fs: invalidate blob created from empty file when written to

Fixes: #47161
PR-URL: #47199
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

lib/internal/blob.js

@@ -1,14 +1,12 @@
 'use strict';
 
 const {
-  ArrayBuffer,
   ArrayFrom,
   MathMax,
   MathMin,
   ObjectDefineProperties,
   ObjectDefineProperty,
   PromiseReject,
-  PromiseResolve,
   ReflectConstruct,
   RegExpPrototypeExec,
   RegExpPrototypeSymbolReplace,
@@ -266,10 +264,6 @@ class Blob {
     if (!isBlob(this))
       return PromiseReject(new ERR_INVALID_THIS('Blob'));
 
-    if (this.size === 0) {
-      return PromiseResolve(new ArrayBuffer(0));
-    }
-
     const { promise, resolve, reject } = createDeferredPromise();
     const reader = this[kHandle].getReader();
     const buffers = [];
@@ -316,12 +310,6 @@ class Blob {
     if (!isBlob(this))
       throw new ERR_INVALID_THIS('Blob');
 
-    if (this.size === 0) {
-      return new lazyReadableStream({
-        start(c) { c.close(); },
-      });
-    }
-
     const reader = this[kHandle].getReader();
     return new lazyReadableStream({
       start(c) {

test/parallel/test-blob-file-backed.js

@@ -20,12 +20,14 @@ const { Blob } = require('buffer');
 const tmpdir = require('../common/tmpdir');
 const testfile = path.join(tmpdir.path, 'test-file-backed-blob.txt');
 const testfile2 = path.join(tmpdir.path, 'test-file-backed-blob2.txt');
+const testfile3 = path.join(tmpdir.path, 'test-file-backed-blob3.txt');
 tmpdir.refresh();
 
 const data = `${'a'.repeat(1000)}${'b'.repeat(2000)}`;
 
 writeFileSync(testfile, data);
 writeFileSync(testfile2, data.repeat(100));
+writeFileSync(testfile3, '');
 
 (async () => {
   const blob = await openAsBlob(testfile);
@@ -79,3 +81,21 @@ writeFileSync(testfile2, data.repeat(100));
 
   await unlink(testfile2);
 })().then(common.mustCall());
+
+(async () => {
+  const blob = await openAsBlob(testfile3);
+  strictEqual(blob.size, 0);
+  strictEqual(await blob.text(), '');
+  writeFileSync(testfile3, 'abc');
+  await rejects(blob.text(), { name: 'NotReadableError' });
+  await unlink(testfile3);
+})().then(common.mustCall());
+
+(async () => {
+  const blob = await openAsBlob(testfile3);
+  strictEqual(blob.size, 0);
+  writeFileSync(testfile3, 'abc');
+  const stream = blob.stream();
+  const reader = stream.getReader();
+  await rejects(() => reader.read(), { name: 'NotReadableError' });
+})().then(common.mustCall());