Adding upstream version 0.0~git20221206.8b7148f.upstream/0.0_git20221206.8b7148f

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

67 files changed, 2426 insertions, 0 deletions

diff --git a/libc-bottom-half/cloudlibc/LICENSE b/libc-bottom-half/cloudlibc/LICENSE
new file mode 100644
index 0000000..dd33b05
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/LICENSE
@@ -0,0 +1,22 @@
+Copyright (c) 2015-2017 Nuxi (https://nuxi.nl/) and contributors.
+
+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.
diff --git a/libc-bottom-half/cloudlibc/src/common/clock.h b/libc-bottom-half/cloudlibc/src/common/clock.h
new file mode 100644
index 0000000..58d40a1
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/common/clock.h
@@ -0,0 +1,19 @@
+// Copyright (c) 2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#ifndef COMMON_CLOCK_H
+#define COMMON_CLOCK_H
+
+#include <wasi/api.h>
+
+// In this implementation we define clockid_t as a pointer type, so that
+// we can implement them as full objects. Right now we only use those
+// objects to store the raw ABI-level clock identifier, but in the
+// future we can use this to provide support for pthread_getcpuclockid()
+// and clock file descriptors.
+struct __clockid {
+  __wasi_clockid_t id;
+};
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/common/limits.h b/libc-bottom-half/cloudlibc/src/common/limits.h
new file mode 100644
index 0000000..67e2f07
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/common/limits.h
@@ -0,0 +1,35 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#ifndef COMMON_LIMITS_H
+#define COMMON_LIMITS_H
+
+#include <limits.h>
+
+#define NUMERIC_MIN(t)                                  \
+  _Generic((t)0, char                                   \
+           : CHAR_MIN, signed char                      \
+           : SCHAR_MIN, unsigned char : 0, short        \
+           : SHRT_MIN, unsigned short : 0, int          \
+           : INT_MIN, unsigned int : 0, long            \
+           : LONG_MIN, unsigned long : 0, long long     \
+           : LLONG_MIN, unsigned long long : 0, default \
+           : (void)0)
+
+#define NUMERIC_MAX(t)                     \
+  _Generic((t)0, char                      \
+           : CHAR_MAX, signed char         \
+           : SCHAR_MAX, unsigned char      \
+           : UCHAR_MAX, short              \
+           : SHRT_MAX, unsigned short      \
+           : USHRT_MAX, int                \
+           : INT_MAX, unsigned int         \
+           : UINT_MAX, long                \
+           : LONG_MAX, unsigned long       \
+           : ULONG_MAX, long long          \
+           : LLONG_MAX, unsigned long long \
+           : ULLONG_MAX, default           \
+           : (void)0)
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/common/time.h b/libc-bottom-half/cloudlibc/src/common/time.h
new file mode 100644
index 0000000..08e2852
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/common/time.h
@@ -0,0 +1,63 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#ifndef COMMON_TIME_H
+#define COMMON_TIME_H
+
+#include <common/limits.h>
+
+#include <sys/time.h>
+
+#include <wasi/api.h>
+#include <stdbool.h>
+#include <time.h>
+
+#define NSEC_PER_SEC 1000000000
+
+static inline bool timespec_to_timestamp_exact(
+    const struct timespec *timespec, __wasi_timestamp_t *timestamp) {
+  // Invalid nanoseconds field.
+  if (timespec->tv_nsec < 0 || timespec->tv_nsec >= NSEC_PER_SEC)
+    return false;
+
+  // Timestamps before the Epoch are not supported.
+  if (timespec->tv_sec < 0)
+    return false;
+
+  // Make sure our timestamp does not overflow.
+  return !__builtin_mul_overflow(timespec->tv_sec, NSEC_PER_SEC, timestamp) &&
+         !__builtin_add_overflow(*timestamp, timespec->tv_nsec, timestamp);
+}
+
+static inline bool timespec_to_timestamp_clamp(
+    const struct timespec *timespec, __wasi_timestamp_t *timestamp) {
+  // Invalid nanoseconds field.
+  if (timespec->tv_nsec < 0 || timespec->tv_nsec >= NSEC_PER_SEC)
+    return false;
+
+  if (timespec->tv_sec < 0) {
+    // Timestamps before the Epoch are not supported.
+    *timestamp = 0;
+  } else if (__builtin_mul_overflow(timespec->tv_sec, NSEC_PER_SEC, timestamp) ||
+             __builtin_add_overflow(*timestamp, timespec->tv_nsec, timestamp)) {
+    // Make sure our timestamp does not overflow.
+    *timestamp = NUMERIC_MAX(__wasi_timestamp_t);
+  }
+  return true;
+}
+
+static inline struct timespec timestamp_to_timespec(
+    __wasi_timestamp_t timestamp) {
+  // Decompose timestamp into seconds and nanoseconds.
+  return (struct timespec){.tv_sec = timestamp / NSEC_PER_SEC,
+                           .tv_nsec = timestamp % NSEC_PER_SEC};
+}
+
+static inline struct timeval timestamp_to_timeval(
+    __wasi_timestamp_t timestamp) {
+  struct timespec ts = timestamp_to_timespec(timestamp);
+  return (struct timeval){.tv_sec = ts.tv_sec, ts.tv_nsec / 1000};
+}
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/include/_/cdefs.h b/libc-bottom-half/cloudlibc/src/include/_/cdefs.h
new file mode 100644
index 0000000..d9a6f54
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/include/_/cdefs.h
@@ -0,0 +1,36 @@
+// Copyright (c) 2015-2017 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 ___CDEFS_H_
+#define ___CDEFS_H_
+
+// Compiler-independent annotations.
+
+#define __strong_reference(oldsym, newsym) \
+  extern __typeof__(oldsym) newsym __attribute__((__alias__(#oldsym)))
+
+// Convenience macros.
+
+#define __arraycount(x) (sizeof(x) / sizeof((x)[0]))
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/closedir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/closedir.c
new file mode 100644
index 0000000..3585737
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/closedir.c
@@ -0,0 +1,10 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <dirent.h>
+#include <unistd.h>
+
+int closedir(DIR *dirp) {
+  return close(fdclosedir(dirp));
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/dirent_impl.h b/libc-bottom-half/cloudlibc/src/libc/dirent/dirent_impl.h
new file mode 100644
index 0000000..642400a
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/dirent_impl.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#ifndef DIRENT_DIRENT_IMPL_H
+#define DIRENT_DIRENT_IMPL_H
+
+#include <wasi/api.h>
+#include <stddef.h>
+
+struct dirent;
+
+#define DIRENT_DEFAULT_BUFFER_SIZE 4096
+
+struct _DIR {
+  // Directory file descriptor and cookie.
+  int fd;
+  __wasi_dircookie_t cookie;
+
+  // Read buffer.
+  char *buffer;
+  size_t buffer_processed;
+  size_t buffer_size;
+  size_t buffer_used;
+
+  // Object returned by readdir().
+  struct dirent *dirent;
+  size_t dirent_size;
+};
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/dirfd.c b/libc-bottom-half/cloudlibc/src/libc/dirent/dirfd.c
new file mode 100644
index 0000000..033157a
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/dirfd.c
@@ -0,0 +1,11 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <dirent.h>
+
+#include "dirent_impl.h"
+
+int dirfd(DIR *dirp) {
+  return dirp->fd;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/fdclosedir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/fdclosedir.c
new file mode 100644
index 0000000..cabe702
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/fdclosedir.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <dirent.h>
+#include <stdlib.h>
+
+#include "dirent_impl.h"
+
+int fdclosedir(DIR *dirp) {
+  int fd = dirp->fd;
+  free(dirp->buffer);
+  free(dirp->dirent);
+  free(dirp);
+  return fd;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/fdopendir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/fdopendir.c
new file mode 100644
index 0000000..4a2136a
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/fdopendir.c
@@ -0,0 +1,44 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <dirent.h>
+#include <errno.h>
+#include <stdlib.h>
+
+#include "dirent_impl.h"
+
+DIR *fdopendir(int fd) {
+  // Allocate new directory object and read buffer.
+  DIR *dirp = malloc(sizeof(*dirp));
+  if (dirp == NULL)
+    return NULL;
+  dirp->buffer = malloc(DIRENT_DEFAULT_BUFFER_SIZE);
+  if (dirp->buffer == NULL) {
+    free(dirp);
+    return NULL;
+  }
+
+  // Ensure that this is really a directory by already loading the first
+  // chunk of data.
+  __wasi_errno_t error =
+      // TODO: Remove the cast on `dirp->buffer` once the witx is updated with char8 support.
+      __wasi_fd_readdir(fd, (uint8_t *)dirp->buffer, DIRENT_DEFAULT_BUFFER_SIZE,
+                                __WASI_DIRCOOKIE_START, &dirp->buffer_used);
+  if (error != 0) {
+    free(dirp->buffer);
+    free(dirp);
+    errno = error;
+    return NULL;
+  }
+
+  // Initialize other members.
+  dirp->fd = fd;
+  dirp->cookie = __WASI_DIRCOOKIE_START;
+  dirp->buffer_processed = 0;
+  dirp->buffer_size = DIRENT_DEFAULT_BUFFER_SIZE;
+  dirp->dirent = NULL;
+  dirp->dirent_size = 1;
+  return dirp;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/opendirat.c b/libc-bottom-half/cloudlibc/src/libc/dirent/opendirat.c
new file mode 100644
index 0000000..e6d1c2a
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/opendirat.c
@@ -0,0 +1,23 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/libc.h>
+#include <wasi/libc-nocwd.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <unistd.h>
+
+DIR *__wasilibc_nocwd_opendirat(int dir, const char *dirname) {
+  // Open directory.
+  int fd = __wasilibc_nocwd_openat_nomode(dir, dirname, O_RDONLY | O_NONBLOCK | O_DIRECTORY);
+  if (fd == -1)
+    return NULL;
+
+  // Create directory handle.
+  DIR *result = fdopendir(fd);
+  if (result == NULL)
+    close(fd);
+  return result;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/readdir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/readdir.c
new file mode 100644
index 0000000..bfd1921
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/readdir.c
@@ -0,0 +1,132 @@
+// Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <dirent.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "dirent_impl.h"
+
+static_assert(DT_BLK == __WASI_FILETYPE_BLOCK_DEVICE, "Value mismatch");
+static_assert(DT_CHR == __WASI_FILETYPE_CHARACTER_DEVICE, "Value mismatch");
+static_assert(DT_DIR == __WASI_FILETYPE_DIRECTORY, "Value mismatch");
+static_assert(DT_FIFO == __WASI_FILETYPE_SOCKET_STREAM, "Value mismatch");
+static_assert(DT_LNK == __WASI_FILETYPE_SYMBOLIC_LINK, "Value mismatch");
+static_assert(DT_REG == __WASI_FILETYPE_REGULAR_FILE, "Value mismatch");
+static_assert(DT_UNKNOWN == __WASI_FILETYPE_UNKNOWN, "Value mismatch");
+
+// Grows a buffer to be large enough to hold a certain amount of data.
+#define GROW(buffer, buffer_size, target_size)      \
+  do {                                              \
+    if ((buffer_size) < (target_size)) {            \
+      size_t new_size = (buffer_size);              \
+      while (new_size < (target_size))              \
+        new_size *= 2;                              \
+      void *new_buffer = realloc(buffer, new_size); \
+      if (new_buffer == NULL)                       \
+        return NULL;                                \
+      (buffer) = new_buffer;                        \
+      (buffer_size) = new_size;                     \
+    }                                               \
+  } while (0)
+
+struct dirent *readdir(DIR *dirp) {
+  for (;;) {
+    // Extract the next dirent header.
+    size_t buffer_left = dirp->buffer_used - dirp->buffer_processed;
+    if (buffer_left < sizeof(__wasi_dirent_t)) {
+      // End-of-file.
+      if (dirp->buffer_used < dirp->buffer_size)
+        return NULL;
+      goto read_entries;
+    }
+    __wasi_dirent_t entry;
+    memcpy(&entry, dirp->buffer + dirp->buffer_processed, sizeof(entry));
+
+    size_t entry_size = sizeof(__wasi_dirent_t) + entry.d_namlen;
+    if (entry.d_namlen == 0) {
+      // Invalid pathname length. Skip the entry.
+      dirp->buffer_processed += entry_size;
+      continue;
+    }
+
+    // The entire entry must be present in buffer space. If not, read
+    // the entry another time. Ensure that the read buffer is large
+    // enough to fit at least this single entry.
+    if (buffer_left < entry_size) {
+      GROW(dirp->buffer, dirp->buffer_size, entry_size);
+      goto read_entries;
+    }
+
+    // Skip entries having null bytes in the filename.
+    const char *name = dirp->buffer + dirp->buffer_processed + sizeof(entry);
+    if (memchr(name, '\0', entry.d_namlen) != NULL) {
+      dirp->buffer_processed += entry_size;
+      continue;
+    }
+
+    // Return the next directory entry. Ensure that the dirent is large
+    // enough to fit the filename.
+    GROW(dirp->dirent, dirp->dirent_size,
+         offsetof(struct dirent, d_name) + entry.d_namlen + 1);
+    struct dirent *dirent = dirp->dirent;
+    dirent->d_type = entry.d_type;
+    memcpy(dirent->d_name, name, entry.d_namlen);
+    dirent->d_name[entry.d_namlen] = '\0';
+
+    // `fd_readdir` implementations may set the inode field to zero if the
+    // the inode number is unknown. In that case, do an `fstatat` to get the
+    // inode number.
+    off_t d_ino = entry.d_ino;
+    unsigned char d_type = entry.d_type;
+    if (d_ino == 0 && strcmp(dirent->d_name, "..") != 0) {
+      struct stat statbuf;
+      if (fstatat(dirp->fd, dirent->d_name, &statbuf, AT_SYMLINK_NOFOLLOW) != 0) {
+	if (errno == ENOENT) {
+	  // The file disappeared before we could read it, so skip it.
+	  dirp->buffer_processed += entry_size;
+	  continue;
+	}
+        return NULL;
+      }
+
+      // Fill in the inode.
+      d_ino = statbuf.st_ino;
+
+      // In case someone raced with us and replaced the object with this name
+      // with another of a different type, update the type too.
+      d_type = __wasilibc_iftodt(statbuf.st_mode & S_IFMT);
+    }
+    dirent->d_ino = d_ino;
+    dirent->d_type = d_type;
+
+    dirp->cookie = entry.d_next;
+    dirp->buffer_processed += entry_size;
+    return dirent;
+
+  read_entries:
+    // Discard data currently stored in the input buffer.
+    dirp->buffer_used = dirp->buffer_processed = dirp->buffer_size;
+
+    // Load more directory entries and continue.
+    __wasi_errno_t error =
+        // TODO: Remove the cast on `dirp->buffer` once the witx is updated with char8 support.
+        __wasi_fd_readdir(dirp->fd, (uint8_t *)dirp->buffer, dirp->buffer_size,
+                                  dirp->cookie, &dirp->buffer_used);
+    if (error != 0) {
+      errno = error;
+      return NULL;
+    }
+    dirp->buffer_processed = 0;
+  }
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/rewinddir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/rewinddir.c
new file mode 100644
index 0000000..8dd5882
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/rewinddir.c
@@ -0,0 +1,15 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <dirent.h>
+
+#include "dirent_impl.h"
+
+void rewinddir(DIR *dirp) {
+  // Update cookie.
+  dirp->cookie = __WASI_DIRCOOKIE_START;
+  // Mark entire buffer as processed to force a read of new data.
+  dirp->buffer_used = dirp->buffer_processed = dirp->buffer_size;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/scandirat.c b/libc-bottom-half/cloudlibc/src/libc/dirent/scandirat.c
new file mode 100644
index 0000000..079b3b3
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/scandirat.c
@@ -0,0 +1,168 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <wasi/libc.h>
+#include <wasi/libc-nocwd.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "dirent_impl.h"
+
+static int sel_true(const struct dirent *de) {
+  return 1;
+}
+
+int __wasilibc_nocwd_scandirat(int dirfd, const char *dir, struct dirent ***namelist,
+                               int (*sel)(const struct dirent *),
+                               int (*compar)(const struct dirent **, const struct dirent **)) {
+  struct stat statbuf;
+
+  // Match all files if no select function is provided.
+  if (sel == NULL)
+    sel = sel_true;
+
+  // Open the directory.
+  int fd = __wasilibc_nocwd_openat_nomode(dirfd, dir, O_RDONLY | O_NONBLOCK | O_DIRECTORY);
+  if (fd == -1)
+    return -1;
+
+  // Allocate a read buffer for the directory entries.
+  size_t buffer_size = DIRENT_DEFAULT_BUFFER_SIZE;
+  char *buffer = malloc(buffer_size);
+  if (buffer == NULL) {
+    close(fd);
+    return -1;
+  }
+  size_t buffer_processed = buffer_size;
+  size_t buffer_used = buffer_size;
+
+  // Space for the array to return to the caller.
+  struct dirent **dirents = NULL;
+  size_t dirents_size = 0;
+  size_t dirents_used = 0;
+
+  __wasi_dircookie_t cookie = __WASI_DIRCOOKIE_START;
+  for (;;) {
+    // Extract the next dirent header.
+    size_t buffer_left = buffer_used - buffer_processed;
+    if (buffer_left < sizeof(__wasi_dirent_t)) {
+      // End-of-file.
+      if (buffer_used < buffer_size)
+        break;
+      goto read_entries;
+    }
+    __wasi_dirent_t entry;
+    memcpy(&entry, buffer + buffer_processed, sizeof(entry));
+
+    size_t entry_size = sizeof(__wasi_dirent_t) + entry.d_namlen;
+    if (entry.d_namlen == 0) {
+      // Invalid pathname length. Skip the entry.
+      buffer_processed += entry_size;
+      continue;
+    }
+
+    // The entire entry must be present in buffer space. If not, read
+    // the entry another time. Ensure that the read buffer is large
+    // enough to fit at least this single entry.
+    if (buffer_left < entry_size) {
+      while (buffer_size < entry_size)
+        buffer_size *= 2;
+      char *new_buffer = realloc(buffer, buffer_size);
+      if (new_buffer == NULL)
+        goto bad;
+      buffer = new_buffer;
+      goto read_entries;
+    }
+
+    // Skip entries having null bytes in the filename.
+    const char *name = buffer + buffer_processed + sizeof(entry);
+    buffer_processed += entry_size;
+    if (memchr(name, '\0', entry.d_namlen) != NULL)
+      continue;
+
+    // Create the new directory entry.
+    struct dirent *dirent =
+        malloc(offsetof(struct dirent, d_name) + entry.d_namlen + 1);
+    if (dirent == NULL)
+      goto bad;
+    dirent->d_type = entry.d_type;
+    memcpy(dirent->d_name, name, entry.d_namlen);
+    dirent->d_name[entry.d_namlen] = '\0';
+
+    // `fd_readdir` implementations may set the inode field to zero if the
+    // the inode number is unknown. In that case, do an `fstatat` to get the
+    // inode number.
+    off_t d_ino = entry.d_ino;
+    unsigned char d_type = entry.d_type;
+    if (d_ino == 0) {
+      if (fstatat(fd, dirent->d_name, &statbuf, AT_SYMLINK_NOFOLLOW) != 0) {
+        return -1;
+      }
+
+      // Fill in the inode.
+      d_ino = statbuf.st_ino;
+
+      // In case someone raced with us and replaced the object with this name
+      // with another of a different type, update the type too.
+      d_type = __wasilibc_iftodt(statbuf.st_mode & S_IFMT);
+    }
+    dirent->d_ino = d_ino;
+    dirent->d_type = d_type;
+
+    cookie = entry.d_next;
+
+    if (sel(dirent)) {
+      // Add the entry to the results.
+      if (dirents_used == dirents_size) {
+        dirents_size = dirents_size < 8 ? 8 : dirents_size * 2;
+        struct dirent **new_dirents =
+            realloc(dirents, dirents_size * sizeof(*dirents));
+        if (new_dirents == NULL) {
+          free(dirent);
+          goto bad;
+        }
+        dirents = new_dirents;
+      }
+      dirents[dirents_used++] = dirent;
+    } else {
+      // Discard the entry.
+      free(dirent);
+    }
+    continue;
+
+  read_entries:;
+    // Load more directory entries and continue.
+    // TODO: Remove the cast on `buffer` once the witx is updated with char8 support.
+    __wasi_errno_t error = __wasi_fd_readdir(fd, (uint8_t *)buffer, buffer_size,
+                                                       cookie, &buffer_used);
+    if (error != 0) {
+      errno = error;
+      goto bad;
+    }
+    buffer_processed = 0;
+  }
+
+  // Sort results and return them.
+  free(buffer);
+  close(fd);
+  (qsort)(dirents, dirents_used, sizeof(*dirents),
+          (int (*)(const void *, const void *))compar);
+  *namelist = dirents;
+  return dirents_used;
+
+bad:
+  // Deallocate partially created results.
+  for (size_t i = 0; i < dirents_used; ++i)
+    free(dirents[i]);
+  free(dirents);
+  free(buffer);
+  close(fd);
+  return -1;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/seekdir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/seekdir.c
new file mode 100644
index 0000000..a865d92
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/seekdir.c
@@ -0,0 +1,15 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <dirent.h>
+
+#include "dirent_impl.h"
+
+void seekdir(DIR *dirp, long loc) {
+  // Update cookie.
+  dirp->cookie = (unsigned long)loc;
+  // Mark entire buffer as processed to force a read of new data.
+  // TODO(ed): We could prevent a read if the offset is in the buffer.
+  dirp->buffer_used = dirp->buffer_processed = dirp->buffer_size;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/dirent/telldir.c b/libc-bottom-half/cloudlibc/src/libc/dirent/telldir.c
new file mode 100644
index 0000000..05687ee
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/dirent/telldir.c
@@ -0,0 +1,11 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <dirent.h>
+
+#include "dirent_impl.h"
+
+long telldir(DIR *dirp) {
+  return dirp->cookie;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/errno/errno.c b/libc-bottom-half/cloudlibc/src/libc/errno/errno.c
new file mode 100644
index 0000000..d7a27f3
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/errno/errno.c
@@ -0,0 +1,87 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <threads.h>
+
+static_assert(E2BIG == __WASI_ERRNO_2BIG, "Value mismatch");
+static_assert(EACCES == __WASI_ERRNO_ACCES, "Value mismatch");
+static_assert(EADDRINUSE == __WASI_ERRNO_ADDRINUSE, "Value mismatch");
+static_assert(EADDRNOTAVAIL == __WASI_ERRNO_ADDRNOTAVAIL, "Value mismatch");
+static_assert(EAFNOSUPPORT == __WASI_ERRNO_AFNOSUPPORT, "Value mismatch");
+static_assert(EAGAIN == __WASI_ERRNO_AGAIN, "Value mismatch");
+static_assert(EALREADY == __WASI_ERRNO_ALREADY, "Value mismatch");
+static_assert(EBADF == __WASI_ERRNO_BADF, "Value mismatch");
+static_assert(EBADMSG == __WASI_ERRNO_BADMSG, "Value mismatch");
+static_assert(EBUSY == __WASI_ERRNO_BUSY, "Value mismatch");
+static_assert(ECANCELED == __WASI_ERRNO_CANCELED, "Value mismatch");
+static_assert(ECHILD == __WASI_ERRNO_CHILD, "Value mismatch");
+static_assert(ECONNABORTED == __WASI_ERRNO_CONNABORTED, "Value mismatch");
+static_assert(ECONNREFUSED == __WASI_ERRNO_CONNREFUSED, "Value mismatch");
+static_assert(ECONNRESET == __WASI_ERRNO_CONNRESET, "Value mismatch");
+static_assert(EDEADLK == __WASI_ERRNO_DEADLK, "Value mismatch");
+static_assert(EDESTADDRREQ == __WASI_ERRNO_DESTADDRREQ, "Value mismatch");
+static_assert(EDOM == __WASI_ERRNO_DOM, "Value mismatch");
+static_assert(EDQUOT == __WASI_ERRNO_DQUOT, "Value mismatch");
+static_assert(EEXIST == __WASI_ERRNO_EXIST, "Value mismatch");
+static_assert(EFAULT == __WASI_ERRNO_FAULT, "Value mismatch");
+static_assert(EFBIG == __WASI_ERRNO_FBIG, "Value mismatch");
+static_assert(EHOSTUNREACH == __WASI_ERRNO_HOSTUNREACH, "Value mismatch");
+static_assert(EIDRM == __WASI_ERRNO_IDRM, "Value mismatch");
+static_assert(EILSEQ == __WASI_ERRNO_ILSEQ, "Value mismatch");
+static_assert(EINPROGRESS == __WASI_ERRNO_INPROGRESS, "Value mismatch");
+static_assert(EINTR == __WASI_ERRNO_INTR, "Value mismatch");
+static_assert(EINVAL == __WASI_ERRNO_INVAL, "Value mismatch");
+static_assert(EIO == __WASI_ERRNO_IO, "Value mismatch");
+static_assert(EISCONN == __WASI_ERRNO_ISCONN, "Value mismatch");
+static_assert(EISDIR == __WASI_ERRNO_ISDIR, "Value mismatch");
+static_assert(ELOOP == __WASI_ERRNO_LOOP, "Value mismatch");
+static_assert(EMFILE == __WASI_ERRNO_MFILE, "Value mismatch");
+static_assert(EMLINK == __WASI_ERRNO_MLINK, "Value mismatch");
+static_assert(EMSGSIZE == __WASI_ERRNO_MSGSIZE, "Value mismatch");
+static_assert(EMULTIHOP == __WASI_ERRNO_MULTIHOP, "Value mismatch");
+static_assert(ENAMETOOLONG == __WASI_ERRNO_NAMETOOLONG, "Value mismatch");
+static_assert(ENETDOWN == __WASI_ERRNO_NETDOWN, "Value mismatch");
+static_assert(ENETRESET == __WASI_ERRNO_NETRESET, "Value mismatch");
+static_assert(ENETUNREACH == __WASI_ERRNO_NETUNREACH, "Value mismatch");
+static_assert(ENFILE == __WASI_ERRNO_NFILE, "Value mismatch");
+static_assert(ENOBUFS == __WASI_ERRNO_NOBUFS, "Value mismatch");
+static_assert(ENODEV == __WASI_ERRNO_NODEV, "Value mismatch");
+static_assert(ENOENT == __WASI_ERRNO_NOENT, "Value mismatch");
+static_assert(ENOEXEC == __WASI_ERRNO_NOEXEC, "Value mismatch");
+static_assert(ENOLCK == __WASI_ERRNO_NOLCK, "Value mismatch");
+static_assert(ENOLINK == __WASI_ERRNO_NOLINK, "Value mismatch");
+static_assert(ENOMEM == __WASI_ERRNO_NOMEM, "Value mismatch");
+static_assert(ENOMSG == __WASI_ERRNO_NOMSG, "Value mismatch");
+static_assert(ENOPROTOOPT == __WASI_ERRNO_NOPROTOOPT, "Value mismatch");
+static_assert(ENOSPC == __WASI_ERRNO_NOSPC, "Value mismatch");
+static_assert(ENOSYS == __WASI_ERRNO_NOSYS, "Value mismatch");
+static_assert(ENOTCAPABLE == __WASI_ERRNO_NOTCAPABLE, "Value mismatch");
+static_assert(ENOTCONN == __WASI_ERRNO_NOTCONN, "Value mismatch");
+static_assert(ENOTDIR == __WASI_ERRNO_NOTDIR, "Value mismatch");
+static_assert(ENOTEMPTY == __WASI_ERRNO_NOTEMPTY, "Value mismatch");
+static_assert(ENOTRECOVERABLE == __WASI_ERRNO_NOTRECOVERABLE, "Value mismatch");
+static_assert(ENOTSOCK == __WASI_ERRNO_NOTSOCK, "Value mismatch");
+static_assert(ENOTSUP == __WASI_ERRNO_NOTSUP, "Value mismatch");
+static_assert(ENOTTY == __WASI_ERRNO_NOTTY, "Value mismatch");
+static_assert(ENXIO == __WASI_ERRNO_NXIO, "Value mismatch");
+static_assert(EOVERFLOW == __WASI_ERRNO_OVERFLOW, "Value mismatch");
+static_assert(EOWNERDEAD == __WASI_ERRNO_OWNERDEAD, "Value mismatch");
+static_assert(EPERM == __WASI_ERRNO_PERM, "Value mismatch");
+static_assert(EPIPE == __WASI_ERRNO_PIPE, "Value mismatch");
+static_assert(EPROTO == __WASI_ERRNO_PROTO, "Value mismatch");
+static_assert(EPROTONOSUPPORT == __WASI_ERRNO_PROTONOSUPPORT, "Value mismatch");
+static_assert(EPROTOTYPE == __WASI_ERRNO_PROTOTYPE, "Value mismatch");
+static_assert(ERANGE == __WASI_ERRNO_RANGE, "Value mismatch");
+static_assert(EROFS == __WASI_ERRNO_ROFS, "Value mismatch");
+static_assert(ESPIPE == __WASI_ERRNO_SPIPE, "Value mismatch");
+static_assert(ESRCH == __WASI_ERRNO_SRCH, "Value mismatch");
+static_assert(ESTALE == __WASI_ERRNO_STALE, "Value mismatch");
+static_assert(ETIMEDOUT == __WASI_ERRNO_TIMEDOUT, "Value mismatch");
+static_assert(ETXTBSY == __WASI_ERRNO_TXTBSY, "Value mismatch");
+static_assert(EXDEV == __WASI_ERRNO_XDEV, "Value mismatch");
+
+thread_local int errno = 0;
diff --git a/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c b/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c
new file mode 100644
index 0000000..5d4055d
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/fcntl/fcntl.c
@@ -0,0 +1,62 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdarg.h>
+
+int fcntl(int fildes, int cmd, ...) {
+  switch (cmd) {
+    case F_GETFD:
+      // Act as if the close-on-exec flag is always set.
+      return FD_CLOEXEC;
+    case F_SETFD:
+      // The close-on-exec flag is ignored.
+      return 0;
+    case F_GETFL: {
+      // Obtain the flags and the rights of the descriptor.
+      __wasi_fdstat_t fds;
+      __wasi_errno_t error = __wasi_fd_fdstat_get(fildes, &fds);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
+
+      // Roughly approximate the access mode by converting the rights.
+      int oflags = fds.fs_flags;
+      if ((fds.fs_rights_base &
+           (__WASI_RIGHTS_FD_READ | __WASI_RIGHTS_FD_READDIR)) != 0) {
+        if ((fds.fs_rights_base & __WASI_RIGHTS_FD_WRITE) != 0)
+          oflags |= O_RDWR;
+        else
+          oflags |= O_RDONLY;
+      } else if ((fds.fs_rights_base & __WASI_RIGHTS_FD_WRITE) != 0) {
+        oflags |= O_WRONLY;
+      } else {
+        oflags |= O_SEARCH;
+      }
+      return oflags;
+    }
+    case F_SETFL: {
+      // Set new file descriptor flags.
+      va_list ap;
+      va_start(ap, cmd);
+      int flags = va_arg(ap, int);
+      va_end(ap);
+
+      __wasi_fdflags_t fs_flags = flags & 0xfff;
+      __wasi_errno_t error =
+          __wasi_fd_fdstat_set_flags(fildes, fs_flags);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
+      return 0;
+    }
+    default:
+      errno = EINVAL;
+      return -1;
+  }
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c b/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c
new file mode 100644
index 0000000..09cbbf8
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c
@@ -0,0 +1,80 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <wasi/libc.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+
+static_assert(O_APPEND == __WASI_FDFLAGS_APPEND, "Value mismatch");
+static_assert(O_DSYNC == __WASI_FDFLAGS_DSYNC, "Value mismatch");
+static_assert(O_NONBLOCK == __WASI_FDFLAGS_NONBLOCK, "Value mismatch");
+static_assert(O_RSYNC == __WASI_FDFLAGS_RSYNC, "Value mismatch");
+static_assert(O_SYNC == __WASI_FDFLAGS_SYNC, "Value mismatch");
+
+static_assert(O_CREAT >> 12 == __WASI_OFLAGS_CREAT, "Value mismatch");
+static_assert(O_DIRECTORY >> 12 == __WASI_OFLAGS_DIRECTORY, "Value mismatch");
+static_assert(O_EXCL >> 12 == __WASI_OFLAGS_EXCL, "Value mismatch");
+static_assert(O_TRUNC >> 12 == __WASI_OFLAGS_TRUNC, "Value mismatch");
+
+int __wasilibc_nocwd_openat_nomode(int fd, const char *path, int oflag) {
+  // Compute rights corresponding with the access modes provided.
+  // Attempt to obtain all rights, except the ones that contradict the
+  // access mode provided to openat().
+  __wasi_rights_t max =
+      ~(__WASI_RIGHTS_FD_DATASYNC | __WASI_RIGHTS_FD_READ |
+        __WASI_RIGHTS_FD_WRITE | __WASI_RIGHTS_FD_ALLOCATE |
+        __WASI_RIGHTS_FD_READDIR | __WASI_RIGHTS_FD_FILESTAT_SET_SIZE);
+  switch (oflag & O_ACCMODE) {
+    case O_RDONLY:
+    case O_RDWR:
+    case O_WRONLY:
+      if ((oflag & O_RDONLY) != 0) {
+        max |= __WASI_RIGHTS_FD_READ | __WASI_RIGHTS_FD_READDIR;
+      }
+      if ((oflag & O_WRONLY) != 0) {
+        max |= __WASI_RIGHTS_FD_DATASYNC | __WASI_RIGHTS_FD_WRITE |
+               __WASI_RIGHTS_FD_ALLOCATE |
+               __WASI_RIGHTS_FD_FILESTAT_SET_SIZE;
+      }
+      break;
+    case O_EXEC:
+      break;
+    case O_SEARCH:
+      break;
+    default:
+      errno = EINVAL;
+      return -1;
+  }
+
+  // Ensure that we can actually obtain the minimal rights needed.
+  __wasi_fdstat_t fsb_cur;
+  __wasi_errno_t error = __wasi_fd_fdstat_get(fd, &fsb_cur);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+
+  // Path lookup properties.
+  __wasi_lookupflags_t lookup_flags = 0;
+  if ((oflag & O_NOFOLLOW) == 0)
+    lookup_flags |= __WASI_LOOKUPFLAGS_SYMLINK_FOLLOW;
+
+  // Open file with appropriate rights.
+  __wasi_fdflags_t fs_flags = oflag & 0xfff;
+  __wasi_rights_t fs_rights_base = max & fsb_cur.fs_rights_inheriting;
+  __wasi_rights_t fs_rights_inheriting = fsb_cur.fs_rights_inheriting;
+  __wasi_fd_t newfd;
+  error = __wasi_path_open(fd, lookup_flags, path,
+                                 (oflag >> 12) & 0xfff,
+                                 fs_rights_base, fs_rights_inheriting, fs_flags,
+                                 &newfd);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return newfd;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/fcntl/posix_fadvise.c b/libc-bottom-half/cloudlibc/src/libc/fcntl/posix_fadvise.c
new file mode 100644
index 0000000..d683d39
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/fcntl/posix_fadvise.c
@@ -0,0 +1,24 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+
+static_assert(POSIX_FADV_DONTNEED == __WASI_ADVICE_DONTNEED,
+              "Value mismatch");
+static_assert(POSIX_FADV_NOREUSE == __WASI_ADVICE_NOREUSE, "Value mismatch");
+static_assert(POSIX_FADV_NORMAL == __WASI_ADVICE_NORMAL, "Value mismatch");
+static_assert(POSIX_FADV_RANDOM == __WASI_ADVICE_RANDOM, "Value mismatch");
+static_assert(POSIX_FADV_SEQUENTIAL == __WASI_ADVICE_SEQUENTIAL,
+              "Value mismatch");
+static_assert(POSIX_FADV_WILLNEED == __WASI_ADVICE_WILLNEED,
+              "Value mismatch");
+
+int posix_fadvise(int fd, off_t offset, off_t len, int advice) {
+  if (offset < 0 || len < 0)
+    return EINVAL;
+  return __wasi_fd_advise(fd, offset, len, advice);
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/fcntl/posix_fallocate.c b/libc-bottom-half/cloudlibc/src/libc/fcntl/posix_fallocate.c
new file mode 100644
index 0000000..4b41c4b
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/fcntl/posix_fallocate.c
@@ -0,0 +1,13 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+
+int posix_fallocate(int fd, off_t offset, off_t len) {
+  if (offset < 0 || len < 0)
+    return EINVAL;
+  return __wasi_fd_allocate(fd, offset, len);
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/poll/poll.c b/libc-bottom-half/cloudlibc/src/libc/poll/poll.c
new file mode 100644
index 0000000..cde4e81
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/poll/poll.c
@@ -0,0 +1,129 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <poll.h>
+#include <stdbool.h>
+
+int poll(struct pollfd *fds, size_t nfds, int timeout) {
+  // Construct events for poll().
+  size_t maxevents = 2 * nfds + 1;
+  __wasi_subscription_t subscriptions[maxevents];
+  size_t nsubscriptions = 0;
+  for (size_t i = 0; i < nfds; ++i) {
+    struct pollfd *pollfd = &fds[i];
+    if (pollfd->fd < 0)
+      continue;
+    bool created_events = false;
+    if ((pollfd->events & POLLRDNORM) != 0) {
+      __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+      *subscription = (__wasi_subscription_t){
+          .userdata = (uintptr_t)pollfd,
+          .u.tag = __WASI_EVENTTYPE_FD_READ,
+          .u.u.fd_read.file_descriptor = pollfd->fd,
+      };
+      created_events = true;
+    }
+    if ((pollfd->events & POLLWRNORM) != 0) {
+      __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+      *subscription = (__wasi_subscription_t){
+          .userdata = (uintptr_t)pollfd,
+          .u.tag = __WASI_EVENTTYPE_FD_WRITE,
+          .u.u.fd_write.file_descriptor = pollfd->fd,
+      };
+      created_events = true;
+    }
+
+    // As entries are decomposed into separate read/write subscriptions,
+    // we cannot detect POLLERR, POLLHUP and POLLNVAL if POLLRDNORM and
+    // POLLWRNORM are not specified. Disallow this for now.
+    if (!created_events) {
+      errno = ENOSYS;
+      return -1;
+    }
+  }
+
+  // Create extra event for the timeout.
+  if (timeout >= 0) {
+    __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+    *subscription = (__wasi_subscription_t){
+        .u.tag = __WASI_EVENTTYPE_CLOCK,
+        .u.u.clock.id = __WASI_CLOCKID_REALTIME,
+        .u.u.clock.timeout = (__wasi_timestamp_t)timeout * 1000000,
+    };
+  }
+
+  // Execute poll().
+  size_t nevents;
+  __wasi_event_t events[nsubscriptions];
+  __wasi_errno_t error =
+      __wasi_poll_oneoff(subscriptions, events, nsubscriptions, &nevents);
+  if (error != 0) {
+    // WASI's poll requires at least one subscription, or else it returns
+    // `EINVAL`. Since a `poll` with nothing to wait for is valid in POSIX,
+    // return `ENOTSUP` to indicate that we don't support that case.
+    //
+    // Wasm has no signal handling, so if none of the user-provided `pollfd`
+    // elements, nor the timeout, led us to producing even one subscription
+    // to wait for, there would be no way for the poll to wake up. WASI
+    // returns `EINVAL` in this case, but for users of `poll`, `ENOTSUP` is
+    // more likely to be understood.
+    if (nsubscriptions == 0)
+      errno = ENOTSUP;
+    else
+      errno = error;
+    return -1;
+  }
+
+  // Clear revents fields.
+  for (size_t i = 0; i < nfds; ++i) {
+    struct pollfd *pollfd = &fds[i];
+    pollfd->revents = 0;
+  }
+
+  // Set revents fields.
+  for (size_t i = 0; i < nevents; ++i) {
+    const __wasi_event_t *event = &events[i];
+    if (event->type == __WASI_EVENTTYPE_FD_READ ||
+        event->type == __WASI_EVENTTYPE_FD_WRITE) {
+      struct pollfd *pollfd = (struct pollfd *)(uintptr_t)event->userdata;
+      if (event->error == __WASI_ERRNO_BADF) {
+        // Invalid file descriptor.
+        pollfd->revents |= POLLNVAL;
+      } else if (event->error == __WASI_ERRNO_PIPE) {
+        // Hangup on write side of pipe.
+        pollfd->revents |= POLLHUP;
+      } else if (event->error != 0) {
+        // Another error occurred.
+        pollfd->revents |= POLLERR;
+      } else {
+        // Data can be read or written.
+        if (event->type == __WASI_EVENTTYPE_FD_READ) {
+            pollfd->revents |= POLLRDNORM;
+            if (event->fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP) {
+              pollfd->revents |= POLLHUP;
+            }
+        } else if (event->type == __WASI_EVENTTYPE_FD_WRITE) {
+            pollfd->revents |= POLLWRNORM;
+            if (event->fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP) {
+              pollfd->revents |= POLLHUP;
+            }
+        }
+      }
+    }
+  }
+
+  // Return the number of events with a non-zero revents value.
+  int retval = 0;
+  for (size_t i = 0; i < nfds; ++i) {
+    struct pollfd *pollfd = &fds[i];
+    // POLLHUP contradicts with POLLWRNORM.
+    if ((pollfd->revents & POLLHUP) != 0)
+      pollfd->revents &= ~POLLWRNORM;
+    if (pollfd->revents != 0)
+      ++retval;
+  }
+  return retval;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sched/sched_yield.c b/libc-bottom-half/cloudlibc/src/libc/sched/sched_yield.c
new file mode 100644
index 0000000..6100ea5
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sched/sched_yield.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <sched.h>
+
+int sched_yield(void) {
+  __wasi_errno_t error = __wasi_sched_yield();
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/stdio/renameat.c b/libc-bottom-half/cloudlibc/src/libc/stdio/renameat.c
new file mode 100644
index 0000000..c1706db
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/stdio/renameat.c
@@ -0,0 +1,17 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+int __wasilibc_nocwd_renameat(int oldfd, const char *old, int newfd, const char *new) {
+  __wasi_errno_t error = __wasi_path_rename(oldfd, old, newfd, new);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/stdlib/_Exit.c b/libc-bottom-half/cloudlibc/src/libc/stdlib/_Exit.c
new file mode 100644
index 0000000..5e266f0
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/stdlib/_Exit.c
@@ -0,0 +1,14 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <_/cdefs.h>
+#include <stdnoreturn.h>
+#include <unistd.h>
+
+noreturn void _Exit(int status) {
+  __wasi_proc_exit(status);
+}
+
+__strong_reference(_Exit, _exit);
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/ioctl/ioctl.c b/libc-bottom-half/cloudlibc/src/libc/sys/ioctl/ioctl.c
new file mode 100644
index 0000000..7d03cc6
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/ioctl/ioctl.c
@@ -0,0 +1,88 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/ioctl.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <stdarg.h>
+
+int ioctl(int fildes, int request, ...) {
+  switch (request) {
+    case FIONREAD: {
+      // Poll the file descriptor to determine how many bytes can be read.
+      __wasi_subscription_t subscriptions[2] = {
+          {
+              .u.tag = __WASI_EVENTTYPE_FD_READ,
+              .u.u.fd_read.file_descriptor = fildes,
+          },
+          {
+              .u.tag = __WASI_EVENTTYPE_CLOCK,
+              .u.u.clock.id = __WASI_CLOCKID_MONOTONIC,
+          },
+      };
+      __wasi_event_t events[__arraycount(subscriptions)];
+      size_t nevents;
+      __wasi_errno_t error = __wasi_poll_oneoff(
+          subscriptions, events, __arraycount(subscriptions), &nevents);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
+
+      // Location where result should be written.
+      va_list ap;
+      va_start(ap, request);
+      int *result = va_arg(ap, int *);
+      va_end(ap);
+
+      // Extract number of bytes for reading from poll results.
+      for (size_t i = 0; i < nevents; ++i) {
+        __wasi_event_t *event = &events[i];
+        if (event->error != 0) {
+          errno = event->error;
+          return -1;
+        }
+        if (event->type == __WASI_EVENTTYPE_FD_READ) {
+          *result = event->fd_readwrite.nbytes;
+          return 0;
+        }
+      }
+
+      // No data available for reading.
+      *result = 0;
+      return 0;
+    }
+    case FIONBIO: {
+      // Obtain the current file descriptor flags.
+      __wasi_fdstat_t fds;
+      __wasi_errno_t error = __wasi_fd_fdstat_get(fildes, &fds);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
+
+      // Toggle the non-blocking flag based on the argument.
+      va_list ap;
+      va_start(ap, request);
+      if (*va_arg(ap, const int *) != 0)
+        fds.fs_flags |= __WASI_FDFLAGS_NONBLOCK;
+      else
+        fds.fs_flags &= ~__WASI_FDFLAGS_NONBLOCK;
+      va_end(ap);
+
+      // Update the file descriptor flags.
+      error = __wasi_fd_fdstat_set_flags(fildes, fds.fs_flags);
+      if (error != 0) {
+        errno = error;
+        return -1;
+      }
+      return 0;
+    }
+    default:
+      // Invalid request.
+      errno = EINVAL;
+      return -1;
+  }
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/select/pselect.c b/libc-bottom-half/cloudlibc/src/libc/sys/select/pselect.c
new file mode 100644
index 0000000..fdc470e
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/select/pselect.c
@@ -0,0 +1,125 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/time.h>
+
+#include <sys/select.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+
+int pselect(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
+            fd_set *restrict errorfds, const struct timespec *restrict timeout,
+            const sigset_t *sigmask) {
+  // Negative file descriptor upperbound.
+  if (nfds < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  // This implementation does not support polling for exceptional
+  // conditions, such as out-of-band data on TCP sockets.
+  if (errorfds != NULL && errorfds->__nfds > 0) {
+    errno = ENOSYS;
+    return -1;
+  }
+
+  // Replace NULL pointers by the empty set.
+  fd_set empty;
+  FD_ZERO(&empty);
+  if (readfds == NULL)
+    readfds = &empty;
+  if (writefds == NULL)
+    writefds = &empty;
+
+  // Determine the maximum number of events.
+  size_t maxevents = readfds->__nfds + writefds->__nfds + 1;
+  __wasi_subscription_t subscriptions[maxevents];
+  size_t nsubscriptions = 0;
+
+  // Convert the readfds set.
+  for (size_t i = 0; i < readfds->__nfds; ++i) {
+    int fd = readfds->__fds[i];
+    if (fd < nfds) {
+      __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+      *subscription = (__wasi_subscription_t){
+          .userdata = fd,
+          .u.tag = __WASI_EVENTTYPE_FD_READ,
+          .u.u.fd_read.file_descriptor = fd,
+      };
+    }
+  }
+
+  // Convert the writefds set.
+  for (size_t i = 0; i < writefds->__nfds; ++i) {
+    int fd = writefds->__fds[i];
+    if (fd < nfds) {
+      __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+      *subscription = (__wasi_subscription_t){
+          .userdata = fd,
+          .u.tag = __WASI_EVENTTYPE_FD_WRITE,
+          .u.u.fd_write.file_descriptor = fd,
+      };
+    }
+  }
+
+  // Create extra event for the timeout.
+  if (timeout != NULL) {
+    __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+    *subscription = (__wasi_subscription_t){
+        .u.tag = __WASI_EVENTTYPE_CLOCK,
+        .u.u.clock.id = __WASI_CLOCKID_REALTIME,
+    };
+    if (!timespec_to_timestamp_clamp(timeout, &subscription->u.u.clock.timeout)) {
+      errno = EINVAL;
+      return -1;
+    }
+  }
+
+  // Execute poll().
+  size_t nevents;
+  __wasi_event_t events[nsubscriptions];
+  __wasi_errno_t error =
+      __wasi_poll_oneoff(subscriptions, events, nsubscriptions, &nevents);
+  if (error != 0) {
+    // WASI's poll requires at least one subscription, or else it returns
+    // `EINVAL`. Since a `pselect` with nothing to wait for is valid in POSIX,
+    // return `ENOTSUP` to indicate that we don't support that case.
+    //
+    // Wasm has no signal handling, so if none of the user-provided `pollfd`
+    // elements, nor the timeout, led us to producing even one subscription
+    // to wait for, there would be no way for the poll to wake up. WASI
+    // returns `EINVAL` in this case, but for users of `poll`, `ENOTSUP` is
+    // more likely to be understood.
+    if (nsubscriptions == 0)
+      errno = ENOTSUP;
+    else
+      errno = error;
+    return -1;
+  }
+
+  // Test for EBADF.
+  for (size_t i = 0; i < nevents; ++i) {
+    const __wasi_event_t *event = &events[i];
+    if ((event->type == __WASI_EVENTTYPE_FD_READ ||
+         event->type == __WASI_EVENTTYPE_FD_WRITE) &&
+        event->error == __WASI_ERRNO_BADF) {
+      errno = EBADF;
+      return -1;
+    }
+  }
+
+  // Clear and set entries in the result sets.
+  FD_ZERO(readfds);
+  FD_ZERO(writefds);
+  for (size_t i = 0; i < nevents; ++i) {
+    const __wasi_event_t *event = &events[i];
+    if (event->type == __WASI_EVENTTYPE_FD_READ) {
+      readfds->__fds[readfds->__nfds++] = event->userdata;
+    } else if (event->type == __WASI_EVENTTYPE_FD_WRITE) {
+      writefds->__fds[writefds->__nfds++] = event->userdata;
+    }
+  }
+  return readfds->__nfds + writefds->__nfds;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/select/select.c b/libc-bottom-half/cloudlibc/src/libc/sys/select/select.c
new file mode 100644
index 0000000..ebe5e8c
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/select/select.c
@@ -0,0 +1,25 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/select.h>
+
+#include <errno.h>
+#include <stddef.h>
+
+int select(int nfds, fd_set *restrict readfds, fd_set *restrict writefds,
+           fd_set *restrict errorfds, struct timeval *restrict timeout) {
+  if (timeout != NULL) {
+    // Timeout specified.
+    if (timeout->tv_usec < 0 || timeout->tv_usec >= 1000000) {
+      errno = EINVAL;
+      return -1;
+    }
+    struct timespec ts = {.tv_sec = timeout->tv_sec,
+                          .tv_nsec = (long)timeout->tv_usec * 1000};
+    return pselect(nfds, readfds, writefds, errorfds, &ts, NULL);
+  } else {
+    // No timeout specified.
+    return pselect(nfds, readfds, writefds, errorfds, NULL, NULL);
+  }
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/socket/getsockopt.c b/libc-bottom-half/cloudlibc/src/libc/sys/socket/getsockopt.c
new file mode 100644
index 0000000..1fe41c4
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/socket/getsockopt.c
@@ -0,0 +1,48 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/socket.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <string.h>
+
+int getsockopt(int socket, int level, int option_name,
+               void *restrict option_value, socklen_t *restrict option_len) {
+  // Only support SOL_SOCKET options for now.
+  if (level != SOL_SOCKET) {
+    errno = ENOPROTOOPT;
+    return -1;
+  }
+
+  int value;
+  switch (option_name) {
+    case SO_TYPE: {
+      // Return the type of the socket. This information can simply be
+      // obtained by looking at the file descriptor type.
+      __wasi_fdstat_t fsb;
+      if (__wasi_fd_fdstat_get(socket, &fsb) != 0) {
+        errno = EBADF;
+        return -1;
+      }
+      if (fsb.fs_filetype != __WASI_FILETYPE_SOCKET_DGRAM &&
+          fsb.fs_filetype != __WASI_FILETYPE_SOCKET_STREAM) {
+        errno = ENOTSOCK;
+        return -1;
+      }
+      value = fsb.fs_filetype;
+      break;
+    }
+    default: {
+      errno = ENOPROTOOPT;
+      return -1;
+    }
+  }
+
+  // Copy out integer value.
+  memcpy(option_value, &value,
+         *option_len < sizeof(int) ? *option_len : sizeof(int));
+  *option_len = sizeof(int);
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/socket/recv.c b/libc-bottom-half/cloudlibc/src/libc/sys/socket/recv.c
new file mode 100644
index 0000000..d35f889
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/socket/recv.c
@@ -0,0 +1,40 @@
+// Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/socket.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <stdint.h>
+
+static_assert(MSG_PEEK == __WASI_RIFLAGS_RECV_PEEK, "Value mismatch");
+static_assert(MSG_WAITALL == __WASI_RIFLAGS_RECV_WAITALL, "Value mismatch");
+
+ssize_t recv(int socket, void *restrict buffer, size_t length, int flags) {
+  // Validate flags.
+  if ((flags & ~(MSG_PEEK | MSG_WAITALL)) != 0) {
+    errno = EOPNOTSUPP;
+    return -1;
+  }
+
+  // Prepare input parameters.
+  __wasi_iovec_t iov = {.buf = buffer, .buf_len = length};
+  __wasi_iovec_t *ri_data = &iov;
+  size_t ri_data_len = 1;
+  __wasi_riflags_t ri_flags = flags;
+
+  // Perform system call.
+  size_t ro_datalen;
+  __wasi_roflags_t ro_flags;
+  __wasi_errno_t error = __wasi_sock_recv(socket,
+                                          ri_data, ri_data_len, ri_flags,
+                                          &ro_datalen,
+                                          &ro_flags);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return ro_datalen;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/socket/send.c b/libc-bottom-half/cloudlibc/src/libc/sys/socket/send.c
new file mode 100644
index 0000000..85a298a
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/socket/send.c
@@ -0,0 +1,32 @@
+// Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/socket.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+
+ssize_t send(int socket, const void *buffer, size_t length, int flags) {
+  // This implementation does not support any flags.
+  if (flags != 0) {
+    errno = EOPNOTSUPP;
+    return -1;
+  }
+
+  // Prepare input parameters.
+  __wasi_ciovec_t iov = {.buf = buffer, .buf_len = length};
+  __wasi_ciovec_t *si_data = &iov;
+  size_t si_data_len = 1;
+  __wasi_siflags_t si_flags = 0;
+
+  // Perform system call.
+  size_t so_datalen;
+  __wasi_errno_t error = __wasi_sock_send(socket, si_data, si_data_len, si_flags, &so_datalen);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return so_datalen;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/socket/shutdown.c b/libc-bottom-half/cloudlibc/src/libc/sys/socket/shutdown.c
new file mode 100644
index 0000000..261fcb8
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/socket/shutdown.c
@@ -0,0 +1,27 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/socket.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+
+static_assert(SHUT_RD == __WASI_SDFLAGS_RD, "Value mismatch");
+static_assert(SHUT_WR == __WASI_SDFLAGS_WR, "Value mismatch");
+
+int shutdown(int socket, int how) {
+  // Validate shutdown flags.
+  if (how != SHUT_RD && how != SHUT_WR && how != SHUT_RDWR) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  __wasi_errno_t error = __wasi_sock_shutdown(socket, how);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return error;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/socket/socket_impl.h b/libc-bottom-half/cloudlibc/src/libc/sys/socket/socket_impl.h
new file mode 100644
index 0000000..7b1a366
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/socket/socket_impl.h
@@ -0,0 +1,57 @@
+// Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#ifndef SYS_SOCKET_SOCKET_IMPL_H
+#define SYS_SOCKET_SOCKET_IMPL_H
+
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#include <netinet/in.h>
+
+#include <assert.h>
+#include <stdalign.h>
+#include <stddef.h>
+#include <stdint.h>
+
+static_assert(sizeof(struct sockaddr_storage) >= sizeof(struct sockaddr),
+              "struct sockaddr_storage too small");
+static_assert(alignof(struct sockaddr_storage) == alignof(struct sockaddr),
+              "struct sockaddr alignment incorrect");
+static_assert(sizeof(struct sockaddr_storage) >= sizeof(struct sockaddr_in),
+              "struct sockaddr_storage too small");
+static_assert(alignof(struct sockaddr_storage) == alignof(struct sockaddr_in),
+              "struct sockaddr_in alignment incorrect");
+static_assert(sizeof(struct sockaddr_storage) >= sizeof(struct sockaddr_in6),
+              "struct sockaddr_storage too small");
+static_assert(alignof(struct sockaddr_storage) == alignof(struct sockaddr_in6),
+              "struct sockaddr_in6 alignment incorrect");
+static_assert(sizeof(struct sockaddr_storage) >= sizeof(struct sockaddr_un),
+              "struct sockaddr_storage too small");
+static_assert(alignof(struct sockaddr_storage) == alignof(struct sockaddr_un),
+              "struct sockaddr_un alignment incorrect");
+
+// Returns the control message header stored at a provided memory
+// address, ensuring that it is stored within the ancillary data buffer
+// of a message header.
+static inline struct cmsghdr *CMSG_GET(const struct msghdr *mhdr, void *cmsg) {
+  // Safety belt: require that the returned object is properly aligned.
+  assert((uintptr_t)cmsg % alignof(struct cmsghdr) == 0 &&
+         "Attempted to access unaligned control message header");
+
+  // Safety belt: the computed starting address of the control message
+  // header may only lie inside the ancillary data buffer, or right
+  // after it in case we've reached the end of the buffer.
+  const unsigned char *begin = mhdr->msg_control;
+  const unsigned char *end = begin + mhdr->msg_controllen;
+  assert((unsigned char *)cmsg >= begin &&
+         (unsigned char *)cmsg < end + alignof(struct cmsghdr) &&
+         "Computed object outside of buffer boundaries");
+
+  // Only return the control message header in case all of its fields
+  // lie within the ancillary data buffer.
+  return CMSG_DATA((struct cmsghdr *)cmsg) <= end ? cmsg : NULL;
+}
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/stat/fstat.c b/libc-bottom-half/cloudlibc/src/libc/sys/stat/fstat.c
new file mode 100644
index 0000000..b8ffdb5
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/stat/fstat.c
@@ -0,0 +1,21 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+
+#include "stat_impl.h"
+
+int fstat(int fildes, struct stat *buf) {
+  __wasi_filestat_t internal_stat;
+  __wasi_errno_t error = __wasi_fd_filestat_get(fildes, &internal_stat);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  to_public_stat(&internal_stat, buf);
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/stat/fstatat.c b/libc-bottom-half/cloudlibc/src/libc/sys/stat/fstatat.c
new file mode 100644
index 0000000..25b29ac
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/stat/fstatat.c
@@ -0,0 +1,31 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+
+#include "stat_impl.h"
+
+int __wasilibc_nocwd_fstatat(int fd, const char *restrict path, struct stat *restrict buf,
+                             int flag) {
+  // Create lookup properties.
+  __wasi_lookupflags_t lookup_flags = 0;
+  if ((flag & AT_SYMLINK_NOFOLLOW) == 0)
+    lookup_flags |= __WASI_LOOKUPFLAGS_SYMLINK_FOLLOW;
+
+  // Perform system call.
+  __wasi_filestat_t internal_stat;
+  __wasi_errno_t error =
+      __wasi_path_filestat_get(fd, lookup_flags, path, &internal_stat);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  to_public_stat(&internal_stat, buf);
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/stat/futimens.c b/libc-bottom-half/cloudlibc/src/libc/sys/stat/futimens.c
new file mode 100644
index 0000000..13357fc
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/stat/futimens.c
@@ -0,0 +1,29 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+
+#include "stat_impl.h"
+
+int futimens(int fd, const struct timespec *times) {
+  // Convert timestamps and extract NOW/OMIT flags.
+  __wasi_timestamp_t st_atim;
+  __wasi_timestamp_t st_mtim;
+  __wasi_fstflags_t flags;
+  if (!utimens_get_timestamps(times, &st_atim, &st_mtim, &flags)) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  // Perform system call.
+  __wasi_errno_t error = __wasi_fd_filestat_set_times(fd, st_atim, st_mtim, flags);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/stat/mkdirat.c b/libc-bottom-half/cloudlibc/src/libc/sys/stat/mkdirat.c
new file mode 100644
index 0000000..fd27d5e
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/stat/mkdirat.c
@@ -0,0 +1,18 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <string.h>
+
+int __wasilibc_nocwd_mkdirat_nomode(int fd, const char *path) {
+  __wasi_errno_t error = __wasi_path_create_directory(fd, path);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/stat/stat_impl.h b/libc-bottom-half/cloudlibc/src/libc/sys/stat/stat_impl.h
new file mode 100644
index 0000000..9726b51
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/stat/stat_impl.h
@@ -0,0 +1,116 @@
+// Copyright (c) 2015-2017 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#ifndef SYS_STAT_STAT_IMPL_H
+#define SYS_STAT_STAT_IMPL_H
+
+#include <common/time.h>
+
+#include <sys/stat.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <stdbool.h>
+
+static_assert(S_ISBLK(S_IFBLK), "Value mismatch");
+static_assert(S_ISCHR(S_IFCHR), "Value mismatch");
+static_assert(S_ISDIR(S_IFDIR), "Value mismatch");
+static_assert(S_ISFIFO(S_IFIFO), "Value mismatch");
+static_assert(S_ISLNK(S_IFLNK), "Value mismatch");
+static_assert(S_ISREG(S_IFREG), "Value mismatch");
+static_assert(S_ISSOCK(S_IFSOCK), "Value mismatch");
+
+static inline void to_public_stat(const __wasi_filestat_t *in,
+                                  struct stat *out) {
+  // Ensure that we don't truncate any values.
+  static_assert(sizeof(in->dev) == sizeof(out->st_dev), "Size mismatch");
+  static_assert(sizeof(in->ino) == sizeof(out->st_ino), "Size mismatch");
+  /*
+   * The non-standard __st_filetype field appears to only be used for shared
+   * memory, which we don't currently support.
+   */
+  /* nlink_t is 64-bit on wasm32, following the x32 ABI. */
+  static_assert(sizeof(in->nlink) <= sizeof(out->st_nlink), "Size shortfall");
+  static_assert(sizeof(in->size) == sizeof(out->st_size), "Size mismatch");
+
+  *out = (struct stat){
+      .st_dev = in->dev,
+      .st_ino = in->ino,
+      .st_nlink = in->nlink,
+      .st_size = in->size,
+      .st_atim = timestamp_to_timespec(in->atim),
+      .st_mtim = timestamp_to_timespec(in->mtim),
+      .st_ctim = timestamp_to_timespec(in->ctim),
+  };
+
+  // Convert file type to legacy types encoded in st_mode.
+  switch (in->filetype) {
+    case __WASI_FILETYPE_BLOCK_DEVICE:
+      out->st_mode |= S_IFBLK;
+      break;
+    case __WASI_FILETYPE_CHARACTER_DEVICE:
+      out->st_mode |= S_IFCHR;
+      break;
+    case __WASI_FILETYPE_DIRECTORY:
+      out->st_mode |= S_IFDIR;
+      break;
+    case __WASI_FILETYPE_REGULAR_FILE:
+      out->st_mode |= S_IFREG;
+      break;
+    case __WASI_FILETYPE_SOCKET_DGRAM:
+    case __WASI_FILETYPE_SOCKET_STREAM:
+      out->st_mode |= S_IFSOCK;
+      break;
+    case __WASI_FILETYPE_SYMBOLIC_LINK:
+      out->st_mode |= S_IFLNK;
+      break;
+  }
+}
+
+static inline bool utimens_get_timestamps(const struct timespec *times,
+                                          __wasi_timestamp_t *st_atim,
+                                          __wasi_timestamp_t *st_mtim,
+                                          __wasi_fstflags_t *flags) {
+  if (times == NULL) {
+    // Update both timestamps.
+    *flags = __WASI_FSTFLAGS_ATIM_NOW | __WASI_FSTFLAGS_MTIM_NOW;
+    *st_atim = (__wasi_timestamp_t) { 0 };
+    *st_mtim = (__wasi_timestamp_t) { 0 };
+  } else {
+    // Set individual timestamps.
+    *flags = 0;
+    switch (times[0].tv_nsec) {
+      case UTIME_NOW:
+        *flags |= __WASI_FSTFLAGS_ATIM_NOW;
+        *st_atim = (__wasi_timestamp_t) { 0 };
+        break;
+      case UTIME_OMIT:
+        *st_atim = (__wasi_timestamp_t) { 0 };
+        break;
+      default:
+        *flags |= __WASI_FSTFLAGS_ATIM;
+        if (!timespec_to_timestamp_exact(&times[0], st_atim))
+          return false;
+        break;
+    }
+
+    switch (times[1].tv_nsec) {
+      case UTIME_NOW:
+        *flags |= __WASI_FSTFLAGS_MTIM_NOW;
+        *st_mtim = (__wasi_timestamp_t) { 0 };
+        break;
+      case UTIME_OMIT:
+        *st_mtim = (__wasi_timestamp_t) { 0 };
+        break;
+      default:
+        *flags |= __WASI_FSTFLAGS_MTIM;
+        if (!timespec_to_timestamp_exact(&times[1], st_mtim))
+          return false;
+        break;
+    }
+  }
+  return true;
+}
+
+#endif
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/stat/utimensat.c b/libc-bottom-half/cloudlibc/src/libc/sys/stat/utimensat.c
new file mode 100644
index 0000000..19508a1
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/stat/utimensat.c
@@ -0,0 +1,38 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/stat.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+
+#include "stat_impl.h"
+
+int __wasilibc_nocwd_utimensat(int fd, const char *path, const struct timespec times[2],
+                               int flag) {
+  // Convert timestamps and extract NOW/OMIT flags.
+  __wasi_timestamp_t st_atim;
+  __wasi_timestamp_t st_mtim;
+  __wasi_fstflags_t flags;
+  if (!utimens_get_timestamps(times, &st_atim, &st_mtim, &flags)) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  // Create lookup properties.
+  __wasi_lookupflags_t lookup_flags = 0;
+  if ((flag & AT_SYMLINK_NOFOLLOW) == 0)
+    lookup_flags |= __WASI_LOOKUPFLAGS_SYMLINK_FOLLOW;
+
+  // Perform system call.
+  __wasi_errno_t error =
+      __wasi_path_filestat_set_times(fd, lookup_flags, path, st_atim, st_mtim, flags);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/time/gettimeofday.c b/libc-bottom-half/cloudlibc/src/libc/sys/time/gettimeofday.c
new file mode 100644
index 0000000..596bdff
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/time/gettimeofday.c
@@ -0,0 +1,18 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/time.h>
+
+#include <sys/time.h>
+
+#include <wasi/api.h>
+
+int gettimeofday(struct timeval *restrict tp, void *tz) {
+  if (tp != NULL) {
+    __wasi_timestamp_t ts = 0;
+    (void)__wasi_clock_time_get(__WASI_CLOCKID_REALTIME, 1000, &ts);
+    *tp = timestamp_to_timeval(ts);
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/uio/preadv.c b/libc-bottom-half/cloudlibc/src/libc/sys/uio/preadv.c
new file mode 100644
index 0000000..36f882d
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/uio/preadv.c
@@ -0,0 +1,24 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/types.h>
+#include <sys/uio.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+
+ssize_t preadv(int fildes, const struct iovec *iov, int iovcnt, off_t offset) {
+  if (iovcnt < 0 || offset < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  size_t bytes_read;
+  __wasi_errno_t error = __wasi_fd_pread(
+      fildes, (const __wasi_iovec_t *)iov, iovcnt, offset, &bytes_read);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return bytes_read;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/uio/pwritev.c b/libc-bottom-half/cloudlibc/src/libc/sys/uio/pwritev.c
new file mode 100644
index 0000000..d6f8851
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/uio/pwritev.c
@@ -0,0 +1,24 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/types.h>
+#include <sys/uio.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+
+ssize_t pwritev(int fildes, const struct iovec *iov, int iovcnt, off_t offset) {
+  if (iovcnt < 0 || offset < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  size_t bytes_written;
+  __wasi_errno_t error = __wasi_fd_pwrite(
+      fildes, (const __wasi_ciovec_t *)iov, iovcnt, offset, &bytes_written);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return bytes_written;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/uio/readv.c b/libc-bottom-half/cloudlibc/src/libc/sys/uio/readv.c
new file mode 100644
index 0000000..e3eaebe
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/uio/readv.c
@@ -0,0 +1,40 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/uio.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <stddef.h>
+
+static_assert(offsetof(struct iovec, iov_base) ==
+                  offsetof(__wasi_iovec_t, buf),
+              "Offset mismatch");
+static_assert(sizeof(((struct iovec *)0)->iov_base) ==
+                  sizeof(((__wasi_iovec_t *)0)->buf),
+              "Size mismatch");
+static_assert(offsetof(struct iovec, iov_len) ==
+                  offsetof(__wasi_iovec_t, buf_len),
+              "Offset mismatch");
+static_assert(sizeof(((struct iovec *)0)->iov_len) ==
+                  sizeof(((__wasi_iovec_t *)0)->buf_len),
+              "Size mismatch");
+static_assert(sizeof(struct iovec) == sizeof(__wasi_iovec_t),
+              "Size mismatch");
+
+ssize_t readv(int fildes, const struct iovec *iov, int iovcnt) {
+  if (iovcnt < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  size_t bytes_read;
+  __wasi_errno_t error = __wasi_fd_read(
+      fildes, (const __wasi_iovec_t *)iov, iovcnt, &bytes_read);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return bytes_read;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/sys/uio/writev.c b/libc-bottom-half/cloudlibc/src/libc/sys/uio/writev.c
new file mode 100644
index 0000000..459b152
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/sys/uio/writev.c
@@ -0,0 +1,40 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <sys/uio.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <stddef.h>
+
+static_assert(offsetof(struct iovec, iov_base) ==
+                  offsetof(__wasi_ciovec_t, buf),
+              "Offset mismatch");
+static_assert(sizeof(((struct iovec *)0)->iov_base) ==
+                  sizeof(((__wasi_ciovec_t *)0)->buf),
+              "Size mismatch");
+static_assert(offsetof(struct iovec, iov_len) ==
+                  offsetof(__wasi_ciovec_t, buf_len),
+              "Offset mismatch");
+static_assert(sizeof(((struct iovec *)0)->iov_len) ==
+                  sizeof(((__wasi_ciovec_t *)0)->buf_len),
+              "Size mismatch");
+static_assert(sizeof(struct iovec) == sizeof(__wasi_ciovec_t),
+              "Size mismatch");
+
+ssize_t writev(int fildes, const struct iovec *iov, int iovcnt) {
+  if (iovcnt < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  size_t bytes_written;
+  __wasi_errno_t error = __wasi_fd_write(
+      fildes, (const __wasi_ciovec_t *)iov, iovcnt, &bytes_written);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return bytes_written;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/CLOCK_MONOTONIC.c b/libc-bottom-half/cloudlibc/src/libc/time/CLOCK_MONOTONIC.c
new file mode 100644
index 0000000..a4c4a62
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/CLOCK_MONOTONIC.c
@@ -0,0 +1,12 @@
+// Copyright (c) 2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/clock.h>
+
+#include <wasi/api.h>
+#include <time.h>
+
+const struct __clockid _CLOCK_MONOTONIC = {
+    .id = __WASI_CLOCKID_MONOTONIC,
+};
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/CLOCK_REALTIME.c b/libc-bottom-half/cloudlibc/src/libc/time/CLOCK_REALTIME.c
new file mode 100644
index 0000000..9523754
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/CLOCK_REALTIME.c
@@ -0,0 +1,12 @@
+// Copyright (c) 2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/clock.h>
+
+#include <wasi/api.h>
+#include <time.h>
+
+const struct __clockid _CLOCK_REALTIME = {
+    .id = __WASI_CLOCKID_REALTIME,
+};
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/clock_getres.c b/libc-bottom-half/cloudlibc/src/libc/time/clock_getres.c
new file mode 100644
index 0000000..8030d4b
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/clock_getres.c
@@ -0,0 +1,21 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/clock.h>
+#include <common/time.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <time.h>
+
+int clock_getres(clockid_t clock_id, struct timespec *res) {
+  __wasi_timestamp_t ts;
+  __wasi_errno_t error = __wasi_clock_res_get(clock_id->id, &ts);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  *res = timestamp_to_timespec(ts);
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/clock_gettime.c b/libc-bottom-half/cloudlibc/src/libc/time/clock_gettime.c
new file mode 100644
index 0000000..c7e1a60
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/clock_gettime.c
@@ -0,0 +1,22 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/clock.h>
+#include <common/time.h>
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <time.h>
+
+int __clock_gettime(clockid_t clock_id, struct timespec *tp) {
+  __wasi_timestamp_t ts;
+  __wasi_errno_t error = __wasi_clock_time_get(clock_id->id, 1, &ts);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  *tp = timestamp_to_timespec(ts);
+  return 0;
+}
+weak_alias(__clock_gettime, clock_gettime);
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/clock_nanosleep.c b/libc-bottom-half/cloudlibc/src/libc/time/clock_nanosleep.c
new file mode 100644
index 0000000..d375056
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/clock_nanosleep.c
@@ -0,0 +1,37 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/clock.h>
+#include <common/time.h>
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <time.h>
+
+static_assert(TIMER_ABSTIME == __WASI_SUBCLOCKFLAGS_SUBSCRIPTION_CLOCK_ABSTIME,
+              "Value mismatch");
+
+int clock_nanosleep(clockid_t clock_id, int flags, const struct timespec *rqtp,
+                    struct timespec *rmtp) {
+  if ((flags & ~TIMER_ABSTIME) != 0)
+    return EINVAL;
+
+  // Prepare polling subscription.
+  __wasi_subscription_t sub = {
+      .u.tag = __WASI_EVENTTYPE_CLOCK,
+      .u.u.clock.id = clock_id->id,
+      .u.u.clock.flags = flags,
+  };
+  if (!timespec_to_timestamp_clamp(rqtp, &sub.u.u.clock.timeout))
+    return EINVAL;
+
+  // Block until polling event is triggered.
+  size_t nevents;
+  __wasi_event_t ev;
+  __wasi_errno_t error = __wasi_poll_oneoff(&sub, &ev, 1, &nevents);
+  return error == 0 && ev.error == 0 ? 0 : ENOTSUP;
+}
+
+weak_alias(clock_nanosleep, __clock_nanosleep);
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/nanosleep.c b/libc-bottom-half/cloudlibc/src/libc/time/nanosleep.c
new file mode 100644
index 0000000..5f26c5c
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/nanosleep.c
@@ -0,0 +1,15 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <errno.h>
+#include <time.h>
+
+int nanosleep(const struct timespec *rqtp, struct timespec *rem) {
+  int error = clock_nanosleep(CLOCK_REALTIME, 0, rqtp, rem);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/time/time.c b/libc-bottom-half/cloudlibc/src/libc/time/time.c
new file mode 100644
index 0000000..52bc0e4
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/time/time.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <common/time.h>
+
+#include <wasi/api.h>
+#include <time.h>
+
+time_t time(time_t *tloc) {
+  __wasi_timestamp_t ts = 0;
+  (void)__wasi_clock_time_get(__WASI_CLOCKID_REALTIME, NSEC_PER_SEC, &ts);
+  if (tloc != NULL)
+    *tloc = ts / NSEC_PER_SEC;
+  return ts / NSEC_PER_SEC;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/close.c b/libc-bottom-half/cloudlibc/src/libc/unistd/close.c
new file mode 100644
index 0000000..2f5814b
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/close.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+int close(int fildes) {
+  __wasi_errno_t error = __wasi_fd_close(fildes);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/faccessat.c b/libc-bottom-half/cloudlibc/src/libc/unistd/faccessat.c
new file mode 100644
index 0000000..ffaef6e
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/faccessat.c
@@ -0,0 +1,53 @@
+// Copyright (c) 2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+int __wasilibc_nocwd_faccessat(int fd, const char *path, int amode, int flag) {
+  // Validate function parameters.
+  if ((amode & ~(F_OK | R_OK | W_OK | X_OK)) != 0 ||
+      (flag & ~AT_EACCESS) != 0) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  // Check for target file existence and obtain the file type.
+  __wasi_lookupflags_t lookup_flags = __WASI_LOOKUPFLAGS_SYMLINK_FOLLOW;
+  __wasi_filestat_t file;
+  __wasi_errno_t error =
+      __wasi_path_filestat_get(fd, lookup_flags, path, &file);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+
+  // Test whether the requested access rights are present on the
+  // directory file descriptor.
+  if (amode != 0) {
+    __wasi_fdstat_t directory;
+    error = __wasi_fd_fdstat_get(fd, &directory);
+    if (error != 0) {
+      errno = error;
+      return -1;
+    }
+
+    __wasi_rights_t min = 0;
+    if ((amode & R_OK) != 0)
+      min |= file.filetype == __WASI_FILETYPE_DIRECTORY
+                 ? __WASI_RIGHTS_FD_READDIR
+                 : __WASI_RIGHTS_FD_READ;
+    if ((amode & W_OK) != 0)
+      min |= __WASI_RIGHTS_FD_WRITE;
+
+    if ((min & directory.fs_rights_inheriting) != min) {
+      errno = EACCES;
+      return -1;
+    }
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/fdatasync.c b/libc-bottom-half/cloudlibc/src/libc/unistd/fdatasync.c
new file mode 100644
index 0000000..b821b06
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/fdatasync.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+int fdatasync(int fildes) {
+  __wasi_errno_t error = __wasi_fd_datasync(fildes);
+  if (error != 0) {
+    errno = error == ENOTCAPABLE ? EBADF : error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/fsync.c b/libc-bottom-half/cloudlibc/src/libc/unistd/fsync.c
new file mode 100644
index 0000000..733e294
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/fsync.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+int fsync(int fildes) {
+  __wasi_errno_t error = __wasi_fd_sync(fildes);
+  if (error != 0) {
+    errno = error == ENOTCAPABLE ? EINVAL : error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/ftruncate.c b/libc-bottom-half/cloudlibc/src/libc/unistd/ftruncate.c
new file mode 100644
index 0000000..7792597
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/ftruncate.c
@@ -0,0 +1,22 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+int ftruncate(int fildes, off_t length) {
+  if (length < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  __wasi_filesize_t st_size = length;
+  __wasi_errno_t error =
+      __wasi_fd_filestat_set_size(fildes, st_size);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/linkat.c b/libc-bottom-half/cloudlibc/src/libc/unistd/linkat.c
new file mode 100644
index 0000000..d57f562
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/linkat.c
@@ -0,0 +1,24 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+int __wasilibc_nocwd_linkat(int fd1, const char *path1, int fd2, const char *path2, int flag) {
+  // Create lookup properties.
+  __wasi_lookupflags_t lookup1_flags = 0;
+  if ((flag & AT_SYMLINK_FOLLOW) != 0)
+    lookup1_flags |= __WASI_LOOKUPFLAGS_SYMLINK_FOLLOW;
+
+  // Perform system call.
+  __wasi_errno_t error = __wasi_path_link(fd1, lookup1_flags, path1, fd2, path2);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/lseek.c b/libc-bottom-half/cloudlibc/src/libc/unistd/lseek.c
new file mode 100644
index 0000000..3e0429f
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/lseek.c
@@ -0,0 +1,25 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <assert.h>
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+static_assert(SEEK_CUR == __WASI_WHENCE_CUR, "Value mismatch");
+static_assert(SEEK_END == __WASI_WHENCE_END, "Value mismatch");
+static_assert(SEEK_SET == __WASI_WHENCE_SET, "Value mismatch");
+
+off_t __lseek(int fildes, off_t offset, int whence) {
+  __wasi_filesize_t new_offset;
+  __wasi_errno_t error =
+      __wasi_fd_seek(fildes, offset, whence, &new_offset);
+  if (error != 0) {
+    errno = error == ENOTCAPABLE ? ESPIPE : error;
+    return -1;
+  }
+  return new_offset;
+}
+
+weak_alias(__lseek, lseek);
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/pread.c b/libc-bottom-half/cloudlibc/src/libc/unistd/pread.c
new file mode 100644
index 0000000..c9944bc
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/pread.c
@@ -0,0 +1,31 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset) {
+  if (offset < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  __wasi_iovec_t iov = {.buf = buf, .buf_len = nbyte};
+  size_t bytes_read;
+  __wasi_errno_t error =
+      __wasi_fd_pread(fildes, &iov, 1, offset, &bytes_read);
+  if (error != 0) {
+    __wasi_fdstat_t fds;
+    if (error == ENOTCAPABLE && __wasi_fd_fdstat_get(fildes, &fds) == 0) {
+      // Determine why we got ENOTCAPABLE.
+      if ((fds.fs_rights_base & __WASI_RIGHTS_FD_READ) == 0)
+        error = EBADF;
+      else
+        error = ESPIPE;
+    }
+    errno = error;
+    return -1;
+  }
+  return bytes_read;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/pwrite.c b/libc-bottom-half/cloudlibc/src/libc/unistd/pwrite.c
new file mode 100644
index 0000000..f80bc40
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/pwrite.c
@@ -0,0 +1,31 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+ssize_t pwrite(int fildes, const void *buf, size_t nbyte, off_t offset) {
+  if (offset < 0) {
+    errno = EINVAL;
+    return -1;
+  }
+  __wasi_ciovec_t iov = {.buf = buf, .buf_len = nbyte};
+  size_t bytes_written;
+  __wasi_errno_t error =
+      __wasi_fd_pwrite(fildes, &iov, 1, offset, &bytes_written);
+  if (error != 0) {
+    __wasi_fdstat_t fds;
+    if (error == ENOTCAPABLE && __wasi_fd_fdstat_get(fildes, &fds) == 0) {
+      // Determine why we got ENOTCAPABLE.
+      if ((fds.fs_rights_base & __WASI_RIGHTS_FD_WRITE) == 0)
+        error = EBADF;
+      else
+        error = ESPIPE;
+    }
+    errno = error;
+    return -1;
+  }
+  return bytes_written;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/read.c b/libc-bottom-half/cloudlibc/src/libc/unistd/read.c
new file mode 100644
index 0000000..1582126
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/read.c
@@ -0,0 +1,18 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+ssize_t read(int fildes, void *buf, size_t nbyte) {
+  __wasi_iovec_t iov = {.buf = buf, .buf_len = nbyte};
+  size_t bytes_read;
+  __wasi_errno_t error = __wasi_fd_read(fildes, &iov, 1, &bytes_read);
+  if (error != 0) {
+    errno = error == ENOTCAPABLE ? EBADF : error;
+    return -1;
+  }
+  return bytes_read;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/readlinkat.c b/libc-bottom-half/cloudlibc/src/libc/unistd/readlinkat.c
new file mode 100644
index 0000000..7a3bce2
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/readlinkat.c
@@ -0,0 +1,21 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+ssize_t __wasilibc_nocwd_readlinkat(int fd, const char *restrict path, char *restrict buf,
+                                    size_t bufsize) {
+  size_t bufused;
+  // TODO: Remove the cast on `buf` once the witx is updated with char8 support.
+  __wasi_errno_t error = __wasi_path_readlink(fd, path,
+                                                      (uint8_t*)buf, bufsize, &bufused);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return bufused;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/sleep.c b/libc-bottom-half/cloudlibc/src/libc/unistd/sleep.c
new file mode 100644
index 0000000..970287b
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/sleep.c
@@ -0,0 +1,13 @@
+// Copyright (c) 2015 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <time.h>
+#include <unistd.h>
+
+unsigned int sleep(unsigned int seconds) {
+  struct timespec ts = {.tv_sec = seconds, .tv_nsec = 0};
+  if (clock_nanosleep(CLOCK_REALTIME, 0, &ts, NULL) != 0)
+    return seconds;
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/symlinkat.c b/libc-bottom-half/cloudlibc/src/libc/unistd/symlinkat.c
new file mode 100644
index 0000000..0aa38be
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/symlinkat.c
@@ -0,0 +1,17 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+int __wasilibc_nocwd_symlinkat(const char *path1, int fd, const char *path2) {
+  __wasi_errno_t error = __wasi_path_symlink(path1, fd, path2);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/unlinkat.c b/libc-bottom-half/cloudlibc/src/libc/unistd/unlinkat.c
new file mode 100644
index 0000000..351bf92
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/unlinkat.c
@@ -0,0 +1,17 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <wasi/libc.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+
+int unlinkat(int fd, const char *path, int flag) {
+  if ((flag & AT_REMOVEDIR) != 0) {
+    return __wasilibc_rmdirat(fd, path);
+  }
+  return __wasilibc_unlinkat(fd, path);
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/usleep.c b/libc-bottom-half/cloudlibc/src/libc/unistd/usleep.c
new file mode 100644
index 0000000..8005f17
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/usleep.c
@@ -0,0 +1,18 @@
+// Copyright (c) 2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <errno.h>
+#include <time.h>
+#include <unistd.h>
+
+int usleep(useconds_t useconds) {
+  struct timespec ts = {.tv_sec = useconds / 1000000,
+                        .tv_nsec = useconds % 1000000 * 1000};
+  int error = clock_nanosleep(CLOCK_REALTIME, 0, &ts, NULL);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
diff --git a/libc-bottom-half/cloudlibc/src/libc/unistd/write.c b/libc-bottom-half/cloudlibc/src/libc/unistd/write.c
new file mode 100644
index 0000000..a6567e8
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/unistd/write.c
@@ -0,0 +1,19 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <unistd.h>
+
+ssize_t write(int fildes, const void *buf, size_t nbyte) {
+  __wasi_ciovec_t iov = {.buf = buf, .buf_len = nbyte};
+  size_t bytes_written;
+  __wasi_errno_t error =
+      __wasi_fd_write(fildes, &iov, 1, &bytes_written);
+  if (error != 0) {
+    errno = error == ENOTCAPABLE ? EBADF : error;
+    return -1;
+  }
+  return bytes_written;
+}