Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

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

11 files changed, 2377 insertions, 0 deletions

diff --git a/library/std/src/sys/wasi/args.rs b/library/std/src/sys/wasi/args.rs
new file mode 100644
index 000000000..c42c310e3
--- /dev/null
+++ b/library/std/src/sys/wasi/args.rs
@@ -0,0 +1,62 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::ffi::{CStr, OsStr, OsString};
+use crate::fmt;
+use crate::os::wasi::ffi::OsStrExt;
+use crate::vec;
+
+pub struct Args {
+    iter: vec::IntoIter<OsString>,
+}
+
+impl !Send for Args {}
+impl !Sync for Args {}
+
+/// Returns the command line arguments
+pub fn args() -> Args {
+    Args { iter: maybe_args().unwrap_or(Vec::new()).into_iter() }
+}
+
+fn maybe_args() -> Option<Vec<OsString>> {
+    unsafe {
+        let (argc, buf_size) = wasi::args_sizes_get().ok()?;
+        let mut argv = Vec::with_capacity(argc);
+        let mut buf = Vec::with_capacity(buf_size);
+        wasi::args_get(argv.as_mut_ptr(), buf.as_mut_ptr()).ok()?;
+        argv.set_len(argc);
+        let mut ret = Vec::with_capacity(argc);
+        for ptr in argv {
+            let s = CStr::from_ptr(ptr.cast());
+            ret.push(OsStr::from_bytes(s.to_bytes()).to_owned());
+        }
+        Some(ret)
+    }
+}
+
+impl fmt::Debug for Args {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.iter.as_slice().fmt(f)
+    }
+}
+
+impl Iterator for Args {
+    type Item = OsString;
+    fn next(&mut self) -> Option<OsString> {
+        self.iter.next()
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl ExactSizeIterator for Args {
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+}
+
+impl DoubleEndedIterator for Args {
+    fn next_back(&mut self) -> Option<OsString> {
+        self.iter.next_back()
+    }
+}
diff --git a/library/std/src/sys/wasi/env.rs b/library/std/src/sys/wasi/env.rs
new file mode 100644
index 000000000..730e356d7
--- /dev/null
+++ b/library/std/src/sys/wasi/env.rs
@@ -0,0 +1,9 @@
+pub mod os {
+    pub const FAMILY: &str = "";
+    pub const OS: &str = "";
+    pub const DLL_PREFIX: &str = "";
+    pub const DLL_SUFFIX: &str = ".wasm";
+    pub const DLL_EXTENSION: &str = "wasm";
+    pub const EXE_SUFFIX: &str = ".wasm";
+    pub const EXE_EXTENSION: &str = "wasm";
+}
diff --git a/library/std/src/sys/wasi/fd.rs b/library/std/src/sys/wasi/fd.rs
new file mode 100644
index 000000000..0b9c8e61d
--- /dev/null
+++ b/library/std/src/sys/wasi/fd.rs
@@ -0,0 +1,307 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+#![allow(dead_code)]
+
+use super::err2io;
+use crate::io::{self, IoSlice, IoSliceMut, SeekFrom};
+use crate::mem;
+use crate::net::Shutdown;
+use crate::os::wasi::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
+use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
+
+#[derive(Debug)]
+pub struct WasiFd {
+    fd: OwnedFd,
+}
+
+fn iovec<'a>(a: &'a mut [IoSliceMut<'_>]) -> &'a [wasi::Iovec] {
+    assert_eq!(mem::size_of::<IoSliceMut<'_>>(), mem::size_of::<wasi::Iovec>());
+    assert_eq!(mem::align_of::<IoSliceMut<'_>>(), mem::align_of::<wasi::Iovec>());
+    // SAFETY: `IoSliceMut` and `IoVec` have exactly the same memory layout
+    unsafe { mem::transmute(a) }
+}
+
+fn ciovec<'a>(a: &'a [IoSlice<'_>]) -> &'a [wasi::Ciovec] {
+    assert_eq!(mem::size_of::<IoSlice<'_>>(), mem::size_of::<wasi::Ciovec>());
+    assert_eq!(mem::align_of::<IoSlice<'_>>(), mem::align_of::<wasi::Ciovec>());
+    // SAFETY: `IoSlice` and `CIoVec` have exactly the same memory layout
+    unsafe { mem::transmute(a) }
+}
+
+impl WasiFd {
+    pub fn datasync(&self) -> io::Result<()> {
+        unsafe { wasi::fd_datasync(self.as_raw_fd() as wasi::Fd).map_err(err2io) }
+    }
+
+    pub fn pread(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
+        unsafe { wasi::fd_pread(self.as_raw_fd() as wasi::Fd, iovec(bufs), offset).map_err(err2io) }
+    }
+
+    pub fn pwrite(&self, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
+        unsafe {
+            wasi::fd_pwrite(self.as_raw_fd() as wasi::Fd, ciovec(bufs), offset).map_err(err2io)
+        }
+    }
+
+    pub fn read(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        unsafe { wasi::fd_read(self.as_raw_fd() as wasi::Fd, iovec(bufs)).map_err(err2io) }
+    }
+
+    pub fn write(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        unsafe { wasi::fd_write(self.as_raw_fd() as wasi::Fd, ciovec(bufs)).map_err(err2io) }
+    }
+
+    pub fn seek(&self, pos: SeekFrom) -> io::Result<u64> {
+        let (whence, offset) = match pos {
+            SeekFrom::Start(pos) => (wasi::WHENCE_SET, pos as i64),
+            SeekFrom::End(pos) => (wasi::WHENCE_END, pos),
+            SeekFrom::Current(pos) => (wasi::WHENCE_CUR, pos),
+        };
+        unsafe { wasi::fd_seek(self.as_raw_fd() as wasi::Fd, offset, whence).map_err(err2io) }
+    }
+
+    pub fn tell(&self) -> io::Result<u64> {
+        unsafe { wasi::fd_tell(self.as_raw_fd() as wasi::Fd).map_err(err2io) }
+    }
+
+    // FIXME: __wasi_fd_fdstat_get
+
+    pub fn set_flags(&self, flags: wasi::Fdflags) -> io::Result<()> {
+        unsafe { wasi::fd_fdstat_set_flags(self.as_raw_fd() as wasi::Fd, flags).map_err(err2io) }
+    }
+
+    pub fn set_rights(&self, base: wasi::Rights, inheriting: wasi::Rights) -> io::Result<()> {
+        unsafe {
+            wasi::fd_fdstat_set_rights(self.as_raw_fd() as wasi::Fd, base, inheriting)
+                .map_err(err2io)
+        }
+    }
+
+    pub fn sync(&self) -> io::Result<()> {
+        unsafe { wasi::fd_sync(self.as_raw_fd() as wasi::Fd).map_err(err2io) }
+    }
+
+    pub fn advise(&self, offset: u64, len: u64, advice: wasi::Advice) -> io::Result<()> {
+        unsafe {
+            wasi::fd_advise(self.as_raw_fd() as wasi::Fd, offset, len, advice).map_err(err2io)
+        }
+    }
+
+    pub fn allocate(&self, offset: u64, len: u64) -> io::Result<()> {
+        unsafe { wasi::fd_allocate(self.as_raw_fd() as wasi::Fd, offset, len).map_err(err2io) }
+    }
+
+    pub fn create_directory(&self, path: &str) -> io::Result<()> {
+        unsafe { wasi::path_create_directory(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
+    }
+
+    pub fn link(
+        &self,
+        old_flags: wasi::Lookupflags,
+        old_path: &str,
+        new_fd: &WasiFd,
+        new_path: &str,
+    ) -> io::Result<()> {
+        unsafe {
+            wasi::path_link(
+                self.as_raw_fd() as wasi::Fd,
+                old_flags,
+                old_path,
+                new_fd.as_raw_fd() as wasi::Fd,
+                new_path,
+            )
+            .map_err(err2io)
+        }
+    }
+
+    pub fn open(
+        &self,
+        dirflags: wasi::Lookupflags,
+        path: &str,
+        oflags: wasi::Oflags,
+        fs_rights_base: wasi::Rights,
+        fs_rights_inheriting: wasi::Rights,
+        fs_flags: wasi::Fdflags,
+    ) -> io::Result<WasiFd> {
+        unsafe {
+            wasi::path_open(
+                self.as_raw_fd() as wasi::Fd,
+                dirflags,
+                path,
+                oflags,
+                fs_rights_base,
+                fs_rights_inheriting,
+                fs_flags,
+            )
+            .map(|fd| WasiFd::from_raw_fd(fd as RawFd))
+            .map_err(err2io)
+        }
+    }
+
+    pub fn readdir(&self, buf: &mut [u8], cookie: wasi::Dircookie) -> io::Result<usize> {
+        unsafe {
+            wasi::fd_readdir(self.as_raw_fd() as wasi::Fd, buf.as_mut_ptr(), buf.len(), cookie)
+                .map_err(err2io)
+        }
+    }
+
+    pub fn readlink(&self, path: &str, buf: &mut [u8]) -> io::Result<usize> {
+        unsafe {
+            wasi::path_readlink(self.as_raw_fd() as wasi::Fd, path, buf.as_mut_ptr(), buf.len())
+                .map_err(err2io)
+        }
+    }
+
+    pub fn rename(&self, old_path: &str, new_fd: &WasiFd, new_path: &str) -> io::Result<()> {
+        unsafe {
+            wasi::path_rename(
+                self.as_raw_fd() as wasi::Fd,
+                old_path,
+                new_fd.as_raw_fd() as wasi::Fd,
+                new_path,
+            )
+            .map_err(err2io)
+        }
+    }
+
+    pub fn filestat_get(&self) -> io::Result<wasi::Filestat> {
+        unsafe { wasi::fd_filestat_get(self.as_raw_fd() as wasi::Fd).map_err(err2io) }
+    }
+
+    pub fn filestat_set_times(
+        &self,
+        atim: wasi::Timestamp,
+        mtim: wasi::Timestamp,
+        fstflags: wasi::Fstflags,
+    ) -> io::Result<()> {
+        unsafe {
+            wasi::fd_filestat_set_times(self.as_raw_fd() as wasi::Fd, atim, mtim, fstflags)
+                .map_err(err2io)
+        }
+    }
+
+    pub fn filestat_set_size(&self, size: u64) -> io::Result<()> {
+        unsafe { wasi::fd_filestat_set_size(self.as_raw_fd() as wasi::Fd, size).map_err(err2io) }
+    }
+
+    pub fn path_filestat_get(
+        &self,
+        flags: wasi::Lookupflags,
+        path: &str,
+    ) -> io::Result<wasi::Filestat> {
+        unsafe {
+            wasi::path_filestat_get(self.as_raw_fd() as wasi::Fd, flags, path).map_err(err2io)
+        }
+    }
+
+    pub fn path_filestat_set_times(
+        &self,
+        flags: wasi::Lookupflags,
+        path: &str,
+        atim: wasi::Timestamp,
+        mtim: wasi::Timestamp,
+        fstflags: wasi::Fstflags,
+    ) -> io::Result<()> {
+        unsafe {
+            wasi::path_filestat_set_times(
+                self.as_raw_fd() as wasi::Fd,
+                flags,
+                path,
+                atim,
+                mtim,
+                fstflags,
+            )
+            .map_err(err2io)
+        }
+    }
+
+    pub fn symlink(&self, old_path: &str, new_path: &str) -> io::Result<()> {
+        unsafe {
+            wasi::path_symlink(old_path, self.as_raw_fd() as wasi::Fd, new_path).map_err(err2io)
+        }
+    }
+
+    pub fn unlink_file(&self, path: &str) -> io::Result<()> {
+        unsafe { wasi::path_unlink_file(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
+    }
+
+    pub fn remove_directory(&self, path: &str) -> io::Result<()> {
+        unsafe { wasi::path_remove_directory(self.as_raw_fd() as wasi::Fd, path).map_err(err2io) }
+    }
+
+    pub fn sock_accept(&self, flags: wasi::Fdflags) -> io::Result<wasi::Fd> {
+        unsafe { wasi::sock_accept(self.as_raw_fd() as wasi::Fd, flags).map_err(err2io) }
+    }
+
+    pub fn sock_recv(
+        &self,
+        ri_data: &mut [IoSliceMut<'_>],
+        ri_flags: wasi::Riflags,
+    ) -> io::Result<(usize, wasi::Roflags)> {
+        unsafe {
+            wasi::sock_recv(self.as_raw_fd() as wasi::Fd, iovec(ri_data), ri_flags).map_err(err2io)
+        }
+    }
+
+    pub fn sock_send(&self, si_data: &[IoSlice<'_>], si_flags: wasi::Siflags) -> io::Result<usize> {
+        unsafe {
+            wasi::sock_send(self.as_raw_fd() as wasi::Fd, ciovec(si_data), si_flags).map_err(err2io)
+        }
+    }
+
+    pub fn sock_shutdown(&self, how: Shutdown) -> io::Result<()> {
+        let how = match how {
+            Shutdown::Read => wasi::SDFLAGS_RD,
+            Shutdown::Write => wasi::SDFLAGS_WR,
+            Shutdown::Both => wasi::SDFLAGS_WR | wasi::SDFLAGS_RD,
+        };
+        unsafe { wasi::sock_shutdown(self.as_raw_fd() as wasi::Fd, how).map_err(err2io) }
+    }
+}
+
+impl AsInner<OwnedFd> for WasiFd {
+    fn as_inner(&self) -> &OwnedFd {
+        &self.fd
+    }
+}
+
+impl AsInnerMut<OwnedFd> for WasiFd {
+    fn as_inner_mut(&mut self) -> &mut OwnedFd {
+        &mut self.fd
+    }
+}
+
+impl IntoInner<OwnedFd> for WasiFd {
+    fn into_inner(self) -> OwnedFd {
+        self.fd
+    }
+}
+
+impl FromInner<OwnedFd> for WasiFd {
+    fn from_inner(owned_fd: OwnedFd) -> Self {
+        Self { fd: owned_fd }
+    }
+}
+
+impl AsFd for WasiFd {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        self.fd.as_fd()
+    }
+}
+
+impl AsRawFd for WasiFd {
+    fn as_raw_fd(&self) -> RawFd {
+        self.fd.as_raw_fd()
+    }
+}
+
+impl IntoRawFd for WasiFd {
+    fn into_raw_fd(self) -> RawFd {
+        self.fd.into_raw_fd()
+    }
+}
+
+impl FromRawFd for WasiFd {
+    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
+        unsafe { Self { fd: FromRawFd::from_raw_fd(raw_fd) } }
+    }
+}
diff --git a/library/std/src/sys/wasi/fs.rs b/library/std/src/sys/wasi/fs.rs
new file mode 100644
index 000000000..6614ae397
--- /dev/null
+++ b/library/std/src/sys/wasi/fs.rs
@@ -0,0 +1,798 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use super::fd::WasiFd;
+use crate::ffi::{CStr, CString, OsStr, OsString};
+use crate::fmt;
+use crate::io::{self, IoSlice, IoSliceMut, ReadBuf, SeekFrom};
+use crate::iter;
+use crate::mem::{self, ManuallyDrop};
+use crate::os::raw::c_int;
+use crate::os::wasi::ffi::{OsStrExt, OsStringExt};
+use crate::os::wasi::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
+use crate::path::{Path, PathBuf};
+use crate::ptr;
+use crate::sync::Arc;
+use crate::sys::time::SystemTime;
+use crate::sys::unsupported;
+use crate::sys_common::{AsInner, FromInner, IntoInner};
+
+pub use crate::sys_common::fs::try_exists;
+
+pub struct File {
+    fd: WasiFd,
+}
+
+#[derive(Clone)]
+pub struct FileAttr {
+    meta: wasi::Filestat,
+}
+
+pub struct ReadDir {
+    inner: Arc<ReadDirInner>,
+    cookie: Option<wasi::Dircookie>,
+    buf: Vec<u8>,
+    offset: usize,
+    cap: usize,
+}
+
+struct ReadDirInner {
+    root: PathBuf,
+    dir: File,
+}
+
+pub struct DirEntry {
+    meta: wasi::Dirent,
+    name: Vec<u8>,
+    inner: Arc<ReadDirInner>,
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct OpenOptions {
+    read: bool,
+    write: bool,
+    append: bool,
+    dirflags: wasi::Lookupflags,
+    fdflags: wasi::Fdflags,
+    oflags: wasi::Oflags,
+    rights_base: Option<wasi::Rights>,
+    rights_inheriting: Option<wasi::Rights>,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct FilePermissions {
+    readonly: bool,
+}
+
+#[derive(Copy, Clone, Debug, Default)]
+pub struct FileTimes {
+    accessed: Option<wasi::Timestamp>,
+    modified: Option<wasi::Timestamp>,
+}
+
+#[derive(PartialEq, Eq, Hash, Debug, Copy, Clone)]
+pub struct FileType {
+    bits: wasi::Filetype,
+}
+
+#[derive(Debug)]
+pub struct DirBuilder {}
+
+impl FileAttr {
+    pub fn size(&self) -> u64 {
+        self.meta.size
+    }
+
+    pub fn perm(&self) -> FilePermissions {
+        // not currently implemented in wasi yet
+        FilePermissions { readonly: false }
+    }
+
+    pub fn file_type(&self) -> FileType {
+        FileType { bits: self.meta.filetype }
+    }
+
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from_wasi_timestamp(self.meta.mtim))
+    }
+
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from_wasi_timestamp(self.meta.atim))
+    }
+
+    pub fn created(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from_wasi_timestamp(self.meta.ctim))
+    }
+
+    pub fn as_wasi(&self) -> &wasi::Filestat {
+        &self.meta
+    }
+}
+
+impl FilePermissions {
+    pub fn readonly(&self) -> bool {
+        self.readonly
+    }
+
+    pub fn set_readonly(&mut self, readonly: bool) {
+        self.readonly = readonly;
+    }
+}
+
+impl FileTimes {
+    pub fn set_accessed(&mut self, t: SystemTime) {
+        self.accessed = Some(t.to_wasi_timestamp_or_panic());
+    }
+
+    pub fn set_modified(&mut self, t: SystemTime) {
+        self.modified = Some(t.to_wasi_timestamp_or_panic());
+    }
+}
+
+impl FileType {
+    pub fn is_dir(&self) -> bool {
+        self.bits == wasi::FILETYPE_DIRECTORY
+    }
+
+    pub fn is_file(&self) -> bool {
+        self.bits == wasi::FILETYPE_REGULAR_FILE
+    }
+
+    pub fn is_symlink(&self) -> bool {
+        self.bits == wasi::FILETYPE_SYMBOLIC_LINK
+    }
+
+    pub fn bits(&self) -> wasi::Filetype {
+        self.bits
+    }
+}
+
+impl ReadDir {
+    fn new(dir: File, root: PathBuf) -> ReadDir {
+        ReadDir {
+            cookie: Some(0),
+            buf: vec![0; 128],
+            offset: 0,
+            cap: 0,
+            inner: Arc::new(ReadDirInner { dir, root }),
+        }
+    }
+}
+
+impl fmt::Debug for ReadDir {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ReadDir").finish_non_exhaustive()
+    }
+}
+
+impl Iterator for ReadDir {
+    type Item = io::Result<DirEntry>;
+
+    fn next(&mut self) -> Option<io::Result<DirEntry>> {
+        loop {
+            // If we've reached the capacity of our buffer then we need to read
+            // some more from the OS, otherwise we pick up at our old offset.
+            let offset = if self.offset == self.cap {
+                let cookie = self.cookie.take()?;
+                match self.inner.dir.fd.readdir(&mut self.buf, cookie) {
+                    Ok(bytes) => self.cap = bytes,
+                    Err(e) => return Some(Err(e)),
+                }
+                self.offset = 0;
+                self.cookie = Some(cookie);
+
+                // If we didn't actually read anything, this is in theory the
+                // end of the directory.
+                if self.cap == 0 {
+                    self.cookie = None;
+                    return None;
+                }
+
+                0
+            } else {
+                self.offset
+            };
+            let data = &self.buf[offset..self.cap];
+
+            // If we're not able to read a directory entry then that means it
+            // must have been truncated at the end of the buffer, so reset our
+            // offset so we can go back and reread into the buffer, picking up
+            // where we last left off.
+            let dirent_size = mem::size_of::<wasi::Dirent>();
+            if data.len() < dirent_size {
+                assert!(self.cookie.is_some());
+                assert!(self.buf.len() >= dirent_size);
+                self.offset = self.cap;
+                continue;
+            }
+            let (dirent, data) = data.split_at(dirent_size);
+            let dirent = unsafe { ptr::read_unaligned(dirent.as_ptr() as *const wasi::Dirent) };
+
+            // If the file name was truncated, then we need to reinvoke
+            // `readdir` so we truncate our buffer to start over and reread this
+            // descriptor. Note that if our offset is 0 that means the file name
+            // is massive and we need a bigger buffer.
+            if data.len() < dirent.d_namlen as usize {
+                if offset == 0 {
+                    let amt_to_add = self.buf.capacity();
+                    self.buf.extend(iter::repeat(0).take(amt_to_add));
+                }
+                assert!(self.cookie.is_some());
+                self.offset = self.cap;
+                continue;
+            }
+            self.cookie = Some(dirent.d_next);
+            self.offset = offset + dirent_size + dirent.d_namlen as usize;
+
+            let name = &data[..(dirent.d_namlen as usize)];
+
+            // These names are skipped on all other platforms, so let's skip
+            // them here too
+            if name == b"." || name == b".." {
+                continue;
+            }
+
+            return Some(Ok(DirEntry {
+                meta: dirent,
+                name: name.to_vec(),
+                inner: self.inner.clone(),
+            }));
+        }
+    }
+}
+
+impl DirEntry {
+    pub fn path(&self) -> PathBuf {
+        let name = OsStr::from_bytes(&self.name);
+        self.inner.root.join(name)
+    }
+
+    pub fn file_name(&self) -> OsString {
+        OsString::from_vec(self.name.clone())
+    }
+
+    pub fn metadata(&self) -> io::Result<FileAttr> {
+        metadata_at(&self.inner.dir.fd, 0, OsStr::from_bytes(&self.name).as_ref())
+    }
+
+    pub fn file_type(&self) -> io::Result<FileType> {
+        Ok(FileType { bits: self.meta.d_type })
+    }
+
+    pub fn ino(&self) -> wasi::Inode {
+        self.meta.d_ino
+    }
+}
+
+impl OpenOptions {
+    pub fn new() -> OpenOptions {
+        let mut base = OpenOptions::default();
+        base.dirflags = wasi::LOOKUPFLAGS_SYMLINK_FOLLOW;
+        return base;
+    }
+
+    pub fn read(&mut self, read: bool) {
+        self.read = read;
+    }
+
+    pub fn write(&mut self, write: bool) {
+        self.write = write;
+    }
+
+    pub fn truncate(&mut self, truncate: bool) {
+        self.oflag(wasi::OFLAGS_TRUNC, truncate);
+    }
+
+    pub fn create(&mut self, create: bool) {
+        self.oflag(wasi::OFLAGS_CREAT, create);
+    }
+
+    pub fn create_new(&mut self, create_new: bool) {
+        self.oflag(wasi::OFLAGS_EXCL, create_new);
+        self.oflag(wasi::OFLAGS_CREAT, create_new);
+    }
+
+    pub fn directory(&mut self, directory: bool) {
+        self.oflag(wasi::OFLAGS_DIRECTORY, directory);
+    }
+
+    fn oflag(&mut self, bit: wasi::Oflags, set: bool) {
+        if set {
+            self.oflags |= bit;
+        } else {
+            self.oflags &= !bit;
+        }
+    }
+
+    pub fn append(&mut self, append: bool) {
+        self.append = append;
+        self.fdflag(wasi::FDFLAGS_APPEND, append);
+    }
+
+    pub fn dsync(&mut self, set: bool) {
+        self.fdflag(wasi::FDFLAGS_DSYNC, set);
+    }
+
+    pub fn nonblock(&mut self, set: bool) {
+        self.fdflag(wasi::FDFLAGS_NONBLOCK, set);
+    }
+
+    pub fn rsync(&mut self, set: bool) {
+        self.fdflag(wasi::FDFLAGS_RSYNC, set);
+    }
+
+    pub fn sync(&mut self, set: bool) {
+        self.fdflag(wasi::FDFLAGS_SYNC, set);
+    }
+
+    fn fdflag(&mut self, bit: wasi::Fdflags, set: bool) {
+        if set {
+            self.fdflags |= bit;
+        } else {
+            self.fdflags &= !bit;
+        }
+    }
+
+    pub fn fs_rights_base(&mut self, rights: wasi::Rights) {
+        self.rights_base = Some(rights);
+    }
+
+    pub fn fs_rights_inheriting(&mut self, rights: wasi::Rights) {
+        self.rights_inheriting = Some(rights);
+    }
+
+    fn rights_base(&self) -> wasi::Rights {
+        if let Some(rights) = self.rights_base {
+            return rights;
+        }
+
+        // If rights haven't otherwise been specified try to pick a reasonable
+        // set. This can always be overridden by users via extension traits, and
+        // implementations may give us fewer rights silently than we ask for. So
+        // given that, just look at `read` and `write` and bucket permissions
+        // based on that.
+        let mut base = 0;
+        if self.read {
+            base |= wasi::RIGHTS_FD_READ;
+            base |= wasi::RIGHTS_FD_READDIR;
+        }
+        if self.write || self.append {
+            base |= wasi::RIGHTS_FD_WRITE;
+            base |= wasi::RIGHTS_FD_DATASYNC;
+            base |= wasi::RIGHTS_FD_ALLOCATE;
+            base |= wasi::RIGHTS_FD_FILESTAT_SET_SIZE;
+        }
+
+        // FIXME: some of these should probably be read-only or write-only...
+        base |= wasi::RIGHTS_FD_ADVISE;
+        base |= wasi::RIGHTS_FD_FDSTAT_SET_FLAGS;
+        base |= wasi::RIGHTS_FD_FILESTAT_GET;
+        base |= wasi::RIGHTS_FD_FILESTAT_SET_TIMES;
+        base |= wasi::RIGHTS_FD_SEEK;
+        base |= wasi::RIGHTS_FD_SYNC;
+        base |= wasi::RIGHTS_FD_TELL;
+        base |= wasi::RIGHTS_PATH_CREATE_DIRECTORY;
+        base |= wasi::RIGHTS_PATH_CREATE_FILE;
+        base |= wasi::RIGHTS_PATH_FILESTAT_GET;
+        base |= wasi::RIGHTS_PATH_LINK_SOURCE;
+        base |= wasi::RIGHTS_PATH_LINK_TARGET;
+        base |= wasi::RIGHTS_PATH_OPEN;
+        base |= wasi::RIGHTS_PATH_READLINK;
+        base |= wasi::RIGHTS_PATH_REMOVE_DIRECTORY;
+        base |= wasi::RIGHTS_PATH_RENAME_SOURCE;
+        base |= wasi::RIGHTS_PATH_RENAME_TARGET;
+        base |= wasi::RIGHTS_PATH_SYMLINK;
+        base |= wasi::RIGHTS_PATH_UNLINK_FILE;
+        base |= wasi::RIGHTS_POLL_FD_READWRITE;
+
+        return base;
+    }
+
+    fn rights_inheriting(&self) -> wasi::Rights {
+        self.rights_inheriting.unwrap_or_else(|| self.rights_base())
+    }
+
+    pub fn lookup_flags(&mut self, flags: wasi::Lookupflags) {
+        self.dirflags = flags;
+    }
+}
+
+impl File {
+    pub fn open(path: &Path, opts: &OpenOptions) -> io::Result<File> {
+        let (dir, file) = open_parent(path)?;
+        open_at(&dir, &file, opts)
+    }
+
+    pub fn open_at(&self, path: &Path, opts: &OpenOptions) -> io::Result<File> {
+        open_at(&self.fd, path, opts)
+    }
+
+    pub fn file_attr(&self) -> io::Result<FileAttr> {
+        self.fd.filestat_get().map(|meta| FileAttr { meta })
+    }
+
+    pub fn metadata_at(&self, flags: wasi::Lookupflags, path: &Path) -> io::Result<FileAttr> {
+        metadata_at(&self.fd, flags, path)
+    }
+
+    pub fn fsync(&self) -> io::Result<()> {
+        self.fd.sync()
+    }
+
+    pub fn datasync(&self) -> io::Result<()> {
+        self.fd.datasync()
+    }
+
+    pub fn truncate(&self, size: u64) -> io::Result<()> {
+        self.fd.filestat_set_size(size)
+    }
+
+    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.read_vectored(&mut [IoSliceMut::new(buf)])
+    }
+
+    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.fd.read(bufs)
+    }
+
+    #[inline]
+    pub fn is_read_vectored(&self) -> bool {
+        true
+    }
+
+    pub fn read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
+        crate::io::default_read_buf(|buf| self.read(buf), buf)
+    }
+
+    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.write_vectored(&[IoSlice::new(buf)])
+    }
+
+    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.fd.write(bufs)
+    }
+
+    #[inline]
+    pub fn is_write_vectored(&self) -> bool {
+        true
+    }
+
+    pub fn flush(&self) -> io::Result<()> {
+        Ok(())
+    }
+
+    pub fn seek(&self, pos: SeekFrom) -> io::Result<u64> {
+        self.fd.seek(pos)
+    }
+
+    pub fn duplicate(&self) -> io::Result<File> {
+        // https://github.com/CraneStation/wasmtime/blob/master/docs/WASI-rationale.md#why-no-dup
+        unsupported()
+    }
+
+    pub fn set_permissions(&self, _perm: FilePermissions) -> io::Result<()> {
+        // Permissions haven't been fully figured out in wasi yet, so this is
+        // likely temporary
+        unsupported()
+    }
+
+    pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
+        self.fd.filestat_set_times(
+            times.accessed.unwrap_or(0),
+            times.modified.unwrap_or(0),
+            times.accessed.map_or(0, |_| wasi::FSTFLAGS_ATIM)
+                | times.modified.map_or(0, |_| wasi::FSTFLAGS_MTIM),
+        )
+    }
+
+    pub fn read_link(&self, file: &Path) -> io::Result<PathBuf> {
+        read_link(&self.fd, file)
+    }
+}
+
+impl AsInner<WasiFd> for File {
+    fn as_inner(&self) -> &WasiFd {
+        &self.fd
+    }
+}
+
+impl IntoInner<WasiFd> for File {
+    fn into_inner(self) -> WasiFd {
+        self.fd
+    }
+}
+
+impl FromInner<WasiFd> for File {
+    fn from_inner(fd: WasiFd) -> File {
+        File { fd }
+    }
+}
+
+impl AsFd for File {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        self.fd.as_fd()
+    }
+}
+
+impl AsRawFd for File {
+    fn as_raw_fd(&self) -> RawFd {
+        self.fd.as_raw_fd()
+    }
+}
+
+impl IntoRawFd for File {
+    fn into_raw_fd(self) -> RawFd {
+        self.fd.into_raw_fd()
+    }
+}
+
+impl FromRawFd for File {
+    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
+        unsafe { Self { fd: FromRawFd::from_raw_fd(raw_fd) } }
+    }
+}
+
+impl DirBuilder {
+    pub fn new() -> DirBuilder {
+        DirBuilder {}
+    }
+
+    pub fn mkdir(&self, p: &Path) -> io::Result<()> {
+        let (dir, file) = open_parent(p)?;
+        dir.create_directory(osstr2str(file.as_ref())?)
+    }
+}
+
+impl fmt::Debug for File {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("File").field("fd", &self.as_raw_fd()).finish()
+    }
+}
+
+pub fn readdir(p: &Path) -> io::Result<ReadDir> {
+    let mut opts = OpenOptions::new();
+    opts.directory(true);
+    opts.read(true);
+    let dir = File::open(p, &opts)?;
+    Ok(ReadDir::new(dir, p.to_path_buf()))
+}
+
+pub fn unlink(p: &Path) -> io::Result<()> {
+    let (dir, file) = open_parent(p)?;
+    dir.unlink_file(osstr2str(file.as_ref())?)
+}
+
+pub fn rename(old: &Path, new: &Path) -> io::Result<()> {
+    let (old, old_file) = open_parent(old)?;
+    let (new, new_file) = open_parent(new)?;
+    old.rename(osstr2str(old_file.as_ref())?, &new, osstr2str(new_file.as_ref())?)
+}
+
+pub fn set_perm(_p: &Path, _perm: FilePermissions) -> io::Result<()> {
+    // Permissions haven't been fully figured out in wasi yet, so this is
+    // likely temporary
+    unsupported()
+}
+
+pub fn rmdir(p: &Path) -> io::Result<()> {
+    let (dir, file) = open_parent(p)?;
+    dir.remove_directory(osstr2str(file.as_ref())?)
+}
+
+pub fn readlink(p: &Path) -> io::Result<PathBuf> {
+    let (dir, file) = open_parent(p)?;
+    read_link(&dir, &file)
+}
+
+fn read_link(fd: &WasiFd, file: &Path) -> io::Result<PathBuf> {
+    // Try to get a best effort initial capacity for the vector we're going to
+    // fill. Note that if it's not a symlink we don't use a file to avoid
+    // allocating gigabytes if you read_link a huge movie file by accident.
+    // Additionally we add 1 to the initial size so if it doesn't change until
+    // when we call `readlink` the returned length will be less than the
+    // capacity, guaranteeing that we got all the data.
+    let meta = metadata_at(fd, 0, file)?;
+    let initial_size = if meta.file_type().is_symlink() {
+        (meta.size() as usize).saturating_add(1)
+    } else {
+        1 // this'll fail in just a moment
+    };
+
+    // Now that we have an initial guess of how big to make our buffer, call
+    // `readlink` in a loop until it fails or reports it filled fewer bytes than
+    // we asked for, indicating we got everything.
+    let file = osstr2str(file.as_ref())?;
+    let mut destination = vec![0u8; initial_size];
+    loop {
+        let len = fd.readlink(file, &mut destination)?;
+        if len < destination.len() {
+            destination.truncate(len);
+            destination.shrink_to_fit();
+            return Ok(PathBuf::from(OsString::from_vec(destination)));
+        }
+        let amt_to_add = destination.len();
+        destination.extend(iter::repeat(0).take(amt_to_add));
+    }
+}
+
+pub fn symlink(original: &Path, link: &Path) -> io::Result<()> {
+    let (link, link_file) = open_parent(link)?;
+    link.symlink(osstr2str(original.as_ref())?, osstr2str(link_file.as_ref())?)
+}
+
+pub fn link(original: &Path, link: &Path) -> io::Result<()> {
+    let (original, original_file) = open_parent(original)?;
+    let (link, link_file) = open_parent(link)?;
+    // Pass 0 as the flags argument, meaning don't follow symlinks.
+    original.link(0, osstr2str(original_file.as_ref())?, &link, osstr2str(link_file.as_ref())?)
+}
+
+pub fn stat(p: &Path) -> io::Result<FileAttr> {
+    let (dir, file) = open_parent(p)?;
+    metadata_at(&dir, wasi::LOOKUPFLAGS_SYMLINK_FOLLOW, &file)
+}
+
+pub fn lstat(p: &Path) -> io::Result<FileAttr> {
+    let (dir, file) = open_parent(p)?;
+    metadata_at(&dir, 0, &file)
+}
+
+fn metadata_at(fd: &WasiFd, flags: wasi::Lookupflags, path: &Path) -> io::Result<FileAttr> {
+    let meta = fd.path_filestat_get(flags, osstr2str(path.as_ref())?)?;
+    Ok(FileAttr { meta })
+}
+
+pub fn canonicalize(_p: &Path) -> io::Result<PathBuf> {
+    // This seems to not be in wasi's API yet, and we may need to end up
+    // emulating it ourselves. For now just return an error.
+    unsupported()
+}
+
+fn open_at(fd: &WasiFd, path: &Path, opts: &OpenOptions) -> io::Result<File> {
+    let fd = fd.open(
+        opts.dirflags,
+        osstr2str(path.as_ref())?,
+        opts.oflags,
+        opts.rights_base(),
+        opts.rights_inheriting(),
+        opts.fdflags,
+    )?;
+    Ok(File { fd })
+}
+
+/// Attempts to open a bare path `p`.
+///
+/// WASI has no fundamental capability to do this. All syscalls and operations
+/// are relative to already-open file descriptors. The C library, however,
+/// manages a map of pre-opened file descriptors to their path, and then the C
+/// library provides an API to look at this. In other words, when you want to
+/// open a path `p`, you have to find a previously opened file descriptor in a
+/// global table and then see if `p` is relative to that file descriptor.
+///
+/// This function, if successful, will return two items:
+///
+/// * The first is a `ManuallyDrop<WasiFd>`. This represents a pre-opened file
+///   descriptor which we don't have ownership of, but we can use. You shouldn't
+///   actually drop the `fd`.
+///
+/// * The second is a path that should be a part of `p` and represents a
+///   relative traversal from the file descriptor specified to the desired
+///   location `p`.
+///
+/// If successful you can use the returned file descriptor to perform
+/// file-descriptor-relative operations on the path returned as well. The
+/// `rights` argument indicates what operations are desired on the returned file
+/// descriptor, and if successful the returned file descriptor should have the
+/// appropriate rights for performing `rights` actions.
+///
+/// Note that this can fail if `p` doesn't look like it can be opened relative
+/// to any pre-opened file descriptor.
+fn open_parent(p: &Path) -> io::Result<(ManuallyDrop<WasiFd>, PathBuf)> {
+    let p = CString::new(p.as_os_str().as_bytes())?;
+    let mut buf = Vec::<u8>::with_capacity(512);
+    loop {
+        unsafe {
+            let mut relative_path = buf.as_ptr().cast();
+            let mut abs_prefix = ptr::null();
+            let fd = __wasilibc_find_relpath(
+                p.as_ptr(),
+                &mut abs_prefix,
+                &mut relative_path,
+                buf.capacity(),
+            );
+            if fd == -1 {
+                if io::Error::last_os_error().raw_os_error() == Some(libc::ENOMEM) {
+                    // Trigger the internal buffer resizing logic of `Vec` by requiring
+                    // more space than the current capacity.
+                    let cap = buf.capacity();
+                    buf.set_len(cap);
+                    buf.reserve(1);
+                    continue;
+                }
+                let msg = format!(
+                    "failed to find a pre-opened file descriptor \
+                     through which {:?} could be opened",
+                    p
+                );
+                return Err(io::Error::new(io::ErrorKind::Uncategorized, msg));
+            }
+            let relative = CStr::from_ptr(relative_path).to_bytes().to_vec();
+
+            return Ok((
+                ManuallyDrop::new(WasiFd::from_raw_fd(fd as c_int)),
+                PathBuf::from(OsString::from_vec(relative)),
+            ));
+        }
+    }
+
+    extern "C" {
+        pub fn __wasilibc_find_relpath(
+            path: *const libc::c_char,
+            abs_prefix: *mut *const libc::c_char,
+            relative_path: *mut *const libc::c_char,
+            relative_path_len: libc::size_t,
+        ) -> libc::c_int;
+    }
+}
+
+pub fn osstr2str(f: &OsStr) -> io::Result<&str> {
+    f.to_str()
+        .ok_or_else(|| io::const_io_error!(io::ErrorKind::Uncategorized, "input must be utf-8"))
+}
+
+pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
+    use crate::fs::File;
+
+    let mut reader = File::open(from)?;
+    let mut writer = File::create(to)?;
+
+    io::copy(&mut reader, &mut writer)
+}
+
+pub fn remove_dir_all(path: &Path) -> io::Result<()> {
+    let (parent, path) = open_parent(path)?;
+    remove_dir_all_recursive(&parent, &path)
+}
+
+fn remove_dir_all_recursive(parent: &WasiFd, path: &Path) -> io::Result<()> {
+    // Open up a file descriptor for the directory itself. Note that we don't
+    // follow symlinks here and we specifically open directories.
+    //
+    // At the root invocation of this function this will correctly handle
+    // symlinks passed to the top-level `remove_dir_all`. At the recursive
+    // level this will double-check that after the `readdir` call deduced this
+    // was a directory it's still a directory by the time we open it up.
+    //
+    // If the opened file was actually a symlink then the symlink is deleted,
+    // not the directory recursively.
+    let mut opts = OpenOptions::new();
+    opts.lookup_flags(0);
+    opts.directory(true);
+    opts.read(true);
+    let fd = open_at(parent, path, &opts)?;
+    if fd.file_attr()?.file_type().is_symlink() {
+        return parent.unlink_file(osstr2str(path.as_ref())?);
+    }
+
+    // this "root" is only used by `DirEntry::path` which we don't use below so
+    // it's ok for this to be a bogus value
+    let dummy_root = PathBuf::new();
+
+    // Iterate over all the entries in this directory, and travel recursively if
+    // necessary
+    for entry in ReadDir::new(fd, dummy_root) {
+        let entry = entry?;
+        let path = crate::str::from_utf8(&entry.name).map_err(|_| {
+            io::const_io_error!(io::ErrorKind::Uncategorized, "invalid utf-8 file name found")
+        })?;
+
+        if entry.file_type()?.is_dir() {
+            remove_dir_all_recursive(&entry.inner.dir.fd, path.as_ref())?;
+        } else {
+            entry.inner.dir.fd.unlink_file(path)?;
+        }
+    }
+
+    // Once all this directory's contents are deleted it should be safe to
+    // delete the directory tiself.
+    parent.remove_directory(osstr2str(path.as_ref())?)
+}
diff --git a/library/std/src/sys/wasi/io.rs b/library/std/src/sys/wasi/io.rs
new file mode 100644
index 000000000..ee017d13a
--- /dev/null
+++ b/library/std/src/sys/wasi/io.rs
@@ -0,0 +1,73 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::marker::PhantomData;
+use crate::slice;
+
+#[derive(Copy, Clone)]
+#[repr(transparent)]
+pub struct IoSlice<'a> {
+    vec: wasi::Ciovec,
+    _p: PhantomData<&'a [u8]>,
+}
+
+impl<'a> IoSlice<'a> {
+    #[inline]
+    pub fn new(buf: &'a [u8]) -> IoSlice<'a> {
+        IoSlice { vec: wasi::Ciovec { buf: buf.as_ptr(), buf_len: buf.len() }, _p: PhantomData }
+    }
+
+    #[inline]
+    pub fn advance(&mut self, n: usize) {
+        if self.vec.buf_len < n {
+            panic!("advancing IoSlice beyond its length");
+        }
+
+        unsafe {
+            self.vec.buf_len -= n;
+            self.vec.buf = self.vec.buf.add(n);
+        }
+    }
+
+    #[inline]
+    pub fn as_slice(&self) -> &[u8] {
+        unsafe { slice::from_raw_parts(self.vec.buf as *const u8, self.vec.buf_len) }
+    }
+}
+
+#[repr(transparent)]
+pub struct IoSliceMut<'a> {
+    vec: wasi::Iovec,
+    _p: PhantomData<&'a mut [u8]>,
+}
+
+impl<'a> IoSliceMut<'a> {
+    #[inline]
+    pub fn new(buf: &'a mut [u8]) -> IoSliceMut<'a> {
+        IoSliceMut {
+            vec: wasi::Iovec { buf: buf.as_mut_ptr(), buf_len: buf.len() },
+            _p: PhantomData,
+        }
+    }
+
+    #[inline]
+    pub fn advance(&mut self, n: usize) {
+        if self.vec.buf_len < n {
+            panic!("advancing IoSlice beyond its length");
+        }
+
+        unsafe {
+            self.vec.buf_len -= n;
+            self.vec.buf = self.vec.buf.add(n);
+        }
+    }
+
+    #[inline]
+    pub fn as_slice(&self) -> &[u8] {
+        unsafe { slice::from_raw_parts(self.vec.buf as *const u8, self.vec.buf_len) }
+    }
+
+    #[inline]
+    pub fn as_mut_slice(&mut self) -> &mut [u8] {
+        unsafe { slice::from_raw_parts_mut(self.vec.buf as *mut u8, self.vec.buf_len) }
+    }
+}
diff --git a/library/std/src/sys/wasi/mod.rs b/library/std/src/sys/wasi/mod.rs
new file mode 100644
index 000000000..683a07a34
--- /dev/null
+++ b/library/std/src/sys/wasi/mod.rs
@@ -0,0 +1,100 @@
+//! System bindings for the wasm/web platform
+//!
+//! This module contains the facade (aka platform-specific) implementations of
+//! OS level functionality for wasm. Note that this wasm is *not* the emscripten
+//! wasm, so we have no runtime here.
+//!
+//! This is all super highly experimental and not actually intended for
+//! wide/production use yet, it's still all in the experimental category. This
+//! will likely change over time.
+//!
+//! Currently all functions here are basically stubs that immediately return
+//! errors. The hope is that with a portability lint we can turn actually just
+//! remove all this and just omit parts of the standard library if we're
+//! compiling for wasm. That way it's a compile time error for something that's
+//! guaranteed to be a runtime error!
+
+use crate::io as std_io;
+use crate::mem;
+
+#[path = "../unix/alloc.rs"]
+pub mod alloc;
+pub mod args;
+#[path = "../unix/cmath.rs"]
+pub mod cmath;
+pub mod env;
+pub mod fd;
+pub mod fs;
+pub mod io;
+#[path = "../unsupported/locks/mod.rs"]
+pub mod locks;
+pub mod net;
+pub mod os;
+#[path = "../unix/os_str.rs"]
+pub mod os_str;
+#[path = "../unix/path.rs"]
+pub mod path;
+#[path = "../unsupported/pipe.rs"]
+pub mod pipe;
+#[path = "../unsupported/process.rs"]
+pub mod process;
+pub mod stdio;
+pub mod thread;
+#[path = "../unsupported/thread_local_dtor.rs"]
+pub mod thread_local_dtor;
+#[path = "../unsupported/thread_local_key.rs"]
+pub mod thread_local_key;
+pub mod time;
+
+#[path = "../unsupported/common.rs"]
+#[deny(unsafe_op_in_unsafe_fn)]
+#[allow(unused)]
+mod common;
+pub use common::*;
+
+pub fn decode_error_kind(errno: i32) -> std_io::ErrorKind {
+    use std_io::ErrorKind::*;
+    if errno > u16::MAX as i32 || errno < 0 {
+        return Uncategorized;
+    }
+
+    match errno {
+        e if e == wasi::ERRNO_CONNREFUSED.raw().into() => ConnectionRefused,
+        e if e == wasi::ERRNO_CONNRESET.raw().into() => ConnectionReset,
+        e if e == wasi::ERRNO_PERM.raw().into() || e == wasi::ERRNO_ACCES.raw().into() => {
+            PermissionDenied
+        }
+        e if e == wasi::ERRNO_PIPE.raw().into() => BrokenPipe,
+        e if e == wasi::ERRNO_NOTCONN.raw().into() => NotConnected,
+        e if e == wasi::ERRNO_CONNABORTED.raw().into() => ConnectionAborted,
+        e if e == wasi::ERRNO_ADDRNOTAVAIL.raw().into() => AddrNotAvailable,
+        e if e == wasi::ERRNO_ADDRINUSE.raw().into() => AddrInUse,
+        e if e == wasi::ERRNO_NOENT.raw().into() => NotFound,
+        e if e == wasi::ERRNO_INTR.raw().into() => Interrupted,
+        e if e == wasi::ERRNO_INVAL.raw().into() => InvalidInput,
+        e if e == wasi::ERRNO_TIMEDOUT.raw().into() => TimedOut,
+        e if e == wasi::ERRNO_EXIST.raw().into() => AlreadyExists,
+        e if e == wasi::ERRNO_AGAIN.raw().into() => WouldBlock,
+        e if e == wasi::ERRNO_NOSYS.raw().into() => Unsupported,
+        e if e == wasi::ERRNO_NOMEM.raw().into() => OutOfMemory,
+        _ => Uncategorized,
+    }
+}
+
+pub fn abort_internal() -> ! {
+    unsafe { libc::abort() }
+}
+
+pub fn hashmap_random_keys() -> (u64, u64) {
+    let mut ret = (0u64, 0u64);
+    unsafe {
+        let base = &mut ret as *mut (u64, u64) as *mut u8;
+        let len = mem::size_of_val(&ret);
+        wasi::random_get(base, len).expect("random_get failure");
+    }
+    return ret;
+}
+
+fn err2io(err: wasi::Errno) -> std_io::Error {
+    std_io::Error::from_raw_os_error(err.raw().into())
+}
diff --git a/library/std/src/sys/wasi/net.rs b/library/std/src/sys/wasi/net.rs
new file mode 100644
index 000000000..590d268c3
--- /dev/null
+++ b/library/std/src/sys/wasi/net.rs
@@ -0,0 +1,527 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use super::err2io;
+use super::fd::WasiFd;
+use crate::fmt;
+use crate::io::{self, IoSlice, IoSliceMut};
+use crate::net::{Ipv4Addr, Ipv6Addr, Shutdown, SocketAddr};
+use crate::os::wasi::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
+use crate::sys::unsupported;
+use crate::sys_common::{AsInner, FromInner, IntoInner};
+use crate::time::Duration;
+
+pub struct Socket(WasiFd);
+
+pub struct TcpStream {
+    inner: Socket,
+}
+
+impl AsInner<WasiFd> for Socket {
+    fn as_inner(&self) -> &WasiFd {
+        &self.0
+    }
+}
+
+impl IntoInner<WasiFd> for Socket {
+    fn into_inner(self) -> WasiFd {
+        self.0
+    }
+}
+
+impl FromInner<WasiFd> for Socket {
+    fn from_inner(inner: WasiFd) -> Socket {
+        Socket(inner)
+    }
+}
+
+impl AsFd for Socket {
+    fn as_fd(&self) -> BorrowedFd<'_> {
+        self.0.as_fd()
+    }
+}
+
+impl AsRawFd for Socket {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0.as_raw_fd()
+    }
+}
+
+impl IntoRawFd for Socket {
+    fn into_raw_fd(self) -> RawFd {
+        self.0.into_raw_fd()
+    }
+}
+
+impl FromRawFd for Socket {
+    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
+        unsafe { Self(FromRawFd::from_raw_fd(raw_fd)) }
+    }
+}
+
+impl TcpStream {
+    pub fn connect(_: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
+        unsupported()
+    }
+
+    pub fn connect_timeout(_: &SocketAddr, _: Duration) -> io::Result<TcpStream> {
+        unsupported()
+    }
+
+    pub fn set_read_timeout(&self, _: Option<Duration>) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn set_write_timeout(&self, _: Option<Duration>) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn read_timeout(&self) -> io::Result<Option<Duration>> {
+        unsupported()
+    }
+
+    pub fn write_timeout(&self) -> io::Result<Option<Duration>> {
+        unsupported()
+    }
+
+    pub fn peek(&self, _: &mut [u8]) -> io::Result<usize> {
+        unsupported()
+    }
+
+    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.read_vectored(&mut [IoSliceMut::new(buf)])
+    }
+
+    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.socket().as_inner().read(bufs)
+    }
+
+    pub fn is_read_vectored(&self) -> bool {
+        true
+    }
+
+    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.write_vectored(&[IoSlice::new(buf)])
+    }
+
+    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.socket().as_inner().write(bufs)
+    }
+
+    pub fn is_write_vectored(&self) -> bool {
+        true
+    }
+
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        unsupported()
+    }
+
+    pub fn socket_addr(&self) -> io::Result<SocketAddr> {
+        unsupported()
+    }
+
+    pub fn shutdown(&self, _: Shutdown) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn duplicate(&self) -> io::Result<TcpStream> {
+        unsupported()
+    }
+
+    pub fn set_linger(&self, _: Option<Duration>) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn linger(&self) -> io::Result<Option<Duration>> {
+        unsupported()
+    }
+
+    pub fn set_nodelay(&self, _: bool) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn nodelay(&self) -> io::Result<bool> {
+        unsupported()
+    }
+
+    pub fn set_ttl(&self, _: u32) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn ttl(&self) -> io::Result<u32> {
+        unsupported()
+    }
+
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        unsupported()
+    }
+
+    pub fn set_nonblocking(&self, state: bool) -> io::Result<()> {
+        let fdstat = unsafe {
+            wasi::fd_fdstat_get(self.socket().as_inner().as_raw_fd() as wasi::Fd).map_err(err2io)?
+        };
+
+        let mut flags = fdstat.fs_flags;
+
+        if state {
+            flags |= wasi::FDFLAGS_NONBLOCK;
+        } else {
+            flags &= !wasi::FDFLAGS_NONBLOCK;
+        }
+
+        unsafe {
+            wasi::fd_fdstat_set_flags(self.socket().as_inner().as_raw_fd() as wasi::Fd, flags)
+                .map_err(err2io)
+        }
+    }
+
+    pub fn socket(&self) -> &Socket {
+        &self.inner
+    }
+
+    pub fn into_socket(self) -> Socket {
+        self.inner
+    }
+}
+
+impl FromInner<Socket> for TcpStream {
+    fn from_inner(socket: Socket) -> TcpStream {
+        TcpStream { inner: socket }
+    }
+}
+
+impl fmt::Debug for TcpStream {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("TcpStream").field("fd", &self.inner.as_raw_fd()).finish()
+    }
+}
+
+pub struct TcpListener {
+    inner: Socket,
+}
+
+impl TcpListener {
+    pub fn bind(_: io::Result<&SocketAddr>) -> io::Result<TcpListener> {
+        unsupported()
+    }
+
+    pub fn socket_addr(&self) -> io::Result<SocketAddr> {
+        unsupported()
+    }
+
+    pub fn accept(&self) -> io::Result<(TcpStream, SocketAddr)> {
+        let fd = unsafe {
+            wasi::sock_accept(self.as_inner().as_inner().as_raw_fd() as _, 0).map_err(err2io)?
+        };
+
+        Ok((
+            TcpStream::from_inner(unsafe { Socket::from_raw_fd(fd as _) }),
+            // WASI has no concept of SocketAddr yet
+            // return an unspecified IPv4Addr
+            SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 0),
+        ))
+    }
+
+    pub fn duplicate(&self) -> io::Result<TcpListener> {
+        unsupported()
+    }
+
+    pub fn set_ttl(&self, _: u32) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn ttl(&self) -> io::Result<u32> {
+        unsupported()
+    }
+
+    pub fn set_only_v6(&self, _: bool) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn only_v6(&self) -> io::Result<bool> {
+        unsupported()
+    }
+
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        unsupported()
+    }
+
+    pub fn set_nonblocking(&self, state: bool) -> io::Result<()> {
+        let fdstat = unsafe {
+            wasi::fd_fdstat_get(self.socket().as_inner().as_raw_fd() as wasi::Fd).map_err(err2io)?
+        };
+
+        let mut flags = fdstat.fs_flags;
+
+        if state {
+            flags |= wasi::FDFLAGS_NONBLOCK;
+        } else {
+            flags &= !wasi::FDFLAGS_NONBLOCK;
+        }
+
+        unsafe {
+            wasi::fd_fdstat_set_flags(self.socket().as_inner().as_raw_fd() as wasi::Fd, flags)
+                .map_err(err2io)
+        }
+    }
+
+    pub fn socket(&self) -> &Socket {
+        &self.inner
+    }
+
+    pub fn into_socket(self) -> Socket {
+        self.inner
+    }
+}
+
+impl AsInner<Socket> for TcpListener {
+    fn as_inner(&self) -> &Socket {
+        &self.inner
+    }
+}
+
+impl IntoInner<Socket> for TcpListener {
+    fn into_inner(self) -> Socket {
+        self.inner
+    }
+}
+
+impl FromInner<Socket> for TcpListener {
+    fn from_inner(inner: Socket) -> TcpListener {
+        TcpListener { inner }
+    }
+}
+
+impl fmt::Debug for TcpListener {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("TcpListener").field("fd", &self.inner.as_raw_fd()).finish()
+    }
+}
+
+pub struct UdpSocket {
+    inner: Socket,
+}
+
+impl UdpSocket {
+    pub fn bind(_: io::Result<&SocketAddr>) -> io::Result<UdpSocket> {
+        unsupported()
+    }
+
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        unsupported()
+    }
+
+    pub fn socket_addr(&self) -> io::Result<SocketAddr> {
+        unsupported()
+    }
+
+    pub fn recv_from(&self, _: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+        unsupported()
+    }
+
+    pub fn peek_from(&self, _: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+        unsupported()
+    }
+
+    pub fn send_to(&self, _: &[u8], _: &SocketAddr) -> io::Result<usize> {
+        unsupported()
+    }
+
+    pub fn duplicate(&self) -> io::Result<UdpSocket> {
+        unsupported()
+    }
+
+    pub fn set_read_timeout(&self, _: Option<Duration>) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn set_write_timeout(&self, _: Option<Duration>) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn read_timeout(&self) -> io::Result<Option<Duration>> {
+        unsupported()
+    }
+
+    pub fn write_timeout(&self) -> io::Result<Option<Duration>> {
+        unsupported()
+    }
+
+    pub fn set_broadcast(&self, _: bool) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn broadcast(&self) -> io::Result<bool> {
+        unsupported()
+    }
+
+    pub fn set_multicast_loop_v4(&self, _: bool) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn multicast_loop_v4(&self) -> io::Result<bool> {
+        unsupported()
+    }
+
+    pub fn set_multicast_ttl_v4(&self, _: u32) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn multicast_ttl_v4(&self) -> io::Result<u32> {
+        unsupported()
+    }
+
+    pub fn set_multicast_loop_v6(&self, _: bool) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn multicast_loop_v6(&self) -> io::Result<bool> {
+        unsupported()
+    }
+
+    pub fn join_multicast_v4(&self, _: &Ipv4Addr, _: &Ipv4Addr) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn join_multicast_v6(&self, _: &Ipv6Addr, _: u32) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn leave_multicast_v4(&self, _: &Ipv4Addr, _: &Ipv4Addr) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn leave_multicast_v6(&self, _: &Ipv6Addr, _: u32) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn set_ttl(&self, _: u32) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn ttl(&self) -> io::Result<u32> {
+        unsupported()
+    }
+
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        unsupported()
+    }
+
+    pub fn set_nonblocking(&self, _: bool) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn recv(&self, _: &mut [u8]) -> io::Result<usize> {
+        unsupported()
+    }
+
+    pub fn peek(&self, _: &mut [u8]) -> io::Result<usize> {
+        unsupported()
+    }
+
+    pub fn send(&self, _: &[u8]) -> io::Result<usize> {
+        unsupported()
+    }
+
+    pub fn connect(&self, _: io::Result<&SocketAddr>) -> io::Result<()> {
+        unsupported()
+    }
+
+    pub fn socket(&self) -> &Socket {
+        &self.inner
+    }
+
+    pub fn into_socket(self) -> Socket {
+        self.inner
+    }
+}
+
+impl AsInner<Socket> for UdpSocket {
+    fn as_inner(&self) -> &Socket {
+        &self.inner
+    }
+}
+
+impl IntoInner<Socket> for UdpSocket {
+    fn into_inner(self) -> Socket {
+        self.inner
+    }
+}
+
+impl FromInner<Socket> for UdpSocket {
+    fn from_inner(inner: Socket) -> UdpSocket {
+        UdpSocket { inner }
+    }
+}
+
+impl fmt::Debug for UdpSocket {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("UdpSocket").field("fd", &self.inner.as_raw_fd()).finish()
+    }
+}
+
+pub struct LookupHost(!);
+
+impl LookupHost {
+    pub fn port(&self) -> u16 {
+        self.0
+    }
+}
+
+impl Iterator for LookupHost {
+    type Item = SocketAddr;
+    fn next(&mut self) -> Option<SocketAddr> {
+        self.0
+    }
+}
+
+impl<'a> TryFrom<&'a str> for LookupHost {
+    type Error = io::Error;
+
+    fn try_from(_v: &'a str) -> io::Result<LookupHost> {
+        unsupported()
+    }
+}
+
+impl<'a> TryFrom<(&'a str, u16)> for LookupHost {
+    type Error = io::Error;
+
+    fn try_from(_v: (&'a str, u16)) -> io::Result<LookupHost> {
+        unsupported()
+    }
+}
+
+#[allow(nonstandard_style)]
+pub mod netc {
+    pub const AF_INET: u8 = 0;
+    pub const AF_INET6: u8 = 1;
+    pub type sa_family_t = u8;
+
+    #[derive(Copy, Clone)]
+    pub struct in_addr {
+        pub s_addr: u32,
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct sockaddr_in {
+        pub sin_family: sa_family_t,
+        pub sin_port: u16,
+        pub sin_addr: in_addr,
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct in6_addr {
+        pub s6_addr: [u8; 16],
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct sockaddr_in6 {
+        pub sin6_family: sa_family_t,
+        pub sin6_port: u16,
+        pub sin6_addr: in6_addr,
+        pub sin6_flowinfo: u32,
+        pub sin6_scope_id: u32,
+    }
+
+    #[derive(Copy, Clone)]
+    pub struct sockaddr {}
+}
diff --git a/library/std/src/sys/wasi/os.rs b/library/std/src/sys/wasi/os.rs
new file mode 100644
index 000000000..c5229a188
--- /dev/null
+++ b/library/std/src/sys/wasi/os.rs
@@ -0,0 +1,243 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::any::Any;
+use crate::error::Error as StdError;
+use crate::ffi::{CStr, CString, OsStr, OsString};
+use crate::fmt;
+use crate::io;
+use crate::marker::PhantomData;
+use crate::os::wasi::prelude::*;
+use crate::path::{self, PathBuf};
+use crate::str;
+use crate::sys::memchr;
+use crate::sys::unsupported;
+use crate::vec;
+
+// Add a few symbols not in upstream `libc` just yet.
+mod libc {
+    pub use libc::*;
+
+    extern "C" {
+        pub fn getcwd(buf: *mut c_char, size: size_t) -> *mut c_char;
+        pub fn chdir(dir: *const c_char) -> c_int;
+    }
+}
+
+#[cfg(not(target_feature = "atomics"))]
+pub unsafe fn env_lock() -> impl Any {
+    // No need for a lock if we're single-threaded, but this function will need
+    // to get implemented for multi-threaded scenarios
+}
+
+pub fn errno() -> i32 {
+    extern "C" {
+        #[thread_local]
+        static errno: libc::c_int;
+    }
+
+    unsafe { errno as i32 }
+}
+
+pub fn error_string(errno: i32) -> String {
+    let mut buf = [0 as libc::c_char; 1024];
+
+    let p = buf.as_mut_ptr();
+    unsafe {
+        if libc::strerror_r(errno as libc::c_int, p, buf.len()) < 0 {
+            panic!("strerror_r failure");
+        }
+        str::from_utf8(CStr::from_ptr(p).to_bytes()).unwrap().to_owned()
+    }
+}
+
+pub fn getcwd() -> io::Result<PathBuf> {
+    let mut buf = Vec::with_capacity(512);
+    loop {
+        unsafe {
+            let ptr = buf.as_mut_ptr() as *mut libc::c_char;
+            if !libc::getcwd(ptr, buf.capacity()).is_null() {
+                let len = CStr::from_ptr(buf.as_ptr() as *const libc::c_char).to_bytes().len();
+                buf.set_len(len);
+                buf.shrink_to_fit();
+                return Ok(PathBuf::from(OsString::from_vec(buf)));
+            } else {
+                let error = io::Error::last_os_error();
+                if error.raw_os_error() != Some(libc::ERANGE) {
+                    return Err(error);
+                }
+            }
+
+            // Trigger the internal buffer resizing logic of `Vec` by requiring
+            // more space than the current capacity.
+            let cap = buf.capacity();
+            buf.set_len(cap);
+            buf.reserve(1);
+        }
+    }
+}
+
+pub fn chdir(p: &path::Path) -> io::Result<()> {
+    let p: &OsStr = p.as_ref();
+    let p = CString::new(p.as_bytes())?;
+    unsafe {
+        match libc::chdir(p.as_ptr()) == (0 as libc::c_int) {
+            true => Ok(()),
+            false => Err(io::Error::last_os_error()),
+        }
+    }
+}
+
+pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
+
+pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
+    panic!("unsupported")
+}
+
+impl<'a> Iterator for SplitPaths<'a> {
+    type Item = PathBuf;
+    fn next(&mut self) -> Option<PathBuf> {
+        self.0
+    }
+}
+
+#[derive(Debug)]
+pub struct JoinPathsError;
+
+pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
+where
+    I: Iterator<Item = T>,
+    T: AsRef<OsStr>,
+{
+    Err(JoinPathsError)
+}
+
+impl fmt::Display for JoinPathsError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        "not supported on wasm yet".fmt(f)
+    }
+}
+
+impl StdError for JoinPathsError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        "not supported on wasm yet"
+    }
+}
+
+pub fn current_exe() -> io::Result<PathBuf> {
+    unsupported()
+}
+pub struct Env {
+    iter: vec::IntoIter<(OsString, OsString)>,
+}
+
+impl !Send for Env {}
+impl !Sync for Env {}
+
+impl Iterator for Env {
+    type Item = (OsString, OsString);
+    fn next(&mut self) -> Option<(OsString, OsString)> {
+        self.iter.next()
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+pub fn env() -> Env {
+    unsafe {
+        let _guard = env_lock();
+        let mut environ = libc::environ;
+        let mut result = Vec::new();
+        if !environ.is_null() {
+            while !(*environ).is_null() {
+                if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
+                    result.push(key_value);
+                }
+                environ = environ.add(1);
+            }
+        }
+        return Env { iter: result.into_iter() };
+    }
+
+    // See src/libstd/sys/unix/os.rs, same as that
+    fn parse(input: &[u8]) -> Option<(OsString, OsString)> {
+        if input.is_empty() {
+            return None;
+        }
+        let pos = memchr::memchr(b'=', &input[1..]).map(|p| p + 1);
+        pos.map(|p| {
+            (
+                OsStringExt::from_vec(input[..p].to_vec()),
+                OsStringExt::from_vec(input[p + 1..].to_vec()),
+            )
+        })
+    }
+}
+
+pub fn getenv(k: &OsStr) -> Option<OsString> {
+    let k = CString::new(k.as_bytes()).ok()?;
+    unsafe {
+        let _guard = env_lock();
+        let s = libc::getenv(k.as_ptr()) as *const libc::c_char;
+        if s.is_null() {
+            None
+        } else {
+            Some(OsStringExt::from_vec(CStr::from_ptr(s).to_bytes().to_vec()))
+        }
+    }
+}
+
+pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
+    let k = CString::new(k.as_bytes())?;
+    let v = CString::new(v.as_bytes())?;
+
+    unsafe {
+        let _guard = env_lock();
+        cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(drop)
+    }
+}
+
+pub fn unsetenv(n: &OsStr) -> io::Result<()> {
+    let nbuf = CString::new(n.as_bytes())?;
+
+    unsafe {
+        let _guard = env_lock();
+        cvt(libc::unsetenv(nbuf.as_ptr())).map(drop)
+    }
+}
+
+pub fn temp_dir() -> PathBuf {
+    panic!("no filesystem on wasm")
+}
+
+pub fn home_dir() -> Option<PathBuf> {
+    None
+}
+
+pub fn exit(code: i32) -> ! {
+    unsafe { libc::exit(code) }
+}
+
+pub fn getpid() -> u32 {
+    panic!("unsupported");
+}
+
+#[doc(hidden)]
+pub trait IsMinusOne {
+    fn is_minus_one(&self) -> bool;
+}
+
+macro_rules! impl_is_minus_one {
+    ($($t:ident)*) => ($(impl IsMinusOne for $t {
+        fn is_minus_one(&self) -> bool {
+            *self == -1
+        }
+    })*)
+}
+
+impl_is_minus_one! { i8 i16 i32 i64 isize }
+
+fn cvt<T: IsMinusOne>(t: T) -> io::Result<T> {
+    if t.is_minus_one() { Err(io::Error::last_os_error()) } else { Ok(t) }
+}
diff --git a/library/std/src/sys/wasi/stdio.rs b/library/std/src/sys/wasi/stdio.rs
new file mode 100644
index 000000000..4cc0e4ed5
--- /dev/null
+++ b/library/std/src/sys/wasi/stdio.rs
@@ -0,0 +1,112 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use super::fd::WasiFd;
+use crate::io::{self, IoSlice, IoSliceMut};
+use crate::mem::ManuallyDrop;
+use crate::os::raw;
+use crate::os::wasi::io::{AsRawFd, FromRawFd};
+
+pub struct Stdin;
+pub struct Stdout;
+pub struct Stderr;
+
+impl Stdin {
+    pub const fn new() -> Stdin {
+        Stdin
+    }
+}
+
+impl AsRawFd for Stdin {
+    #[inline]
+    fn as_raw_fd(&self) -> raw::c_int {
+        0
+    }
+}
+
+impl io::Read for Stdin {
+    fn read(&mut self, data: &mut [u8]) -> io::Result<usize> {
+        self.read_vectored(&mut [IoSliceMut::new(data)])
+    }
+
+    fn read_vectored(&mut self, data: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        ManuallyDrop::new(unsafe { WasiFd::from_raw_fd(self.as_raw_fd()) }).read(data)
+    }
+
+    #[inline]
+    fn is_read_vectored(&self) -> bool {
+        true
+    }
+}
+
+impl Stdout {
+    pub const fn new() -> Stdout {
+        Stdout
+    }
+}
+
+impl AsRawFd for Stdout {
+    #[inline]
+    fn as_raw_fd(&self) -> raw::c_int {
+        1
+    }
+}
+
+impl io::Write for Stdout {
+    fn write(&mut self, data: &[u8]) -> io::Result<usize> {
+        self.write_vectored(&[IoSlice::new(data)])
+    }
+
+    fn write_vectored(&mut self, data: &[IoSlice<'_>]) -> io::Result<usize> {
+        ManuallyDrop::new(unsafe { WasiFd::from_raw_fd(self.as_raw_fd()) }).write(data)
+    }
+
+    #[inline]
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+impl Stderr {
+    pub const fn new() -> Stderr {
+        Stderr
+    }
+}
+
+impl AsRawFd for Stderr {
+    #[inline]
+    fn as_raw_fd(&self) -> raw::c_int {
+        2
+    }
+}
+
+impl io::Write for Stderr {
+    fn write(&mut self, data: &[u8]) -> io::Result<usize> {
+        self.write_vectored(&[IoSlice::new(data)])
+    }
+
+    fn write_vectored(&mut self, data: &[IoSlice<'_>]) -> io::Result<usize> {
+        ManuallyDrop::new(unsafe { WasiFd::from_raw_fd(self.as_raw_fd()) }).write(data)
+    }
+
+    #[inline]
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+pub const STDIN_BUF_SIZE: usize = crate::sys_common::io::DEFAULT_BUF_SIZE;
+
+pub fn is_ebadf(err: &io::Error) -> bool {
+    err.raw_os_error() == Some(wasi::ERRNO_BADF.raw().into())
+}
+
+pub fn panic_output() -> Option<impl io::Write> {
+    Some(Stderr::new())
+}
diff --git a/library/std/src/sys/wasi/thread.rs b/library/std/src/sys/wasi/thread.rs
new file mode 100644
index 000000000..e7a6ab4be
--- /dev/null
+++ b/library/std/src/sys/wasi/thread.rs
@@ -0,0 +1,81 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::ffi::CStr;
+use crate::io;
+use crate::mem;
+use crate::num::NonZeroUsize;
+use crate::sys::unsupported;
+use crate::time::Duration;
+
+pub struct Thread(!);
+
+pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;
+
+impl Thread {
+    // unsafe: see thread::Builder::spawn_unchecked for safety requirements
+    pub unsafe fn new(_stack: usize, _p: Box<dyn FnOnce()>) -> io::Result<Thread> {
+        unsupported()
+    }
+
+    pub fn yield_now() {
+        let ret = unsafe { wasi::sched_yield() };
+        debug_assert_eq!(ret, Ok(()));
+    }
+
+    pub fn set_name(_name: &CStr) {
+        // nope
+    }
+
+    pub fn sleep(dur: Duration) {
+        let nanos = dur.as_nanos();
+        assert!(nanos <= u64::MAX as u128);
+
+        const USERDATA: wasi::Userdata = 0x0123_45678;
+
+        let clock = wasi::SubscriptionClock {
+            id: wasi::CLOCKID_MONOTONIC,
+            timeout: nanos as u64,
+            precision: 0,
+            flags: 0,
+        };
+
+        let in_ = wasi::Subscription {
+            userdata: USERDATA,
+            u: wasi::SubscriptionU { tag: 0, u: wasi::SubscriptionUU { clock } },
+        };
+        unsafe {
+            let mut event: wasi::Event = mem::zeroed();
+            let res = wasi::poll_oneoff(&in_, &mut event, 1);
+            match (res, event) {
+                (
+                    Ok(1),
+                    wasi::Event {
+                        userdata: USERDATA,
+                        error: wasi::ERRNO_SUCCESS,
+                        type_: wasi::EVENTTYPE_CLOCK,
+                        ..
+                    },
+                ) => {}
+                _ => panic!("thread::sleep(): unexpected result of poll_oneoff"),
+            }
+        }
+    }
+
+    pub fn join(self) {
+        self.0
+    }
+}
+
+pub fn available_parallelism() -> io::Result<NonZeroUsize> {
+    unsupported()
+}
+
+pub mod guard {
+    pub type Guard = !;
+    pub unsafe fn current() -> Option<Guard> {
+        None
+    }
+    pub unsafe fn init() -> Option<Guard> {
+        None
+    }
+}
diff --git a/library/std/src/sys/wasi/time.rs b/library/std/src/sys/wasi/time.rs
new file mode 100644
index 000000000..3d326e491
--- /dev/null
+++ b/library/std/src/sys/wasi/time.rs
@@ -0,0 +1,65 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::time::Duration;
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct Instant(Duration);
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct SystemTime(Duration);
+
+pub const UNIX_EPOCH: SystemTime = SystemTime(Duration::from_secs(0));
+
+fn current_time(clock: wasi::Clockid) -> Duration {
+    let ts = unsafe {
+        wasi::clock_time_get(
+            clock, 1, // precision... seems ignored though?
+        )
+        .unwrap()
+    };
+    Duration::new((ts / 1_000_000_000) as u64, (ts % 1_000_000_000) as u32)
+}
+
+impl Instant {
+    pub fn now() -> Instant {
+        Instant(current_time(wasi::CLOCKID_MONOTONIC))
+    }
+
+    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
+        self.0.checked_sub(other.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant(self.0.checked_add(*other)?))
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant(self.0.checked_sub(*other)?))
+    }
+}
+
+impl SystemTime {
+    pub fn now() -> SystemTime {
+        SystemTime(current_time(wasi::CLOCKID_REALTIME))
+    }
+
+    pub fn from_wasi_timestamp(ts: wasi::Timestamp) -> SystemTime {
+        SystemTime(Duration::from_nanos(ts))
+    }
+
+    pub fn to_wasi_timestamp_or_panic(&self) -> wasi::Timestamp {
+        self.0.as_nanos().try_into().expect("time does not fit in WASI timestamp")
+    }
+
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.0.checked_sub(other.0).ok_or_else(|| other.0 - self.0)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime(self.0.checked_add(*other)?))
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime(self.0.checked_sub(*other)?))
+    }
+}