QuickJS in Wasm in Nix #4
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,11 @@ | ||
| [package] | ||
| name = "nix-wasm-plugin-quickjs" | ||
| version = "0.1.0" | ||
| edition = "2021" | ||
|
|
||
| [lib] | ||
| crate-type = ["cdylib"] | ||
|
|
||
| [dependencies] | ||
| nix-wasm-rust = { path = "../nix-wasm-rust" } | ||
| rquickjs = { version = "0.11.0", features = ["bindgen"] } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,82 @@ | ||
| use nix_wasm_rust::{nix_wasm_init_v1, warn, wasi_arg, Value}; | ||
| use rquickjs::{Array, Context, Object, Runtime, Value as JsValue}; | ||
| use std::string::String as StdString; | ||
|
|
||
| fn fail(context: &str, err: impl std::fmt::Display) -> ! { | ||
| warn!("quickjs {context} failed: {err}"); | ||
| panic!("quickjs {context} failed: {err}"); | ||
| } | ||
|
|
||
| fn js_value_to_nix(value: JsValue) -> Value { | ||
| if value.is_null() || value.is_undefined() { | ||
| return Value::make_null(); | ||
| } | ||
| if let Some(b) = value.as_bool() { | ||
| return Value::make_bool(b); | ||
| } | ||
| if let Some(i) = value.as_int() { | ||
| return Value::make_int(i as i64); | ||
| } | ||
| if let Some(f) = value.as_float() { | ||
| return Value::make_float(f); | ||
| } | ||
| if let Some(js_str) = value.as_string() { | ||
| let s = js_str.to_string().unwrap_or_else(|err| fail("string conversion", err)); | ||
| return Value::make_string(&s); | ||
| } | ||
| if value.is_array() { | ||
| let array: Array = value | ||
| .clone() | ||
| .into_array() | ||
| .unwrap_or_else(|| fail("array conversion", "value is not an array")); | ||
| let mut items = Vec::new(); | ||
| for entry in array.into_iter() { | ||
| let entry = entry.unwrap_or_else(|err| fail("array iteration", err)); | ||
| items.push(js_value_to_nix(entry)); | ||
| } | ||
| return Value::make_list(&items); | ||
| } | ||
| if value.is_object() { | ||
| let object: Object = value | ||
| .into_object() | ||
| .unwrap_or_else(|| fail("object conversion", "value is not an object")); | ||
| let mut entries: Vec<(StdString, Value)> = Vec::new(); | ||
| for entry in object.props::<StdString, JsValue>() { | ||
| let (key, value) = entry.unwrap_or_else(|err| fail("object iteration", err)); | ||
| entries.push((key, js_value_to_nix(value))); | ||
| } | ||
| let attrs: Vec<(&str, Value)> = entries | ||
| .iter() | ||
| .map(|(key, value)| (key.as_str(), *value)) | ||
| .collect(); | ||
| return Value::make_attrset(&attrs); | ||
| } | ||
|
Comment on lines
+10
to
+53
Contributor
There was a problem hiding this comment. Add recursion guard for nested/cyclic JS values. Lines [10-53] recurse without depth/cycle limits; deeply nested or self-referential objects can overflow the stack instead of failing cleanly. Proposed hardening patch-fn js_value_to_nix(value: JsValue) -> Value {
+const MAX_CONVERSION_DEPTH: usize = 256;
+
+fn js_value_to_nix(value: JsValue) -> Value {
+ js_value_to_nix_with_depth(value, 0)
+}
+
+fn js_value_to_nix_with_depth(value: JsValue, depth: usize) -> Value {
+ if depth > MAX_CONVERSION_DEPTH {
+ fail("value conversion", "maximum nesting depth exceeded");
+ }
if value.is_null() || value.is_undefined() {
return Value::make_null();
}
@@
if value.is_array() {
let array: Array = value
.clone()
.into_array()
.unwrap_or_else(|| fail("array conversion", "value is not an array"));
let mut items = Vec::new();
for entry in array.into_iter() {
let entry = entry.unwrap_or_else(|err| fail("array iteration", err));
- items.push(js_value_to_nix(entry));
+ items.push(js_value_to_nix_with_depth(entry, depth + 1));
}
return Value::make_list(&items);
}
@@
let mut entries: Vec<(StdString, Value)> = Vec::new();
for entry in object.props::<StdString, JsValue>() {
let (key, value) = entry.unwrap_or_else(|err| fail("object iteration", err));
- entries.push((key, js_value_to_nix(value)));
+ entries.push((key, js_value_to_nix_with_depth(value, depth + 1)));
}🤖 Prompt for AI Agents |
||
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| warn!("quickjs value type not supported: {:?}", value.type_of()); | ||
| panic!("quickjs value type not supported: {:?}", value.type_of()); | ||
| } | ||
|
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| fn eval_impl(arg: Value) -> Value { | ||
| let code = arg.get_string(); | ||
|
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| let runtime = Runtime::new().unwrap_or_else(|err| fail("runtime init", err)); | ||
| let context = Context::full(&runtime).unwrap_or_else(|err| fail("context init", err)); | ||
|
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| context.with(|ctx| { | ||
| let value: JsValue = ctx.eval(code).unwrap_or_else(|err| fail("eval", err)); | ||
| js_value_to_nix(value) | ||
| }) | ||
| } | ||
|
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||
| #[no_mangle] | ||
| pub extern "C" fn eval(arg: Value) -> Value { | ||
| nix_wasm_init_v1(); | ||
| eval_impl(arg) | ||
| } | ||
|
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| #[no_mangle] | ||
| pub extern "C" fn _start() { | ||
| nix_wasm_init_v1(); | ||
| let result = eval_impl(wasi_arg()); | ||
| result.return_to_nix(); | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| {"arr":[1,"two",false],"bool":true,"float":1.5,"nil":null,"num":1,"obj":{"nested":3},"str":"hello","undef":null} |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,12 @@ | ||
| builtins.wasi <plugins/nix_wasm_plugin_quickjs.wasm> '' | ||
| ({ | ||
| num: 1, | ||
| float: 1.5, | ||
| str: "hello", | ||
| bool: true, | ||
| nil: null, | ||
| undef: undefined, | ||
| arr: [1, "two", false], | ||
| obj: { nested: 3 } | ||
| }) | ||
| '' |
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🧩 Analysis chain
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# First, check the flake.nix file content to understand the setup head -50 flake.nixRepository: DeterminateSystems/nix-wasm-rust
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Hard-coded Rust version dependency is rigid; ensure it remains compatible with nixpkgs updates.
The reference to
rustPackages_1_89depends on the pinned nixpkgs providing this attribute. While the current flake.lock (Jan 2025) should include Rust 1.89, this creates a maintenance risk if nixpkgs is updated to an older version or if the attribute is removed in future nixpkgs releases. Consider adding version flexibility or explicit handling for version availability.🤖 Prompt for AI Agents