Files
wasmtime/wasmtime-wasi/src/translate.rs
Dan Gohman b2fefe7714 WASI prototype design, implementation, and documentation.
This adds documents describing the WASI Core API, and an implementation in
Wasmtime.
2019-03-27 10:58:43 -07:00

509 lines
15 KiB
Rust

use cast;
use cast::From as _0;
use host;
use std::mem::{align_of, size_of};
use std::slice;
use wasm32;
use wasmtime_runtime::{Export, VMContext};
/// Translate a wasm pointer into a native pointer.
///
/// This is unsafe due to trusting the contents of vmctx. The pointer result
/// is bounds and alignment checked.
unsafe fn decode_ptr(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: usize,
align: usize,
) -> Result<*mut u8, host::__wasi_errno_t> {
match vmctx.lookup_global_export("memory") {
Some(Export::Memory {
definition,
vmctx: _,
memory: _,
}) => {
if len > 0 {
// Check for overflow within the access.
let last = match (ptr as usize).checked_add(len - 1) {
Some(sum) => sum,
None => {
println!("!!! overflow");
return Err(host::__WASI_EFAULT as host::__wasi_errno_t);
}
};
// Check for out of bounds.
if last >= (*definition).current_length {
println!("!!! out of bounds");
return Err(host::__WASI_EFAULT as host::__wasi_errno_t);
}
}
// Check alignment.
if (ptr as usize) % align != 0 {
println!("!!! bad alignment: {} % {}", ptr, align);
return Err(host::__WASI_EINVAL as host::__wasi_errno_t);
}
// Ok, translate the address.
Ok((((*definition).base as usize) + (ptr as usize)) as *mut u8)
}
// No export named "__wasi_memory", or the export isn't a memory.
// FIXME: Is EINVAL the best code here?
x => {
println!(
"!!! no export named __wasi_memory, or the export isn't a mem: {:?}",
x
);
Err(host::__WASI_EINVAL as host::__wasi_errno_t)
}
}
}
unsafe fn decode_ptr_to<T>(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
) -> Result<*mut T, host::__wasi_errno_t> {
decode_ptr(vmctx, ptr, size_of::<T>(), align_of::<T>()).map(|ptr| ptr as *mut T)
}
unsafe fn decode_pointee<T>(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
) -> Result<T, host::__wasi_errno_t> {
let ptr = decode_ptr_to::<T>(vmctx, ptr)?;
// Size and alignment are checked by `decode_ptr_to`.
Ok(ptr.read())
}
pub unsafe fn encode_pointee<T>(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
t: T,
) -> Result<(), host::__wasi_errno_t> {
let ptr = decode_ptr_to::<T>(vmctx, ptr)?;
// Size and alignment are checked by `decode_ptr_to`.
Ok(ptr.write(t))
}
pub unsafe fn decode_slice_of<T>(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: wasm32::size_t,
) -> Result<(*mut T, usize), host::__wasi_errno_t> {
let len = cast::usize(len);
let ptr = decode_ptr(
vmctx,
ptr,
size_of::<T>().checked_mul(len).unwrap(),
align_of::<T>(),
)? as *mut T;
Ok((ptr, len))
}
pub fn decode_usize(len: wasm32::size_t) -> usize {
cast::usize(len)
}
pub fn encode_usize(len: usize) -> wasm32::size_t {
cast::u32(len).unwrap()
}
pub unsafe fn decode_filesize(filesize: wasm32::__wasi_filesize_t) -> host::__wasi_filesize_t {
filesize
}
pub fn decode_fd(fd: wasm32::__wasi_fd_t) -> host::__wasi_fd_t {
fd
}
pub fn decode_filedelta(filedelta: wasm32::__wasi_filedelta_t) -> host::__wasi_filedelta_t {
filedelta
}
pub fn decode_whence(whence: wasm32::__wasi_whence_t) -> host::__wasi_whence_t {
whence
}
pub fn decode_clockid(clockid: wasm32::__wasi_clockid_t) -> host::__wasi_clockid_t {
clockid
}
pub fn decode_timestamp(timestamp: wasm32::__wasi_timestamp_t) -> host::__wasi_timestamp_t {
timestamp
}
pub fn decode_exitcode(exitcode: wasm32::__wasi_exitcode_t) -> host::__wasi_exitcode_t {
exitcode
}
pub fn decode_lookupflags(lookupflags: wasm32::__wasi_lookupflags_t) -> host::__wasi_lookupflags_t {
lookupflags
}
pub fn decode_roflags(roflags: wasm32::__wasi_roflags_t) -> host::__wasi_roflags_t {
roflags
}
pub fn decode_oflags(oflags: wasm32::__wasi_oflags_t) -> host::__wasi_oflags_t {
oflags
}
pub fn decode_advice(advice: wasm32::__wasi_advice_t) -> host::__wasi_advice_t {
advice
}
pub fn decode_dircookie(dircookie: wasm32::__wasi_dircookie_t) -> host::__wasi_dircookie_t {
dircookie
}
pub fn decode_preopentype(preopentype: wasm32::__wasi_preopentype_t) -> host::__wasi_preopentype_t {
preopentype
}
pub fn encode_preopentype(preopentype: host::__wasi_preopentype_t) -> wasm32::__wasi_preopentype_t {
preopentype
}
pub fn decode_filetype(filetype: wasm32::__wasi_filetype_t) -> host::__wasi_filetype_t {
filetype
}
pub fn encode_filetype(filetype: host::__wasi_filetype_t) -> wasm32::__wasi_filetype_t {
filetype
}
pub fn decode_fstflags(fstflags: wasm32::__wasi_fstflags_t) -> host::__wasi_fstflags_t {
fstflags
}
#[allow(dead_code)]
pub fn encode_fstflags(fstflags: host::__wasi_fstflags_t) -> wasm32::__wasi_fstflags_t {
fstflags
}
pub fn decode_fdflags(fdflags: wasm32::__wasi_fdflags_t) -> host::__wasi_fdflags_t {
fdflags
}
pub fn encode_fdflags(fdflags: host::__wasi_fdflags_t) -> wasm32::__wasi_fdflags_t {
fdflags
}
pub fn decode_sdflags(sdflags: wasm32::__wasi_sdflags_t) -> host::__wasi_sdflags_t {
sdflags
}
pub fn decode_rights(rights: wasm32::__wasi_rights_t) -> host::__wasi_rights_t {
rights
}
pub fn encode_rights(rights: host::__wasi_rights_t) -> wasm32::__wasi_rights_t {
rights
}
pub fn decode_riflags(riflags: wasm32::__wasi_riflags_t) -> host::__wasi_riflags_t {
riflags
}
pub fn decode_siflags(siflags: wasm32::__wasi_siflags_t) -> host::__wasi_siflags_t {
siflags
}
pub unsafe fn decode_char_slice(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: wasm32::size_t,
) -> Result<(*mut host::char, usize), host::__wasi_errno_t> {
decode_slice_of::<wasm32::char>(vmctx, ptr, len)
}
pub unsafe fn decode_charstar_slice(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
count: wasm32::size_t,
) -> Result<(*mut wasm32::uintptr_t, usize), host::__wasi_errno_t> {
decode_slice_of::<wasm32::uintptr_t>(vmctx, ptr, count)
}
pub unsafe fn encode_charstar_slice(
ptr: *mut wasm32::uintptr_t,
host_ptr: *mut *mut libc::c_char,
count: usize,
guest_base: wasm32::uintptr_t,
host_base: *mut libc::c_char,
) {
for i in 0..count {
let host = host_ptr.add(i).read();
let guest = if host.is_null() {
0
} else {
guest_base + (host as usize - host_base as usize) as wasm32::uintptr_t
};
ptr.add(i).write(guest);
}
}
pub unsafe fn decode_ciovec(
vmctx: &mut VMContext,
ciovec: &wasm32::__wasi_ciovec_t,
) -> Result<host::__wasi_ciovec_t, host::__wasi_errno_t> {
let len = cast::usize(ciovec.buf_len);
Ok(host::__wasi_ciovec_t {
buf: decode_ptr(vmctx, ciovec.buf, len, 1)? as *const host::void,
buf_len: len,
})
}
pub unsafe fn decode_iovec(
vmctx: &mut VMContext,
iovec: &wasm32::__wasi_iovec_t,
) -> Result<host::__wasi_iovec_t, host::__wasi_errno_t> {
let len = cast::usize(iovec.buf_len);
Ok(host::__wasi_iovec_t {
buf: decode_ptr(vmctx, iovec.buf, len, 1)? as *mut host::void,
buf_len: len,
})
}
pub unsafe fn decode_ciovec_slice(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: wasm32::size_t,
) -> Result<Vec<host::__wasi_ciovec_t>, host::__wasi_errno_t> {
let slice = decode_slice_of::<wasm32::__wasi_ciovec_t>(vmctx, ptr, len)?;
let slice = slice::from_raw_parts(slice.0, slice.1);
slice.iter().map(|iov| decode_ciovec(vmctx, iov)).collect()
}
pub unsafe fn decode_iovec_slice(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: wasm32::size_t,
) -> Result<Vec<host::__wasi_iovec_t>, host::__wasi_errno_t> {
let slice = decode_slice_of::<wasm32::__wasi_iovec_t>(vmctx, ptr, len)?;
let slice = slice::from_raw_parts(slice.0, slice.1);
slice.iter().map(|iov| decode_iovec(vmctx, iov)).collect()
}
pub unsafe fn decode_subscription(
_vmctx: &mut VMContext,
_subscription: wasm32::__wasi_subscription_t,
) -> host::__wasi_subscription_t {
unimplemented!("decode_subscription");
}
pub unsafe fn decode_subscription_slice(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: wasm32::size_t,
) -> Result<Vec<host::__wasi_subscription_t>, host::__wasi_errno_t> {
let slice = decode_slice_of::<wasm32::__wasi_subscription_t>(vmctx, ptr, len)?;
let slice = slice::from_raw_parts(slice.0, slice.1);
Ok(slice
.iter()
.map(|subscription| decode_subscription(vmctx, *subscription))
.collect())
}
pub unsafe fn decode_event(
_vmctx: &mut VMContext,
_event: wasm32::__wasi_event_t,
) -> host::__wasi_event_t {
unimplemented!("decode_event");
}
pub unsafe fn decode_event_slice(
vmctx: &mut VMContext,
ptr: wasm32::uintptr_t,
len: wasm32::size_t,
) -> Result<Vec<host::__wasi_event_t>, host::__wasi_errno_t> {
let slice = decode_slice_of::<wasm32::__wasi_event_t>(vmctx, ptr, len)?;
let slice = slice::from_raw_parts(slice.0, slice.1);
Ok(slice
.iter()
.map(|event| decode_event(vmctx, *event))
.collect())
}
pub unsafe fn encode_event_slice(
_vmctx: &mut VMContext,
_ptr: wasm32::uintptr_t,
_host: Vec<host::__wasi_event_t>,
) -> Result<(), host::__wasi_errno_t> {
unimplemented!("encode_event_slice");
}
pub unsafe fn decode_fd_byref(
vmctx: &mut VMContext,
fd_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_fd_t, host::__wasi_errno_t> {
decode_pointee::<wasm32::__wasi_fd_t>(vmctx, fd_ptr).map(decode_fd)
}
pub unsafe fn encode_fd_byref(
vmctx: &mut VMContext,
fd_ptr: wasm32::uintptr_t,
fd: host::__wasi_fd_t,
) -> Result<(), host::__wasi_errno_t> {
encode_pointee::<wasm32::__wasi_fd_t>(vmctx, fd_ptr, wasm32::size_t::cast(fd))
}
pub unsafe fn decode_timestamp_byref(
vmctx: &mut VMContext,
timestamp_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_timestamp_t, host::__wasi_errno_t> {
decode_pointee::<wasm32::__wasi_timestamp_t>(vmctx, timestamp_ptr)
.map(host::__wasi_timestamp_t::cast)
}
pub unsafe fn encode_timestamp_byref(
vmctx: &mut VMContext,
timestamp_ptr: wasm32::uintptr_t,
host_timestamp: host::__wasi_timestamp_t,
) -> Result<(), host::__wasi_errno_t> {
encode_pointee::<wasm32::__wasi_timestamp_t>(
vmctx,
timestamp_ptr,
wasm32::__wasi_timestamp_t::cast(host_timestamp),
)
}
pub unsafe fn decode_filesize_byref(
vmctx: &mut VMContext,
filesize_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_filesize_t, host::__wasi_errno_t> {
decode_pointee::<wasm32::__wasi_filesize_t>(vmctx, filesize_ptr)
.map(host::__wasi_filesize_t::cast)
}
pub unsafe fn encode_filesize_byref(
vmctx: &mut VMContext,
filesize_ptr: wasm32::uintptr_t,
host_filesize: host::__wasi_filesize_t,
) -> Result<(), host::__wasi_errno_t> {
encode_pointee::<wasm32::__wasi_filesize_t>(
vmctx,
filesize_ptr,
wasm32::__wasi_filesize_t::cast(host_filesize),
)
}
pub unsafe fn decode_roflags_byref(
vmctx: &mut VMContext,
roflags_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_roflags_t, host::__wasi_errno_t> {
decode_pointee::<wasm32::__wasi_roflags_t>(vmctx, roflags_ptr).map(decode_roflags)
}
pub unsafe fn encode_roflags_byref(
vmctx: &mut VMContext,
roflags_ptr: wasm32::uintptr_t,
host_roflags: host::__wasi_roflags_t,
) -> Result<(), host::__wasi_errno_t> {
encode_pointee::<wasm32::__wasi_roflags_t>(
vmctx,
roflags_ptr,
wasm32::__wasi_roflags_t::cast(host_roflags),
)
}
pub unsafe fn decode_usize_byref(
vmctx: &mut VMContext,
usize_ptr: wasm32::uintptr_t,
) -> Result<usize, host::__wasi_errno_t> {
decode_pointee::<wasm32::size_t>(vmctx, usize_ptr).map(decode_usize)
}
pub unsafe fn encode_usize_byref(
vmctx: &mut VMContext,
usize_ptr: wasm32::uintptr_t,
host_usize: usize,
) -> Result<(), host::__wasi_errno_t> {
encode_pointee::<wasm32::size_t>(vmctx, usize_ptr, wasm32::size_t::cast(host_usize).unwrap())
}
pub unsafe fn decode_prestat_byref(
vmctx: &mut VMContext,
prestat_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_prestat_t, host::__wasi_errno_t> {
let wasm32_prestat = decode_pointee::<wasm32::__wasi_prestat_t>(vmctx, prestat_ptr)?;
Ok(host::__wasi_prestat_t {
pr_type: decode_preopentype(wasm32_prestat.pr_type),
u: host::__wasi_prestat_t___wasi_prestat_u {
dir: host::__wasi_prestat_t___wasi_prestat_u___wasi_prestat_u_dir_t {
pr_name_len: decode_usize(wasm32_prestat.u.dir.pr_name_len),
},
},
})
}
pub unsafe fn encode_prestat_byref(
vmctx: &mut VMContext,
prestat_ptr: wasm32::uintptr_t,
host_prestat: host::__wasi_prestat_t,
) -> Result<(), host::__wasi_errno_t> {
let wasm32_prestat = wasm32::__wasi_prestat_t {
pr_type: encode_preopentype(host_prestat.pr_type),
u: wasm32::__wasi_prestat_t___wasi_prestat_u {
dir: wasm32::__wasi_prestat_t___wasi_prestat_u___wasi_prestat_u_dir_t {
pr_name_len: encode_usize(host_prestat.u.dir.pr_name_len),
},
},
};
encode_pointee::<wasm32::__wasi_prestat_t>(vmctx, prestat_ptr, wasm32_prestat)
}
pub unsafe fn decode_fdstat_byref(
vmctx: &mut VMContext,
fdstat_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_fdstat_t, host::__wasi_errno_t> {
let wasm32_fdstat = decode_pointee::<wasm32::__wasi_fdstat_t>(vmctx, fdstat_ptr)?;
Ok(host::__wasi_fdstat_t {
fs_filetype: decode_filetype(wasm32_fdstat.fs_filetype),
fs_flags: decode_fdflags(wasm32_fdstat.fs_flags),
fs_rights_base: decode_rights(wasm32_fdstat.fs_rights_base),
fs_rights_inheriting: decode_rights(wasm32_fdstat.fs_rights_inheriting),
})
}
pub unsafe fn encode_fdstat_byref(
vmctx: &mut VMContext,
fdstat_ptr: wasm32::uintptr_t,
host_fdstat: host::__wasi_fdstat_t,
) -> Result<(), host::__wasi_errno_t> {
let wasm32_fdstat = wasm32::__wasi_fdstat_t {
fs_filetype: encode_filetype(host_fdstat.fs_filetype),
fs_flags: encode_fdflags(host_fdstat.fs_flags),
__bindgen_padding_0: 0,
fs_rights_base: encode_rights(host_fdstat.fs_rights_base),
fs_rights_inheriting: encode_rights(host_fdstat.fs_rights_inheriting),
};
encode_pointee::<wasm32::__wasi_fdstat_t>(vmctx, fdstat_ptr, wasm32_fdstat)
}
pub unsafe fn decode_filestat_byref(
_vmctx: &mut VMContext,
_filestat_ptr: wasm32::uintptr_t,
) -> Result<host::__wasi_filestat_t, host::__wasi_errno_t> {
unimplemented!("decode_filestat_byref");
}
pub unsafe fn encode_filestat_byref(
_vmctx: &mut VMContext,
_filestat_ptr: wasm32::uintptr_t,
_host_filestat: host::__wasi_filestat_t,
) -> Result<(), host::__wasi_errno_t> {
unimplemented!("encode_filestat_byref");
}
pub fn encode_errno(e: host::__wasi_errno_t) -> wasm32::__wasi_errno_t {
assert!(e <= wasm32::__WASI_ENOTCAPABLE);
e
}