fix: fix symlink pointing error in filesystem.insertLink (#301)

Co-authored-by: jrainliu <jrainliu@tencent.com>

lib/filesystem.js

@@ -99,7 +99,9 @@ class Filesystem {
   }
 
   insertLink (p) {
-    const link = path.relative(fs.realpathSync(this.src), fs.realpathSync(p))
+    const symlink = fs.readlinkSync(p)
+    const parentPath = path.dirname(p)
+    const link = path.relative(fs.realpathSync(this.src), path.join(parentPath, symlink))
     if (link.substr(0, 2) === '..') {
       throw new Error(`${p}: file "${link}" links out of the package`)
     }

test/api-spec.js

@@ -81,6 +81,11 @@ describe('api', function () {
     asar.extractAll('test/input/extractthis-unpack-dir.asar', 'tmp/extractthis-unpack-dir-api/')
     return compDirs('tmp/extractthis-unpack-dir-api/', 'test/expected/extractthis')
   })
+  it('should extract an archive with symlink', async () => {
+    await asar.createPackageWithOptions('test/input/packthis-with-symlink/', 'tmp/packthis-with-symlink.asar', { dot: false })
+    asar.extractAll('tmp/packthis-with-symlink.asar', 'tmp/packthis-with-symlink/')
+    return compFiles('tmp/packthis-with-symlink/real.txt', 'test/input/packthis-with-symlink/real.txt')
+  })
   it('should handle multibyte characters in paths', async () => {
     await asar.createPackageWithOptions('test/input/packthis-unicode-path/', 'tmp/packthis-unicode-path.asar', {
       globOptions: {

test/input/packthis-with-symlink/A/real.txt

@@ -0,0 +1 @@
+I AM REAL TXT FILE

test/input/packthis-with-symlink/Current

@@ -0,0 +1 @@
+A

test/input/packthis-with-symlink/real.txt

@@ -0,0 +1 @@
+Current/real.txt

test/util/compareFiles.js

@@ -7,6 +7,19 @@ module.exports = async function (actualFilePath, expectedFilePath) {
   if (process.env.ELECTRON_ASAR_SPEC_UPDATE) {
     await fs.writeFile(expectedFilePath, await fs.readFile(actualFilePath))
   }
-  const [actual, expected] = await Promise.all([fs.readFile(actualFilePath, 'utf8'), fs.readFile(expectedFilePath, 'utf8')])
-  assert.strictEqual(actual, expected)
+  const [actualFileContent, expectedFileContent] = await Promise.all([fs.readFile(actualFilePath, 'utf8'), fs.readFile(expectedFilePath, 'utf8')])
+  assert.strictEqual(actualFileContent, expectedFileContent)
+
+  const [actualIsSymlink, expectedIsSymlink] = [isSymbolicLinkSync(actualFilePath), isSymbolicLinkSync(expectedFilePath)]
+  assert.strictEqual(actualIsSymlink, expectedIsSymlink)
+
+  if (actualIsSymlink && expectedIsSymlink) {
+    const [actualSymlinkPointer, expectedSymlinkPointer] = [fs.readlinkSync(actualFilePath), fs.readlinkSync(expectedFilePath)]
+    assert.strictEqual(actualSymlinkPointer, expectedSymlinkPointer)
+  }
+}
+
+function isSymbolicLinkSync (path) {
+  const stats = fs.lstatSync(path)
+  return stats.isSymbolicLink()
 }