Fix c tester witness file read

c tester (c/tester.js) was using a method to read the witness file
called 'readBinaryFile' that was obtaining a wrong number of witness
elements, and as consequence was returning a wrong array of witness.

Changed that method to 'readBinWitnessFile', which makes use of
wtnsUtils method from snarkjs to read the witness binary file, so now
the c tester returns the correct witness.

c/tester.js

@@ -0,0 +1,234 @@
+const chai = require("chai");
+const assert = chai.assert;
+
+const fs = require("fs");
+var tmp = require("tmp-promise");
+const path = require("path");
+
+const util = require("util");
+const exec = util.promisify(require("child_process").exec);
+
+const loadR1cs = require("r1csfile").load;
+const ZqField = require("ffjavascript").ZqField;
+
+const readWtns = require("snarkjs").wtns.exportJson;
+
+module.exports = c_tester;
+
+async function  c_tester(circomInput, _options) {
+
+    assert(await compiler_above_version("2.0.0"),"Wrong compiler version. Must be at least 2.0.0");
+    
+    tmp.setGracefulCleanup();
+
+    const dir = await tmp.dir({prefix: "circom_", unsafeCleanup: true });
+
+    // console.log(dir.path);
+
+    const baseName = path.basename(circomInput, ".circom");
+    const options = Object.assign({}, _options);
+
+    options.wasm = true;
+
+    options.sym = true;
+    options.json = options.json || false; // costraints in json format
+    //options.r1cs = options.r1cs || false; // costraints in r1cs format
+    //if (!options.json) options.r1cs = true; // r1cs if not json
+    options.r1cs = true;
+    options.output = dir.path;
+
+    await compile(baseName, circomInput, options);
+
+    return new WasmTester(dir, baseName, run);
+}
+
+async function compile (baseName, fileName, options) {    
+    var flags = "--c ";
+    if (options.sym) flags += "--sym ";
+    if (options.r1cs) flags += "--r1cs ";
+    if (options.json) flags += "--json ";
+    if (options.output) flags += "--output " + options.output + " ";
+    if (options.O === 0) flags += "--O0 "
+    if (options.O === 1) flags += "--O1 "
+
+    b = await exec("circom " + flags + fileName); 
+    assert(b.stderr == "",
+	   "circom compiler error \n" + b.stderr);
+    
+    const c_folder = path.join(options.output, baseName+"_cpp/")
+    b = await exec("make -C "+c_folder);
+    assert(b.stderr == "",
+	   "error building the executable C program\n" + b.stderr);
+}
+    
+class WasmTester {
+
+    constructor(dir, baseName, witnessCalculator) {
+        this.dir=dir;
+        this.baseName = baseName;
+        this.witnessCalculator = witnessCalculator;
+    }
+
+    async release() {
+        await this.dir.cleanup();
+    }
+
+    async calculateWitness(input) {
+	const inputjson = JSON.stringify(input);
+	const inputFile = path.join(this.dir.path, this.baseName+"_cpp/" + this.baseName + ".json");
+	const wtnsFile = path.join(this.dir.path, this.baseName+"_cpp/" + this.baseName + ".wtns");
+	const runc = path.join(this.dir.path, this.baseName+"_cpp/" + this.baseName);	
+        fs.writeFile(inputFile, inputjson, function(err) {
+	    if (err) throw err;
+	});
+	await exec("ls " + path.join(this.dir.path, this.baseName+"_cpp/"));
+	await exec(runc + " " + inputFile + " " + wtnsFile);
+	return await readBinWitnessFile(wtnsFile);
+    }
+
+    async loadSymbols() {
+        if (this.symbols) return;
+        this.symbols = {};
+        const symsStr = await fs.promises.readFile(
+            path.join(this.dir.path, this.baseName + ".sym"),
+            "utf8"
+        );
+        const lines = symsStr.split("\n");
+        for (let i=0; i<lines.length; i++) {
+            const arr = lines[i].split(",");
+            if (arr.length!=4) continue;
+            this.symbols[arr[3]] = {
+                labelIdx: Number(arr[0]),
+                varIdx: Number(arr[1]),
+                componentIdx: Number(arr[2]),
+            };
+        }
+    }
+
+    async loadConstraints() {
+        const self = this;
+        if (this.constraints) return;
+        const r1cs = await loadR1cs(path.join(this.dir.path, this.baseName + ".r1cs"),true, false);
+        self.F = new ZqField(r1cs.prime);
+        self.nVars = r1cs.nVars;
+        self.constraints = r1cs.constraints;
+    }
+
+    async assertOut(actualOut, expectedOut) {
+        const self = this;
+        if (!self.symbols) await self.loadSymbols();
+
+        checkObject("main", expectedOut);
+
+        function checkObject(prefix, eOut) {
+
+            if (Array.isArray(eOut)) {
+                for (let i=0; i<eOut.length; i++) {
+                    checkObject(prefix + "["+i+"]", eOut[i]);
+                }
+            } else if ((typeof eOut == "object")&&(eOut.constructor.name == "Object")) {
+                for (let k in eOut) {
+                    checkObject(prefix + "."+k, eOut[k]);
+                }
+            } else {
+                if (typeof self.symbols[prefix] == "undefined") {
+                    assert(false, "Output variable not defined: "+ prefix);
+                }
+                const ba = actualOut[self.symbols[prefix].varIdx].toString();
+                const be = eOut.toString();
+                assert.strictEqual(ba, be, prefix);
+            }
+        }
+    }
+
+    async getDecoratedOutput(witness) {
+        const self = this;
+        const lines = [];
+        if (!self.symbols) await self.loadSymbols();
+        for (let n in self.symbols) {
+            let v;
+            if (utils.isDefined(witness[self.symbols[n].varIdx])) {
+                v = witness[self.symbols[n].varIdx].toString();
+            } else {
+                v = "undefined";
+            }
+            lines.push(`${n} --> ${v}`);
+        }
+        return lines.join("\n");
+    }
+
+    async checkConstraints(witness) {
+        const self = this;
+        if (!self.constraints) await self.loadConstraints();
+        for (let i=0; i<self.constraints.length; i++) {
+            checkConstraint(self.constraints[i]);
+        }
+
+        function checkConstraint(constraint) {
+	    
+            const F = self.F;
+            const a = evalLC(constraint[0]);
+            const b = evalLC(constraint[1]);
+            const c = evalLC(constraint[2]);
+            assert (F.isZero(F.sub(F.mul(a,b), c)), "Constraint doesn't match");
+        }
+
+        function evalLC(lc) {
+            const F = self.F;
+            let v = F.zero;
+            for (let w in lc) {
+                v = F.add(
+                    v,
+                    F.mul( lc[w], witness[w] )
+                );
+            }
+            return v;
+        }
+    }
+
+}
+
+function version_to_list ( v ) {
+    return v.split(".").map(function(x) {
+	return parseInt(x, 10);
+    });
+}
+
+function check_versions ( v1, v2 ) {
+    //check if v1 is newer than or equal to v2
+    for (let i = 0; i < v2.length; i++) {
+	if (v1[i] > v2[i]) return true;
+	if (v1[i] < v2[i]) return false;
+    }
+    return true;
+}
+
+async function compiler_above_version(v) {
+    let output = await exec('circom --version').toString();
+    let compiler_version = version_to_list(output.slice(output.search(/\d/),-1));
+    vlist = version_to_list(v);
+    return check_versions ( compiler_version, vlist );
+}
+
+async function readBinWitnessFile(fileName) {
+    const buffWitness = await readWtns(fileName);
+    return buffWitness;
+}
+
+function fromArray8(arr) { //returns a BigInt
+    var res = BigInt(0);
+    const radix = BigInt(0x100);
+    for (let i = arr.length-1 ; i>=0; i--) {
+        res = res*radix + BigInt(arr[i]);
+    }
+    return res;
+}
+
+function fromArray8ToUint(arr) { //returns a BigInt
+    var res = 0;
+    const radix = 8;
+    for (let i = arr.length-1 ; i>=0; i--) {
+        res = res*radix + arr[i];
+    }
+    return res;
+}

index.js

@@ -1,2 +1,2 @@
 exports.wasm = require("./wasm/tester");
-//exports.c = require("./c/tester");
+exports.c = require("./c/tester");

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "circom_tester",
-  "version": "0.0.4",
+  "version": "0.0.7",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "circom_tester",
-      "version": "0.0.4",
+      "version": "0.0.7",
       "license": "GPL-3.0",
       "dependencies": {
         "chai": "^4.3.4",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "circom_tester",
-  "version": "0.0.4",
+  "version": "0.0.7",
   "description": "Tools for testing circom circuits.",
   "main": "index.js",
   "scripts": {
@@ -29,6 +29,7 @@
     "fnv-plus": "^1.3.1",
     "r1csfile": "0.0.16",
     "tmp-promise": "^3.0.2",
-    "util": "^0.12.4"
+    "util": "^0.12.4",
+    "snarkjs": "0.4.10"
   }
 }

test/multiplier2.js

@@ -1,6 +1,7 @@
 const chai = require("chai");
 const path = require("path");
 const wasm_tester = require("./../index").wasm;
+const c_tester = require("./../index").c;
 
 const F1Field = require("ffjavascript").F1Field;
 const Scalar = require("ffjavascript").Scalar;
@@ -9,14 +10,20 @@ const Fr = new F1Field(exports.p);
 
 const assert = chai.assert;
 
-describe("Exponentioation test", function () {
+describe("Simple test", function () {
     this.timeout(100000);
 
-    it("Should generate the Exponentiation table in k=0", async () => {
+    it("Checking the compilation of a simple circuit generating wasm", async () => {
 
         const circuit = await wasm_tester(path.join(__dirname, "Multiplier2.circom"));
         const w = await circuit.calculateWitness({a: 2, b: 4});
+        await circuit.checkConstraints(w);
+    });
 
+    it("Checking the compilation of a simple circuit generating C", async () => {
+
+        const circuit = await c_tester(path.join(__dirname, "Multiplier2.circom"));
+        const w = await circuit.calculateWitness({a: 2, b: 4});
         await circuit.checkConstraints(w);
 
     });

wasm/tester.js

@@ -51,8 +51,12 @@ async function compile (fileName, options) {
     if (options.r1cs) flags += "--r1cs ";
     if (options.json) flags += "--json ";
     if (options.output) flags += "--output " + options.output + " ";
-    
-    await exec("circom " + flags + fileName);
+    if (options.O === 0) flags += "--O0 "
+    if (options.O === 1) flags += "--O1 "
+
+    b = await exec("circom " + flags + fileName);
+    assert(b.stderr == "",
+	  "circom compiler error \n" + b.stderr);
 }
     
 class WasmTester {