_OFFSET(startup_data_t, sd_arg, 0, 0);
+ASSERT_OFFSET(startup_data_t, sd_arglen, 4, 8);
+ASSERT_OFFSET(startup_data_t, sd_elf_phdr, 8, 16);
+ASSERT_OFFSET(startup_data_t, sd_elf_phdrlen, 12, 24);
+ASSERT_OFFSET(startup_data_t, sd_thread_id, 16, 32);
+ASSERT_OFFSET(startup_data_t, sd_random_seed, 24, 40);
+ASSERT_OFFSET(startup_data_t, sd_ncpus, 32, 48);
+ASSERT_OFFSET(startup_data_t, sd_pagesize, 36, 52);
+ASSERT_SIZE(startup_data_t, 40, 56);
+
+typedef struct {
+  MEMBER(cloudabi_userdata_t) userdata;
+  MEMBER(uint16_t) flags;
+  MEMBER(cloudabi_eventtype_t) type;
+  union {
+    // CLOUDABI_EVENTTYPE_CLOCK: Wait until the value of a clock
+    // exceeds a value.
+    struct {
+      MEMBER(cloudabi_userdata_t) identifier;
+      MEMBER(cloudabi_clockid_t) clock_id;
+      MEMBER(cloudabi_timestamp_t) timeout;
+      MEMBER(cloudabi_timestamp_t) precision;
+    } clock;
+
+    // CLOUDABI_EVENTTYPE_CONDVAR: Release a lock and wait on a
+    // condition variable.
+    struct {
+      MEMBER(PTR(_Atomic(cloudabi_condvar_t))) condvar;
+      MEMBER(PTR(_Atomic(cloudabi_lock_t))) lock;
+    } condvar;
+
+    // CLOUDABI_EVENTTYPE_FD_READ and CLOUDABI_EVENTTYPE_FD_WRITE:
+    // Wait for a file descriptor to allow read() and write() to be
+    // called without blocking.
+    struct {
+      MEMBER(cloudabi_fd_t) fd;
+    } fd_readwrite;
+
+    // CLOUDABI_EVENT_LOCK_RDLOCK and CLOUDABI_EVENT_LOCK_WRLOCK: Wait
+    // and acquire a read or write lock.
+    struct {
+      MEMBER(PTR(_Atomic(cloudabi_lock_t))) lock;
+    } lock;
+
+    // CLOUDABI_EVENTTYPE_PROC_TERMINATE: Wait for a process to terminate.
+    struct {
+      MEMBER(cloudabi_fd_t) fd;
+    } proc_terminate;
+  };
+} IDENT(subscription_t);
+ASSERT_OFFSET(subscription_t, userdata, 0, 0);
+ASSERT_OFFSET(subscription_t, flags, 8, 8);
+ASSERT_OFFSET(subscription_t, type, 10, 10);
+ASSERT_OFFSET(subscription_t, clock.identifier, 16, 16);
+ASSERT_OFFSET(subscription_t, clock.clock_id, 24, 24);
+ASSERT_OFFSET(subscription_t, clock.timeout, 32, 32);
+ASSERT_OFFSET(subscription_t, clock.precision, 40, 40);
+ASSERT_OFFSET(subscription_t, condvar.condvar, 16, 16);
+ASSERT_OFFSET(subscription_t, condvar.lock, 20, 24);
+ASSERT_OFFSET(subscription_t, fd_readwrite.fd, 16, 16);
+ASSERT_OFFSET(subscription_t, lock.lock, 16, 16);
+ASSERT_OFFSET(subscription_t, proc_terminate.fd, 16, 16);
+ASSERT_SIZE(subscription_t, 48, 48);
+
+typedef struct {
+  MEMBER(PTR(IDENT(threadentry_t))) entry_point;  // Entry point.
+  MEMBER(PTR(void)) stack;                        // Pointer to stack buffer.
+  MEMBER(IDENT(size_t)) stack_size;               // Size of stack buffer.
+  MEMBER(PTR(void)) argument;  // Argument to be passed to entry point.
+} IDENT(threadattr_t);
+ASSERT_OFFSET(threadattr_t, entry_point, 0, 0);
+ASSERT_OFFSET(threadattr_t, stack, 4, 8);
+ASSERT_OFFSET(threadattr_t, stack_size, 8, 16);
+ASSERT_OFFSET(threadattr_t, argument, 12, 24);
+ASSERT_SIZE(threadattr_t, 16, 32);
+
+#undef MEMBER
+#undef ASSERT_OFFSET
+#undef ASSERT_SIZE
diff --git a/sys/contrib/cloudabi/syscalldefs_mi.h b/sys/contrib/cloudabi/syscalldefs_mi.h
new file mode 100644
index 0000000..75d79f4
--- /dev/null
+++ b/sys/contrib/cloudabi/syscalldefs_mi.h
@@ -0,0 +1,457 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in the
+//    documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+// SUCH DAMAGE.
+
+#ifndef COMMON_SYSCALLDEFS_MI_H
+#define COMMON_SYSCALLDEFS_MI_H
+
+// Machine independent definitions.
+
+// Socket address families.
+#define CLOUDABI_AF_UNSPEC 0
+#define CLOUDABI_AF_INET 1
+#define CLOUDABI_AF_INET6 2
+#define CLOUDABI_AF_UNIX 3
+
+// File and memory I/O advice.
+#define CLOUDABI_ADVICE_DONTNEED 1
+#define CLOUDABI_ADVICE_NOREUSE 2
+#define CLOUDABI_ADVICE_NORMAL 3
+#define CLOUDABI_ADVICE_RANDOM 4
+#define CLOUDABI_ADVICE_SEQUENTIAL 5
+#define CLOUDABI_ADVICE_WILLNEED 6
+
+// Clocks.
+#define CLOUDABI_CLOCK_MONOTONIC 1
+#define CLOUDABI_CLOCK_PROCESS_CPUTIME_ID 2
+#define CLOUDABI_CLOCK_REALTIME 3
+#define CLOUDABI_CLOCK_THREAD_CPUTIME_ID 4
+
+// Condition variables.
+#define CLOUDABI_CONDVAR_HAS_NO_WAITERS 0
+
+// The start of a directory, to be passed to readdir().
+#define CLOUDABI_DIRCOOKIE_START 0
+
+// POSIX standard error numbers.
+#define CLOUDABI_E2BIG 1
+#define CLOUDABI_EACCES 2
+#define CLOUDABI_EADDRINUSE 3
+#define CLOUDABI_EADDRNOTAVAIL 4
+#define CLOUDABI_EAFNOSUPPORT 5
+#define CLOUDABI_EAGAIN 6
+#define CLOUDABI_EALREADY 7
+#define CLOUDABI_EBADF 8
+#define CLOUDABI_EBADMSG 9
+#define CLOUDABI_EBUSY 10
+#define CLOUDABI_ECANCELED 11
+#define CLOUDABI_ECHILD 12
+#define CLOUDABI_ECONNABORTED 13
+#define CLOUDABI_ECONNREFUSED 14
+#define CLOUDABI_ECONNRESET 15
+#define CLOUDABI_EDEADLK 16
+#define CLOUDABI_EDESTADDRREQ 17
+#define CLOUDABI_EDOM 18
+#define CLOUDABI_EDQUOT 19
+#define CLOUDABI_EEXIST 20
+#define CLOUDABI_EFAULT 21
+#define CLOUDABI_EFBIG 22
+#define CLOUDABI_EHOSTUNREACH 23
+#define CLOUDABI_EIDRM 24
+#define CLOUDABI_EILSEQ 25
+#define CLOUDABI_EINPROGRESS 26
+#define CLOUDABI_EINTR 27
+#define CLOUDABI_EINVAL 28
+#define CLOUDABI_EIO 29
+#define CLOUDABI_EISCONN 30
+#define CLOUDABI_EISDIR 31
+#define CLOUDABI_ELOOP 32
+#define CLOUDABI_EMFILE 33
+#define CLOUDABI_EMLINK 34
+#define CLOUDABI_EMSGSIZE 35
+#define CLOUDABI_EMULTIHOP 36
+#define CLOUDABI_ENAMETOOLONG 37
+#define CLOUDABI_ENETDOWN 38
+#define CLOUDABI_ENETRESET 39
+#define CLOUDABI_ENETUNREACH 40
+#define CLOUDABI_ENFILE 41
+#define CLOUDABI_ENOBUFS 42
+#define CLOUDABI_ENODEV 43
+#define CLOUDABI_ENOENT 44
+#define CLOUDABI_ENOEXEC 45
+#define CLOUDABI_ENOLCK 46
+#define CLOUDABI_ENOLINK 47
+#define CLOUDABI_ENOMEM 48
+#define CLOUDABI_ENOMSG 49
+#define CLOUDABI_ENOPROTOOPT 50
+#define CLOUDABI_ENOSPC 51
+#define CLOUDABI_ENOSYS 52
+#define CLOUDABI_ENOTCONN 53
+#define CLOUDABI_ENOTDIR 54
+#define CLOUDABI_ENOTEMPTY 55
+#define CLOUDABI_ENOTRECOVERABLE 56
+#define CLOUDABI_ENOTSOCK 57
+#define CLOUDABI_ENOTSUP 58
+#define CLOUDABI_ENOTTY 59
+#define CLOUDABI_ENXIO 60
+#define CLOUDABI_EOVERFLOW 61
+#define CLOUDABI_EOWNERDEAD 62
+#define CLOUDABI_EPERM 63
+#define CLOUDABI_EPIPE 64
+#define CLOUDABI_EPROTO 65
+#define CLOUDABI_EPROTONOSUPPORT 66
+#define CLOUDABI_EPROTOTYPE 67
+#define CLOUDABI_ERANGE 68
+#define CLOUDABI_EROFS 69
+#define CLOUDABI_ESPIPE 70
+#define CLOUDABI_ESRCH 71
+#define CLOUDABI_ESTALE 72
+#define CLOUDABI_ETIMEDOUT 73
+#define CLOUDABI_ETXTBSY 74
+#define CLOUDABI_EXDEV 75
+
+// Non-standard error numbers.
+#define CLOUDABI_ENOTCAPABLE 76
+
+#define CLOUDABI_EVENT_FD_READWRITE_HANGUP 0x1
+
+// Filter types for cloudabi_eventtype_t.
+#define CLOUDABI_EVENTTYPE_CLOCK 1
+#define CLOUDABI_EVENTTYPE_CONDVAR 2
+#define CLOUDABI_EVENTTYPE_FD_READ 3
+#define CLOUDABI_EVENTTYPE_FD_WRITE 4
+#define CLOUDABI_EVENTTYPE_LOCK_RDLOCK 5
+#define CLOUDABI_EVENTTYPE_LOCK_WRLOCK 6
+#define CLOUDABI_EVENTTYPE_PROC_TERMINATE 7
+
+// File descriptor behavior flags.
+#define CLOUDABI_FDFLAG_APPEND 0x1
+#define CLOUDABI_FDFLAG_DSYNC 0x2
+#define CLOUDABI_FDFLAG_NONBLOCK 0x4
+#define CLOUDABI_FDFLAG_RSYNC 0x8
+#define CLOUDABI_FDFLAG_SYNC 0x10
+
+// fdstat_put() flags.
+#define CLOUDABI_FDSTAT_FLAGS 0x1
+#define CLOUDABI_FDSTAT_RIGHTS 0x2
+
+// filestat_put() flags.
+#define CLOUDABI_FILESTAT_ATIM 0x1
+#define CLOUDABI_FILESTAT_ATIM_NOW 0x2
+#define CLOUDABI_FILESTAT_MTIM 0x4
+#define CLOUDABI_FILESTAT_MTIM_NOW 0x8
+#define CLOUDABI_FILESTAT_SIZE 0x10
+
+// File types returned through struct stat::st_mode.
+#define CLOUDABI_FILETYPE_UNKNOWN 0
+#define CLOUDABI_FILETYPE_BLOCK_DEVICE 0x10
+#define CLOUDABI_FILETYPE_CHARACTER_DEVICE 0x11
+#define CLOUDABI_FILETYPE_DIRECTORY 0x20
+#define CLOUDABI_FILETYPE_FIFO 0x30
+#define CLOUDABI_FILETYPE_POLL 0x40
+#define CLOUDABI_FILETYPE_PROCESS 0x50
+#define CLOUDABI_FILETYPE_REGULAR_FILE 0x60
+#define CLOUDABI_FILETYPE_SHARED_MEMORY 0x70
+#define CLOUDABI_FILETYPE_SOCKET_DGRAM 0x80
+#define CLOUDABI_FILETYPE_SOCKET_SEQPACKET 0x81
+#define CLOUDABI_FILETYPE_SOCKET_STREAM 0x82
+#define CLOUDABI_FILETYPE_SYMBOLIC_LINK 0x90
+
+// Read-write lock related constants.
+#define CLOUDABI_LOCK_UNLOCKED 0                 // Lock is unlocked.
+#define CLOUDABI_LOCK_WRLOCKED 0x40000000        // Lock is write locked.
+#define CLOUDABI_LOCK_KERNEL_MANAGED 0x80000000  // Lock has waiters.
+#define CLOUDABI_LOCK_BOGUS 0x80000000           // Lock is broken.
+
+// Lookup properties for *at() functions.
+#define CLOUDABI_LOOKUP_SYMLINK_FOLLOW (UINT64_C(0x1) << 32)
+
+// Open flags for openat(), etc.
+#define CLOUDABI_O_CREAT 0x1
+#define CLOUDABI_O_DIRECTORY 0x2
+#define CLOUDABI_O_EXCL 0x4
+#define CLOUDABI_O_TRUNC 0x8
+
+// File descriptor passed to poll() to poll just once.
+#define CLOUDABI_POLL_ONCE 0xffffffff
+
+// File descriptor returned to pdfork()'s child process.
+#define CLOUDABI_PROCESS_CHILD 0xffffffff
+
+// mmap() map flags.
+#define CLOUDABI_MAP_ANON 0x1
+#define CLOUDABI_MAP_FIXED 0x2
+#define CLOUDABI_MAP_PRIVATE 0x4
+#define CLOUDABI_MAP_SHARED 0x8
+
+// msync() flags.
+#define CLOUDABI_MS_ASYNC 0x1
+#define CLOUDABI_MS_INVALIDATE 0x2
+#define CLOUDABI_MS_SYNC 0x4
+
+// send() and recv() flags.
+#define CLOUDABI_MSG_CTRUNC 0x1    // Control data truncated.
+#define CLOUDABI_MSG_EOR 0x2       // Terminates a record.
+#define CLOUDABI_MSG_PEEK 0x4      // Leave received data in queue.
+#define CLOUDABI_MSG_TRUNC 0x8     // Normal data truncated.
+#define CLOUDABI_MSG_WAITALL 0x10  // Attempt to fill the read buffer.
+
+// mmap()/mprotect() protection flags.
+#define CLOUDABI_PROT_EXEC 0x1
+#define CLOUDABI_PROT_WRITE 0x2
+#define CLOUDABI_PROT_READ 0x4
+
+// File descriptor capabilities/rights.
+#define CLOUDABI_RIGHT_BIT(bit) (UINT64_C(1) << (bit))
+#define CLOUDABI_RIGHT_FD_DATASYNC CLOUDABI_RIGHT_BIT(0)
+#define CLOUDABI_RIGHT_FD_READ CLOUDABI_RIGHT_BIT(1)
+#define CLOUDABI_RIGHT_FD_SEEK CLOUDABI_RIGHT_BIT(2)
+#define CLOUDABI_RIGHT_FD_STAT_PUT_FLAGS CLOUDABI_RIGHT_BIT(3)
+#define CLOUDABI_RIGHT_FD_SYNC CLOUDABI_RIGHT_BIT(4)
+#define CLOUDABI_RIGHT_FD_TELL CLOUDABI_RIGHT_BIT(5)
+#define CLOUDABI_RIGHT_FD_WRITE CLOUDABI_RIGHT_BIT(6)
+#define CLOUDABI_RIGHT_FILE_ADVISE CLOUDABI_RIGHT_BIT(7)
+#define CLOUDABI_RIGHT_FILE_ALLOCATE CLOUDABI_RIGHT_BIT(8)
+#define CLOUDABI_RIGHT_FILE_CREATE_DIRECTORY CLOUDABI_RIGHT_BIT(9)
+#define CLOUDABI_RIGHT_FILE_CREATE_FILE CLOUDABI_RIGHT_BIT(10)
+#define CLOUDABI_RIGHT_FILE_CREATE_FIFO CLOUDABI_RIGHT_BIT(11)
+#define CLOUDABI_RIGHT_FILE_LINK_SOURCE CLOUDABI_RIGHT_BIT(12)
+#define CLOUDABI_RIGHT_FILE_LINK_TARGET CLOUDABI_RIGHT_BIT(13)
+#define CLOUDABI_RIGHT_FILE_OPEN CLOUDABI_RIGHT_BIT(14)
+#define CLOUDABI_RIGHT_FILE_READDIR CLOUDABI_RIGHT_BIT(15)
+#define CLOUDABI_RIGHT_FILE_READLINK CLOUDABI_RIGHT_BIT(16)
+#define CLOUDABI_RIGHT_FILE_RENAME_SOURCE CLOUDABI_RIGHT_BIT(17)
+#define CLOUDABI_RIGHT_FILE_RENAME_TARGET CLOUDABI_RIGHT_BIT(18)
+#define CLOUDABI_RIGHT_FILE_STAT_FGET CLOUDABI_RIGHT_BIT(19)
+#define CLOUDABI_RIGHT_FILE_STAT_FPUT_SIZE CLOUDABI_RIGHT_BIT(20)
+#define CLOUDABI_RIGHT_FILE_STAT_FPUT_TIMES CLOUDABI_RIGHT_BIT(21)
+#define CLOUDABI_RIGHT_FILE_STAT_GET CLOUDABI_RIGHT_BIT(22)
+#define CLOUDABI_RIGHT_FILE_STAT_PUT_TIMES CLOUDABI_RIGHT_BIT(23)
+#define CLOUDABI_RIGHT_FILE_SYMLINK CLOUDABI_RIGHT_BIT(24)
+#define CLOUDABI_RIGHT_FILE_UNLINK CLOUDABI_RIGHT_BIT(25)
+#define CLOUDABI_RIGHT_MEM_MAP CLOUDABI_RIGHT_BIT(26)
+#define CLOUDABI_RIGHT_MEM_MAP_EXEC CLOUDABI_RIGHT_BIT(27)
+#define CLOUDABI_RIGHT_POLL_FD_READWRITE CLOUDABI_RIGHT_BIT(28)
+#define CLOUDABI_RIGHT_POLL_MODIFY CLOUDABI_RIGHT_BIT(29)
+#define CLOUDABI_RIGHT_POLL_PROC_TERMINATE CLOUDABI_RIGHT_BIT(30)
+#define CLOUDABI_RIGHT_POLL_WAIT CLOUDABI_RIGHT_BIT(31)
+#define CLOUDABI_RIGHT_PROC_EXEC CLOUDABI_RIGHT_BIT(32)
+#define CLOUDABI_RIGHT_SOCK_ACCEPT CLOUDABI_RIGHT_BIT(33)
+#define CLOUDABI_RIGHT_SOCK_BIND_DIRECTORY CLOUDABI_RIGHT_BIT(34)
+#define CLOUDABI_RIGHT_SOCK_BIND_SOCKET CLOUDABI_RIGHT_BIT(35)
+#define CLOUDABI_RIGHT_SOCK_CONNECT_DIRECTORY CLOUDABI_RIGHT_BIT(36)
+#define CLOUDABI_RIGHT_SOCK_CONNECT_SOCKET CLOUDABI_RIGHT_BIT(37)
+#define CLOUDABI_RIGHT_SOCK_LISTEN CLOUDABI_RIGHT_BIT(38)
+#define CLOUDABI_RIGHT_SOCK_SHUTDOWN CLOUDABI_RIGHT_BIT(39)
+#define CLOUDABI_RIGHT_SOCK_STAT_GET CLOUDABI_RIGHT_BIT(40)
+
+// Socket shutdown flags.
+#define CLOUDABI_SHUT_RD 0x1
+#define CLOUDABI_SHUT_WR 0x2
+
+// Signals.
+#define CLOUDABI_SIGABRT 1
+#define CLOUDABI_SIGALRM 2
+#define CLOUDABI_SIGBUS 3
+#define CLOUDABI_SIGCHLD 4
+#define CLOUDABI_SIGCONT 5
+#define CLOUDABI_SIGFPE 6
+#define CLOUDABI_SIGHUP 7
+#define CLOUDABI_SIGILL 8
+#define CLOUDABI_SIGINT 9
+#define CLOUDABI_SIGKILL 10
+#define CLOUDABI_SIGPIPE 11
+#define CLOUDABI_SIGQUIT 12
+#define CLOUDABI_SIGSEGV 13
+#define CLOUDABI_SIGSTOP 14
+#define CLOUDABI_SIGSYS 15
+#define CLOUDABI_SIGTERM 16
+#define CLOUDABI_SIGTRAP 17
+#define CLOUDABI_SIGTSTP 18
+#define CLOUDABI_SIGTTIN 19
+#define CLOUDABI_SIGTTOU 20
+#define CLOUDABI_SIGURG 21
+#define CLOUDABI_SIGUSR1 22
+#define CLOUDABI_SIGUSR2 23
+#define CLOUDABI_SIGVTALRM 24
+#define CLOUDABI_SIGXCPU 25
+#define CLOUDABI_SIGXFSZ 26
+
+// sockstat() flags.
+#define CLOUDABI_SOCKSTAT_CLEAR_ERROR 0x1
+
+// sockstat() state.
+#define CLOUDABI_SOCKSTAT_ACCEPTCONN 0x1
+
+// cloudabi_subscription_t flags.
+#define CLOUDABI_SUBSCRIPTION_ADD 0x1
+#define CLOUDABI_SUBSCRIPTION_CLEAR 0x2
+#define CLOUDABI_SUBSCRIPTION_DELETE 0x4
+#define CLOUDABI_SUBSCRIPTION_DISABLE 0x8
+#define CLOUDABI_SUBSCRIPTION_ENABLE 0x10
+#define CLOUDABI_SUBSCRIPTION_ONESHOT 0x20
+
+// unlinkat().
+#define CLOUDABI_UNLINK_REMOVEDIR 0x1
+
+// Seeking.
+#define CLOUDABI_WHENCE_CUR 1
+#define CLOUDABI_WHENCE_END 2
+#define CLOUDABI_WHENCE_SET 3
+
+typedef uint8_t cloudabi_advice_t;      // posix_fadvise() and posix_madvise().
+typedef uint32_t cloudabi_backlog_t;    // listen().
+typedef uint32_t cloudabi_clockid_t;    // clock_*().
+typedef uint32_t cloudabi_condvar_t;    // pthread_cond_*().
+typedef uint64_t cloudabi_device_t;     // struct stat::st_dev.
+typedef uint64_t cloudabi_dircookie_t;  // readdir().
+typedef uint16_t cloudabi_errno_t;      // errno.
+typedef uint8_t cloudabi_eventtype_t;   // poll().
+typedef uint32_t cloudabi_exitcode_t;   // _exit() and _Exit().
+typedef uint32_t cloudabi_fd_t;         // File descriptors.
+typedef uint16_t cloudabi_fdflags_t;    // cloudabi_fdstat_t.
+typedef uint16_t cloudabi_fdsflags_t;   // fd_stat_put().
+typedef int64_t cloudabi_filedelta_t;   // lseek().
+typedef uint64_t cloudabi_filesize_t;   // ftruncate(), struct stat::st_size.
+typedef uint8_t cloudabi_filetype_t;    // struct stat::st_mode.
+typedef uint16_t cloudabi_fsflags_t;    // file_stat_put().
+typedef uint64_t cloudabi_inode_t;      // struct stat::st_ino.
+typedef uint32_t cloudabi_linkcount_t;  // struct stat::st_nlink.
+typedef uint32_t cloudabi_lock_t;       // pthread_{mutex,rwlock}_*().
+typedef uint64_t cloudabi_lookup_t;     // openat(), linkat(), etc.
+typedef uint8_t cloudabi_mflags_t;      // mmap().
+typedef uint8_t cloudabi_mprot_t;       // mmap().
+typedef uint8_t cloudabi_msflags_t;     // msync().
+typedef uint16_t cloudabi_msgflags_t;   // send() and recv().
+typedef uint32_t cloudabi_nthreads_t;   // pthread_cond_*().
+typedef uint16_t cloudabi_oflags_t;     // openat(), etc.
+typedef uint64_t cloudabi_rights_t;     // File descriptor rights.
+typedef uint8_t cloudabi_sa_family_t;   // Socket address family.
+typedef uint8_t cloudabi_sdflags_t;     // shutdown().
+typedef uint8_t cloudabi_ssflags_t;     // sockstat().
+typedef uint8_t cloudabi_signal_t;      // raise().
+typedef uint32_t cloudabi_tid_t;        // Thread ID.
+typedef uint64_t cloudabi_timestamp_t;  // clock_*(), struct stat::st_*tim.
+typedef uint8_t cloudabi_ulflags_t;     // unlinkat().
+typedef uint64_t cloudabi_userdata_t;   // User-supplied data for callbacks.
+typedef uint8_t cloudabi_whence_t;      // lseek().
+
+// Macro to force sane alignment rules.
+//
+// On x86-32 it is the case that 64-bit integers are 4-byte aligned when
+// embedded in structs, even though they are 8-byte aligned when not
+// embedded. Force 8-byte alignment explicitly.
+#define MEMBER(type) alignas(alignof(type)) type
+#define ASSERT_OFFSET(type, field, offset)                    \
+  static_assert(offsetof(cloudabi_##type, field) == (offset), \
+                "Offset incorrect")
+#define ASSERT_SIZE(type, size) \
+  static_assert(sizeof(cloudabi_##type) == (size), "Size incorrect")
+
+// Directory entries.
+typedef struct {
+  MEMBER(cloudabi_dircookie_t) d_next;  // Cookie of the next entry.
+  MEMBER(cloudabi_inode_t) d_ino;       // Inode number of the current entry.
+  MEMBER(uint32_t) d_namlen;  // Length of the name of the current entry.
+  MEMBER(cloudabi_filetype_t) d_type;  // File type of the current entry.
+} cloudabi_dirent_t;
+ASSERT_OFFSET(dirent_t, d_next, 0);
+ASSERT_OFFSET(dirent_t, d_ino, 8);
+ASSERT_OFFSET(dirent_t, d_namlen, 16);
+ASSERT_OFFSET(dirent_t, d_type, 20);
+ASSERT_SIZE(dirent_t, 24);
+
+// File descriptor status.
+typedef struct {
+  MEMBER(cloudabi_filetype_t) fs_filetype;         // File descriptor type.
+  MEMBER(cloudabi_fdflags_t) fs_flags;             // Non-blocking mode, etc.
+  MEMBER(cloudabi_rights_t) fs_rights_base;        // Base rights.
+  MEMBER(cloudabi_rights_t) fs_rights_inheriting;  // Inheriting rights.
+} cloudabi_fdstat_t;
+ASSERT_OFFSET(fdstat_t, fs_filetype, 0);
+ASSERT_OFFSET(fdstat_t, fs_flags, 2);
+ASSERT_OFFSET(fdstat_t, fs_rights_base, 8);
+ASSERT_OFFSET(fdstat_t, fs_rights_inheriting, 16);
+ASSERT_SIZE(fdstat_t, 24);
+
+// File status.
+typedef struct {
+  MEMBER(cloudabi_device_t) st_dev;         // Device storing the file.
+  MEMBER(cloudabi_inode_t) st_ino;          // Inode of the file.
+  MEMBER(cloudabi_filetype_t) st_filetype;  // File type.
+  MEMBER(cloudabi_linkcount_t) st_nlink;    // Number of hardlinks.
+  MEMBER(cloudabi_filesize_t) st_size;      // Size of the file.
+  MEMBER(cloudabi_timestamp_t) st_atim;     // Access time.
+  MEMBER(cloudabi_timestamp_t) st_mtim;     // Modification time.
+  MEMBER(cloudabi_timestamp_t) st_ctim;     // Change time.
+} cloudabi_filestat_t;
+ASSERT_OFFSET(filestat_t, st_dev, 0);
+ASSERT_OFFSET(filestat_t, st_ino, 8);
+ASSERT_OFFSET(filestat_t, st_filetype, 16);
+ASSERT_OFFSET(filestat_t, st_nlink, 20);
+ASSERT_OFFSET(filestat_t, st_size, 24);
+ASSERT_OFFSET(filestat_t, st_atim, 32);
+ASSERT_OFFSET(filestat_t, st_mtim, 40);
+ASSERT_OFFSET(filestat_t, st_ctim, 48);
+ASSERT_SIZE(filestat_t, 56);
+
+typedef struct {
+  MEMBER(cloudabi_sa_family_t) sa_family;
+  union {
+    struct {
+      // IPv4 address and port number.
+      MEMBER(uint8_t) addr[4];
+      MEMBER(uint16_t) port;
+    } sa_inet;
+    struct {
+      // IPv6 address and port number.
+      // TODO(ed): What about the flow info and scope ID?
+      MEMBER(uint8_t) addr[16];
+      MEMBER(uint16_t) port;
+    } sa_inet6;
+  };
+} cloudabi_sockaddr_t;
+ASSERT_OFFSET(sockaddr_t, sa_family, 0);
+ASSERT_OFFSET(sockaddr_t, sa_inet.addr, 2);
+ASSERT_OFFSET(sockaddr_t, sa_inet.port, 6);
+ASSERT_OFFSET(sockaddr_t, sa_inet6.addr, 2);
+ASSERT_OFFSET(sockaddr_t, sa_inet6.port, 18);
+ASSERT_SIZE(sockaddr_t, 20);
+
+// Socket status.
+typedef struct {
+  MEMBER(cloudabi_sockaddr_t) ss_sockname;  // Socket address.
+  MEMBER(cloudabi_sockaddr_t) ss_peername;  // Peer address.
+  MEMBER(cloudabi_errno_t) ss_error;        // Current error state.
+  MEMBER(uint32_t) ss_state;                // State flags.
+} cloudabi_sockstat_t;
+ASSERT_OFFSET(sockstat_t, ss_sockname, 0);
+ASSERT_OFFSET(sockstat_t, ss_peername, 20);
+ASSERT_OFFSET(sockstat_t, ss_error, 40);
+ASSERT_OFFSET(sockstat_t, ss_state, 44);
+ASSERT_SIZE(sockstat_t, 48);
+
+#undef MEMBER
+#undef ASSERT_OFFSET
+#undef ASSERT_SIZE
+
+#endif