use crate::state::{WasiFile, WasiFs, WasiFsError, WasiState};
use crate::syscalls::types::{__WASI_STDERR_FILENO, __WASI_STDIN_FILENO, __WASI_STDOUT_FILENO};
use crate::WasiEnv;
use std::path::{Path, PathBuf};
use thiserror::Error;
pub(crate) fn create_wasi_state(program_name: &str) -> WasiStateBuilder {
WasiStateBuilder {
args: vec![program_name.bytes().collect()],
..WasiStateBuilder::default()
}
}
#[derive(Default)]
pub struct WasiStateBuilder {
args: Vec<Vec<u8>>,
envs: Vec<(Vec<u8>, Vec<u8>)>,
preopens: Vec<PreopenedDir>,
#[allow(clippy::type_complexity)]
setup_fs_fn: Option<Box<dyn Fn(&mut WasiFs) -> Result<(), String> + Send>>,
stdout_override: Option<Box<dyn WasiFile>>,
stderr_override: Option<Box<dyn WasiFile>>,
stdin_override: Option<Box<dyn WasiFile>>,
}
impl std::fmt::Debug for WasiStateBuilder {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("WasiStateBuilder")
.field("args", &self.args)
.field("envs", &self.envs)
.field("preopens", &self.preopens)
.field("setup_fs_fn exists", &self.setup_fs_fn.is_some())
.field("stdout_override exists", &self.stdout_override.is_some())
.field("stderr_override exists", &self.stderr_override.is_some())
.field("stdin_override exists", &self.stdin_override.is_some())
.finish()
}
}
#[derive(Error, Debug, PartialEq, Eq)]
pub enum WasiStateCreationError {
#[error("bad environment variable format: `{0}`")]
EnvironmentVariableFormatError(String),
#[error("argument contains null byte: `{0}`")]
ArgumentContainsNulByte(String),
#[error("preopened directory not found: `{0}`")]
PreopenedDirectoryNotFound(PathBuf),
#[error("preopened directory error: `{0}`")]
PreopenedDirectoryError(String),
#[error("mapped dir alias has wrong format: `{0}`")]
MappedDirAliasFormattingError(String),
#[error("wasi filesystem creation error: `{0}`")]
WasiFsCreationError(String),
#[error("wasi filesystem setup error: `{0}`")]
WasiFsSetupError(String),
#[error(transparent)]
WasiFsError(WasiFsError),
}
fn validate_mapped_dir_alias(alias: &str) -> Result<(), WasiStateCreationError> {
if !alias.bytes().all(|b| b != b'\0') {
return Err(WasiStateCreationError::MappedDirAliasFormattingError(
format!("Alias \"{}\" contains a nul byte", alias),
));
}
Ok(())
}
impl WasiStateBuilder {
pub fn env<Key, Value>(&mut self, key: Key, value: Value) -> &mut Self
where
Key: AsRef<[u8]>,
Value: AsRef<[u8]>,
{
self.envs
.push((key.as_ref().to_vec(), value.as_ref().to_vec()));
self
}
pub fn arg<Arg>(&mut self, arg: Arg) -> &mut Self
where
Arg: AsRef<[u8]>,
{
self.args.push(arg.as_ref().to_vec());
self
}
pub fn envs<I, Key, Value>(&mut self, env_pairs: I) -> &mut Self
where
I: IntoIterator<Item = (Key, Value)>,
Key: AsRef<[u8]>,
Value: AsRef<[u8]>,
{
env_pairs.into_iter().for_each(|(key, value)| {
self.env(key, value);
});
self
}
pub fn args<I, Arg>(&mut self, args: I) -> &mut Self
where
I: IntoIterator<Item = Arg>,
Arg: AsRef<[u8]>,
{
args.into_iter().for_each(|arg| {
self.arg(arg);
});
self
}
pub fn preopen_dir<FilePath>(
&mut self,
po_dir: FilePath,
) -> Result<&mut Self, WasiStateCreationError>
where
FilePath: AsRef<Path>,
{
let mut pdb = PreopenDirBuilder::new();
let path = po_dir.as_ref();
pdb.directory(path).read(true).write(true).create(true);
let preopen = pdb.build()?;
self.preopens.push(preopen);
Ok(self)
}
pub fn preopen<F>(&mut self, inner: F) -> Result<&mut Self, WasiStateCreationError>
where
F: Fn(&mut PreopenDirBuilder) -> &mut PreopenDirBuilder,
{
let mut pdb = PreopenDirBuilder::new();
let po_dir = inner(&mut pdb).build()?;
self.preopens.push(po_dir);
Ok(self)
}
pub fn preopen_dirs<I, FilePath>(
&mut self,
po_dirs: I,
) -> Result<&mut Self, WasiStateCreationError>
where
I: IntoIterator<Item = FilePath>,
FilePath: AsRef<Path>,
{
for po_dir in po_dirs {
self.preopen_dir(po_dir)?;
}
Ok(self)
}
pub fn map_dir<FilePath>(
&mut self,
alias: &str,
po_dir: FilePath,
) -> Result<&mut Self, WasiStateCreationError>
where
FilePath: AsRef<Path>,
{
let mut pdb = PreopenDirBuilder::new();
let path = po_dir.as_ref();
pdb.directory(path)
.alias(alias)
.read(true)
.write(true)
.create(true);
let preopen = pdb.build()?;
self.preopens.push(preopen);
Ok(self)
}
pub fn map_dirs<I, FilePath>(
&mut self,
mapped_dirs: I,
) -> Result<&mut Self, WasiStateCreationError>
where
I: IntoIterator<Item = (String, FilePath)>,
FilePath: AsRef<Path>,
{
for (alias, dir) in mapped_dirs {
self.map_dir(&alias, dir)?;
}
Ok(self)
}
pub fn stdout(&mut self, new_file: Box<dyn WasiFile>) -> &mut Self {
self.stdout_override = Some(new_file);
self
}
pub fn stderr(&mut self, new_file: Box<dyn WasiFile>) -> &mut Self {
self.stderr_override = Some(new_file);
self
}
pub fn stdin(&mut self, new_file: Box<dyn WasiFile>) -> &mut Self {
self.stdin_override = Some(new_file);
self
}
pub fn setup_fs(
&mut self,
setup_fs_fn: Box<dyn Fn(&mut WasiFs) -> Result<(), String> + Send>,
) -> &mut Self {
self.setup_fs_fn = Some(setup_fs_fn);
self
}
pub fn build(&mut self) -> Result<WasiState, WasiStateCreationError> {
for (i, arg) in self.args.iter().enumerate() {
for b in arg.iter() {
if *b == 0 {
return Err(WasiStateCreationError::ArgumentContainsNulByte(
std::str::from_utf8(arg)
.unwrap_or(if i == 0 {
"Inner error: program name is invalid utf8!"
} else {
"Inner error: arg is invalid utf8!"
})
.to_string(),
));
}
}
}
enum InvalidCharacter {
Nul,
Equal,
}
for (env_key, env_value) in self.envs.iter() {
match env_key.iter().find_map(|&ch| {
if ch == 0 {
Some(InvalidCharacter::Nul)
} else if ch == b'=' {
Some(InvalidCharacter::Equal)
} else {
None
}
}) {
Some(InvalidCharacter::Nul) => {
return Err(WasiStateCreationError::EnvironmentVariableFormatError(
format!(
"found nul byte in env var key \"{}\" (key=value)",
String::from_utf8_lossy(env_key)
),
))
}
Some(InvalidCharacter::Equal) => {
return Err(WasiStateCreationError::EnvironmentVariableFormatError(
format!(
"found equal sign in env var key \"{}\" (key=value)",
String::from_utf8_lossy(env_key)
),
))
}
None => (),
}
if env_value.iter().find(|&&ch| ch == 0).is_some() {
return Err(WasiStateCreationError::EnvironmentVariableFormatError(
format!(
"found nul byte in env var value \"{}\" (key=value)",
String::from_utf8_lossy(env_value)
),
));
}
}
#[allow(deprecated)]
let mut wasi_fs = WasiFs::new_with_preopen(&self.preopens)
.map_err(WasiStateCreationError::WasiFsCreationError)?;
if let Some(stdin_override) = self.stdin_override.take() {
wasi_fs
.swap_file(__WASI_STDIN_FILENO, stdin_override)
.map_err(WasiStateCreationError::WasiFsError)?;
}
if let Some(stdout_override) = self.stdout_override.take() {
wasi_fs
.swap_file(__WASI_STDOUT_FILENO, stdout_override)
.map_err(WasiStateCreationError::WasiFsError)?;
}
if let Some(stderr_override) = self.stderr_override.take() {
wasi_fs
.swap_file(__WASI_STDERR_FILENO, stderr_override)
.map_err(WasiStateCreationError::WasiFsError)?;
}
if let Some(f) = &self.setup_fs_fn {
f(&mut wasi_fs).map_err(WasiStateCreationError::WasiFsSetupError)?;
}
Ok(WasiState {
fs: wasi_fs,
args: self.args.clone(),
envs: self
.envs
.iter()
.map(|(key, value)| {
let mut env = Vec::with_capacity(key.len() + value.len() + 1);
env.extend_from_slice(&key);
env.push(b'=');
env.extend_from_slice(&value);
env
})
.collect(),
})
}
pub fn finalize(&mut self) -> Result<WasiEnv, WasiStateCreationError> {
let state = self.build()?;
Ok(WasiEnv::new(state))
}
}
#[derive(Debug, Default)]
pub struct PreopenDirBuilder {
path: Option<PathBuf>,
alias: Option<String>,
read: bool,
write: bool,
create: bool,
}
#[derive(Debug, Default)]
pub(crate) struct PreopenedDir {
pub(crate) path: PathBuf,
pub(crate) alias: Option<String>,
pub(crate) read: bool,
pub(crate) write: bool,
pub(crate) create: bool,
}
impl PreopenDirBuilder {
pub(crate) fn new() -> Self {
PreopenDirBuilder::default()
}
pub fn directory<FilePath>(&mut self, po_dir: FilePath) -> &mut Self
where
FilePath: AsRef<Path>,
{
let path = po_dir.as_ref();
self.path = Some(path.to_path_buf());
self
}
pub fn alias(&mut self, alias: &str) -> &mut Self {
let alias = alias.trim_start_matches('/');
self.alias = Some(alias.to_string());
self
}
pub fn read(&mut self, toggle: bool) -> &mut Self {
self.read = toggle;
self
}
pub fn write(&mut self, toggle: bool) -> &mut Self {
self.write = toggle;
self
}
pub fn create(&mut self, toggle: bool) -> &mut Self {
self.create = toggle;
if toggle {
self.write = true;
}
self
}
pub(crate) fn build(&self) -> Result<PreopenedDir, WasiStateCreationError> {
if !(self.read || self.write || self.create) {
return Err(WasiStateCreationError::PreopenedDirectoryError("Preopened directories must have at least one of read, write, create permissions set".to_string()));
}
if self.path.is_none() {
return Err(WasiStateCreationError::PreopenedDirectoryError(
"Preopened directories must point to a host directory".to_string(),
));
}
let path = self.path.clone().unwrap();
if !path.exists() {
return Err(WasiStateCreationError::PreopenedDirectoryNotFound(path));
}
if let Some(alias) = &self.alias {
validate_mapped_dir_alias(alias)?;
}
Ok(PreopenedDir {
path,
alias: self.alias.clone(),
read: self.read,
write: self.write,
create: self.create,
})
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn env_var_errors() {
assert!(
create_wasi_state("test_prog")
.env("HOM=E", "/home/home")
.build()
.is_err(),
"equal sign in key must be invalid"
);
assert!(
create_wasi_state("test_prog")
.env("HOME\0", "/home/home")
.build()
.is_err(),
"nul in key must be invalid"
);
assert!(
create_wasi_state("test_prog")
.env("HOME", "/home/home=home")
.build()
.is_ok(),
"equal sign in the value must be valid"
);
assert!(
create_wasi_state("test_prog")
.env("HOME", "/home/home\0")
.build()
.is_err(),
"nul in value must be invalid"
);
}
#[test]
fn nul_character_in_args() {
let output = create_wasi_state("test_prog").arg("--h\0elp").build();
match output {
Err(WasiStateCreationError::ArgumentContainsNulByte(_)) => assert!(true),
_ => assert!(false),
}
let output = create_wasi_state("test_prog")
.args(&["--help", "--wat\0"])
.build();
match output {
Err(WasiStateCreationError::ArgumentContainsNulByte(_)) => assert!(true),
_ => assert!(false),
}
}
}