fs: validate falsy openAsBlob type option

openAsBlob() and openAsBlobSync() read the MIME type as
options.type || '' before validating it, causing falsy non-string
values to be replaced with the default before reaching validateString().
As a result, { type: 0 }, { type: false }, { type: null }, and
{ type: NaN } are accepted as an empty type, while { type: 1 }
throws ERR_INVALID_ARG_TYPE.

Default the option only when it is undefined so all other values are
validated against the documented string type.

Signed-off-by: Christian Aurich Zanettini Martins <christian.aurichzm@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/66125
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>

lib/fs.js

@@ -790,7 +790,7 @@ function openSync(path, flags, mode) {
  */
 function openAsBlob(path, options = kEmptyObject) {
   validateObject(options, 'options');
-  const type = options.type || '';
+  const { type = '' } = options;
   validateString(type, 'options.type');
 
   const h = vfsState.handlers;
@@ -816,7 +816,7 @@ function openAsBlob(path, options = kEmptyObject) {
  */
 function openAsBlobSync(path, options = kEmptyObject) {
   validateObject(options, 'options');
-  const type = options.type || '';
+  const { type = '' } = options;
   validateString(type, 'options.type');
   path = getValidatedPath(path);
 

test/parallel/test-fs-openAsBlobSync.js

@@ -23,9 +23,14 @@ assert.throws(() => fs.openAsBlobSync(1), {
 assert.throws(() => fs.openAsBlobSync(testfile, null), {
   code: 'ERR_INVALID_ARG_TYPE',
 });
-assert.throws(() => fs.openAsBlobSync(testfile, { type: 1 }), {
-  code: 'ERR_INVALID_ARG_TYPE',
-});
+for (const type of [1, 0, false, null, NaN, {}]) {
+  assert.throws(() => fs.openAsBlobSync(testfile, { type }), {
+    code: 'ERR_INVALID_ARG_TYPE',
+  });
+  assert.throws(() => fs.openAsBlob(testfile, { type }), {
+    code: 'ERR_INVALID_ARG_TYPE',
+  });
+}
 assert.throws(() => fs.openAsBlobSync(missing), {
   code: 'ENOENT',
   syscall: 'stat',