Files
wasmtime/src/sys/unix/hostcalls_impl/fs.rs
2019-07-22 16:05:30 -07:00

620 lines
21 KiB
Rust

#![allow(non_camel_case_types)]
#![allow(unused_unsafe)]
use super::fs_helpers::*;
use crate::ctx::WasiCtx;
use crate::fdentry::{Descriptor, FdEntry};
use crate::sys::errno_from_host;
use crate::sys::fdentry_impl::determine_type_rights;
use crate::sys::host_impl;
use crate::{host, wasm32, Result};
use nix::libc::{self, c_long, c_void, off_t};
use std::ffi::CString;
use std::fs::File;
use std::os::unix::fs::FileExt;
use std::os::unix::prelude::{AsRawFd, FromRawFd};
pub(crate) fn fd_pread(
file: &File,
buf: &mut [u8],
offset: host::__wasi_filesize_t,
) -> Result<usize> {
file.read_at(buf, offset)
.map_err(|e| e.raw_os_error().map_or(host::__WASI_EIO, errno_from_host))
}
pub(crate) fn fd_pwrite(file: &File, buf: &[u8], offset: host::__wasi_filesize_t) -> Result<usize> {
file.write_at(buf, offset)
.map_err(|e| e.raw_os_error().map_or(host::__WASI_EIO, errno_from_host))
}
pub(crate) fn fd_fdstat_get(fd: &File) -> Result<host::__wasi_fdflags_t> {
use nix::fcntl::{fcntl, OFlag, F_GETFL};
match fcntl(fd.as_raw_fd(), F_GETFL).map(OFlag::from_bits_truncate) {
Ok(flags) => Ok(host_impl::fdflags_from_nix(flags)),
Err(e) => Err(host_impl::errno_from_nix(e.as_errno().unwrap())),
}
}
pub(crate) fn fd_fdstat_set_flags(fd: &File, fdflags: host::__wasi_fdflags_t) -> Result<()> {
let nix_flags = host_impl::nix_from_fdflags(fdflags);
match nix::fcntl::fcntl(fd.as_raw_fd(), nix::fcntl::F_SETFL(nix_flags)) {
Ok(_) => Ok(()),
Err(e) => Err(host_impl::errno_from_nix(e.as_errno().unwrap())),
}
}
pub(crate) fn fd_advise(
file: &File,
advice: host::__wasi_advice_t,
offset: host::__wasi_filesize_t,
len: host::__wasi_filesize_t,
) -> Result<()> {
#[cfg(target_os = "linux")]
{
let host_advice = match advice {
host::__WASI_ADVICE_DONTNEED => libc::POSIX_FADV_DONTNEED,
host::__WASI_ADVICE_SEQUENTIAL => libc::POSIX_FADV_SEQUENTIAL,
host::__WASI_ADVICE_WILLNEED => libc::POSIX_FADV_DONTNEED,
host::__WASI_ADVICE_NOREUSE => libc::POSIX_FADV_NOREUSE,
host::__WASI_ADVICE_RANDOM => libc::POSIX_FADV_RANDOM,
host::__WASI_ADVICE_NORMAL => libc::POSIX_FADV_NORMAL,
_ => return Err(host::__WASI_EINVAL),
};
let res = unsafe {
libc::posix_fadvise(file.as_raw_fd(), offset as off_t, len as off_t, host_advice)
};
if res != 0 {
return Err(host_impl::errno_from_nix(nix::errno::Errno::last()));
}
}
#[cfg(not(target_os = "linux"))]
{
let _ = (file, offset, len);
match advice {
host::__WASI_ADVICE_DONTNEED
| host::__WASI_ADVICE_SEQUENTIAL
| host::__WASI_ADVICE_WILLNEED
| host::__WASI_ADVICE_NOREUSE
| host::__WASI_ADVICE_RANDOM
| host::__WASI_ADVICE_NORMAL => {}
_ => return Err(host::__WASI_EINVAL),
}
}
Ok(())
}
pub(crate) fn path_create_directory(dirfd: &File, path: &str) -> Result<()> {
use nix::libc::mkdirat;
let (dir, path) = match path_get(dirfd, 0, path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let path_cstr = CString::new(path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
// nix doesn't expose mkdirat() yet
match unsafe { mkdirat(dir.as_raw_fd(), path_cstr.as_ptr(), 0o777) } {
0 => Ok(()),
_ => Err(host_impl::errno_from_nix(nix::errno::Errno::last())),
}
}
pub(crate) fn path_link(
old_dirfd: &File,
new_dirfd: &File,
old_path: &str,
new_path: &str,
) -> Result<()> {
use nix::libc::linkat;
let (old_dir, old_path) = match path_get(old_dirfd, 0, old_path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let (new_dir, new_path) = match path_get(new_dirfd, 0, new_path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let old_path_cstr = CString::new(old_path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
let new_path_cstr = CString::new(new_path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
// Not setting AT_SYMLINK_FOLLOW fails on most filesystems
let atflags = libc::AT_SYMLINK_FOLLOW;
let res = unsafe {
linkat(
old_dir.as_raw_fd(),
old_path_cstr.as_ptr(),
new_dir.as_raw_fd(),
new_path_cstr.as_ptr(),
atflags,
)
};
if res != 0 {
Err(host_impl::errno_from_nix(nix::errno::Errno::last()))
} else {
Ok(())
}
}
pub(crate) fn path_open(
ctx: &WasiCtx,
dirfd: host::__wasi_fd_t,
dirflags: host::__wasi_lookupflags_t,
path: &str,
oflags: host::__wasi_oflags_t,
read: bool,
write: bool,
mut needed_base: host::__wasi_rights_t,
mut needed_inheriting: host::__wasi_rights_t,
fs_flags: host::__wasi_fdflags_t,
) -> Result<FdEntry> {
use nix::errno::Errno;
use nix::fcntl::{openat, AtFlags, OFlag};
use nix::sys::stat::{fstatat, Mode, SFlag};
let mut nix_all_oflags = if read && write {
OFlag::O_RDWR
} else if write {
OFlag::O_WRONLY
} else {
OFlag::O_RDONLY
};
// on non-Capsicum systems, we always want nofollow
nix_all_oflags.insert(OFlag::O_NOFOLLOW);
// convert open flags
let nix_oflags = host_impl::nix_from_oflags(oflags);
nix_all_oflags.insert(nix_oflags);
if nix_all_oflags.contains(OFlag::O_CREAT) {
needed_base |= host::__WASI_RIGHT_PATH_CREATE_FILE;
}
if nix_all_oflags.contains(OFlag::O_TRUNC) {
needed_base |= host::__WASI_RIGHT_PATH_FILESTAT_SET_SIZE;
}
// convert file descriptor flags
nix_all_oflags.insert(host_impl::nix_from_fdflags(fs_flags));
if nix_all_oflags.contains(OFlag::O_DSYNC) {
needed_inheriting |= host::__WASI_RIGHT_FD_DATASYNC;
}
if nix_all_oflags.intersects(host_impl::O_RSYNC | OFlag::O_SYNC) {
needed_inheriting |= host::__WASI_RIGHT_FD_SYNC;
}
let dirfe = ctx.get_fd_entry(dirfd, needed_base, needed_inheriting)?;
let dirfd = match &*dirfe.fd_object.descriptor {
Descriptor::File(f) => f,
_ => return Err(host::__WASI_EBADF),
};
let (dir, path) = match path_get(dirfd, dirflags, path, nix_oflags.contains(OFlag::O_CREAT)) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
// Call openat. Use mode 0o666 so that we follow whatever the user's
// umask is, but don't set the executable flag, because it isn't yet
// meaningful for WASI programs to create executable files.
let new_fd = match openat(
dir.as_raw_fd(),
path.as_str(),
nix_all_oflags,
Mode::from_bits_truncate(0o666),
) {
Ok(fd) => fd,
Err(e) => {
match e.as_errno() {
// Linux returns ENXIO instead of EOPNOTSUPP when opening a socket
Some(Errno::ENXIO) => {
if let Ok(stat) =
fstatat(dir.as_raw_fd(), path.as_str(), AtFlags::AT_SYMLINK_NOFOLLOW)
{
if SFlag::from_bits_truncate(stat.st_mode).contains(SFlag::S_IFSOCK) {
return Err(host::__WASI_ENOTSUP);
} else {
return Err(host::__WASI_ENXIO);
}
} else {
return Err(host::__WASI_ENXIO);
}
}
// Linux returns ENOTDIR instead of ELOOP when using O_NOFOLLOW|O_DIRECTORY
// on a symlink.
Some(Errno::ENOTDIR)
if !(nix_all_oflags & (OFlag::O_NOFOLLOW | OFlag::O_DIRECTORY)).is_empty() =>
{
if let Ok(stat) =
fstatat(dir.as_raw_fd(), path.as_str(), AtFlags::AT_SYMLINK_NOFOLLOW)
{
if SFlag::from_bits_truncate(stat.st_mode).contains(SFlag::S_IFLNK) {
return Err(host::__WASI_ELOOP);
}
}
return Err(host::__WASI_ENOTDIR);
}
// FreeBSD returns EMLINK instead of ELOOP when using O_NOFOLLOW on
// a symlink.
Some(Errno::EMLINK) if !(nix_all_oflags & OFlag::O_NOFOLLOW).is_empty() => {
return Err(host::__WASI_ELOOP);
}
Some(e) => return Err(host_impl::errno_from_nix(e)),
None => return Err(host::__WASI_ENOSYS),
}
}
};
// Determine the type of the new file descriptor and which rights contradict with this type
let file = unsafe { File::from_raw_fd(new_fd) };
match determine_type_rights(&file) {
Err(e) => Err(e),
Ok((_ty, max_base, max_inheriting)) => {
let mut fe = FdEntry::from(file)?;
fe.rights_base &= max_base;
fe.rights_inheriting &= max_inheriting;
Ok(fe)
}
}
}
pub(crate) fn fd_readdir(
fd: &File,
host_buf: &mut [u8],
cookie: host::__wasi_dircookie_t,
) -> Result<usize> {
use libc::{dirent, fdopendir, memcpy, readdir_r, seekdir};
let host_buf_ptr = host_buf.as_mut_ptr();
let host_buf_len = host_buf.len();
let dir = unsafe { fdopendir(fd.as_raw_fd()) };
if dir.is_null() {
return Err(host_impl::errno_from_nix(nix::errno::Errno::last()));
}
if cookie != wasm32::__WASI_DIRCOOKIE_START {
unsafe { seekdir(dir, cookie as c_long) };
}
let mut entry_buf = unsafe { std::mem::uninitialized::<dirent>() };
let mut left = host_buf_len;
let mut host_buf_offset: usize = 0;
while left > 0 {
let mut host_entry: *mut dirent = std::ptr::null_mut();
let res = unsafe { readdir_r(dir, &mut entry_buf, &mut host_entry) };
if res == -1 {
return Err(host_impl::errno_from_nix(nix::errno::Errno::last()));
}
if host_entry.is_null() {
break;
}
let entry: wasm32::__wasi_dirent_t =
match host_impl::dirent_from_host(&unsafe { *host_entry }) {
Ok(entry) => entry,
Err(e) => return Err(e),
};
let name_len = entry.d_namlen as usize;
let required_space = std::mem::size_of_val(&entry) + name_len;
if required_space > left {
break;
}
unsafe {
let ptr = host_buf_ptr.offset(host_buf_offset as isize) as *mut c_void
as *mut wasm32::__wasi_dirent_t;
*ptr = entry;
}
host_buf_offset += std::mem::size_of_val(&entry);
let name_ptr = unsafe { *host_entry }.d_name.as_ptr();
unsafe {
memcpy(
host_buf_ptr.offset(host_buf_offset as isize) as *mut _,
name_ptr as *const _,
name_len,
)
};
host_buf_offset += name_len;
left -= required_space;
}
Ok(host_buf_len - left)
}
pub(crate) fn path_readlink(dirfd: &File, path: &str, buf: &mut [u8]) -> Result<usize> {
use nix::errno::Errno;
let (dir, path) = match path_get(dirfd, 0, path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let path_cstr = CString::new(path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
// Linux requires that the buffer size is positive, whereas POSIX does not.
// Use a fake buffer to store the results if the size is zero.
// TODO: instead of using raw libc::readlinkat call here, this should really
// be fixed in `nix` crate
let fakebuf: &mut [u8] = &mut [0];
let buf_len = buf.len();
let len = unsafe {
libc::readlinkat(
dir.as_raw_fd(),
path_cstr.as_ptr() as *const libc::c_char,
if buf_len == 0 {
fakebuf.as_mut_ptr()
} else {
buf.as_mut_ptr()
} as *mut libc::c_char,
if buf_len == 0 { fakebuf.len() } else { buf_len },
)
};
if len < 0 {
Err(host_impl::errno_from_nix(Errno::last()))
} else {
let len = len as usize;
Ok(if len < buf_len { len } else { buf_len })
}
}
pub(crate) fn path_rename(
old_dirfd: &File,
old_path: &str,
new_dirfd: &File,
new_path: &str,
) -> Result<()> {
use nix::libc::renameat;
let (old_dir, old_path) = match path_get(old_dirfd, 0, old_path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let (new_dir, new_path) = match path_get(new_dirfd, 0, new_path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let old_path_cstr = CString::new(old_path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
let new_path_cstr = CString::new(new_path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
let res = unsafe {
renameat(
old_dir.as_raw_fd(),
old_path_cstr.as_ptr(),
new_dir.as_raw_fd(),
new_path_cstr.as_ptr(),
)
};
if res != 0 {
Err(host_impl::errno_from_nix(nix::errno::Errno::last()))
} else {
Ok(())
}
}
pub(crate) fn fd_filestat_get(fd: &File) -> Result<host::__wasi_filestat_t> {
use nix::sys::stat::fstat;
match fstat(fd.as_raw_fd()) {
Err(e) => Err(host_impl::errno_from_nix(e.as_errno().unwrap())),
Ok(filestat) => Ok(host_impl::filestat_from_nix(filestat)?),
}
}
pub(crate) fn fd_filestat_set_times(
fd: &File,
st_atim: host::__wasi_timestamp_t,
mut st_mtim: host::__wasi_timestamp_t,
fst_flags: host::__wasi_fstflags_t,
) -> Result<()> {
use nix::sys::time::{TimeSpec, TimeValLike};
if fst_flags & host::__WASI_FILESTAT_SET_MTIM_NOW != 0 {
let clock_id = libc::CLOCK_REALTIME;
let mut timespec = unsafe { std::mem::uninitialized::<libc::timespec>() };
let res = unsafe { libc::clock_gettime(clock_id, &mut timespec as *mut libc::timespec) };
if res != 0 {
return Err(host_impl::errno_from_nix(nix::errno::Errno::last()));
}
let time_ns = match (timespec.tv_sec as host::__wasi_timestamp_t)
.checked_mul(1_000_000_000)
.and_then(|sec_ns| sec_ns.checked_add(timespec.tv_nsec as host::__wasi_timestamp_t))
{
Some(time_ns) => time_ns,
None => return Err(host::__WASI_EOVERFLOW),
};
st_mtim = time_ns;
}
let ts_atime = match fst_flags {
f if f & host::__WASI_FILESTAT_SET_ATIM_NOW != 0 => libc::timespec {
tv_sec: 0,
tv_nsec: utime_now(),
},
f if f & host::__WASI_FILESTAT_SET_ATIM != 0 => {
*TimeSpec::nanoseconds(st_atim as i64).as_ref()
}
_ => libc::timespec {
tv_sec: 0,
tv_nsec: utime_omit(),
},
};
let ts_mtime = *TimeSpec::nanoseconds(st_mtim as i64).as_ref();
let times = [ts_atime, ts_mtime];
let res = unsafe { libc::futimens(fd.as_raw_fd(), times.as_ptr()) };
if res != 0 {
Err(host_impl::errno_from_nix(nix::errno::Errno::last()))
} else {
Ok(())
}
}
pub(crate) fn fd_filestat_set_size(fd: &File, st_size: host::__wasi_filesize_t) -> Result<()> {
use nix::unistd::ftruncate;
ftruncate(fd.as_raw_fd(), st_size as off_t)
.map_err(|e| host_impl::errno_from_nix(e.as_errno().unwrap()))
}
pub(crate) fn path_filestat_get(
dirfd: &File,
dirflags: host::__wasi_lookupflags_t,
path: &str,
) -> Result<host::__wasi_filestat_t> {
use nix::fcntl::AtFlags;
use nix::sys::stat::fstatat;
let (dir, path) = match path_get(dirfd, dirflags, path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let atflags = match dirflags {
0 => AtFlags::empty(),
_ => AtFlags::AT_SYMLINK_NOFOLLOW,
};
match fstatat(dir.as_raw_fd(), path.as_str(), atflags) {
Err(e) => Err(host_impl::errno_from_nix(e.as_errno().unwrap())),
Ok(filestat) => Ok(host_impl::filestat_from_nix(filestat)?),
}
}
pub(crate) fn path_filestat_set_times(
dirfd: &File,
dirflags: host::__wasi_lookupflags_t,
path: &str,
st_atim: host::__wasi_timestamp_t,
mut st_mtim: host::__wasi_timestamp_t,
fst_flags: host::__wasi_fstflags_t,
) -> Result<()> {
use nix::sys::time::{TimeSpec, TimeValLike};
let (dir, path) = match path_get(dirfd, dirflags, &path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let atflags = match dirflags {
wasm32::__WASI_LOOKUP_SYMLINK_FOLLOW => 0,
_ => libc::AT_SYMLINK_NOFOLLOW,
};
if fst_flags & host::__WASI_FILESTAT_SET_MTIM_NOW != 0 {
let clock_id = libc::CLOCK_REALTIME;
let mut timespec = unsafe { std::mem::uninitialized::<libc::timespec>() };
let res = unsafe { libc::clock_gettime(clock_id, &mut timespec as *mut libc::timespec) };
if res != 0 {
return Err(host_impl::errno_from_nix(nix::errno::Errno::last()));
}
let time_ns = match (timespec.tv_sec as host::__wasi_timestamp_t)
.checked_mul(1_000_000_000)
.and_then(|sec_ns| sec_ns.checked_add(timespec.tv_nsec as host::__wasi_timestamp_t))
{
Some(time_ns) => time_ns,
None => return Err(host::__WASI_EOVERFLOW),
};
st_mtim = time_ns;
}
let ts_atime = match fst_flags {
f if f & host::__WASI_FILESTAT_SET_ATIM_NOW != 0 => libc::timespec {
tv_sec: 0,
tv_nsec: utime_now(),
},
f if f & host::__WASI_FILESTAT_SET_ATIM != 0 => {
*TimeSpec::nanoseconds(st_atim as i64).as_ref()
}
_ => libc::timespec {
tv_sec: 0,
tv_nsec: utime_omit(),
},
};
let ts_mtime = *TimeSpec::nanoseconds(st_mtim as i64).as_ref();
let times = [ts_atime, ts_mtime];
let path_cstr = CString::new(path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
let res =
unsafe { libc::utimensat(dir.as_raw_fd(), path_cstr.as_ptr(), times.as_ptr(), atflags) };
if res != 0 {
Err(host_impl::errno_from_nix(nix::errno::Errno::last()))
} else {
Ok(())
}
}
pub(crate) fn path_symlink(dirfd: &File, old_path: &str, new_path: &str) -> Result<()> {
use nix::libc::symlinkat;
let (dir, new_path) = match path_get(dirfd, 0, new_path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let old_path_cstr = CString::new(old_path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
let new_path_cstr = CString::new(new_path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
let res = unsafe {
symlinkat(
old_path_cstr.as_ptr(),
dir.as_raw_fd(),
new_path_cstr.as_ptr(),
)
};
if res != 0 {
Err(host_impl::errno_from_nix(nix::errno::Errno::last()))
} else {
Ok(())
}
}
pub(crate) fn path_unlink_file(dirfd: &File, path: &str) -> Result<()> {
use nix::errno;
use nix::libc::unlinkat;
let (dir, path) = match path_get(dirfd, 0, path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let path_cstr = CString::new(path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
// nix doesn't expose unlinkat() yet
match unsafe { unlinkat(dir.as_raw_fd(), path_cstr.as_ptr(), 0) } {
0 => Ok(()),
_ => {
let mut e = errno::Errno::last();
#[cfg(not(linux))]
{
// Non-Linux implementations may return EPERM when attempting to remove a
// directory without REMOVEDIR. While that's what POSIX specifies, it's
// less useful. Adjust this to EISDIR. It doesn't matter that this is not
// atomic with the unlinkat, because if the file is removed and a directory
// is created before fstatat sees it, we're racing with that change anyway
// and unlinkat could have legitimately seen the directory if the race had
// turned out differently.
use nix::fcntl::AtFlags;
use nix::sys::stat::{fstatat, SFlag};
if e == errno::Errno::EPERM {
if let Ok(stat) =
fstatat(dir.as_raw_fd(), path.as_str(), AtFlags::AT_SYMLINK_NOFOLLOW)
{
if SFlag::from_bits_truncate(stat.st_mode).contains(SFlag::S_IFDIR) {
e = errno::Errno::EISDIR;
}
} else {
e = errno::Errno::last();
}
}
}
Err(host_impl::errno_from_nix(e))
}
}
}
pub(crate) fn path_remove_directory(dirfd: &File, path: &str) -> Result<()> {
use nix::errno;
use nix::libc::{unlinkat, AT_REMOVEDIR};
let (dir, path) = match path_get(dirfd, 0, path, false) {
Ok((dir, path)) => (dir, path),
Err(e) => return Err(e),
};
let path_cstr = CString::new(path.as_bytes()).map_err(|_| host::__WASI_EILSEQ)?;
// nix doesn't expose unlinkat() yet
match unsafe { unlinkat(dir.as_raw_fd(), path_cstr.as_ptr(), AT_REMOVEDIR) } {
0 => Ok(()),
_ => Err(host_impl::errno_from_nix(errno::Errno::last())),
}
}