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Reduce boilerplate in wasmtime-wasi (#707)

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This commit uses the `*.witx` files describing the current wasi API to
reduce the boilerplate used to define implementations in the
`wasmtime-wasi` crate. Eventually I'd like to remove lots of boilerplate
in the `wasi-common` crate too, but this should at least be a good start!

The boilerplate removed here is:

* No need to list each function to add it to the
  `wasmtime_runtime::Module` being created

* No need to list the signature of the function in a separate
  `syscalls.rs` file.

Instead the `*.witx` file is processed in a single-use macro inside the
`wasmtime-wasi` crate. This macro uses the signatures known from
`*.witx` to automatically register with the right type in the wasm
module as well as define a wrapper that the wasm module will call into.
Functionally this is all the same as before, it's just defined in a
different way now!

The shim generated by this macro which wasmtime calls into only uses
`i32`/`i64`/etc wasm types, and it internally uses `as` casts to convert
to the right wasi types when delegating into the `wasi-common` crate.

One change was necessary to get this implemented, however. The functions
in `wasi-common` sometimes took `WasiCtx` and sometimes took a slice of
memory. After this PR they uniformly all require both `WasiCtx` and
memory so the wrappers can be auto-generated. The arguments are ignored
if they weren't previously required.
This commit is contained in:
Alex Crichton
2019-12-16 16:37:20 -06:00
committed by GitHub
parent c2ba419409
commit cc4be18119
13 changed files with 343 additions and 1067 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
crates/wasi-common/src/fs/dir.rs
View File

@@ -199,7 +199,7 @@ impl<'ctx> Drop for Dir<'ctx> {
// the file descriptor was closed or not, and if we retried (for
// something like EINTR), we might close another valid file descriptor
// opened after we closed ours.
let _ = unsafe { hostcalls::fd_close(self.ctx, self.fd) };
let _ = unsafe { hostcalls::fd_close(self.ctx, &mut [], self.fd) };
}
}

10
crates/wasi-common/src/fs/file.rs
View File

@@ -35,7 +35,7 @@ impl<'ctx> File<'ctx> {
///
/// [`std::fs::File::sync_all`]: https://doc.rust-lang.org/std/fs/struct.File.html#method.sync_all
pub fn sync_all(&self) -> io::Result<()> {
wasi_errno_to_io_error(unsafe { hostcalls::fd_sync(self.ctx, self.fd) })
wasi_errno_to_io_error(unsafe { hostcalls::fd_sync(self.ctx, &mut [], self.fd) })
}
/// This function is similar to `sync_all`, except that it may not synchronize
@@ -45,7 +45,7 @@ impl<'ctx> File<'ctx> {
///
/// [`std::fs::File::sync_data`]: https://doc.rust-lang.org/std/fs/struct.File.html#method.sync_data
pub fn sync_data(&self) -> io::Result<()> {
wasi_errno_to_io_error(unsafe { hostcalls::fd_datasync(self.ctx, self.fd) })
wasi_errno_to_io_error(unsafe { hostcalls::fd_datasync(self.ctx, &mut [], self.fd) })
}
/// Truncates or extends the underlying file, updating the size of this file
@@ -55,7 +55,9 @@ impl<'ctx> File<'ctx> {
///
/// [`std::fs::File::set_len`]: https://doc.rust-lang.org/std/fs/struct.File.html#method.set_len
pub fn set_len(&self, size: u64) -> io::Result<()> {
wasi_errno_to_io_error(unsafe { hostcalls::fd_filestat_set_size(self.ctx, self.fd, size) })
wasi_errno_to_io_error(unsafe {
hostcalls::fd_filestat_set_size(self.ctx, &mut [], self.fd, size)
})
}
/// Queries metadata about the underlying file.
@@ -75,7 +77,7 @@ impl<'ctx> Drop for File<'ctx> {
// the file descriptor was closed or not, and if we retried (for
// something like EINTR), we might close another valid file descriptor
// opened after we closed ours.
let _ = unsafe { hostcalls::fd_close(self.ctx, self.fd) };
let _ = unsafe { hostcalls::fd_close(self.ctx, &mut [], self.fd) };
}
}

13
crates/wasi-common/src/hostcalls/fs.rs
View File

@@ -3,9 +3,9 @@ use crate::ctx::WasiCtx;
use crate::{hostcalls_impl, wasi, wasi32};
hostcalls! {
pub unsafe fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasi::__wasi_fd_t,) -> wasi::__wasi_errno_t;
pub unsafe fn fd_close(wasi_ctx: &mut WasiCtx, memory: &mut [u8], fd: wasi::__wasi_fd_t,) -> wasi::__wasi_errno_t;
pub unsafe fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasi::__wasi_fd_t,) -> wasi::__wasi_errno_t;
pub unsafe fn fd_datasync(wasi_ctx: &WasiCtx, memory: &mut [u8], fd: wasi::__wasi_fd_t,) -> wasi::__wasi_errno_t;
pub unsafe fn fd_pread(
wasi_ctx: &WasiCtx,
@@ -38,6 +38,7 @@ hostcalls! {
pub unsafe fn fd_renumber(
wasi_ctx: &mut WasiCtx,
memory: &mut [u8],
from: wasi::__wasi_fd_t,
to: wasi::__wasi_fd_t,
) -> wasi::__wasi_errno_t;
@@ -67,18 +68,20 @@ hostcalls! {
pub unsafe fn fd_fdstat_set_flags(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
fdflags: wasi::__wasi_fdflags_t,
) -> wasi::__wasi_errno_t;
pub unsafe fn fd_fdstat_set_rights(
wasi_ctx: &mut WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
fs_rights_base: wasi::__wasi_rights_t,
fs_rights_inheriting: wasi::__wasi_rights_t,
) -> wasi::__wasi_errno_t;
pub unsafe fn fd_sync(wasi_ctx: &WasiCtx, fd: wasi::__wasi_fd_t,) -> wasi::__wasi_errno_t;
pub unsafe fn fd_sync(wasi_ctx: &WasiCtx, memory: &mut [u8], fd: wasi::__wasi_fd_t,) -> wasi::__wasi_errno_t;
pub unsafe fn fd_write(
wasi_ctx: &mut WasiCtx,
@@ -91,6 +94,7 @@ hostcalls! {
pub unsafe fn fd_advise(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
offset: wasi::__wasi_filesize_t,
len: wasi::__wasi_filesize_t,
@@ -99,6 +103,7 @@ hostcalls! {
pub unsafe fn fd_allocate(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
offset: wasi::__wasi_filesize_t,
len: wasi::__wasi_filesize_t,
@@ -179,6 +184,7 @@ hostcalls! {
pub unsafe fn fd_filestat_set_times(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
st_atim: wasi::__wasi_timestamp_t,
st_mtim: wasi::__wasi_timestamp_t,
@@ -187,6 +193,7 @@ hostcalls! {
pub unsafe fn fd_filestat_set_size(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
fd: wasi::__wasi_fd_t,
st_size: wasi::__wasi_filesize_t,
) -> wasi::__wasi_errno_t;

10
crates/wasi-common/src/hostcalls/misc.rs
View File

@@ -5,7 +5,7 @@ use log::trace;
use wasi_common_cbindgen::wasi_common_cbindgen;
#[wasi_common_cbindgen]
pub unsafe fn proc_exit(rval: wasi::__wasi_exitcode_t) {
pub unsafe fn proc_exit(_wasi_ctx: &WasiCtx, _memory: &mut [u8], rval: wasi::__wasi_exitcode_t) {
trace!("proc_exit(rval={:?})", rval);
// TODO: Rather than call std::process::exit here, we should trigger a
// stack unwind similar to a trap.
@@ -51,18 +51,21 @@ hostcalls! {
) -> wasi::__wasi_errno_t;
pub unsafe fn random_get(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
buf_ptr: wasi32::uintptr_t,
buf_len: wasi32::size_t,
) -> wasi::__wasi_errno_t;
pub unsafe fn clock_res_get(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
clock_id: wasi::__wasi_clockid_t,
resolution_ptr: wasi32::uintptr_t,
) -> wasi::__wasi_errno_t;
pub unsafe fn clock_time_get(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
clock_id: wasi::__wasi_clockid_t,
precision: wasi::__wasi_timestamp_t,
@@ -78,5 +81,8 @@ hostcalls! {
nevents: wasi32::uintptr_t,
) -> wasi::__wasi_errno_t;
pub unsafe fn sched_yield() -> wasi::__wasi_errno_t;
pub unsafe fn sched_yield(
wasi_ctx: &WasiCtx,
memory: &mut [u8],
) -> wasi::__wasi_errno_t;
}

25
crates/wasi-common/src/hostcalls_impl/fs.rs
View File

@@ -14,7 +14,11 @@ use std::fs::File;
use std::io::{self, Read, Seek, SeekFrom, Write};
use std::time::{Duration, SystemTime, UNIX_EPOCH};
pub(crate) unsafe fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasi::__wasi_fd_t) -> Result<()> {
pub(crate) unsafe fn fd_close(
wasi_ctx: &mut WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
) -> Result<()> {
trace!("fd_close(fd={:?})", fd);
if let Ok(fe) = wasi_ctx.get_fd_entry(fd) {
@@ -28,7 +32,11 @@ pub(crate) unsafe fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasi::__wasi_fd_t) ->
Ok(())
}
pub(crate) unsafe fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasi::__wasi_fd_t) -> Result<()> {
pub(crate) unsafe fn fd_datasync(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
) -> Result<()> {
trace!("fd_datasync(fd={:?})", fd);
let fd = wasi_ctx
@@ -173,6 +181,7 @@ pub(crate) unsafe fn fd_read(
pub(crate) unsafe fn fd_renumber(
wasi_ctx: &mut WasiCtx,
_memory: &mut [u8],
from: wasi::__wasi_fd_t,
to: wasi::__wasi_fd_t,
) -> Result<()> {
@@ -289,6 +298,7 @@ pub(crate) unsafe fn fd_fdstat_get(
pub(crate) unsafe fn fd_fdstat_set_flags(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
fdflags: wasi::__wasi_fdflags_t,
) -> Result<()> {
@@ -304,6 +314,7 @@ pub(crate) unsafe fn fd_fdstat_set_flags(
pub(crate) unsafe fn fd_fdstat_set_rights(
wasi_ctx: &mut WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
fs_rights_base: wasi::__wasi_rights_t,
fs_rights_inheriting: wasi::__wasi_rights_t,
@@ -327,7 +338,11 @@ pub(crate) unsafe fn fd_fdstat_set_rights(
Ok(())
}
pub(crate) unsafe fn fd_sync(wasi_ctx: &WasiCtx, fd: wasi::__wasi_fd_t) -> Result<()> {
pub(crate) unsafe fn fd_sync(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
) -> Result<()> {
trace!("fd_sync(fd={:?})", fd);
let fd = wasi_ctx
@@ -381,6 +396,7 @@ pub(crate) unsafe fn fd_write(
pub(crate) unsafe fn fd_advise(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
offset: wasi::__wasi_filesize_t,
len: wasi::__wasi_filesize_t,
@@ -404,6 +420,7 @@ pub(crate) unsafe fn fd_advise(
pub(crate) unsafe fn fd_allocate(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
offset: wasi::__wasi_filesize_t,
len: wasi::__wasi_filesize_t,
@@ -687,6 +704,7 @@ pub(crate) unsafe fn fd_filestat_get(
pub(crate) unsafe fn fd_filestat_set_times(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
st_atim: wasi::__wasi_timestamp_t,
st_mtim: wasi::__wasi_timestamp_t,
@@ -746,6 +764,7 @@ pub(crate) fn fd_filestat_set_times_impl(
pub(crate) unsafe fn fd_filestat_set_size(
wasi_ctx: &WasiCtx,
_memory: &mut [u8],
fd: wasi::__wasi_fd_t,
st_size: wasi::__wasi_filesize_t,
) -> Result<()> {

5
crates/wasi-common/src/hostcalls_impl/misc.rs
View File

@@ -128,6 +128,7 @@ pub(crate) fn environ_sizes_get(
}
pub(crate) fn random_get(
_wasi_ctx: &WasiCtx,
memory: &mut [u8],
buf_ptr: wasi32::uintptr_t,
buf_len: wasi32::size_t,
@@ -143,6 +144,7 @@ pub(crate) fn random_get(
}
pub(crate) fn clock_res_get(
_wasi_ctx: &WasiCtx,
memory: &mut [u8],
clock_id: wasi::__wasi_clockid_t,
resolution_ptr: wasi32::uintptr_t,
@@ -161,6 +163,7 @@ pub(crate) fn clock_res_get(
}
pub(crate) fn clock_time_get(
_wasi_ctx: &WasiCtx,
memory: &mut [u8],
clock_id: wasi::__wasi_clockid_t,
precision: wasi::__wasi_timestamp_t,
@@ -180,7 +183,7 @@ pub(crate) fn clock_time_get(
enc_timestamp_byref(memory, time_ptr, time)
}
pub(crate) fn sched_yield() -> Result<()> {
pub(crate) fn sched_yield(_wasi_ctx: &WasiCtx, _memory: &mut [u8]) -> Result<()> {
trace!("sched_yield()");
std::thread::yield_now();

7
crates/wasi-common/wig/src/lib.rs
View File

@@ -2,6 +2,7 @@ extern crate proc_macro;
mod raw_types;
mod utils;
mod wasi;
use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
@@ -29,3 +30,9 @@ pub fn witx_wasi32_types(args: TokenStream) -> TokenStream {
raw_types::Mode::Wasi32,
))
}
/// A single-use macro in the `wasmtime-wasi` crate.
#[proc_macro]
pub fn define_add_wrappers_to_module(args: TokenStream) -> TokenStream {
wasi::add_wrappers_to_module(args.into()).into()
}

5
crates/wasi-common/wig/src/utils.rs
View File

@@ -1,4 +1,5 @@
use proc_macro2::{Literal, TokenStream, TokenTree};
/// Given the input tokens to a macro invocation, return the path to the
/// witx file to process.
pub(crate) fn witx_path_from_args(args: TokenStream) -> (String, String) {
@@ -26,8 +27,8 @@ pub(crate) fn witx_path_from_args(args: TokenStream) -> (String, String) {
}
fn witx_path(phase: &str, id: &str) -> String {
let root = std::env::var("CARGO_MANIFEST_DIR").unwrap_or(".".into());
format!("{}/WASI/phases/{}/witx/{}.witx", root, phase, id)
let root = env!("CARGO_MANIFEST_DIR");
format!("{}/../WASI/phases/{}/witx/{}.witx", root, phase, id)
}
// Convert a `Literal` holding a string literal into the `String`.

231
crates/wasi-common/wig/src/wasi.rs Normal file
View File

@@ -0,0 +1,231 @@
use crate::utils;
use proc_macro2::{Ident, Span, TokenStream};
use quote::{format_ident, quote};
enum Abi {
I32,
I64,
F32,
F64,
}
/// This is a single-use macro intended to be used in the `wasmtime-wasi` crate.
///
/// This macro will generate a function, `add_wrappers_to_module`, which will
/// use the input arguments to register all wasi functions inside of a `Module`
/// instance. This will automatically assign the wasm underlying types and
/// perform conversions from the wasm type to the underlying wasi type (often
/// unsigned or of a smaller width).
///
/// The generated shim functions here will also `trace!` their arguments for
/// logging purposes. Otherwise this is hopefully somewhat straightforward!
///
/// I'd recommend using `cargo +nightly expand` to explore the output of this
/// macro some more.
pub fn add_wrappers_to_module(args: TokenStream) -> TokenStream {
let (path, _phase) = utils::witx_path_from_args(args);
let doc = match witx::load(&[&path]) {
Ok(doc) => doc,
Err(e) => {
panic!("error opening file {}: {}", path, e);
}
};
let mut add = Vec::new();
for module in doc.modules() {
for func in module.funcs() {
let name = func.name.as_str();
let name_ident = Ident::new(func.name.as_str(), Span::call_site());
let mut shim_arg_decls = Vec::new();
let mut params = Vec::new();
let mut formats = Vec::new();
let mut format_args = Vec::new();
let mut hostcall_args = Vec::new();
for param in func.params.iter() {
let name = format_ident!(
"{}",
match param.name.as_str() {
"in" | "type" => format!("r#{}", param.name.as_str()),
s => s.to_string(),
}
);
// Registers a new parameter to the shim we're making with the
// given `name`, the `abi_ty` wasm type and `hex` defines
// whether it's debug-printed in a hex format or not.
//
// This will register a whole bunch of things:
//
// * The cranelift type for the parameter
// * Syntax to specify the actual function parameter
// * How to log the parameter value in a call to `trace!`
// * How to actually pass this argument to the host
// implementation, converting as necessary.
let mut add_param = |name: &Ident, abi_ty: Abi, hex: bool| {
match abi_ty {
Abi::I32 => {
params.push(quote! { types::I32 });
shim_arg_decls.push(quote! { #name: i32 });
}
Abi::I64 => {
params.push(quote! { types::I64 });
shim_arg_decls.push(quote! { #name: i64 });
}
Abi::F32 => {
params.push(quote! { types::F32 });
shim_arg_decls.push(quote! { #name: f32 });
}
Abi::F64 => {
params.push(quote! { types::F64 });
shim_arg_decls.push(quote! { #name: f64 });
}
}
formats.push(format!("{}={}", name, if hex { "{:#x}" } else { "{}" },));
format_args.push(name.clone());
hostcall_args.push(quote! { #name as _ });
};
match &*param.tref.type_() {
witx::Type::Enum(e) => match e.repr {
witx::IntRepr::U64 => add_param(&name, Abi::I64, false),
_ => add_param(&name, Abi::I32, false),
},
witx::Type::Flags(f) => match f.repr {
witx::IntRepr::U64 => add_param(&name, Abi::I64, true),
_ => add_param(&name, Abi::I32, true),
},
witx::Type::Builtin(witx::BuiltinType::S8)
| witx::Type::Builtin(witx::BuiltinType::U8)
| witx::Type::Builtin(witx::BuiltinType::S16)
| witx::Type::Builtin(witx::BuiltinType::U16)
| witx::Type::Builtin(witx::BuiltinType::S32)
| witx::Type::Builtin(witx::BuiltinType::U32) => {
add_param(&name, Abi::I32, false);
}
witx::Type::Builtin(witx::BuiltinType::S64)
| witx::Type::Builtin(witx::BuiltinType::U64) => {
add_param(&name, Abi::I64, false);
}
witx::Type::Builtin(witx::BuiltinType::F32) => {
add_param(&name, Abi::F32, false);
}
witx::Type::Builtin(witx::BuiltinType::F64) => {
add_param(&name, Abi::F64, false);
}
// strings/arrays have an extra ABI parameter for the length
// of the array passed.
witx::Type::Builtin(witx::BuiltinType::String) | witx::Type::Array(_) => {
add_param(&name, Abi::I32, true);
let len = format_ident!("{}_len", name);
add_param(&len, Abi::I32, false);
}
witx::Type::ConstPointer(_)
| witx::Type::Handle(_)
| witx::Type::Pointer(_) => {
add_param(&name, Abi::I32, true);
}
witx::Type::Struct(_) | witx::Type::Union(_) => {
panic!("unsupported argument type")
}
}
}
let mut results = func.results.iter();
let mut ret_ty = quote! { () };
let mut cvt_ret = quote! {};
let mut returns = Vec::new();
let mut handle_early_error = quote! { panic!("error: {:?}", e) };
// The first result is returned bare right now...
if let Some(ret) = results.next() {
handle_early_error = quote! { return e.into() };
match &*ret.tref.type_() {
// Eventually we'll want to add support for more returned
// types, but for now let's just conform to what `*.witx`
// definitions currently use.
witx::Type::Enum(e) => match e.repr {
witx::IntRepr::U16 => {
returns.push(quote! { types::I32 });
ret_ty = quote! { i32 };
cvt_ret = quote! { .into() }
}
other => panic!("unsupported ret enum repr {:?}", other),
},
other => panic!("unsupported first return {:?}", other),
}
}
// ... and all remaining results are returned via out-poiners
for result in results {
let name = format_ident!("{}", result.name.as_str());
params.push(quote! { types::I32 });
shim_arg_decls.push(quote! { #name: i32 });
formats.push(format!("{}={{:#x}}", name));
format_args.push(name.clone());
hostcall_args.push(quote! { #name as u32 });
}
let format_str = format!("{}({})", name, formats.join(", "));
add.push(quote! {
let sig = module.signatures.push(translate_signature(
ir::Signature {
params: vec![#(cranelift_codegen::ir::AbiParam::new(#params)),*],
returns: vec![#(cranelift_codegen::ir::AbiParam::new(#returns)),*],
call_conv,
},
pointer_type,
));
let func = module.functions.push(sig);
module
.exports
.insert(#name.to_owned(), Export::Function(func));
unsafe extern "C" fn #name_ident(
ctx: *mut wasmtime_runtime::VMContext,
#(#shim_arg_decls),*
) -> #ret_ty {
log::trace!(
#format_str,
#(#format_args),*
);
let wasi_ctx = match get_wasi_ctx(&mut *ctx) {
Ok(e) => e,
Err(e) => #handle_early_error,
};
let memory = match get_memory(&mut *ctx) {
Ok(e) => e,
Err(e) => #handle_early_error,
};
wasi_common::hostcalls::#name_ident(
wasi_ctx,
memory,
#(#hostcall_args),*
) #cvt_ret
}
finished_functions.push(#name_ident as *const _);
});
}
}
quote! {
pub fn add_wrappers_to_module(
module: &mut Module,
finished_functions: &mut PrimaryMap<DefinedFuncIndex, *const wasmtime_runtime::VMFunctionBody>,
call_conv: isa::CallConv,
pointer_type: types::Type,
) {
#(#add)*
}
}
}