wasmer/lib/wasi/src/utils.rs

82 lines
2.8 KiB
Rust

use wasmer_runtime_core::module::Module;
#[allow(dead_code)]
/// Check if a provided module is compiled for some version of WASI.
/// Use [`get_wasi_version`] to find out which version of WASI the module is.
pub fn is_wasi_module(module: &Module) -> bool {
get_wasi_version(module, false).is_some()
}
/// The version of WASI. This is determined by the imports namespace
/// string.
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum WasiVersion {
/// `wasi_unstable`.
Snapshot0,
/// `wasi_snapshot_preview1`.
Snapshot1,
/// Latest version.
///
/// It's a “floating” version, i.e. it's an alias to the latest
/// version (for the moment, `Snapshot1`). Using this version is a
/// way to ensure that modules will run only if they come with the
/// latest WASI version (in case of security issues for instance),
/// by just updating the runtime.
///
/// Note that this version is never returned by an API. It is
/// provided only by the user.
Latest,
}
/// Namespace for the `Snapshot0` version.
const SNAPSHOT0_NAMESPACE: &str = "wasi_unstable";
/// Namespace for the `Snapshot1` version.
const SNAPSHOT1_NAMESPACE: &str = "wasi_snapshot_preview1";
/// Detect the version of WASI being used based on the import
/// namespaces.
///
/// A strict detection expects that all imports live in a single WASI
/// namespace. A non-strict detection expects that at least one WASI
/// namespace exits to detect the version. Note that the strict
/// detection is faster than the non-strict one.
pub fn get_wasi_version(module: &Module, strict: bool) -> Option<WasiVersion> {
let module_info = &module.info();
let mut imports = module_info.imported_functions.iter();
if strict {
let mut imports = imports.map(|(_, import_name)| import_name.namespace_index);
// Returns `None` if empty.
let first = imports.next()?;
// If there is only one namespace…
if imports.all(|index| index == first) {
// … and that this namespace is a WASI one.
match module_info.namespace_table.get(first) {
SNAPSHOT0_NAMESPACE => Some(WasiVersion::Snapshot0),
SNAPSHOT1_NAMESPACE => Some(WasiVersion::Snapshot1),
_ => None,
}
} else {
None
}
} else {
let namespace_table = &module_info.namespace_table;
// Check that at least a WASI namespace exists, and use the
// first one in the list to detect the WASI version.
imports.find_map(|(_, import_name)| {
let namespace_index = import_name.namespace_index;
match namespace_table.get(namespace_index) {
SNAPSHOT0_NAMESPACE => Some(WasiVersion::Snapshot0),
SNAPSHOT1_NAMESPACE => Some(WasiVersion::Snapshot1),
_ => None,
}
})
}
}