Attachments: resolve windows paths issue

Author: DmitryAstafyev

application/client/src/app/ui/views/sidebar/attachments/preview/image/component.ts

@@ -199,7 +199,7 @@ export class Preview extends ChangesDetector implements AfterViewInit, AfterCont
                 closable: false,
             },
         );
-        new URLFileReader(`attachment://${this.attachment.filepath}`)
+        new URLFileReader(`attachment://${encodeURIComponent(this.attachment.filepath)}`)
             .read('blob')
             .then((response) => {
                 if (!(response instanceof Blob)) {
@@ -225,7 +225,7 @@ export class Preview extends ChangesDetector implements AfterViewInit, AfterCont
     }
 
     protected update() {
-        this.url = `attachment://${this.attachment.filepath}`;
+        this.url = `attachment://${encodeURIComponent(this.attachment.filepath)}`;
     }
 }
 export interface Preview extends IlcInterface {}

application/client/src/app/ui/views/sidebar/attachments/preview/text/component.ts

@@ -89,7 +89,7 @@ export class Preview extends ChangesDetector implements AfterContentInit {
     protected update() {
         this.reading = true;
         this.detectChanges();
-        new URLFileReader(`attachment://${this.attachment.filepath}`)
+        new URLFileReader(`attachment://${encodeURIComponent(this.attachment.filepath)}`)
             .read()
             .then((response) => {
                 if (typeof response !== 'string') {

application/holder/src/service/electron/protocol.ts

@@ -3,13 +3,47 @@ import { protocol } from 'electron';
 import * as url from 'url';
 import * as fs from 'fs';
 
+/// The primary communication channel between the renderer and the backend is IPC.
+/// However, attachments are delivered via direct links. For security reasons these
+/// links are URL‑encoded, which is especially important to safely carry Windows
+/// paths with backslashes.
 export class Protocol {
+    /**
+     * Registers the custom `attachment:` scheme handler in the Electron main process.
+     *
+     * The handler serves local files referenced by `attachment://` URLs.
+     * See {@link Protocol.attachment}.
+     *
+     * @remarks
+     * This uses `protocol.handle` (Electron 20+) and binds the instance method as the
+     * request handler.
+     */
     public register() {
         protocol.handle('attachment', this.attachment.bind(this));
     }
 
+    /**
+     * Attachment handler that resolves an `attachment:` URL to a local file and
+     * returns it as a `Response`.
+     *
+     * @param request - Incoming request targeting the `attachment:` scheme.
+     * @returns A promise that resolves to:
+     * - `200 OK` with the file content in the body when the file exists and can be read;
+     * - `404 Not Found` when the file cannot be read (e.g., missing or inaccessible).
+     *
+     * @remarks
+     * - The URL is first decoded (with `decodeURIComponent`) and converted to a `file:`
+     *   URL, then to a filesystem path via `url.fileURLToPath`. This preserves Windows
+     *   paths that contain backslashes and disallows accidental scheme confusion.
+     * - If the path does not exist, the method rejects the promise with an Error.
+     *   Any read errors are converted into a `404` HTTP-like response.
+     * - Do not call `fetch(file://…)` in Node/Electron; Node’s `fetch` (undici)
+     *   does not implement the `file:` scheme. Read the file directly, as below.
+     */
     protected async attachment(request: Request): Promise<Response> {
-        const path = url.fileURLToPath(new URL(request.url.replace(/^attachment:/, 'file:')));
+        const path = url.fileURLToPath(
+            new URL(decodeURIComponent(request.url.replace(/^attachment:/, 'file:'))),
+        );
         if (!fs.existsSync(path)) {
             return Promise.reject(new Error(`File doesn't exist`));
         }