vfs: add callback readv and writev handlers

A mounted VSF causes callback readv and writev to call missing handlers, breaking both virtual and real file descriptors.

This adds both handelrs and preserves I/O for real descriptors.

Signed-off-by: Daniel Cavalcante <dcavalcante@gmail.com>

Author: dcavalcante

lib/internal/vfs/setup.js

@@ -621,12 +621,24 @@ function createVfsHandlers() {
       return vfd.entry.read(buffer, offset, length, position)
         .then(({ bytesRead }) => bytesRead);
     },
+    readv(fd, buffers, position) {
+      const vfd = getVirtualFd(fd);
+      if (!vfd) return undefined;
+      return vfd.entry.readv(buffers, position)
+        .then(({ bytesRead }) => bytesRead);
+    },
     write(fd, buffer, offset, length, position) {
       const vfd = getVirtualFd(fd);
       if (!vfd) return undefined;
       return vfd.entry.write(buffer, offset, length, position)
         .then(({ bytesWritten }) => bytesWritten);
     },
+    writev(fd, buffers, position) {
+      const vfd = getVirtualFd(fd);
+      if (!vfd) return undefined;
+      return vfd.entry.writev(buffers, position)
+        .then(({ bytesWritten }) => bytesWritten);
+    },
     fstat(fd, options) {
       const vfd = getVirtualFd(fd);
       if (!vfd) return undefined;

test/parallel/test-vfs-fs-readv-writev.js

@@ -0,0 +1,35 @@
+// Flags: --experimental-vfs
+'use strict';
+
+const common = require('../common');
+const assert = require('node:assert');
+const fs = require('node:fs');
+const path = require('node:path');
+const tmpdir = require('../common/tmpdir');
+const vfs = require('node:vfs');
+
+tmpdir.refresh();
+const mounted = vfs.create();
+mounted.mkdirSync('/files', { recursive: true });
+const mountPoint = mounted.mount();
+
+const realFd = fs.openSync(tmpdir.resolve('real.txt'), 'w+');
+const virtualFd = fs.openSync(path.join(mountPoint, 'files/virtual.txt'), 'w+');
+let remaining = 2;
+
+for (const fd of [realFd, virtualFd]) {
+  const chunks = [Buffer.from('hello'), Buffer.from('world')];
+  fs.writev(fd, chunks, null, common.mustSucceed((bytesWritten, buffers) => {
+    assert.strictEqual(bytesWritten, 10);
+    assert.strictEqual(buffers, chunks);
+
+    const received = [Buffer.alloc(5), Buffer.alloc(5)];
+    fs.readv(fd, received, 0, common.mustSucceed((bytesRead, readBuffers) => {
+      assert.strictEqual(bytesRead, 10);
+      assert.strictEqual(readBuffers, received);
+      assert.strictEqual(Buffer.concat(received).toString(), 'helloworld');
+      fs.closeSync(fd);
+      if (--remaining === 0) mounted.unmount();
+    }));
+  }));
+}