111 lines
2.6 KiB
JavaScript
111 lines
2.6 KiB
JavaScript
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'use strict';
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/**
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* Module dependencies.
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*/
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const ref = require('ref-napi');
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const assert = require('assert');
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const bindings = require('./bindings');
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const Callback = require('./callback');
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const ForeignFunction = require('./foreign_function');
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const debug = require('debug')('ffi:FunctionType');
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/**
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* Module exports.
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*/
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module.exports = Function;
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/**
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* Creates and returns a "type" object for a C "function pointer".
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*
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* @api public
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*/
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function Function (retType, argTypes, abi) {
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if (!(this instanceof Function)) {
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return new Function(retType, argTypes, abi);
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}
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debug('creating new FunctionType');
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// check args
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assert(!!retType, 'expected a return "type" object as the first argument');
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assert(Array.isArray(argTypes), 'expected Array of arg "type" objects as the second argument');
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// normalize the "types" (they could be strings, so turn into real type
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// instances)
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this.retType = ref.coerceType(retType);
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this.argTypes = argTypes.map(ref.coerceType);
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this.abi = null == abi ? bindings.FFI_DEFAULT_ABI : abi;
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}
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/**
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* The "ffi_type" is set for node-ffi functions.
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*/
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Function.prototype.ffi_type = bindings.FFI_TYPES.pointer;
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/**
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* The "size" is always pointer-sized.
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*/
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Function.prototype.size = ref.sizeof.pointer;
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/**
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* The "alignment" is always pointer-aligned.
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*/
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Function.prototype.alignment = ref.alignof.pointer;
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/**
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* The "indirection" is always 1 to ensure that our get()/set() get called.
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*/
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Function.prototype.indirection = 1;
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/**
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* Returns a ffi.Callback pointer (Buffer) of this function type for the
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* given `fn` Function.
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*/
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Function.prototype.toPointer = function toPointer (fn) {
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return Callback(this.retType, this.argTypes, this.abi, fn);
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};
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/**
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* Returns a ffi.ForeignFunction (Function) of this function type for the
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* given `buf` Buffer.
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*/
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Function.prototype.toFunction = function toFunction (buf) {
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return ForeignFunction(buf, this.retType, this.argTypes, this.abi);
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};
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/**
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* get function; return a ForeignFunction instance.
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*/
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Function.prototype.get = function get (buffer, offset) {
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debug('ffi FunctionType "get" function');
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const ptr = buffer.readPointer(offset);
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return this.toFunction(ptr);
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};
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/**
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* set function; return a Callback buffer.
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*/
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Function.prototype.set = function set (buffer, offset, value) {
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debug('ffi FunctionType "set" function');
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let ptr;
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if ('function' == typeof value) {
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ptr = this.toPointer(value);
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} else if (Buffer.isBuffer(value)) {
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ptr = value;
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} else {
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throw new Error('don\'t know how to set callback function for: ' + value);
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}
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buffer.writePointer(ptr, offset);
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};
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