fix: relative link error

lib/filesystem.js

@@ -100,9 +100,10 @@ class Filesystem {
 
   insertLink (p) {
     const symlink = fs.readlinkSync(p)
-    const parentPath = path.dirname(p)
+    // /var => /private/var
+    const parentPath = fs.realpathSync(path.dirname(p))
     const link = path.relative(fs.realpathSync(this.src), path.join(parentPath, symlink))
-    if (link.substr(0, 2) === '..') {
+    if (link.startsWith('..')) {
       throw new Error(`${p}: file "${link}" links out of the package`)
     }
     const node = this.searchNodeFromPath(p)

test/filesystem-spec.js

@@ -0,0 +1,41 @@
+'use strict'
+
+const assert = require('assert')
+const fs = require('../lib/wrapped-fs')
+const path = require('path')
+const rimraf = require('rimraf')
+
+const Filesystem = require('../lib/filesystem')
+
+describe('filesystem', function () {
+  beforeEach(() => { rimraf.sync(path.join(__dirname, '..', 'tmp'), fs) })
+
+  it('should does not throw an error when the src path includes a symbol link', async () => {
+    /**
+     * Directory structure:
+     * tmp
+     * ├── private
+     * │   └── var
+     * │       ├── app
+     * │       │   └── file.txt -> ../file.txt
+     * │       └── file.txt
+     * └── var -> private/var
+     */
+    const tmpPath = path.join(__dirname, '..', 'tmp')
+    const privateVarPath = path.join(tmpPath, 'private', 'var')
+    const varPath = path.join(tmpPath, 'var')
+    fs.mkdirSync(privateVarPath, { recursive: true })
+    fs.symlinkSync(path.relative(tmpPath, privateVarPath), varPath)
+
+    const originFilePath = path.join(varPath, 'file.txt')
+    fs.writeFileSync(originFilePath, 'hello world')
+    const appPath = path.join(varPath, 'app')
+    fs.mkdirpSync(appPath)
+    fs.symlinkSync('../file.txt', path.join(appPath, 'file.txt'))
+
+    const filesystem = new Filesystem(varPath)
+    assert.doesNotThrow(() => {
+      filesystem.insertLink(path.join(appPath, 'file.txt'))
+    })
+  })
+})