fs: add *timeNs properties to BigInt Stats objects

- Extend the aliased buffer for stats objects to contain
  the entire time spec (seconds and nanoseconds) for the time
  values instead of calculating the milliseconds in C++ and
  lose precision there.
- Calculate the nanosecond-precision time values in JS and expose
  them in BigInt Stats objects as `*timeNs`. The
  millisecond-precision values are now calculated from the
  nanosecond-precision values.

PR-URL: #21387
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>

Author: joyeecheung

doc/api/fs.md

@@ -512,7 +512,8 @@ A `fs.Stats` object provides information about a file.
 Objects returned from [`fs.stat()`][], [`fs.lstat()`][] and [`fs.fstat()`][] and
 their synchronous counterparts are of this type.
 If `bigint` in the `options` passed to those methods is true, the numeric values
-will be `bigint` instead of `number`.
+will be `bigint` instead of `number`, and the object will contain additional
+nanosecond-precision properties suffixed with `Ns`.
 
 ```console
 Stats {
@@ -539,7 +540,7 @@ Stats {
 `bigint` version:
 
 ```console
-Stats {
+BigIntStats {
   dev: 2114n,
   ino: 48064969n,
   mode: 33188n,
@@ -554,6 +555,10 @@ Stats {
   mtimeMs: 1318289051000n,
   ctimeMs: 1318289051000n,
   birthtimeMs: 1318289051000n,
+  atimeNs: 1318289051000000000n,
+  mtimeNs: 1318289051000000000n,
+  ctimeNs: 1318289051000000000n,
+  birthtimeNs: 1318289051000000000n,
   atime: Mon, 10 Oct 2011 23:24:11 GMT,
   mtime: Mon, 10 Oct 2011 23:24:11 GMT,
   ctime: Mon, 10 Oct 2011 23:24:11 GMT,
@@ -726,6 +731,54 @@ added: v8.1.0
 The timestamp indicating the creation time of this file expressed in
 milliseconds since the POSIX Epoch.
 
+### stats.atimeNs
+<!-- YAML
+added: REPLACEME
+-->
+
+* {bigint}
+
+Only present when `bigint: true` is passed into the method that generates
+the object.
+The timestamp indicating the last time this file was accessed expressed in
+nanoseconds since the POSIX Epoch.
+
+### stats.mtimeNs
+<!-- YAML
+added: REPLACEME
+-->
+
+* {bigint}
+
+Only present when `bigint: true` is passed into the method that generates
+the object.
+The timestamp indicating the last time this file was modified expressed in
+nanoseconds since the POSIX Epoch.
+
+### stats.ctimeNs
+<!-- YAML
+added: REPLACEME
+-->
+
+* {bigint}
+
+Only present when `bigint: true` is passed into the method that generates
+the object.
+The timestamp indicating the last time the file status was changed expressed
+in nanoseconds since the POSIX Epoch.
+
+### stats.birthtimeNs
+<!-- YAML
+added: REPLACEME
+-->
+
+* {bigint}
+
+Only present when `bigint: true` is passed into the method that generates
+the object.
+The timestamp indicating the creation time of this file expressed in
+nanoseconds since the POSIX Epoch.
+
 ### stats.atime
 <!-- YAML
 added: v0.11.13
@@ -765,8 +818,17 @@ The timestamp indicating the creation time of this file.
 ### Stat Time Values
 
 The `atimeMs`, `mtimeMs`, `ctimeMs`, `birthtimeMs` properties are
-[numbers][MDN-Number] that hold the corresponding times in milliseconds. Their
-precision is platform specific. `atime`, `mtime`, `ctime`, and `birthtime` are
+numeric values that hold the corresponding times in milliseconds. Their
+precision is platform specific. When `bigint: true` is passed into the
+method that generates the object, the properties will be [bigints][],
+otherwise they will be [numbers][MDN-Number].
+
+The `atimeNs`, `mtimeNs`, `ctimeNs`, `birthtimeNs` properties are
+[bigints][] that hold the corresponding times in nanoseconds. They are
+only present when `bigint: true` is passed into the method that generates
+the object. Their precision is platform specific.
+
+`atime`, `mtime`, `ctime`, and `birthtime` are
 [`Date`][MDN-Date] object alternate representations of the various times. The
 `Date` and number values are not connected. Assigning a new number value, or
 mutating the `Date` value, will not be reflected in the corresponding alternate
@@ -5129,6 +5191,7 @@ the file contents.
 [`net.Socket`]: net.html#net_class_net_socket
 [`stat()`]: fs.html#fs_fs_stat_path_options_callback
 [`util.promisify()`]: util.html#util_util_promisify_original
+[bigints]: https://tc39.github.io/proposal-bigint
 [Caveats]: #fs_caveats
 [Common System Errors]: errors.html#errors_common_system_errors
 [FS Constants]: #fs_fs_constants_1

lib/internal/fs/utils.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const { Reflect } = primordials;
+const { Object, Reflect } = primordials;
 
 const { Buffer, kMaxLength } = require('buffer');
 const {
@@ -17,7 +17,8 @@ const {
 const {
   isArrayBufferView,
   isUint8Array,
-  isDate
+  isDate,
+  isBigUint64Array
 } = require('internal/util/types');
 const { once } = require('internal/util');
 const { toPathIfFileURL } = require('internal/url');
@@ -231,27 +232,9 @@ function preprocessSymlinkDestination(path, type, linkPath) {
   }
 }
 
-function dateFromNumeric(num) {
-  return new Date(Number(num) + 0.5);
-}
-
 // Constructor for file stats.
-function Stats(
-  dev,
-  mode,
-  nlink,
-  uid,
-  gid,
-  rdev,
-  blksize,
-  ino,
-  size,
-  blocks,
-  atim_msec,
-  mtim_msec,
-  ctim_msec,
-  birthtim_msec
-) {
+function StatsBase(dev, mode, nlink, uid, gid, rdev, blksize,
+                   ino, size, blocks) {
   this.dev = dev;
   this.mode = mode;
   this.nlink = nlink;
@@ -262,63 +245,132 @@ function Stats(
   this.ino = ino;
   this.size = size;
   this.blocks = blocks;
-  this.atimeMs = atim_msec;
-  this.mtimeMs = mtim_msec;
-  this.ctimeMs = ctim_msec;
-  this.birthtimeMs = birthtim_msec;
-  this.atime = dateFromNumeric(atim_msec);
-  this.mtime = dateFromNumeric(mtim_msec);
-  this.ctime = dateFromNumeric(ctim_msec);
-  this.birthtime = dateFromNumeric(birthtim_msec);
 }
 
-Stats.prototype._checkModeProperty = function(property) {
-  if (isWindows && (property === S_IFIFO || property === S_IFBLK ||
-    property === S_IFSOCK)) {
-    return false;  // Some types are not available on Windows
-  }
-  if (typeof this.mode === 'bigint') {
-    return (this.mode & BigInt(S_IFMT)) === BigInt(property);
-  }
-  return (this.mode & S_IFMT) === property;
-};
-
-Stats.prototype.isDirectory = function() {
+StatsBase.prototype.isDirectory = function() {
   return this._checkModeProperty(S_IFDIR);
 };
 
-Stats.prototype.isFile = function() {
+StatsBase.prototype.isFile = function() {
   return this._checkModeProperty(S_IFREG);
 };
 
-Stats.prototype.isBlockDevice = function() {
+StatsBase.prototype.isBlockDevice = function() {
   return this._checkModeProperty(S_IFBLK);
 };
 
-Stats.prototype.isCharacterDevice = function() {
+StatsBase.prototype.isCharacterDevice = function() {
   return this._checkModeProperty(S_IFCHR);
 };
 
-Stats.prototype.isSymbolicLink = function() {
+StatsBase.prototype.isSymbolicLink = function() {
   return this._checkModeProperty(S_IFLNK);
 };
 
-Stats.prototype.isFIFO = function() {
+StatsBase.prototype.isFIFO = function() {
   return this._checkModeProperty(S_IFIFO);
 };
 
-Stats.prototype.isSocket = function() {
+StatsBase.prototype.isSocket = function() {
   return this._checkModeProperty(S_IFSOCK);
 };
 
+const kNsPerMsBigInt = 10n ** 6n;
+const kNsPerSecBigInt = 10n ** 9n;
+const kMsPerSec = 10 ** 3;
+const kNsPerMs = 10 ** 6;
+function msFromTimeSpec(sec, nsec) {
+  return sec * kMsPerSec + nsec / kNsPerMs;
+}
+
+function nsFromTimeSpecBigInt(sec, nsec) {
+  return sec * kNsPerSecBigInt + nsec;
+}
+
+function dateFromMs(ms) {
+  return new Date(Number(ms) + 0.5);
+}
+
+function BigIntStats(dev, mode, nlink, uid, gid, rdev, blksize,
+                     ino, size, blocks,
+                     atimeNs, mtimeNs, ctimeNs, birthtimeNs) {
+  StatsBase.call(this, dev, mode, nlink, uid, gid, rdev, blksize,
+                 ino, size, blocks);
+
+  this.atimeMs = atimeNs / kNsPerMsBigInt;
+  this.mtimeMs = mtimeNs / kNsPerMsBigInt;
+  this.ctimeMs = ctimeNs / kNsPerMsBigInt;
+  this.birthtimeMs = birthtimeNs / kNsPerMsBigInt;
+  this.atimeNs = atimeNs;
+  this.mtimeNs = mtimeNs;
+  this.ctimeNs = ctimeNs;
+  this.birthtimeNs = birthtimeNs;
+  this.atime = dateFromMs(this.atimeMs);
+  this.mtime = dateFromMs(this.mtimeMs);
+  this.ctime = dateFromMs(this.ctimeMs);
+  this.birthtime = dateFromMs(this.birthtimeMs);
+}
+
+Object.setPrototypeOf(BigIntStats.prototype, StatsBase.prototype);
+Object.setPrototypeOf(BigIntStats, StatsBase);
+
+BigIntStats.prototype._checkModeProperty = function(property) {
+  if (isWindows && (property === S_IFIFO || property === S_IFBLK ||
+    property === S_IFSOCK)) {
+    return false;  // Some types are not available on Windows
+  }
+  return (this.mode & BigInt(S_IFMT)) === BigInt(property);
+};
+
+function Stats(dev, mode, nlink, uid, gid, rdev, blksize,
+               ino, size, blocks,
+               atimeMs, mtimeMs, ctimeMs, birthtimeMs) {
+  StatsBase.call(this, dev, mode, nlink, uid, gid, rdev, blksize,
+                 ino, size, blocks);
+  this.atimeMs = atimeMs;
+  this.mtimeMs = mtimeMs;
+  this.ctimeMs = ctimeMs;
+  this.birthtimeMs = birthtimeMs;
+  this.atime = dateFromMs(atimeMs);
+  this.mtime = dateFromMs(mtimeMs);
+  this.ctime = dateFromMs(ctimeMs);
+  this.birthtime = dateFromMs(birthtimeMs);
+}
+
+Object.setPrototypeOf(Stats.prototype, StatsBase.prototype);
+Object.setPrototypeOf(Stats, StatsBase);
+
+Stats.prototype._checkModeProperty = function(property) {
+  if (isWindows && (property === S_IFIFO || property === S_IFBLK ||
+    property === S_IFSOCK)) {
+    return false;  // Some types are not available on Windows
+  }
+  return (this.mode & S_IFMT) === property;
+};
+
 function getStatsFromBinding(stats, offset = 0) {
-  return new Stats(stats[0 + offset], stats[1 + offset], stats[2 + offset],
-                   stats[3 + offset], stats[4 + offset], stats[5 + offset],
-                   stats[6 + offset],  // blksize
-                   stats[7 + offset], stats[8 + offset],
-                   stats[9 + offset],  // blocks
-                   stats[10 + offset], stats[11 + offset],
-                   stats[12 + offset], stats[13 + offset]);
+  if (isBigUint64Array(stats)) {
+    return new BigIntStats(
+      stats[0 + offset], stats[1 + offset], stats[2 + offset],
+      stats[3 + offset], stats[4 + offset], stats[5 + offset],
+      stats[6 + offset], stats[7 + offset], stats[8 + offset],
+      stats[9 + offset],
+      nsFromTimeSpecBigInt(stats[10 + offset], stats[11 + offset]),
+      nsFromTimeSpecBigInt(stats[12 + offset], stats[13 + offset]),
+      nsFromTimeSpecBigInt(stats[14 + offset], stats[15 + offset]),
+      nsFromTimeSpecBigInt(stats[16 + offset], stats[17 + offset])
+    );
+  }
+  return new Stats(
+    stats[0 + offset], stats[1 + offset], stats[2 + offset],
+    stats[3 + offset], stats[4 + offset], stats[5 + offset],
+    stats[6 + offset], stats[7 + offset], stats[8 + offset],
+    stats[9 + offset],
+    msFromTimeSpec(stats[10 + offset], stats[11 + offset]),
+    msFromTimeSpec(stats[12 + offset], stats[13 + offset]),
+    msFromTimeSpec(stats[14 + offset], stats[15 + offset]),
+    msFromTimeSpec(stats[16 + offset], stats[17 + offset])
+  );
 }
 
 function stringToFlags(flags) {
@@ -466,6 +518,7 @@ function warnOnNonPortableTemplate(template) {
 
 module.exports = {
   assertEncoding,
+  BigIntStats,  // for testing
   copyObject,
   Dirent,
   getDirents,

src/env.h

@@ -105,10 +105,32 @@ struct PackageConfig {
 };
 }  // namespace loader
 
+enum class FsStatsOffset {
+  kDev = 0,
+  kMode,
+  kNlink,
+  kUid,
+  kGid,
+  kRdev,
+  kBlkSize,
+  kIno,
+  kSize,
+  kBlocks,
+  kATimeSec,
+  kATimeNsec,
+  kMTimeSec,
+  kMTimeNsec,
+  kCTimeSec,
+  kCTimeNsec,
+  kBirthTimeSec,
+  kBirthTimeNsec,
+  kFsStatsFieldsNumber
+};
+
 // Stat fields buffers contain twice the number of entries in an uv_stat_t
 // because `fs.StatWatcher` needs room to store 2 `fs.Stats` instances.
-constexpr size_t kFsStatsFieldsNumber = 14;
-constexpr size_t kFsStatsBufferLength = kFsStatsFieldsNumber * 2;
+constexpr size_t kFsStatsBufferLength =
+    static_cast<size_t>(FsStatsOffset::kFsStatsFieldsNumber) * 2;
 
 // PER_ISOLATE_* macros: We have a lot of per-isolate properties
 // and adding and maintaining their getters and setters by hand would be

src/node_file.cc

@@ -2197,10 +2197,13 @@ void Initialize(Local<Object> target,
 
   env->SetMethod(target, "mkdtemp", Mkdtemp);
 
-  target->Set(context,
-              FIXED_ONE_BYTE_STRING(isolate, "kFsStatsFieldsNumber"),
-              Integer::New(isolate, kFsStatsFieldsNumber))
-        .Check();
+  target
+      ->Set(context,
+            FIXED_ONE_BYTE_STRING(isolate, "kFsStatsFieldsNumber"),
+            Integer::New(
+                isolate,
+                static_cast<int32_t>(FsStatsOffset::kFsStatsFieldsNumber)))
+      .Check();
 
   target->Set(context,
               FIXED_ONE_BYTE_STRING(isolate, "statValues"),