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feat: full subsystem support
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@guybedford
guybedford committed Jul 31, 2023
1 parent 107da15 commit c2e44fb
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Showing 8 changed files with 1,100 additions and 231 deletions.
12 changes: 6 additions & 6 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -18,15 +18,15 @@ Supports all of the current WASI subsystems:

- [x] Environment: Set environment variables, configure host environment variable permissions
- [x] Filesystem: Mount a read-only filesystem, configure host filesystem pass-through
- [x] Stdio: Currently only supports disabling
- [ ] Sockets
- [ ] Clocks
- [x] Exit
- [ ] Random
- [x] Stdio: Allow / Ignore
- [ ] Sockets: Allow / Ignore
- [ ] Clocks: Allow / Ignore
- [x] Exit: Allow / Ignore
- [ ] Random: Allow / Ignore

While current virtualization support is limited, the goal for this project is to support a wide range of WASI virtualization use cases.

Have an unhandled use case? Post a [virtualization suggestion](https://github.com/bytecodealliance/WASI-Virt/issues/new).
Have an unhandled use case? Post a virtualization [suggestion](https://github.com/bytecodealliance/WASI-Virt/issues/new).

## Explainer

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33 changes: 33 additions & 0 deletions src/bin/wasi-virt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,20 @@ struct Args {
#[arg(long)]
allow_exit: Option<bool>,

// STDIO
/// Enable all stdio
#[arg(long)]
allow_stdio: Option<bool>,
/// Enable stdin
#[arg(long)]
allow_stdin: Option<bool>,
/// Enable stdout
#[arg(long)]
allow_stdout: Option<bool>,
/// Enable stderr
#[arg(long)]
allow_stderr: Option<bool>,

// ENV
/// Allow host access to all environment variables, or to a specific comma-separated list of variable names.
#[arg(long, num_args(0..), use_value_delimiter(true), require_equals(true), value_name("ENV_VAR"))]
Expand All @@ -40,6 +54,11 @@ struct Args {
#[arg(long, value_name("preopen=virtualdir"), value_parser = parse_key_val::<String, String>)]
mount: Option<Vec<(String, String)>>,

// CLOCKS

// SOCKETS

//
/// Wasm binary to compose the virtualization with
/// If not provided, the virtualization component itself will only generated.
#[arg(required(false))]
Expand Down Expand Up @@ -83,6 +102,20 @@ fn main() -> Result<()> {
// By default, we virtualize all subsystems
// This ensures full encapsulation in the default (no argument) case

// stdio
virt_opts.stdio().stdin(
args.allow_stdin
.unwrap_or(args.allow_stdio.unwrap_or(false)),
);
virt_opts.stdio().stdout(
args.allow_stdout
.unwrap_or(args.allow_stdio.unwrap_or(false)),
);
virt_opts.stdio().stderr(
args.allow_stderr
.unwrap_or(args.allow_stdio.unwrap_or(false)),
);

// exit
virt_opts.exit(if args.allow_exit.unwrap_or_default() {
VirtExit::Passthrough
Expand Down
163 changes: 67 additions & 96 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,13 +4,14 @@ use std::env;
use std::fs;
use std::time::SystemTime;
use virt_env::{create_env_virt, strip_env_virt};
use virt_io::create_io_virt;
use virt_io::stub_io_virt;
use virt_io::strip_clocks_virt;
use virt_io::strip_fs_virt;
use virt_io::strip_http_virt;
use virt_io::strip_stdio_virt;
use virt_io::VirtStdio;
use walrus::Module;
use virt_io::{create_io_virt, strip_io_virt};
use walrus::ValType;
use walrus_ops::add_stub_exported_func;
use walrus_ops::remove_exported_func;
use wasm_metadata::Producers;
use wasm_opt::Feature;
use wasm_opt::OptimizationOptions;
Expand Down Expand Up @@ -54,6 +55,12 @@ pub struct WasiVirt {
pub stdio: Option<VirtStdio>,
/// Exit virtualization
pub exit: Option<VirtExit>,
/// Clocks virtualization
#[serde(default)]
pub clocks: bool,
/// Http virtualization
#[serde(default)]
pub http: bool,
/// Disable wasm-opt run if desired
pub wasm_opt: Option<bool>,
}
Expand All @@ -68,6 +75,14 @@ impl WasiVirt {
Self::default()
}

pub fn clocks(&mut self) {
self.clocks = true;
}

pub fn http(&mut self) {
self.http = true;
}

pub fn exit(&mut self, virt_exit: VirtExit) {
self.exit = Some(virt_exit);
}
Expand Down Expand Up @@ -95,29 +110,10 @@ impl WasiVirt {
let mut module = config.parse(virt_adapter)?;
module.name = Some("wasi_virt".into());

let mut has_io = false;

// very few subsystems are fully independent of io, these are them
if let Some(env) = &self.env {
create_env_virt(&mut module, env)?;
} else {
strip_env_virt(&mut module)?;
}

let virtual_files = if self.fs.is_some() || self.stdio.is_some() {
has_io = true;
// pull in one io subsystem -> pull in all io subsystems
// (due to virtualization wrapping required for streams + poll)
self.fs();
self.stdio();
create_io_virt(
&mut module,
self.fs.as_ref().unwrap(),
self.stdio.as_ref().unwrap(),
)?
} else {
Default::default()
};

if matches!(self.exit, Some(VirtExit::Unreachable)) {
add_stub_exported_func(
&mut module,
Expand All @@ -127,9 +123,14 @@ impl WasiVirt {
)?;
}

if !has_io {
strip_io_virt(&mut module)?;
}
let has_io = self.fs.is_some() || self.stdio.is_some();

let virtual_files = if has_io {
// io virt is managed through a singular io configuration
create_io_virt(&mut module, self.fs.as_ref(), self.stdio.as_ref())?
} else {
Default::default()
};

// decode the component custom section to strip out the unused world exports
// before reencoding.
Expand All @@ -152,12 +153,51 @@ impl WasiVirt {

let env_world = bindgen.resolve.select_world(*pkg_id, Some("virtual-env"))?;
let io_world = bindgen.resolve.select_world(*pkg_id, Some("virtual-io"))?;
// let exit_world = bindgen
// .resolve
// .select_world(*pkg_id, Some("virtual-exit"))?;
let fs_world = bindgen.resolve.select_world(*pkg_id, Some("virtual-fs"))?;
let stdio_world = bindgen
.resolve
.select_world(*pkg_id, Some("virtual-stdio"))?;
let clocks_world = bindgen
.resolve
.select_world(*pkg_id, Some("virtual-clocks"))?;
let http_world = bindgen
.resolve
.select_world(*pkg_id, Some("virtual-http"))?;

if self.env.is_some() {
bindgen.resolve.merge_worlds(env_world, base_world)?;
} else {
strip_env_virt(&mut module)?;
}
if has_io {
bindgen.resolve.merge_worlds(io_world, base_world)?;

// io subsystems have io dependence due to streams + poll
if self.clocks {
bindgen.resolve.merge_worlds(clocks_world, base_world)?;
} else {
strip_clocks_virt(&mut module)?;
}
if self.http {
bindgen.resolve.merge_worlds(http_world, base_world)?;
} else {
strip_http_virt(&mut module)?;
}
if self.stdio.is_some() {
bindgen.resolve.merge_worlds(stdio_world, base_world)?;
} else {
strip_stdio_virt(&mut module)?;
}
if self.fs.is_some() {
bindgen.resolve.merge_worlds(fs_world, base_world)?;
} else {
strip_fs_virt(&mut module)?;
}
} else {
strip_io_virt(&mut module)?;
}

let mut producers = Producers::default();
Expand Down Expand Up @@ -213,72 +253,3 @@ fn timestamp() -> u64 {
Err(_) => panic!(),
}
}

fn strip_io_virt(module: &mut Module) -> Result<()> {
stub_io_virt(module)?;

remove_exported_func(module, "wasi:cli-base/preopens#get-directories")?;

remove_exported_func(module, "wasi:filesystem/filesystem#read-via-stream")?;
remove_exported_func(module, "wasi:filesystem/filesystem#write-via-stream")?;
remove_exported_func(module, "wasi:filesystem/filesystem#append-via-stream")?;
remove_exported_func(module, "wasi:filesystem/filesystem#advise")?;
remove_exported_func(module, "wasi:filesystem/filesystem#sync-data")?;
remove_exported_func(module, "wasi:filesystem/filesystem#get-flags")?;
remove_exported_func(module, "wasi:filesystem/filesystem#get-type")?;
remove_exported_func(module, "wasi:filesystem/filesystem#set-size")?;
remove_exported_func(module, "wasi:filesystem/filesystem#set-times")?;
remove_exported_func(module, "wasi:filesystem/filesystem#read")?;
remove_exported_func(module, "wasi:filesystem/filesystem#write")?;
remove_exported_func(module, "wasi:filesystem/filesystem#read-directory")?;
remove_exported_func(module, "wasi:filesystem/filesystem#sync")?;
remove_exported_func(module, "wasi:filesystem/filesystem#create-directory-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#stat")?;
remove_exported_func(module, "wasi:filesystem/filesystem#stat-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#set-times-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#link-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#open-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#readlink-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#remove-directory-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#rename-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#symlink-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#access-at")?;
remove_exported_func(module, "wasi:filesystem/filesystem#unlink-file-at")?;
remove_exported_func(
module,
"wasi:filesystem/filesystem#change-file-permissions-at",
)?;
remove_exported_func(
module,
"wasi:filesystem/filesystem#change-directory-permissions-at",
)?;
remove_exported_func(module, "wasi:filesystem/filesystem#lock-shared")?;
remove_exported_func(module, "wasi:filesystem/filesystem#lock-exclusive")?;
remove_exported_func(module, "wasi:filesystem/filesystem#try-lock-shared")?;
remove_exported_func(module, "wasi:filesystem/filesystem#try-lock-exclusive")?;
remove_exported_func(module, "wasi:filesystem/filesystem#unlock")?;
remove_exported_func(module, "wasi:filesystem/filesystem#drop-descriptor")?;
remove_exported_func(module, "wasi:filesystem/filesystem#read-directory-entry")?;
remove_exported_func(
module,
"wasi:filesystem/filesystem#drop-directory-entry-stream",
)?;

remove_exported_func(module, "wasi:io/streams#read")?;
remove_exported_func(module, "wasi:io/streams#blocking-read")?;
remove_exported_func(module, "wasi:io/streams#skip")?;
remove_exported_func(module, "wasi:io/streams#blocking-skip")?;
remove_exported_func(module, "wasi:io/streams#subscribe-to-input-stream")?;
remove_exported_func(module, "wasi:io/streams#drop-input-stream")?;
remove_exported_func(module, "wasi:io/streams#write")?;
remove_exported_func(module, "wasi:io/streams#blocking-write")?;
remove_exported_func(module, "wasi:io/streams#write-zeroes")?;
remove_exported_func(module, "wasi:io/streams#blocking-write-zeroes")?;
remove_exported_func(module, "wasi:io/streams#splice")?;
remove_exported_func(module, "wasi:io/streams#blocking-splice")?;
remove_exported_func(module, "wasi:io/streams#forward")?;
remove_exported_func(module, "wasi:io/streams#subscribe-to-output-stream")?;
remove_exported_func(module, "wasi:io/streams#drop-output-stream")?;

Ok(())
}
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