automatically convert files with #! and CRLF

It is a common mistake for Windows users to not notice the line endings
of the file. The default on Windows is to use CRLF which causes files
with a #! to fail to execute when run on the EV3. This automatically
converts the file when downloading so that users don't have to worry
about it.

Author: dlech

CHANGELOG.md

@@ -7,6 +7,7 @@ All notable changes to the "ev3dev-browser" extension will be documented in this
 
 ### Fixed
 - Fixed Windows path separator in "program" in `.vscode/launch.json` not converted to UNIX path.
+- Fixed running files with `#!` and Windows line endings (CRLF vs. LF).
 
 ## v1.2.0 - 2020-07-20
 ### Changed

src/extension.ts

@@ -17,6 +17,7 @@ import {
     toastStatusBarMessage,
     verifyFileHeader,
     getPlatform,
+    normalizeLineEndings,
 } from './utils';
 
 // fs.constants.S_IXUSR is undefined on win32!
@@ -438,6 +439,10 @@ async function download(folder: vscode.WorkspaceFolder, device: Device): Promise
                 let mode: string;
                 if (await verifyFileHeader(f.fsPath, Buffer.from('#!/'))) {
                     mode = '755';
+                    // Bash will fail to execute a file when the shebang line
+                    // contains Windows line endings because it treats \r as
+                    // text rather than a line break.
+                    await normalizeLineEndings(f.fsPath);
                 }
                 else {
                     const stat = fs.statSync(f.fsPath);

src/utils.ts

@@ -33,6 +33,40 @@ export function getSharedTempDir(sharedKey: string): Promise<string> {
     });
 }
 
+/**
+ * Checks a file for Windows line endings. If found, modifies the file to remove
+ * the Windows line endings.
+ * @param path The path to the file.
+ * @returns true if the file was modified, otherwise false
+ */
+export function normalizeLineEndings(path: string): Promise<boolean> {
+    return new Promise((resolve, reject) => {
+        fs.readFile(path, { encoding: "utf8" }, (err, data) => {
+            if (err) {
+                reject(err);
+                return;
+            }
+
+            const replace = data.replace("\r\n", "\n");
+
+            if (replace === data) {
+                // not changed
+                resolve(false);
+                return;
+            }
+
+            fs.writeFile(path, replace, (err) => {
+                if (err) {
+                    reject(err);
+                    return;
+                }
+
+                resolve(true);
+            });
+        });
+    });
+}
+
 export function openAndRead(path: string, offset: number, length: number, position: number): Promise<Buffer> {
     return new Promise((resolve, reject) => {
         fs.open(path, 'r', (err, fd) => {