fs.Stat fails on pre-epoch mtime (<1970-01-01T00:00:00Z)

Version: v13.10.1
Platform: Darwin dirac.imetrical.com 18.7.0 Darwin Kernel Version 18.7.0: Sun Dec 1 18:59:03 PST 2019; root:xnu-4903.278.19~1/RELEASE_X86_64 x86_64
Subsystem: fs.stat

What steps will reproduce the bug?

// statPreEpoch.js
const fs = require('fs')
const path = 'coco.txt'
const { mtime } = fs.statSync(path)
console.log(`mtime of ${path}: ${mtime}`)

This is on Darwin (macOS)

# This is correct
$ touch -mt 197001010000.00 coco.txt
$ stat coco.txt 
16777220 104232499 -rw-r--r-- 1 daniel staff 0 0 "Mar 19 13:26:22 2020" "Jan  1 00:00:00 1970" "Mar 19 15:01:21 2020" "Dec 31 19:00:00 1969" 4096 0 0 coco.txt
$ node statPreEpoch.js 
mtime of coco.txt: Thu Jan 01 1970 00:00:00 GMT-0500 (GMT-05:00)

# This is the bug:
touch -mt 196805160000.00 coco.txt 
stat coco.txt 
16777220 104232499 -rw-r--r-- 1 daniel staff 0 0 "Mar 19 13:26:22 2020" "May 16 00:00:00 1968" "Mar 19 15:00:23 2020" "Dec 31 19:00:00 1969" 4096 0 0 coco.txt
$ node statPreEpoch.js 
mtime of coco.txt: Invalid Date

This is on Linux (in Docker

$ docker run --rm -it -v $(pwd)/statPreEpoch.js:/src/statPreEpoch.js node:13.10 bash
$ uname -a
Linux 38f95bbffb38 4.19.76-linuxkit #1 SMP Thu Oct 17 19:31:58 UTC 2019 x86_64 GNU/Linux
$ touch -mt 197001010000.00 coco.txt
$ stat coco.txt 
  File: coco.txt
  Size: 0         	Blocks: 0          IO Block: 4096   regular empty file
Device: abh/171d	Inode: 2910905     Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2020-03-19 19:10:48.080137057 +0000
Modify: 1970-01-01 00:00:00.000000000 +0000
Change: 2020-03-19 19:10:48.080137057 +0000
$ node  /src/statPreEpoch.js
mtime of coco.txt: Thu Jan 01 1970 00:00:00 GMT+0000 (Coordinated Universal Time)

# This is the bug
$ touch -mt 196805160000.00 coco.txt 
$ stat coco.txt 
  File: coco.txt
  Size: 0         	Blocks: 0          IO Block: 4096   regular empty file
Device: abh/171d	Inode: 2910905     Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2020-03-19 19:10:48.080137057 +0000
Modify: 1968-05-16 00:00:00.000000000 +0000
Change: 2020-03-19 19:12:24.343012135 +0000
 Birth: -
$ node  /src/statPreEpoch.js
mtime of coco.txt: Invalid Date

How often does it reproduce? Is there a required condition?

Every time that mtime < unix epoch (1970-01-01T00:00:00Z)

What is the expected behavior?

Return a valid Date Object, for example

$ node  /src/statPreEpoch.js
mtime of coco.txt: Thu May 16 1968 00:00:00 GMT+0000 (Coordinated Universal Time)

> new Date("1968-05-16T00:00:00-04:00")
1968-05-16T04:00:00.000Z
> new Date("1968-05-16T00:00:00-04:00").getTime()
-51393600000

What do you see instead?

$ node  /src/statPreEpoch.js
mtime of coco.txt: Invalid Date

Additional information

I discovered this behavior by trying to use fs.utimes which is also not able to correctly handle dates before unix epoch, although fs.utimes seems to have a workaround by using the string representation of unix time.

FWIW, the fix is trivial (see below) but I'm still working on a reliable, portable regression test. Not all file systems and operating systems let you set the date that far back.

diff --git a/src/node_file-inl.h b/src/node_file-inl.h
index e9ed18a75f..346a557f86 100644
--- a/src/node_file-inl.h
+++ b/src/node_file-inl.h
@@ -86,7 +86,7 @@ void FillStatsArray(AliasedBufferBase<NativeT, V8T>* fields,
 
 #define SET_FIELD_WITH_TIME_STAT(stat_offset, stat)                          \
   /* NOLINTNEXTLINE(runtime/int) */                                          \
-  SET_FIELD_WITH_STAT(stat_offset, static_cast<unsigned long>(stat))
+  SET_FIELD_WITH_STAT(stat_offset, static_cast<double>(stat))
 
   SET_FIELD_WITH_STAT(kDev, s->st_dev);
   SET_FIELD_WITH_STAT(kMode, s->st_mode);

There's also a secondary libuv bug: conversion from double to struct timespec exhibits rounding errors for large values.

E.g. 1969-07-20T02:56:00.00 round-trips as 1969-07-20T02:56:00.55161.

unix: fix utime/futime timestamp rounding errors

lib: remove file timestamp rounding hack

src: make fs functions handle pre-epoch timestamps

Very happy you caught the rounding error too. Great work.

unix: fix utime/futime timestamp rounding errors

fs: fix utime/futime timestamp rounding errors

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fs.Stat fails on pre-epoch mtime (<1970-01-01T00:00:00Z) #32369

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior?

What do you see instead?

Additional information

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fs.Stat fails on pre-epoch mtime (<1970-01-01T00:00:00Z) #32369

Description

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior?

What do you see instead?

Additional information

Activity

bnoordhuis commented on Mar 21, 2020

bnoordhuis commented on Mar 21, 2020

daneroo commented on Mar 22, 2020

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