test: do not use uninitialized memory in common flags check

Only use the amount of data that was actually read from the test file. Otherwise, there is a small risk of getting false positives, and generally reading uninitialized memory makes using automated memory error detection tools harder. PR-URL: #25475 Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Richard Lau <[email protected]> Reviewed-By: Tobias Nießen <[email protected]> Reviewed-By: Rich Trott <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: James M Snell <[email protected]>
nodejs · Jan 23, 2019 · 4c207d9 · 4c207d9
1 parent 688fb8d
commit 4c207d9
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/test/common/index.js b/test/common/index.js
@@ -57,9 +57,9 @@ if (process.argv.length === 2 &&
   const bytesToRead = 1500;
   const buffer = Buffer.allocUnsafe(bytesToRead);
   const fd = fs.openSync(module.parent.filename, 'r');
-  fs.readSync(fd, buffer, 0, bytesToRead);
+  const bytesRead = fs.readSync(fd, buffer, 0, bytesToRead);
   fs.closeSync(fd);
-  const source = buffer.toString();
+  const source = buffer.toString('utf8', 0, bytesRead);
 
   const flagStart = source.indexOf('// Flags: --') + 10;
   if (flagStart !== 9) {