It's wiggle time! (#1202)
* Use wiggle in place of wig in wasi-common This is a rather massive commit that introduces `wiggle` into the picture. We still use `wig`'s macro in `old` snapshot and to generate `wasmtime-wasi` glue, but everything else is now autogenerated by `wiggle`. In summary, thanks to `wiggle`, we no longer need to worry about serialising and deserialising to and from the guest memory, and all guest (WASI) types are now proper idiomatic Rust types. While we're here, in preparation for the ephemeral snapshot, I went ahead and reorganised the internal structure of the crate. Instead of modules like `hostcalls_impl` or `hostcalls_impl::fs`, the structure now resembles that in ephemeral with modules like `path`, `fd`, etc. Now, I'm not requiring we leave it like this, but I reckon it looks cleaner this way after all. * Fix wig to use new first-class access to caller's mem * Ignore warning in proc_exit for the moment * Group unsafes together in args and environ calls * Simplify pwrite; more unsafe blocks * Simplify fd_read * Bundle up unsafes in fd_readdir * Simplify fd_write * Add comment to path_readlink re zero-len buffers * Simplify unsafes in random_get * Hide GuestPtr<str> to &str in path::get * Rewrite pread and pwrite using SeekFrom and read/write_vectored I've left the implementation of VirtualFs pretty much untouched as I don't feel that comfortable in changing the API too much. Having said that, I reckon `pread` and `pwrite` could be refactored out, and `preadv` and `pwritev` could be entirely rewritten using `seek` and `read_vectored` and `write_vectored`. * Add comment about VirtFs unsafety * Fix all mentions of FdEntry to Entry * Fix warnings on Win * Add aux struct EntryTable responsible for Fds and Entries This commit adds aux struct `EntryTable` which is private to `WasiCtx` and is basically responsible for `Fd` alloc/dealloc as well as storing matching `Entry`s. This struct is entirely private to `WasiCtx` and as such as should remain transparent to `WasiCtx` users. * Remove redundant check for empty buffer in path_readlink * Preserve and rewind file cursor in pread/pwrite * Use GuestPtr<[u8]>::copy_from_slice wherever copying bytes directly * Use GuestPtr<[u8]>::copy_from_slice in fd_readdir * Clean up unsafes around WasiCtx accessors * Fix bugs in args_get and environ_get * Fix conflicts after rebase
This commit is contained in:
Jakub Konka
298
crates/wasi-common/src/sys/unix/path.rs
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298
crates/wasi-common/src/sys/unix/path.rs
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use crate::entry::Descriptor;
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use crate::path::PathGet;
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use crate::sys::entry::OsHandle;
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use crate::sys::unix::sys_impl;
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use crate::wasi::{types, Errno, Result};
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use std::convert::TryInto;
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use std::ffi::OsStr;
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use std::fs::File;
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use std::os::unix::prelude::{AsRawFd, FromRawFd, OsStrExt};
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use std::str;
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use yanix::file::OFlag;
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pub(crate) use sys_impl::path::*;
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/// Creates owned WASI path from OS string.
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///
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/// NB WASI spec requires OS string to be valid UTF-8. Otherwise,
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/// `__WASI_ERRNO_ILSEQ` error is returned.
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pub(crate) fn from_host<S: AsRef<OsStr>>(s: S) -> Result<String> {
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let s = str::from_utf8(s.as_ref().as_bytes())?;
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Ok(s.to_owned())
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}
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pub(crate) fn open_rights(
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rights_base: types::Rights,
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rights_inheriting: types::Rights,
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oflags: types::Oflags,
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fs_flags: types::Fdflags,
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) -> (types::Rights, types::Rights) {
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// which rights are needed on the dirfd?
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let mut needed_base = types::Rights::PATH_OPEN;
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let mut needed_inheriting = rights_base | rights_inheriting;
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// convert open flags
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let oflags: OFlag = oflags.into();
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if oflags.contains(OFlag::CREAT) {
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needed_base |= types::Rights::PATH_CREATE_FILE;
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}
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if oflags.contains(OFlag::TRUNC) {
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needed_base |= types::Rights::PATH_FILESTAT_SET_SIZE;
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}
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// convert file descriptor flags
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let fdflags: OFlag = fs_flags.into();
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if fdflags.contains(OFlag::DSYNC) {
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needed_inheriting |= types::Rights::FD_DATASYNC;
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}
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if fdflags.intersects(sys_impl::O_RSYNC | OFlag::SYNC) {
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needed_inheriting |= types::Rights::FD_SYNC;
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}
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(needed_base, needed_inheriting)
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}
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pub(crate) fn openat(dirfd: &File, path: &str) -> Result<File> {
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use std::os::unix::prelude::{AsRawFd, FromRawFd};
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use yanix::file::{openat, Mode};
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log::debug!("path_get openat path = {:?}", path);
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let raw_fd = unsafe {
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openat(
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dirfd.as_raw_fd(),
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path,
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OFlag::RDONLY | OFlag::DIRECTORY | OFlag::NOFOLLOW,
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Mode::empty(),
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)?
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};
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let file = unsafe { File::from_raw_fd(raw_fd) };
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Ok(file)
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}
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pub(crate) fn readlinkat(dirfd: &File, path: &str) -> Result<String> {
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use std::os::unix::prelude::AsRawFd;
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use yanix::file::readlinkat;
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log::debug!("path_get readlinkat path = {:?}", path);
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let path = unsafe { readlinkat(dirfd.as_raw_fd(), path)? };
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let path = from_host(path)?;
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Ok(path)
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}
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pub(crate) fn create_directory(base: &File, path: &str) -> Result<()> {
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use yanix::file::{mkdirat, Mode};
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unsafe { mkdirat(base.as_raw_fd(), path, Mode::from_bits_truncate(0o777))? };
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Ok(())
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}
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pub(crate) fn link(
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resolved_old: PathGet,
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resolved_new: PathGet,
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follow_symlinks: bool,
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) -> Result<()> {
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use yanix::file::{linkat, AtFlag};
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let flags = if follow_symlinks {
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AtFlag::SYMLINK_FOLLOW
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} else {
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AtFlag::empty()
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};
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unsafe {
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linkat(
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resolved_old.dirfd().as_raw_fd(),
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resolved_old.path(),
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resolved_new.dirfd().as_raw_fd(),
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resolved_new.path(),
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flags,
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)?
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};
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Ok(())
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}
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pub(crate) fn open(
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resolved: PathGet,
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read: bool,
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write: bool,
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oflags: types::Oflags,
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fs_flags: types::Fdflags,
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) -> Result<Descriptor> {
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use yanix::file::{fstatat, openat, AtFlag, FileType, Mode, OFlag};
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let mut nix_all_oflags = if read && write {
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OFlag::RDWR
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} else if write {
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OFlag::WRONLY
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} else {
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OFlag::RDONLY
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};
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// on non-Capsicum systems, we always want nofollow
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nix_all_oflags.insert(OFlag::NOFOLLOW);
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// convert open flags
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nix_all_oflags.insert(oflags.into());
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// convert file descriptor flags
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nix_all_oflags.insert(fs_flags.into());
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// Call openat. Use mode 0o666 so that we follow whatever the user's
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// umask is, but don't set the executable flag, because it isn't yet
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// meaningful for WASI programs to create executable files.
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log::debug!("path_open resolved = {:?}", resolved);
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log::debug!("path_open oflags = {:?}", nix_all_oflags);
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let fd_no = unsafe {
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openat(
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resolved.dirfd().as_raw_fd(),
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resolved.path(),
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nix_all_oflags,
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Mode::from_bits_truncate(0o666),
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)
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};
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let new_fd = match fd_no {
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Ok(fd) => fd,
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Err(e) => {
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match e.raw_os_error().unwrap() {
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// Linux returns ENXIO instead of EOPNOTSUPP when opening a socket
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libc::ENXIO => {
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match unsafe {
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fstatat(
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resolved.dirfd().as_raw_fd(),
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resolved.path(),
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AtFlag::SYMLINK_NOFOLLOW,
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)
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} {
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Ok(stat) => {
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if FileType::from_stat_st_mode(stat.st_mode) == FileType::Socket {
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return Err(Errno::Notsup);
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}
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}
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Err(err) => {
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log::debug!("path_open fstatat error: {:?}", err);
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}
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}
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}
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// Linux returns ENOTDIR instead of ELOOP when using O_NOFOLLOW|O_DIRECTORY
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// on a symlink.
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libc::ENOTDIR
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if !(nix_all_oflags & (OFlag::NOFOLLOW | OFlag::DIRECTORY)).is_empty() =>
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{
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match unsafe {
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fstatat(
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resolved.dirfd().as_raw_fd(),
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resolved.path(),
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AtFlag::SYMLINK_NOFOLLOW,
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)
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} {
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Ok(stat) => {
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if FileType::from_stat_st_mode(stat.st_mode) == FileType::Symlink {
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return Err(Errno::Loop);
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}
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}
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Err(err) => {
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log::debug!("path_open fstatat error: {:?}", err);
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}
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}
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}
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// FreeBSD returns EMLINK instead of ELOOP when using O_NOFOLLOW on
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// a symlink.
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libc::EMLINK if !(nix_all_oflags & OFlag::NOFOLLOW).is_empty() => {
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return Err(Errno::Loop);
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}
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_ => {}
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}
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return Err(e.into());
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}
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};
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log::debug!("path_open (host) new_fd = {:?}", new_fd);
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// Determine the type of the new file descriptor and which rights contradict with this type
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Ok(OsHandle::from(unsafe { File::from_raw_fd(new_fd) }).into())
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}
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pub(crate) fn readlink(resolved: PathGet, buf: &mut [u8]) -> Result<usize> {
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use std::cmp::min;
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use yanix::file::readlinkat;
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let read_link = unsafe { readlinkat(resolved.dirfd().as_raw_fd(), resolved.path())? };
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let read_link = from_host(read_link)?;
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let copy_len = min(read_link.len(), buf.len());
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if copy_len > 0 {
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buf[..copy_len].copy_from_slice(&read_link.as_bytes()[..copy_len]);
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}
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Ok(copy_len)
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}
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pub(crate) fn filestat_get(
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resolved: PathGet,
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dirflags: types::Lookupflags,
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) -> Result<types::Filestat> {
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use yanix::file::fstatat;
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let atflags = dirflags.into();
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let filestat = unsafe { fstatat(resolved.dirfd().as_raw_fd(), resolved.path(), atflags)? };
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let filestat = filestat.try_into()?;
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Ok(filestat)
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}
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pub(crate) fn filestat_set_times(
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resolved: PathGet,
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dirflags: types::Lookupflags,
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st_atim: types::Timestamp,
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st_mtim: types::Timestamp,
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fst_flags: types::Fstflags,
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) -> Result<()> {
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use std::time::{Duration, UNIX_EPOCH};
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use yanix::filetime::*;
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let set_atim = fst_flags.contains(&types::Fstflags::ATIM);
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let set_atim_now = fst_flags.contains(&types::Fstflags::ATIM_NOW);
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let set_mtim = fst_flags.contains(&types::Fstflags::MTIM);
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let set_mtim_now = fst_flags.contains(&types::Fstflags::MTIM_NOW);
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if (set_atim && set_atim_now) || (set_mtim && set_mtim_now) {
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return Err(Errno::Inval);
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}
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let symlink_nofollow = types::Lookupflags::SYMLINK_FOLLOW != dirflags;
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let atim = if set_atim {
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let time = UNIX_EPOCH + Duration::from_nanos(st_atim);
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FileTime::FileTime(filetime::FileTime::from_system_time(time))
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} else if set_atim_now {
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FileTime::Now
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} else {
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FileTime::Omit
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};
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let mtim = if set_mtim {
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let time = UNIX_EPOCH + Duration::from_nanos(st_mtim);
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FileTime::FileTime(filetime::FileTime::from_system_time(time))
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} else if set_mtim_now {
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FileTime::Now
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} else {
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FileTime::Omit
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};
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utimensat(
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&resolved.dirfd().as_os_handle(),
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resolved.path(),
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atim,
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mtim,
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symlink_nofollow,
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)?;
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Ok(())
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}
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pub(crate) fn remove_directory(resolved: PathGet) -> Result<()> {
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use yanix::file::{unlinkat, AtFlag};
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unsafe {
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unlinkat(
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resolved.dirfd().as_raw_fd(),
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resolved.path(),
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AtFlag::REMOVEDIR,
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)?
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};
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Ok(())
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}
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