fs: add statfs() functions

This commit adds statfs() and statfsSync() to the fs module, and
statfs() to the fsPromises module.

Co-authored-by: cjihrig <cjihrig@gmail.com>
Fixes: #10745
Refs: #31351
PR-URL: #46358
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/fs.md

@@ -1525,6 +1525,19 @@ changes:
 * Returns: {Promise}  Fulfills with the {fs.Stats} object for the
   given `path`.
 
+### `fsPromises.statfs(path[, options])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `path` {string|Buffer|URL}
+* `options` {Object}
+  * `bigint` {boolean} Whether the numeric values in the returned
+    {fs.StatFs} object should be `bigint`. **Default:** `false`.
+* Returns: {Promise} Fulfills with the {fs.StatFs} object for the
+  given `path`.
+
 ### `fsPromises.symlink(target, path[, type])`
 
 <!-- YAML
@@ -4082,6 +4095,26 @@ Stats {
 }
 ```
 
+### `fs.statfs(path[, options], callback)`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `path` {string|Buffer|URL}
+* `options` {Object}
+  * `bigint` {boolean} Whether the numeric values in the returned
+    {fs.StatFs} object should be `bigint`. **Default:** `false`.
+* `callback` {Function}
+  * `err` {Error}
+  * `stats` {fs.StatFs}
+
+Asynchronous statfs(2). Returns information about the mounted file system which
+contains `path`. The callback gets two arguments `(err, stats)` where `stats`
+is an {fs.StatFs} object.
+
+In case of an error, the `err.code` will be one of [Common System Errors][].
+
 ### `fs.symlink(target, path[, type], callback)`
 
 <!-- YAML
@@ -5822,6 +5855,23 @@ changes:
 
 Retrieves the {fs.Stats} for the path.
 
+### `fs.statfsSync(path[, options])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* `path` {string|Buffer|URL}
+* `options` {Object}
+  * `bigint` {boolean} Whether the numeric values in the returned
+    {fs.StatFs} object should be `bigint`. **Default:** `false`.
+* Returns: {fs.StatFs}
+
+Synchronous statfs(2). Returns information about the mounted file system which
+contains `path`.
+
+In case of an error, the `err.code` will be one of [Common System Errors][].
+
 ### `fs.symlinkSync(target, path[, type])`
 
 <!-- YAML
@@ -6908,6 +6958,114 @@ The times in the stat object have the following semantics:
 Prior to Node.js 0.12, the `ctime` held the `birthtime` on Windows systems. As
 of 0.12, `ctime` is not "creation time", and on Unix systems, it never was.
 
+### Class: `fs.StatFs`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Provides information about a mounted file system.
+
+Objects returned from [`fs.statfs()`][] and its synchronous counterpart are of
+this type. If `bigint` in the `options` passed to those methods is `true`, the
+numeric values will be `bigint` instead of `number`.
+
+```console
+StatFs {
+  type: 1397114950,
+  bsize: 4096,
+  blocks: 121938943,
+  bfree: 61058895,
+  bavail: 61058895,
+  files: 999,
+  ffree: 1000000
+}
+```
+
+`bigint` version:
+
+```console
+StatFs {
+  type: 1397114950n,
+  bsize: 4096n,
+  blocks: 121938943n,
+  bfree: 61058895n,
+  bavail: 61058895n,
+  files: 999n,
+  ffree: 1000000n
+}
+```
+
+#### `statfs.bavail`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Free blocks available to unprivileged users.
+
+#### `statfs.bfree`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Free blocks in file system.
+
+#### `statfs.blocks`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Total data blocks in file system.
+
+#### `statfs.bsize`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Optimal transfer block size.
+
+#### `statfs.ffree`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Free file nodes in file system.
+
+#### `statfs.files`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Total file nodes in file system.
+
+#### `statfs.type`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {number|bigint}
+
+Type of file system.
+
 ### Class: `fs.WriteStream`
 
 <!-- YAML
@@ -7751,6 +7909,7 @@ the file contents.
 [`fs.rmSync()`]: #fsrmsyncpath-options
 [`fs.rmdir()`]: #fsrmdirpath-options-callback
 [`fs.stat()`]: #fsstatpath-options-callback
+[`fs.statfs()`]: #fsstatfspath-options-callback
 [`fs.symlink()`]: #fssymlinktarget-path-type-callback
 [`fs.utimes()`]: #fsutimespath-atime-mtime-callback
 [`fs.watch()`]: #fswatchfilename-options-listener

lib/fs.js

@@ -104,6 +104,7 @@ const {
   nullCheck,
   preprocessSymlinkDestination,
   Stats,
+  getStatFsFromBinding,
   getStatsFromBinding,
   realpathCacheKey,
   stringToFlags,
@@ -1523,6 +1524,24 @@ function stat(path, options = { bigint: false }, callback) {
   binding.stat(pathModule.toNamespacedPath(path), options.bigint, req);
 }
 
+function statfs(path, options = { bigint: false }, callback) {
+  if (typeof options === 'function') {
+    callback = options;
+    options = kEmptyObject;
+  }
+  callback = maybeCallback(callback);
+  path = getValidatedPath(path);
+  const req = new FSReqCallback(options.bigint);
+  req.oncomplete = (err, stats) => {
+    if (err) {
+      return callback(err);
+    }
+
+    callback(err, getStatFsFromBinding(stats));
+  };
+  binding.statfs(pathModule.toNamespacedPath(path), options.bigint, req);
+}
+
 function hasNoEntryError(ctx) {
   if (ctx.errno) {
     const uvErr = uvErrmapGet(ctx.errno);
@@ -1597,6 +1616,15 @@ function statSync(path, options = { bigint: false, throwIfNoEntry: true }) {
   return getStatsFromBinding(stats);
 }
 
+function statfsSync(path, options = { bigint: false }) {
+  path = getValidatedPath(path);
+  const ctx = { path };
+  const stats = binding.statfs(pathModule.toNamespacedPath(path),
+                               options.bigint, undefined, ctx);
+  handleErrorFromBinding(ctx);
+  return getStatFsFromBinding(stats);
+}
+
 /**
  * Reads the contents of a symbolic link
  * referred to by `path`.
@@ -3025,7 +3053,9 @@ module.exports = fs = {
   rmdir,
   rmdirSync,
   stat,
+  statfs,
   statSync,
+  statfsSync,
   symlink,
   symlinkSync,
   truncate,

lib/internal/fs/promises.js

@@ -52,6 +52,7 @@ const {
   emitRecursiveRmdirWarning,
   getDirents,
   getOptions,
+  getStatFsFromBinding,
   getStatsFromBinding,
   getValidatedPath,
   getValidMode,
@@ -767,6 +768,13 @@ async function stat(path, options = { bigint: false }) {
   return getStatsFromBinding(result);
 }
 
+async function statfs(path, options = { bigint: false }) {
+  path = getValidatedPath(path);
+  const result = await binding.statfs(pathModule.toNamespacedPath(path),
+                                      options.bigint, kUsePromises);
+  return getStatFsFromBinding(result);
+}
+
 async function link(existingPath, newPath) {
   existingPath = getValidatedPath(existingPath, 'existingPath');
   newPath = getValidatedPath(newPath, 'newPath');
@@ -919,6 +927,7 @@ module.exports = {
     symlink,
     lstat,
     stat,
+    statfs,
     link,
     unlink,
     chmod,

lib/internal/fs/utils.js

@@ -557,6 +557,24 @@ function getStatsFromBinding(stats, offset = 0) {
   );
 }
 
+class StatFs {
+  constructor(type, bsize, blocks, bfree, bavail, files, ffree) {
+    this.type = type;
+    this.bsize = bsize;
+    this.blocks = blocks;
+    this.bfree = bfree;
+    this.bavail = bavail;
+    this.files = files;
+    this.ffree = ffree;
+  }
+}
+
+function getStatFsFromBinding(stats) {
+  return new StatFs(
+    stats[0], stats[1], stats[2], stats[3], stats[4], stats[5], stats[6]
+  );
+}
+
 function stringToFlags(flags, name = 'flags') {
   if (typeof flags === 'number') {
     validateInt32(flags, name);
@@ -934,6 +952,7 @@ module.exports = {
   nullCheck,
   preprocessSymlinkDestination,
   realpathCacheKey: Symbol('realpathCacheKey'),
+  getStatFsFromBinding,
   getStatsFromBinding,
   stringToFlags,
   stringToSymlinkType,