Add symbolic link support (#802)

* Allow symbolic links

* Update changelog

.github/CHANGELOG.md

@@ -79,6 +79,7 @@ This update **fixes a XSS security vulnerability** when exporting a document.
 - Fixed multiple parser issues (update marked.js to v0.6.1)
 - Fixed [...] is displayed in gray and orange (#432)
 - Fixed an issue that relative images are not loaded after closing a tab
+- Add symbolic link support
 
 ### 0.13.65
 

src/main/actions/file.js

@@ -7,7 +7,7 @@ import appWindow from '../window'
 import { EXTENSION_HASN, EXTENSIONS, PANDOC_EXTENSIONS, URL_REG } from '../config'
 import { loadMarkdownFile, writeFile, writeMarkdownFile } from '../utils/filesystem'
 import appMenu from '../menu'
-import { getPath, isMarkdownFile, log, isFile, isDirectory, getRecommendTitle } from '../utils'
+import { getPath, isMarkdownFile, isMarkdownFileOrLink, normalizeAndResolvePath, log, isFile, isDirectory, getRecommendTitle } from '../utils'
 import userPreference from '../preference'
 import pandoc from '../utils/pandoc'
 
@@ -213,7 +213,7 @@ ipcMain.on('AGANI::close-window', e => {
 ipcMain.on('AGANI::window::drop', async (e, fileList) => {
   const win = BrowserWindow.fromWebContents(e.sender)
   for (const file of fileList) {
-    if (isMarkdownFile(file)) {
+    if (isMarkdownFileOrLink(file)) {
       openFileOrFolder(win, file)
       break
     }
@@ -327,12 +327,13 @@ export const print = win => {
 }
 
 export const openFileOrFolder = (win, pathname) => {
-  if (isFile(pathname)) {
+  const resolvedPath = normalizeAndResolvePath(pathname)
+  if (isFile(resolvedPath)) {
     const { openFilesInNewWindow } = userPreference.getAll()
     if (openFilesInNewWindow) {
-      appWindow.createWindow(pathname)
+      appWindow.createWindow(resolvedPath)
     } else {
-      loadMarkdownFile(pathname).then(rawDocument => {
+      loadMarkdownFile(resolvedPath).then(rawDocument => {
         newTab(win, rawDocument)
       }).catch(err => {
         // TODO: Handle error --> create a end-user error handler.
@@ -340,10 +341,10 @@ export const openFileOrFolder = (win, pathname) => {
         log(err)
       })
     }
-  } else if (isDirectory(pathname)) {
-    appWindow.createWindow(pathname)
+  } else if (isDirectory(resolvedPath)) {
+    appWindow.createWindow(resolvedPath)
   } else {
-    console.error(`[ERROR] Cannot open unknown file: "${pathname}"`)
+    console.error(`[ERROR] Cannot open unknown file: "${resolvedPath}"`)
   }
 }
 

src/main/app.js

@@ -1,9 +1,8 @@
-import path from 'path'
 import { app, systemPreferences } from 'electron'
 import appWindow from './window'
 import { isOsx } from './config'
 import { dockMenu } from './menus'
-import { isDirectory, isMarkdownFile, getMenuItemById } from './utils'
+import { isDirectory, isMarkdownFileOrLink, getMenuItemById, normalizeAndResolvePath } from './utils'
 import { watchers } from './utils/imagePathAutoComplement'
 import { selectTheme } from './actions/theme'
 import preference from './preference'
@@ -70,10 +69,16 @@ class App {
       for (const arg of process.argv) {
         if (arg.startsWith('--')) {
           continue
-        } else if (isDirectory(arg) || isMarkdownFile(arg)) {
-          // Normalize path into an absolute path.
-          this.openFilesCache = [ path.resolve(arg) ]
+        } else if (isDirectory(arg) || isMarkdownFileOrLink(arg)) {
+          // Normalize and resolve the path or link target.
+          const resolved = normalizeAndResolvePath(arg)
+          if (resolved) {
+            // TODO: Allow to open multiple files.
+            this.openFilesCache = [ resolved ]
             break
+          } else {
+            console.error(`[ERROR] Cannot resolve "${arg}".`)
+          }
         }
       }
     }

src/main/utils/index.js

@@ -64,32 +64,93 @@ export const hasSameKeys = (a, b) => {
   return JSON.stringify(aKeys) === JSON.stringify(bKeys)
 }
 
+/**
+ * Returns true if the path is a directory with read access.
+ *
+ * @param {string} dirPath The directory path.
+ */
 export const isDirectory = dirPath => {
   try {
     return fs.existsSync(dirPath) && fs.lstatSync(dirPath).isDirectory()
   } catch (e) {
-    // No permissions
-    log(e)
     return false
   }
 }
 
-// returns true if the path is a file with read access.
+/**
+ * Returns true if the path is a file with read access.
+ *
+ * @param {string} filepath The file path.
+ */
 export const isFile = filepath => {
   try {
     return fs.existsSync(filepath) && fs.lstatSync(filepath).isFile()
   } catch (e) {
-    // No permissions
-    log(e)
     return false
   }
 }
 
-// returns true if the file is a supported markdown file.
+/**
+ * Returns true if the path is a symbolic link with read access.
+ *
+ * @param {string} filepath The link path.
+ */
+export const isSymbolicLink = filepath => {
+  try {
+    return fs.existsSync(filepath) && fs.lstatSync(filepath).isSymbolicLink()
+  } catch (e) {
+    return false
+  }
+}
+
+/**
+ * Returns true if the path is a markdown file.
+ *
+ * @param {string} filepath The path or link path.
+ */
 export const isMarkdownFile = filepath => {
   return isFile(filepath) && hasMarkdownExtension(filepath)
 }
 
+/**
+ * Returns true if the path is a markdown file or symbolic link to a markdown file.
+ *
+ * @param {string} filepath The path or link path.
+ */
+export const isMarkdownFileOrLink = filepath => {
+  if (!isFile(filepath)) return false
+  if (hasMarkdownExtension(filepath)) {
+    return true
+  }
+
+  // Symbolic link to a markdown file
+  if (isSymbolicLink(filepath)) {
+    const targetPath = fs.readlinkSync(filepath)
+    return isFile(targetPath) && hasMarkdownExtension(targetPath)
+  }
+  return false
+}
+
+/**
+ * Normalize the path into an absolute path and resolves the link target if needed.
+ *
+ * @param {string} pathname The path or link path.
+ * @returns {string} Returns the absolute path and resolved link. If the link target
+ *                   cannot be resolved, an empty string is returned.
+ */
+export const normalizeAndResolvePath = pathname => {
+  if (isSymbolicLink(pathname)) {
+    const absPath = path.dirname(pathname)
+    const targetPath = path.resolve(absPath, fs.readlinkSync(pathname))
+    if (isFile(targetPath) || isDirectory(targetPath)) {
+      return path.resolve(targetPath)
+    }
+    console.error(`Cannot resolve link target "${pathname}" (${targetPath}).`)
+    return ''
+  }
+  return path.resolve(pathname)
+}
+
 export const readJson = (filePath, printError) => {
   try {
     const content = fs.readFileSync(filePath, 'utf-8')

src/main/window.js

@@ -1,10 +1,9 @@
-import path from 'path'
 import { app, BrowserWindow, screen } from 'electron'
 import windowStateKeeper from 'electron-window-state'
 import { getOsLineEndingName, loadMarkdownFile, getDefaultTextDirection } from './utils/filesystem'
 import appMenu from './menu'
 import Watcher from './watcher'
-import { isMarkdownFile, isDirectory, log } from './utils'
+import { isMarkdownFile, isDirectory, normalizeAndResolvePath, log } from './utils'
 import { TITLE_BAR_HEIGHT, defaultWinOptions, isLinux } from './config'
 import userPreference from './preference'
 
@@ -48,10 +47,17 @@ class AppWindow {
     }
   }
 
+  /**
+   * Creates a new editor window.
+   *
+   * @param {string} [pathname] Path to a file, directory or link.
+   * @param {string} [markdown] Markdown content.
+   * @param {*} [options] BrowserWindow options.
+   */
   createWindow (pathname = null, markdown = '', options = {}) {
     // Ensure path is normalized
     if (pathname) {
-      pathname = path.resolve(pathname)
+      pathname = normalizeAndResolvePath(pathname)
     }
 
     const { windows } = this
@@ -88,7 +94,7 @@ class AppWindow {
       mainWindowState.manage(win)
       win.show()
 
-      // open single mrkdown file
+      // open single markdown file
       if (pathname && isMarkdownFile(pathname)) {
         appMenu.addRecentlyUsedDocument(pathname)
         loadMarkdownFile(pathname)