`fe52b32db444`

source

bindings/jsonnet/src/native.rs2.9 KiBsource history
1use std::{2	borrow::Cow,3	ffi::{c_void, CStr},4	os::raw::{c_char, c_int},5};67use jrsonnet_evaluator::{8	error::{Error, LocError},9	function::builtin::{NativeCallback, NativeCallbackHandler},10	tb,11	typed::Typed,12	IStr, State, Val,13};14use jrsonnet_gcmodule::Cc;1516/// The returned `JsonnetJsonValue*` should be allocated with `jsonnet_realloc`. It will be cleaned up17/// along with the objects rooted at `argv` by `libjsonnet` when no-longer needed. Return a string upon18/// failure, which will appear in Jsonnet as an error. The `argv` pointer is an array whose size19/// matches the array of parameters supplied when the native callback was originally registered.20///21/// - `ctx` User pointer, given in jsonnet_native_callback.22/// - `argv` Array of arguments from Jsonnet code.23/// - `param` success Set this byref param to 1 to indicate success and 0 for failure.24/// Returns the content of the imported file, or an error message.25type JsonnetNativeCallback = unsafe extern "C" fn(26	ctx: *const c_void,27	argv: *const *const Val,28	success: *mut c_int,29) -> *mut Val;3031#[derive(jrsonnet_gcmodule::Trace)]32struct JsonnetNativeCallbackHandler {33	#[trace(skip)]34	ctx: *const c_void,35	#[trace(skip)]36	cb: JsonnetNativeCallback,37}38impl NativeCallbackHandler for JsonnetNativeCallbackHandler {39	fn call(&self, args: &[Val]) -> Result<Val, LocError> {40		let mut n_args = Vec::new();41		for a in args {42			n_args.push(Some(Box::new(a.clone())));43		}44		n_args.push(None);45		let mut success = 1;46		let v = unsafe {47			(self.cb)(48				self.ctx,49				&n_args as *const _ as *const *const Val,50				&mut success,51			)52		};53		let v = unsafe { *Box::from_raw(v) };54		if success == 1 {55			Ok(v)56		} else {57			let e = IStr::from_untyped(v).expect("error msg should be a string");58			Err(Error::RuntimeError(e).into())59		}60	}61}6263/// Callback to provide native extensions to Jsonnet.64///65/// # Safety66///67/// `vm` should be a vm allocated by `jsonnet_make`68/// `name` should be a NUL-terminated string69/// `cb` should be a function pointer70/// `raw_params` should point to a NULL-terminated array of NUL-terminated strings71#[no_mangle]72pub unsafe extern "C" fn jsonnet_native_callback(73	vm: &State,74	name: *const c_char,75	cb: JsonnetNativeCallback,76	ctx: *const c_void,77	mut raw_params: *const *const c_char,78) {79	let name = CStr::from_ptr(name)80		.to_str()81		.expect("name is not utf-8")82		.into();83	let mut params = Vec::new();84	loop {85		if (*raw_params).is_null() {86			break;87		}88		let param = CStr::from_ptr(*raw_params)89			.to_str()90			.expect("param name is not utf-8");91		params.push(Cow::Owned(param.into()));92		raw_params = raw_params.offset(1);93	}9495	let any_resolver = vm.context_initializer();96	any_resolver97		.as_any()98		.downcast_ref::<jrsonnet_stdlib::ContextInitializer>()99		.expect("only stdlib context initializer supported")100		.add_native(101			name,102			#[allow(deprecated)]103			Cc::new(tb!(NativeCallback::new(104				params,105				tb!(JsonnetNativeCallbackHandler { ctx, cb }),106			))),107		)108}