feat: add support for compiling big-endian .mo files

This commit adds support for compiling big-endian .mo files. This facilitates
the use of .mo files in big-endian systems, the ability to parser big-endian
.mo files was already present.

This commit also does the following:

- Adds a new mo parser options type, used to indicate `endian = 'le' | 'be'`
- Adds tests and fixtures for big-endian .mo files.
- Renames the existing .mo fixtures to indicate that they are little-endian.
- Fixes direct usages of `writeUInt32LE`.

Fixes #97

Author: johnhooks

src/mocompiler.js

@@ -21,15 +21,22 @@ import contentType from 'content-type';
  * @typedef {{ msgid: Buffer, msgstr: Buffer }} TranslationBuffers A translation object partially parsed.
  */
 
+/**
+ *
+ * @typedef {Object} CompilerOptions MO compiler options
+ * @property {'be'|'le'} [endian='le'] Endianness of the output buffer. Default is 'le'
+ */
+
 /**
  * Exposes general compiler function. Takes a translation
  * object as a parameter and returns binary MO object
  *
  * @param {GetTextTranslations} table Translation object
+ * @param {CompilerOptions} [options] MO compiler options
  * @return {Buffer} Compiled binary MO object
  */
-export default function (table) {
-  const compiler = new Compiler(table);
+export default function (table, options = { endian: 'le' }) {
+  const compiler = new Compiler(table, options);
 
   return compiler.compile();
 }
@@ -91,8 +98,9 @@ function prepareTranslations (translations) {
  * @this {Compiler & Transform}
  *
  * @param {GetTextTranslations} [table] Translation table as defined in the README
+ * @param {CompilerOptions} [options] MO compiler options
  */
-function Compiler (table) {
+function Compiler (table, options = { endian: 'le' }) {
   /** @type {GetTextTranslations} _table The translation table */
   this._table = {
     charset: undefined,
@@ -101,10 +109,11 @@ function Compiler (table) {
   };
 
   this._translations = [];
+
   /**
    * @type {WriteFunc}
    */
-  this._writeFunc = 'writeUInt32LE';
+  this._writeFunc = options?.endian === 'le' ? 'writeUInt32LE' : 'writeUInt32BE';
 
   this._handleCharset();
 
@@ -258,8 +267,8 @@ Compiler.prototype._build = function (list, size) {
   for (i = 0, len = list.length; i < len; i++) {
     const msgidLength = /** @type {Buffer} */(/** @type {unknown} */(list[i].msgid));
     msgidLength.copy(returnBuffer, curPosition);
-    returnBuffer.writeUInt32LE(list[i].msgid.length, 28 + i * 8);
-    returnBuffer.writeUInt32LE(curPosition, 28 + i * 8 + 4);
+    returnBuffer[this._writeFunc](list[i].msgid.length, 28 + i * 8);
+    returnBuffer[this._writeFunc](curPosition, 28 + i * 8 + 4);
     returnBuffer[curPosition + list[i].msgid.length] = 0x00;
     curPosition += list[i].msgid.length + 1;
   }
@@ -268,8 +277,8 @@ Compiler.prototype._build = function (list, size) {
   for (i = 0, len = list.length; i < len; i++) {
     const msgstrLength = /** @type {Buffer} */(/** @type {unknown} */(list[i].msgstr));
     msgstrLength.copy(returnBuffer, curPosition);
-    returnBuffer.writeUInt32LE(list[i].msgstr.length, 28 + (4 + 4) * list.length + i * 8);
-    returnBuffer.writeUInt32LE(curPosition, 28 + (4 + 4) * list.length + i * 8 + 4);
+    returnBuffer[this._writeFunc](list[i].msgstr.length, 28 + (4 + 4) * list.length + i * 8);
+    returnBuffer[this._writeFunc](curPosition, 28 + (4 + 4) * list.length + i * 8 + 4);
     returnBuffer[curPosition + list[i].msgstr.length] = 0x00;
     curPosition += list[i].msgstr.length + 1;
   }

test/fixtures/latin13-be.mo

@@ -11,32 +11,85 @@ const __dirname = path.dirname(__filename);
 const readFile = promisify(fsReadFile);
 
 const expect = chai.expect;
+
+const littleEndianMagic = [0xde, 0x12, 0x04, 0x95];
+const bigEndianMagic = [0x95, 0x04, 0x12, 0xde];
+
 chai.config.includeStack = true;
 
 describe('MO Compiler', () => {
-  describe('UTF-8', () => {
+  describe('UTF-8 LE', async () => {
+    const [json, moData] = await Promise.all([
+      readFile(path.join(__dirname, 'fixtures/utf8-po.json'), 'utf8'),
+      readFile(path.join(__dirname, 'fixtures/utf8-le.mo'))
+    ]);
+
     it('should compile', async () => {
-      const [json, moData] = await Promise.all([
-        readFile(path.join(__dirname, 'fixtures/utf8-po.json'), 'utf8'),
-        readFile(path.join(__dirname, 'fixtures/utf8.mo'))
-      ]);
+      const compiled = mo.compile(JSON.parse(json));
 
+      expect(compiled.toString('utf8')).to.deep.equal(moData.toString('utf8'));
+    });
+
+    it('should have the correct magic number', () => {
       const compiled = mo.compile(JSON.parse(json));
 
+      expect(Array.from(compiled.subarray(0, 4))).to.eql(littleEndianMagic);
+    });
+  });
+
+  describe('UTF-8 BE', async () => {
+    const [json, moData] = await Promise.all([
+      readFile(path.join(__dirname, 'fixtures/utf8-po.json'), 'utf8'),
+      readFile(path.join(__dirname, 'fixtures/utf8-be.mo'))
+    ]);
+
+    it('should compile', async () => {
+      const compiled = mo.compile(JSON.parse(json), { endian: 'be' });
+
       expect(compiled.toString('utf8')).to.deep.equal(moData.toString('utf8'));
     });
+
+    it('should have the correct magic number', () => {
+      const compiled = mo.compile(JSON.parse(json), { endian: 'be' });
+
+      expect(Array.from(compiled.subarray(0, 4))).to.eql(bigEndianMagic);
+    });
   });
 
-  describe('Latin-13', () => {
+  describe('Latin-13 LE', async () => {
+    const [json, moData] = await Promise.all([
+      readFile(path.join(__dirname, 'fixtures/latin13-po.json'), 'utf8'),
+      readFile(path.join(__dirname, 'fixtures/latin13-le.mo'))
+    ]);
+
     it('should compile', async () => {
-      const [json, moData] = await Promise.all([
-        readFile(path.join(__dirname, 'fixtures/latin13-po.json'), 'utf8'),
-        readFile(path.join(__dirname, 'fixtures/latin13.mo'))
-      ]);
+      const compiled = mo.compile(JSON.parse(json));
 
+      expect(compiled.toString('utf8')).to.equal(moData.toString('utf8'));
+    });
+
+    it('should have the correct magic number', () => {
       const compiled = mo.compile(JSON.parse(json));
 
+      expect(Array.from(compiled.subarray(0, 4))).to.eql(littleEndianMagic);
+    });
+  });
+
+  describe('Latin-13 BE', async () => {
+    const [json, moData] = await Promise.all([
+      readFile(path.join(__dirname, 'fixtures/latin13-po.json'), 'utf8'),
+      readFile(path.join(__dirname, 'fixtures/latin13-be.mo'))
+    ]);
+
+    it('should compile', async () => {
+      const compiled = mo.compile(JSON.parse(json), { endian: 'be' });
+
       expect(compiled.toString('utf8')).to.equal(moData.toString('utf8'));
     });
+
+    it('should have the correct magic number', () => {
+      const compiled = mo.compile(JSON.parse(json), { endian: 'be' });
+      expect(Array.from(compiled.subarray(0, 4))).to.eql(bigEndianMagic);
+    });
   });
 });

test/fixtures/latin13.mo test/fixtures/latin13-le.motest/fixtures/latin13.mo renamed to test/fixtures/latin13-le.mo

@@ -14,10 +14,10 @@ const expect = chai.expect;
 chai.config.includeStack = true;
 
 describe('MO Parser', () => {
-  describe('UTF-8', () => {
+  describe('UTF-8 LE', () => {
     it('should parse', async () => {
       const [moData, json] = await Promise.all([
-        readFile(path.join(__dirname, 'fixtures/utf8.mo')),
+        readFile(path.join(__dirname, 'fixtures/utf8-le.mo')),
         readFile(path.join(__dirname, 'fixtures/utf8-mo.json'), 'utf8')
       ]);
 
@@ -27,10 +27,36 @@ describe('MO Parser', () => {
     });
   });
 
-  describe('Latin-13', () => {
+  describe('UTF-8 BE', () => {
     it('should parse', async () => {
       const [moData, json] = await Promise.all([
-        readFile(path.join(__dirname, 'fixtures/latin13.mo')),
+        readFile(path.join(__dirname, 'fixtures/utf8-be.mo')),
+        readFile(path.join(__dirname, 'fixtures/utf8-mo.json'), 'utf8')
+      ]);
+
+      const parsed = mo.parse(moData);
+
+      expect(parsed).to.deep.equal(JSON.parse(json));
+    });
+  });
+
+  describe('Latin-13 LE', () => {
+    it('should parse', async () => {
+      const [moData, json] = await Promise.all([
+        readFile(path.join(__dirname, 'fixtures/latin13-le.mo')),
+        readFile(path.join(__dirname, 'fixtures/latin13-mo.json'), 'utf8')
+      ]);
+
+      const parsed = mo.parse(moData);
+
+      expect(parsed).to.deep.equal(JSON.parse(json));
+    });
+  });
+
+  describe('Latin-13 BE', () => {
+    it('should parse', async () => {
+      const [moData, json] = await Promise.all([
+        readFile(path.join(__dirname, 'fixtures/latin13-be.mo')),
         readFile(path.join(__dirname, 'fixtures/latin13-mo.json'), 'utf8')
       ]);
 

test/fixtures/obsolete-be.mo

@@ -17,7 +17,7 @@ chai.config.includeStack = true;
 describe('Obsolete', async () => {
   const [po, mo, jsonString] = await Promise.all([
     readFile(path.join(__dirname, 'fixtures/obsolete.po')),
-    readFile(path.join(__dirname, 'fixtures/obsolete.mo')),
+    readFile(path.join(__dirname, 'fixtures/obsolete-le.mo')),
     readFile(path.join(__dirname, 'fixtures/obsolete.json'), 'utf8')
   ]);