From f8f902c1f21c0aff158638e73778344c6fed1888 Mon Sep 17 00:00:00 2001
From: greenhead <greenheadhq@gmail.com>
Date: Sat, 29 Aug 2026 19:50:33 +0900
Subject: [PATCH] fs: add openAsBlobSync

Signed-off-by: greenhead <greenheadhq@gmail.com>
Assisted-by: Codex
---
 doc/api/fs.md                                 | 15 +++++
 lib/fs.js                                     | 24 ++++++++
 .../bootstrap/switches/is_main_thread.js      |  6 +-
 lib/internal/vfs/setup.js                     |  2 +
 test/fixtures/permission/fs-read.js           | 27 ++++++++-
 test/parallel/test-fs-openAsBlobSync.js       | 58 +++++++++++++++++++
 test/parallel/test-permission-fs-supported.js |  2 +-
 test/parallel/test-vfs-fs-openAsBlob.js       | 42 ++++++++++++--
 8 files changed, 165 insertions(+), 11 deletions(-)
 create mode 100644 test/parallel/test-fs-openAsBlobSync.js

diff --git a/doc/api/fs.md b/doc/api/fs.md
index 9b35dcb3b458..66d996c46201 100644
--- a/doc/api/fs.md
+++ b/doc/api/fs.md
@@ -6541,6 +6541,20 @@ with the [`using`][] syntax.
 The optional `options` argument can be a string specifying an encoding, or an
 object with an `encoding` property specifying the character encoding to use.
 
+### `fs.openAsBlobSync(path[, options])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `path` {string|Buffer|URL}
+* `options` {Object}
+  * `type` {string} An optional mime type for the blob.
+* Returns: {Blob}
+
+For detailed information, see the documentation of the Promise-returning
+version of this API: [`fs.openAsBlob()`][].
+
 ### `fs.opendirSync(path[, options])`
 
 <!-- YAML
@@ -9450,6 +9464,7 @@ the file contents.
 [`fs.mkdir()`]: #fsmkdirpath-options-callback
 [`fs.mkdtemp()`]: #fsmkdtempprefix-options-callback
 [`fs.open()`]: #fsopenpath-flags-mode-callback
+[`fs.openAsBlob()`]: #fsopenasblobpath-options
 [`fs.opendir()`]: #fsopendirpath-options-callback
 [`fs.opendirSync()`]: #fsopendirsyncpath-options
 [`fs.read()`]: #fsreadfd-buffer-offset-length-position-callback
diff --git a/lib/fs.js b/lib/fs.js
index c7b6b7deb08b..0cc5ad0ca468 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -810,6 +810,29 @@ function openAsBlob(path, options = kEmptyObject) {
   return PromiseResolve(createBlobFromFilePath(path, { type }));
 }
 
+/**
+ * @param {string | Buffer | URL} path
+ * @param {{
+ *   type?: string;
+ *   }} [options]
+ * @returns {Blob}
+ */
+function openAsBlobSync(path, options = kEmptyObject) {
+  validateObject(options, 'options');
+  const type = options.type || '';
+  validateString(type, 'options.type');
+  path = getValidatedPath(path);
+
+  const h = vfsState.handlers;
+  if (h !== null) {
+    const result = h.openAsBlobSync(path, options);
+    if (result !== undefined) return result;
+  }
+
+  const { createBlobFromFilePath } = require('internal/blob');
+  return createBlobFromFilePath(path, { type });
+}
+
 /**
  * Reads file from the specified `fd` (file descriptor).
  * @param {number} fd
@@ -3965,6 +3988,7 @@ module.exports = fs = {
   open,
   openSync,
   openAsBlob,
+  openAsBlobSync,
   readdir,
   readdirSync,
   read,
diff --git a/lib/internal/bootstrap/switches/is_main_thread.js b/lib/internal/bootstrap/switches/is_main_thread.js
index 8cf57b231856..e9e37275b17f 100644
--- a/lib/internal/bootstrap/switches/is_main_thread.js
+++ b/lib/internal/bootstrap/switches/is_main_thread.js
@@ -302,9 +302,9 @@ if (isBuildingSnapshot()) {
   // loaded on first use instead: the ESM loader (with its translators,
   // resolver and their dependencies) by run_main/import(), the public util
   // and url modules by whoever requires them, data: URL and TypeScript
-  // support by the module loaders, internal/blob by fs.openAsBlob(), and the
-  // DNS helpers by node:dns or an explicit --dns-result-order (see
-  // pre_execution).
+  // support by the module loaders, internal/blob by fs.openAsBlob() or
+  // fs.openAsBlobSync(), and the DNS helpers by node:dns or an explicit
+  // --dns-result-order (see pre_execution).
   require('util');
   require('url'); // eslint-disable-line no-restricted-modules
   require('internal/modules/esm/loader');
diff --git a/lib/internal/vfs/setup.js b/lib/internal/vfs/setup.js
index b063c31a0a32..281d1d0d8d6e 100644
--- a/lib/internal/vfs/setup.js
+++ b/lib/internal/vfs/setup.js
@@ -376,6 +376,8 @@ function createVfsHandlers() {
       }
       return undefined;
     },
+    openAsBlobSync: (path, options) =>
+      vfsRead(path, 'stat', (vfs, n) => vfs.openAsBlob(n, options)),
 
     // ==================== Sync FD-based ops ====================
 
diff --git a/test/fixtures/permission/fs-read.js b/test/fixtures/permission/fs-read.js
index 2e75d57ebd07..1ad12707ba55 100644
--- a/test/fixtures/permission/fs-read.js
+++ b/test/fixtures/permission/fs-read.js
@@ -414,6 +414,31 @@ const regularFile = __filename;
   }));
 }
 
+// fs.openAsBlobSync
+{
+  assert.throws(() => {
+    fs.openAsBlobSync(blockedFile);
+  }, common.expectsError({
+    code: 'ERR_ACCESS_DENIED',
+    permission: 'FileSystemRead',
+    resource: path.toNamespacedPath(blockedFile),
+  }));
+  assert.throws(() => {
+    fs.openAsBlobSync(bufferBlockedFile);
+  }, common.expectsError({
+    code: 'ERR_ACCESS_DENIED',
+    permission: 'FileSystemRead',
+    resource: path.toNamespacedPath(blockedFile),
+  }));
+  assert.throws(() => {
+    fs.openAsBlobSync(blockedFileURL);
+  }, common.expectsError({
+    code: 'ERR_ACCESS_DENIED',
+    permission: 'FileSystemRead',
+    resource: path.toNamespacedPath(blockedFile),
+  }));
+}
+
 // fs.exists
 {
   // It will return false (without performing IO) when permissions is not met
@@ -710,4 +735,4 @@ const regularFile = __filename;
   fs.realpath.native(regularFile, (err) => {
     assert.ifError(err);
   });
-}
\ No newline at end of file
+}
diff --git a/test/parallel/test-fs-openAsBlobSync.js b/test/parallel/test-fs-openAsBlobSync.js
new file mode 100644
index 000000000000..aa135eb1fd5b
--- /dev/null
+++ b/test/parallel/test-fs-openAsBlobSync.js
@@ -0,0 +1,58 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const { Blob, Buffer } = require('buffer');
+const fs = require('fs');
+const tmpdir = require('../common/tmpdir');
+
+tmpdir.refresh();
+
+const filename = 'open-as-blob-sync.txt';
+const testfile = tmpdir.resolve(filename);
+const mutationFile = tmpdir.resolve('open-as-blob-sync-mutation.txt');
+const missing = tmpdir.resolve('does-not-exist.txt');
+const data = 'hello openAsBlobSync';
+
+fs.writeFileSync(testfile, data);
+fs.writeFileSync(mutationFile, data);
+
+assert.throws(() => fs.openAsBlobSync(1), {
+  code: 'ERR_INVALID_ARG_TYPE',
+});
+assert.throws(() => fs.openAsBlobSync(testfile, null), {
+  code: 'ERR_INVALID_ARG_TYPE',
+});
+assert.throws(() => fs.openAsBlobSync(testfile, { type: 1 }), {
+  code: 'ERR_INVALID_ARG_TYPE',
+});
+assert.throws(() => fs.openAsBlobSync(missing), {
+  code: 'ENOENT',
+  syscall: 'stat',
+  path: missing,
+});
+
+(async () => {
+  for (const path of [
+    testfile,
+    Buffer.from(testfile),
+    tmpdir.fileURL(filename),
+  ]) {
+    const blob = fs.openAsBlobSync(path, { type: 'text/plain' });
+
+    assert.ok(blob instanceof Blob);
+    assert.strictEqual(blob.size, Buffer.byteLength(data));
+    assert.strictEqual(blob.type, 'text/plain');
+    assert.strictEqual(await blob.text(), data);
+  }
+
+  const promise = fs.openAsBlob(testfile);
+  assert.ok(promise instanceof Promise);
+  await promise;
+
+  const blob = fs.openAsBlobSync(mutationFile);
+  fs.writeFileSync(mutationFile, `${data}!`);
+  await assert.rejects(blob.text(), {
+    name: 'NotReadableError',
+  });
+})().then(common.mustCall());
diff --git a/test/parallel/test-permission-fs-supported.js b/test/parallel/test-permission-fs-supported.js
index 0c0da9500f25..5da01d338c49 100644
--- a/test/parallel/test-permission-fs-supported.js
+++ b/test/parallel/test-permission-fs-supported.js
@@ -36,7 +36,7 @@ const supportedApis = [
   ...syncAndAsyncAPI('mkdir'),
   ...syncAndAsyncAPI('mkdtemp'),
   ...syncAndAsyncAPI('open'),
-  'openAsBlob',
+  ...syncAndAsyncAPI('openAsBlob'),
   ...syncAndAsyncAPI('mkdtemp'),
   'mkdtempDisposableSync',
   ...syncAndAsyncAPI('readdir'),
diff --git a/test/parallel/test-vfs-fs-openAsBlob.js b/test/parallel/test-vfs-fs-openAsBlob.js
index 1c8d175c8f99..f92ec99e21f2 100644
--- a/test/parallel/test-vfs-fs-openAsBlob.js
+++ b/test/parallel/test-vfs-fs-openAsBlob.js
@@ -1,25 +1,55 @@
 // Flags: --experimental-vfs
 'use strict';
 
-// fs.openAsBlob dispatches to VFS and returns a Blob over the virtual file.
+// fs.openAsBlob and fs.openAsBlobSync dispatch to VFS and return Blobs over the virtual file.
 
 const common = require('../common');
 const assert = require('assert');
 const fs = require('fs');
 const path = require('path');
+const tmpdir = require('../common/tmpdir');
 const vfs = require('node:vfs');
 
-const mountPoint = path.resolve('/tmp/vfs-openAsBlob-' + process.pid);
+tmpdir.refresh();
+
+const mountPoint = tmpdir.resolve('vfs-openAsBlob');
+const hostOnlyPath = path.join(mountPoint, 'host-only.txt');
+const nulName = 'nul\0file.txt';
+const nulPath = path.join(mountPoint, 'src', nulName);
+fs.mkdirSync(mountPoint);
+fs.writeFileSync(hostOnlyPath, 'host content');
+
 const myVfs = vfs.create();
 myVfs.mkdirSync('/src', { recursive: true });
 myVfs.writeFileSync('/src/hello.txt', 'hello world');
+myVfs.writeFileSync(`/src/${nulName}`, 'nul content');
 myVfs.mount(mountPoint);
 
-fs.openAsBlob(path.join(mountPoint, 'src/hello.txt'))
-  .then(async (blob) => {
+const filePath = path.join(mountPoint, 'src/hello.txt');
+
+(async () => {
+  try {
+    const syncBlob = fs.openAsBlobSync(filePath, { type: 'text/plain' });
+    assert.ok(syncBlob instanceof Blob);
+    assert.strictEqual(syncBlob.size, 11);
+    assert.strictEqual(syncBlob.type, 'text/plain');
+    assert.strictEqual(await syncBlob.text(), 'hello world');
+    assert.throws(() => fs.openAsBlobSync(hostOnlyPath), {
+      code: 'ENOENT',
+      syscall: 'stat',
+      path: hostOnlyPath,
+    });
+    for (const input of [nulPath, Buffer.from(nulPath)]) {
+      assert.throws(() => fs.openAsBlobSync(input), {
+        code: 'ERR_INVALID_ARG_VALUE',
+      });
+    }
+
+    const blob = await fs.openAsBlob(filePath);
     assert.ok(blob instanceof Blob);
     assert.strictEqual(blob.size, 11);
     assert.strictEqual(await blob.text(), 'hello world');
+  } finally {
     myVfs.unmount();
-  })
-  .then(common.mustCall());
+  }
+})().then(common.mustCall());