Add new options and fix path

server/controllers/FileSystemController.js

@@ -88,7 +88,10 @@ class FileSystemController {
       return res.sendStatus(403)
     }
 
-    const { directory, folderPath } = req.body
+    // fileName - If fileName is provided, the check only returns true if the actual file exists, not just the directory
+    // allowBookFiles - If true, allows containing other book related files (e.g. .pdf, .epub, etc.)
+    // allowAudioFiles - If true, allows containing other audio related files (e.g. .mp3, .m4b, etc.)
+    const { directory, folderPath, fileName, allowBookFiles, allowAudioFiles } = req.body
     if (!directory?.length || typeof directory !== 'string' || !folderPath?.length || typeof folderPath !== 'string') {
       Logger.error(`[FileSystemController] Invalid request body: ${JSON.stringify(req.body)}`)
       return res.status(400).json({
@@ -96,6 +99,20 @@ class FileSystemController {
       })
     }
 
+    if (fileName && typeof fileName !== 'string') {
+      Logger.error(`[FileSystemController] Invalid fileName in request body: ${JSON.stringify(req.body)}`)
+      return res.status(400).json({
+        error: 'Invalid fileName'
+      })
+    }
+
+    if (allowBookFiles && typeof allowBookFiles !== 'boolean' || allowAudioFiles && typeof allowAudioFiles !== 'boolean' || (allowBookFiles && allowAudioFiles)) {
+      Logger.error(`[FileSystemController] Invalid allowBookFiles or allowAudioFiles in request body: ${JSON.stringify(req.body)}`)
+      return res.status(400).json({
+        error: 'Invalid allowBookFiles or allowAudioFiles'
+      })
+    }
+
     // Check that library folder exists
     const libraryFolder = await Database.libraryFolderModel.findOne({
       where: {
@@ -110,20 +127,52 @@ class FileSystemController {
 
     const filepath = Path.join(libraryFolder.path, directory)
 
-    // Ensure filepath is inside library folder (prevents directory traversal)
-    if (!filepath.startsWith(libraryFolder.path)) {
+    // Ensure filepath is inside library folder (prevents directory traversal) (And convert libraryFolder to Path to normalize)
+    if (!filepath.startsWith(Path.join(libraryFolder.path))) {
       Logger.error(`[FileSystemController] Filepath is not inside library folder: ${filepath}`)
       return res.sendStatus(400)
     }
 
     if (await fs.pathExists(filepath)) {
+      if (fileName) {
+        // Check if a specific file exists
+        const filePath = Path.join(filepath, fileName)
+        if (await fs.pathExists(filePath)) {
+          return res.json({
+            exists: true,
+          })
+        }
+      } else if(allowBookFiles || allowAudioFiles) {
+          let allowedExtensions = []
+          if (allowBookFiles && !allowAudioFiles) {
+            allowedExtensions = ['epub', 'pdf', 'mobi', 'azw3', 'cbr', 'cbz']
+          } else if (allowAudioFiles && !allowBookFiles) {
+            allowedExtensions = ['m4b', 'mp3', 'm4a', 'flac', 'opus', 'ogg', 'oga', 'mp4', 'aac', 'wma', 'aiff', 'aif', 'wav', 'webm', 'webma', 'mka', 'awb', 'caf', 'mpeg', 'mpg']
+          } else {
+            allowedExtensions = []
+          }
+          const files = await fs.readdir(filepath)
+          const exists = allowedExtensions.length === 0
+            ? files.length > 0
+            : files.some((file) => {
+                const ext = Path.extname(file).toLowerCase().replace(/^\./, '')
+                return allowedExtensions.includes(ext)
+              })
+
+          // To let the sub dir check run
+          if(exists) return res.json({
+            exists: exists
+          })
+      } else {
         return res.json({
           exists: true
         })
       }
+    }
 
     // Check if a library item exists in a subdirectory
     // See: https://github.com/advplyr/audiobookshelf/issues/4146
+    // For filenames it does not matter if the file is in a subdirectory or not because the file is not allowed to be created
     const cleanedDirectory = directory.split('/').filter(Boolean).join('/')
     if (cleanedDirectory.includes('/')) {
       // Can only be 2 levels deep