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Minor cleanups (bytecodealliance#49)
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* Use `use` imports consistently.

* Rename `flags_from_descriptor_flags` to `descriptor_flags_from_flags`.

* Rename `black_box` to `obscure`.

* Make some comments be doc comments.

* Use a hyphen for compound adjectives.

* Delete an unused variable.

* Update the name of `change-file-permissions-at`.

* Use generated typedefs instead of hard-coding u64.

* Use core::hint::black_box now that it's stabilized.
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@sunfishcode
sunfishcode authored Jan 6, 2023
1 parent 359a796 commit 3a49d68
Showing 1 changed file with 38 additions and 43 deletions.
81 changes: 38 additions & 43 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,11 +4,13 @@ use crate::bindings::{
wasi_clocks, wasi_default_clocks, wasi_exit, wasi_filesystem, wasi_logging, wasi_poll,
wasi_random, wasi_tcp,
};
use core::arch::wasm32::unreachable;
use core::arch::wasm32::{self, unreachable};
use core::cell::{Cell, RefCell, UnsafeCell};
use core::cmp::min;
use core::ffi::c_void;
use core::mem::{self, forget, replace, size_of, ManuallyDrop, MaybeUninit};
use core::ptr::{self, copy_nonoverlapping, null_mut};
use core::hint::black_box;
use core::mem::{align_of, forget, replace, size_of, ManuallyDrop, MaybeUninit};
use core::ptr::{self, null_mut};
use core::slice;
use wasi::*;
use wasi_poll::{WasiFuture, WasiStream};
Expand Down Expand Up @@ -302,7 +304,7 @@ pub extern "C" fn clock_res_get(id: Clockid, resolution: &mut Timestamp) -> Errn
}
CLOCKID_REALTIME => {
let res = wasi_clocks::wall_clock_resolution(state.default_wall_clock());
*resolution = u64::from(res.nanoseconds)
*resolution = Timestamp::from(res.nanoseconds)
.checked_add(res.seconds)
.and_then(|secs| secs.checked_mul(1_000_000_000))
.ok_or(ERRNO_OVERFLOW)?;
Expand All @@ -328,7 +330,7 @@ pub unsafe extern "C" fn clock_time_get(
}
CLOCKID_REALTIME => {
let res = wasi_clocks::wall_clock_now(state.default_wall_clock());
*time = u64::from(res.nanoseconds)
*time = Timestamp::from(res.nanoseconds)
.checked_add(res.seconds)
.and_then(|secs| secs.checked_mul(1_000_000_000))
.ok_or(ERRNO_OVERFLOW)?;
Expand Down Expand Up @@ -763,7 +765,8 @@ pub unsafe extern "C" fn fd_read(

// If this is a file, keep the current-position pointer up to date.
if let StreamType::File(file) = &streams.type_ {
file.position.set(file.position.get() + data.len() as u64);
file.position
.set(file.position.get() + data.len() as wasi_filesystem::Filesize);
}

let len = data.len();
Expand Down Expand Up @@ -799,7 +802,7 @@ pub unsafe extern "C" fn fd_readdir(
cookie: Dircookie,
bufused: *mut Size,
) -> Errno {
let mut buf = core::slice::from_raw_parts_mut(buf, buf_len);
let mut buf = slice::from_raw_parts_mut(buf, buf_len);
return State::with(|state| {
// First determine if there's an entry in the dirent cache to use. This
// is done to optimize the use case where a large directory is being
Expand Down Expand Up @@ -869,7 +872,7 @@ pub unsafe extern "C" fn fd_readdir(

// Copy a `dirent` describing this entry into the destination `buf`,
// truncating it if it doesn't fit entirely.
let bytes = core::slice::from_raw_parts(
let bytes = slice::from_raw_parts(
(&dirent as *const wasi::Dirent).cast::<u8>(),
size_of::<Dirent>(),
);
Expand All @@ -883,11 +886,7 @@ pub unsafe extern "C" fn fd_readdir(
// Note that this might be a 0-byte copy if the `dirent` was
// truncated or fit entirely into the destination.
let name_bytes_to_copy = buf.len().min(name.len());
core::ptr::copy_nonoverlapping(
name.as_ptr().cast(),
buf.as_mut_ptr(),
name_bytes_to_copy,
);
ptr::copy_nonoverlapping(name.as_ptr().cast(), buf.as_mut_ptr(), name_bytes_to_copy);

buf = &mut buf[name_bytes_to_copy..];

Expand All @@ -910,7 +909,7 @@ pub unsafe extern "C" fn fd_readdir(
state.dirent_cache.for_fd.set(fd);
state.dirent_cache.cookie.set(cookie - 1);
state.dirent_cache.cached_dirent.set(dirent);
std::ptr::copy(
ptr::copy(
name.as_ptr().cast::<u8>(),
(*state.dirent_cache.path_data.get()).as_mut_ptr() as *mut u8,
name.len(),
Expand Down Expand Up @@ -945,7 +944,7 @@ pub unsafe extern "C" fn fd_readdir(
let ptr = (*(*self.state.dirent_cache.path_data.get()).as_ptr())
.as_ptr()
.cast();
let buffer = core::slice::from_raw_parts(ptr, dirent.d_namlen as usize);
let buffer = slice::from_raw_parts(ptr, dirent.d_namlen as usize);
Ok((dirent, buffer))
});
}
Expand All @@ -969,7 +968,7 @@ pub unsafe extern "C" fn fd_readdir(
// this iterator since the data for the name lives within state.
let name = unsafe {
assert_eq!(name.as_ptr(), self.state.path_buf.get().cast());
core::slice::from_raw_parts(name.as_ptr().cast(), name.len())
slice::from_raw_parts(name.as_ptr().cast(), name.len())
};
Some(Ok((dirent, name)))
}
Expand Down Expand Up @@ -1031,8 +1030,8 @@ pub unsafe extern "C" fn fd_seek(
};
stream.input.set(None);
stream.output.set(None);
file.position.set(from as u64);
*newoffset = from as u64;
file.position.set(from as wasi_filesystem::Filesize);
*newoffset = from as wasi_filesystem::Filesize;
Ok(())
} else {
Err(ERRNO_SPIPE)
Expand Down Expand Up @@ -1092,7 +1091,8 @@ pub unsafe extern "C" fn fd_write(

// If this is a file, keep the current-position pointer up to date.
if let StreamType::File(file) = &streams.type_ {
file.position.set(file.position.get() + u64::from(bytes));
file.position
.set(file.position.get() + wasi_filesystem::Filesize::from(bytes));
}

*nwritten = bytes as usize;
Expand Down Expand Up @@ -1243,12 +1243,10 @@ pub unsafe extern "C" fn path_open(
let path = slice::from_raw_parts(path_ptr, path_len);
let at_flags = at_flags_from_lookupflags(dirflags);
let o_flags = o_flags_from_oflags(oflags);
let flags = flags_from_descriptor_flags(fs_rights_base, fdflags);
let flags = descriptor_flags_from_flags(fs_rights_base, fdflags);
let mode = wasi_filesystem::Mode::READABLE | wasi_filesystem::Mode::WRITEABLE;

State::with_mut(|state| {
let desc = state.get_mut(fd)?;

let file = state.get_dir(fd)?;
let result = wasi_filesystem::open_at(file.fd, at_flags, path, o_flags, flags, mode)?;
let desc = Descriptor::Streams(Streams {
Expand Down Expand Up @@ -1316,8 +1314,8 @@ pub unsafe extern "C" fn path_readlink(
if use_state_buf {
// Preview1 follows POSIX in truncating the returned path if it
// doesn't fit.
let len = core::cmp::min(path.len(), buf_len);
copy_nonoverlapping(path.as_ptr().cast(), buf, len);
let len = min(path.len(), buf_len);
ptr::copy_nonoverlapping(path.as_ptr().cast(), buf, len);
}

// The returned string's memory was allocated in `buf`, so don't separately
Expand Down Expand Up @@ -1429,6 +1427,8 @@ impl From<wasi_tcp::Error> for Errno {
use wasi_tcp::Error::*;

match error {
// Use a black box to prevent the optimizer from generating a
// lookup table, which would require a static initializer.
ConnectionAborted => black_box(ERRNO_CONNABORTED),
ConnectionRefused => ERRNO_CONNREFUSED,
ConnectionReset => ERRNO_CONNRESET,
Expand Down Expand Up @@ -1456,13 +1456,13 @@ pub unsafe extern "C" fn poll_oneoff(
// and the other to store the bool results.
//
// First, we assert that this is possible:
assert!(mem::align_of::<Event>() >= mem::align_of::<WasiFuture>());
assert!(mem::align_of::<WasiFuture>() >= mem::align_of::<u8>());
assert!(align_of::<Event>() >= align_of::<WasiFuture>());
assert!(align_of::<WasiFuture>() >= align_of::<u8>());
assert!(
unwrap(nsubscriptions.checked_mul(mem::size_of::<Event>()))
unwrap(nsubscriptions.checked_mul(size_of::<Event>()))
> unwrap(
unwrap(nsubscriptions.checked_mul(mem::size_of::<WasiFuture>()))
.checked_add(unwrap(nsubscriptions.checked_mul(mem::size_of::<u8>())))
unwrap(nsubscriptions.checked_mul(size_of::<WasiFuture>()))
.checked_add(unwrap(nsubscriptions.checked_mul(size_of::<u8>())))
)
);

Expand All @@ -1472,7 +1472,7 @@ pub unsafe extern "C" fn poll_oneoff(
State::with(|state| {
state.register_buffer(
results,
unwrap(nsubscriptions.checked_mul(mem::size_of::<bool>())),
unwrap(nsubscriptions.checked_mul(size_of::<bool>())),
);

let mut futures = Futures {
Expand Down Expand Up @@ -1552,7 +1552,7 @@ pub unsafe extern "C" fn poll_oneoff(

assert!(vec.len() == nsubscriptions);
assert_eq!(vec.as_ptr(), results);
mem::forget(vec);
forget(vec);

drop(futures);

Expand Down Expand Up @@ -1746,7 +1746,7 @@ fn o_flags_from_oflags(flags: Oflags) -> wasi_filesystem::OFlags {
o_flags
}

fn flags_from_descriptor_flags(
fn descriptor_flags_from_flags(
rights: Rights,
fdflags: Fdflags,
) -> wasi_filesystem::DescriptorFlags {
Expand Down Expand Up @@ -1776,6 +1776,8 @@ impl From<wasi_filesystem::Errno> for Errno {
#[inline(never)] // Disable inlining as this is bulky and relatively cold.
fn from(err: wasi_filesystem::Errno) -> Errno {
match err {
// Use a black box to prevent the optimizer from generating a
// lookup table, which would require a static initializer.
wasi_filesystem::Errno::Toobig => black_box(ERRNO_2BIG),
wasi_filesystem::Errno::Access => ERRNO_ACCES,
wasi_filesystem::Errno::Addrinuse => ERRNO_ADDRINUSE,
Expand Down Expand Up @@ -1867,13 +1869,6 @@ impl From<wasi_filesystem::DescriptorType> for wasi::Filetype {
}
}

// A black box to prevent the optimizer from generating a lookup table
// from the match above, which would require a static initializer.
fn black_box(x: Errno) -> Errno {
core::sync::atomic::compiler_fence(core::sync::atomic::Ordering::SeqCst);
x
}

#[repr(C)]
enum Descriptor {
/// A closed descriptor, holding a reference to the previous closed
Expand Down Expand Up @@ -1986,7 +1981,7 @@ struct File {
fd: wasi_filesystem::Descriptor,

/// The current-position pointer.
position: Cell<u64>,
position: Cell<wasi_filesystem::Filesize>,
}

const PAGE_SIZE: usize = 65536;
Expand Down Expand Up @@ -2156,7 +2151,7 @@ impl State {

#[cold]
fn new() -> &'static RefCell<State> {
let grew = core::arch::wasm32::memory_grow(0, 1);
let grew = wasm32::memory_grow(0, 1);
if grew == usize::MAX {
unreachable();
}
Expand Down Expand Up @@ -2222,7 +2217,7 @@ impl State {

fn descriptors(&self) -> &[Descriptor] {
unsafe {
core::slice::from_raw_parts(
slice::from_raw_parts(
self.descriptors.as_ptr().cast(),
unwrap_result(usize::try_from(self.ndescriptors)),
)
Expand All @@ -2231,7 +2226,7 @@ impl State {

fn descriptors_mut(&mut self) -> &mut [Descriptor] {
unsafe {
core::slice::from_raw_parts_mut(
slice::from_raw_parts_mut(
self.descriptors.as_mut_ptr().cast(),
unwrap_result(usize::try_from(self.ndescriptors)),
)
Expand Down

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