vfs: reject statfs for missing paths

Validate mounted VFS paths before returning synthetic statfs data
so fs.statfsSync() and fs.promises.statfs() report ENOENT for missing
paths. Forward validation errors asynchronously to fs.statfs()
callbacks.

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
Assisted-by: codex:gpt-5.6-sol
PR-URL: #65693
Fixes: #65692
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: trivikr

lib/fs.js

@@ -2050,7 +2050,13 @@ function statfs(path, options = { __proto__: null, bigint: false }, callback) {
 
   const h = vfsState.handlers;
   if (h !== null) {
-    const result = h.statfsSync(path, options);
+    let result;
+    try {
+      result = h.statfsSync(path, options);
+    } catch (err) {
+      process.nextTick(callback, err);
+      return;
+    }
     if (result !== undefined) {
       process.nextTick(callback, null, result);
       return;

lib/internal/vfs/setup.js

@@ -320,6 +320,7 @@ function findVFSWith(filename, syscall, fn) {
   const r = findVFS(filename);
   if (r === null) return undefined;
   if (r.vfs.existsSync(filename)) {
+    if (fn === undefined) return true;
     return fn(r.vfs, filename);
   }
   throw createENOENT(syscall, filename);
@@ -432,7 +433,7 @@ function createVfsHandlers() {
     },
     statfsSync(path, options) {
       const pathStr = toPathStr(path);
-      if (pathStr !== null && findVFSForPath(pathStr) !== null) {
+      if (pathStr !== null && findVFSWith(pathStr, 'statfs')) {
         if (options?.bigint) {
           return {
             type: 0n, bsize: 4096n, blocks: 0n,
@@ -709,7 +710,7 @@ function createVfsHandlers() {
       vfsOp(path, (vfs, n) => vfs.promises.lutimes(n, atime, mtime).then(() => true)),
     statfs(path, options) {
       const pathStr = toPathStr(path);
-      if (pathStr !== null && findVFSForPath(pathStr) !== null) {
+      if (pathStr !== null && findVFSWith(pathStr, 'statfs')) {
         if (options?.bigint) {
           return {
             __proto__: null,

test/parallel/test-vfs-fs-promises.js

@@ -31,6 +31,11 @@ const vfs = require('node:vfs');
   // statfs
   const sfs = await fsp.statfs(p('src/hello.txt'));
   assert.strictEqual(typeof sfs.bsize, 'number');
+  await assert.rejects(fsp.statfs(p('missing')), {
+    code: 'ENOENT',
+    syscall: 'statfs',
+    path: p('missing'),
+  });
 
   // Path-based writes
   await fsp.writeFile(p('src/pw.txt'), 'pdata');

test/parallel/test-vfs-fs-statSync.js

@@ -4,7 +4,7 @@
 // fs.statSync / fs.lstatSync / fs.statfsSync dispatch through the VFS layer,
 // including the `throwIfNoEntry: false` option.
 
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const fs = require('fs');
 const path = require('path');
@@ -57,4 +57,19 @@ assert.strictEqual(
   assert.strictEqual(typeof s.bsize, 'bigint');
 }
 
+// statfsSync on a missing path throws ENOENT
+assert.throws(() => fs.statfsSync(path.join(mountPoint, 'missing')),
+              {
+                code: 'ENOENT',
+                syscall: 'statfs',
+                path: path.join(mountPoint, 'missing'),
+              });
+
+// Statfs on a missing path reports ENOENT through the callback
+fs.statfs(path.join(mountPoint, 'missing'), common.mustCall((err) => {
+  assert.strictEqual(err.code, 'ENOENT');
+  assert.strictEqual(err.syscall, 'statfs');
+  assert.strictEqual(err.path, path.join(mountPoint, 'missing'));
+}));
+
 myVfs.unmount();