POSIX: change struct stat/stat64 times to timespec by xbjfk · Pull Request #5069 · rust-lang/libc

xbjfk · 2026-04-21T10:25:56Z

Why?

The primary reason for this change is that this is the correct POSIX specification, and using _nsec etc. may be considered deprecated - meaning this better follows the C struct definition more closely as well as C man pages / docs. Additionally, this makes the struct easier to read, and removes the need for many test skips, and brings all established platforms in parity with Hurd etc. which already use the new declaration in this crate. More discussion in #4965

Description

Since this was evidently a problem when doing musl changes and v1 being in alpha, it's time to rip the band aid off and do it.

Of course, there are a couple unsolved questions:

Windows doesn't have the _nsec fields:

libc/src/windows/mod.rs

Lines 52 to 54 in 17adf2d

    
           pub st_atime: time64_t, 
        
           pub st_mtime: time64_t, 
        
           pub st_ctime: time64_t,

There is also a note that should probably be addressed before 1.0:

libc/src/windows/mod.rs

Line 43 in 17adf2d

pub struct stat {

Newlib has padding where the nsecs should be:

libc/src/unix/newlib/generic.rs

Lines 22 to 27 in 0dddfc8

    
           pub st_atime: crate::time_t, 
        
           pub st_spare1: c_long, 
        
           pub st_mtime: crate::time_t, 
        
           pub st_spare2: c_long, 
        
           pub st_ctime: crate::time_t, 
        
           pub st_spare3: c_long,

But upstream uses timespec for some architectures: https://github.com/cygwin/cygwin/blob/a0ccec7e7a16b01037ece1947610f768ab7f081a/newlib/libc/include/sys/stat.h#L37-L59

I don't know what is going on with Apple - they use xtimespec instead of xtim: https://github.com/apple-oss-distributions/xnu/blob/f6217f891ac0bb64f3d375211650a4c1ff8ca1ea/bsd/sys/stat.h#L202-L206 - but interestingly, Swift seems to rename this to the POSIX correct form, despite the underlying C headers not having it: https://github.com/apple/swift-system/blob/main/Sources/System/FileSystem/Stat.swift#L428. We need to pick one.

Also, solid and qurt do not have nsec at all. NTO and VxWorks have already migrated.

Sources

In each relevant commit.

Checklist

Relevant tests in libc-test/semver have been updated
No placeholder or unstable values like *LAST or *MAX are
included (see #3131)
Tested locally (cd libc-test && cargo test --target mytarget);
especially relevant for platforms that may not be checked in CI

As discussed in / Fixes: #4965

rustbot · 2026-04-21T10:26:00Z

Some changes occurred in a solarish module

cc @jclulow, @pfmooney

Some changes occurred in an Android module

cc @maurer

Some changes occurred in an OpenBSD module

cc @semarie

Some changes occurred in a NetBSD-like module

cc @semarie

xbjfk · 2026-04-21T13:35:10Z

Hmm, since freebsd11 no longer depends on c_long, the prelude is no longer necessary - but it feels wrong to remove.

rustbot · 2026-04-26T10:36:28Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

tgross35

All of this looks pretty good to me, but I'm going to hold off on merging for a bit. We have a handful of changes coming down the pipeline that are doing 64-bit time conversions, which this will conflict with, and it will be easier to apply this after all of that rather than before. (Not on its own, but taking stable backports into consideration).

Would you mind adding the reasoning (posix spec alignment) to the PR description? For any drive by readers.

View changes since this review

tgross35 · 2026-06-19T07:26:19Z

For some time to get time64 changes in,
@SnoozeThis 2 months

tgross35 · 2026-06-19T07:45:28Z

Come on alarm clock...
@rustbot blocked
@SnoozeThis wait 2 months -> remove label S-blocked, add label S-waiting-on-review

SnoozeThis · 2026-06-19T07:46:40Z

(https://snoozeth.is/WTvxKr50tBM) I will wait until Wed, 19 Aug 2026 07:45:28 UTC and then add label S-waiting-on-review and remove label S-blocked.

@rustbot claim.

xbjfk · 2026-06-20T09:01:24Z

Would you mind adding the reasoning (posix spec alignment) to the PR description? For any drive by readers.

Done - I made a nice and prominent "Why?" section at the top :)

maurer

Looks OK for Android. https://cs.android.com/android/platform/superproject/+/android-latest-release:bionic/libc/include/sys/types.h;l=97-99?q=include%2Fsys%2Ftypes.h had me worried, but that maps it to long in the end, so we're fine.

View changes since this review

SnoozeThis · 2026-08-19T08:00:31Z

Resolved.

@rustbot label +S-waiting-on-review -S-blocked. @rustbot release-assignment.

tgross35

Would you be up for merging these definitions in a commit prior to the timespec change? Similar to what fc8a345, 72f0135, and others did, that would reduce the surface area quite a bit.

I've been meaning to do this before replying on this PR but still haven't yet, so figured I'd at least let you know that's what it's blocked on in case you have the time to pick it up.

View changes since this review

xbjfk · 2026-10-05T06:11:11Z

I rebased and fixed conflicts, will now move to src/new

rustbot · 2026-10-05T06:20:01Z

⚠️ Warning ⚠️

There are links that are not permanent in the commit message of the following commits. Please use a permalink instead.
- 2830915

Source: https://github.com/freebsd/freebsd-src/blob/ced74610217ff0be071e4614c64a4ff66c40bc6b/sys/sys/stat.h#L157

Source: https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/stat.h

Source: https://github.com/openbsd/src/blob/976c316f788ad8622366f6452e787413e76fede1/sys/sys/stat.h#L53

Source: https://github.com/NetBSD/src/blob/c802b18990b9adaa6593241cd6a8b3bf4ce9753d/sys/sys/stat.h#L67

Source: https://github.com/redox-os/relibc/blob/30cc2de953d5dfe319b9e0d5755ec6437c88e307/src/header/sys_stat/mod.rs#L73-L75

Souce: https://man7.org/linux/man-pages/man3/stat.3type.html

Source: https://github.com/wbx-github/uclibc-ng/blob/3dcc84c74ece048b62c992edceab9cce54446f57/libc/sysdeps/linux/common-generic/bits/stat.h#L32

SOURCE: https://cs.android.com/android/platform/superproject/main/+/main:bionic/libc/include/sys/stat.h;l=44?ss=android%2Fplatform%2Fsuperproject%2Fmain

SOURCE: https://github.com/kraj/musl/blob/8cb84492b0245d70b2cd0edd523e2b55c7ad67a9/arch/generic/bits/stat.h#L14

They have all been fixed.

xbjfk · 2026-10-05T09:33:56Z

@tgross35 Working on this now, but one question: how important are argument names? I see currently a lot don't match the headers/man pages, but I want to know for sure before I go too deep one way or another.

I made a topic on Zulip as well with more details: #t-libs/crates > Policy for function argument names in libc?

rustbot added the S-waiting-on-review label Apr 21, 2026

xbjfk force-pushed the stat-timespec branch from 8d04ac4 to 0403fff Compare April 21, 2026 11:54

xbjfk mentioned this pull request Apr 21, 2026

What time fields should struct stat have? #4965

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xbjfk force-pushed the stat-timespec branch from 0403fff to b0859fb Compare April 22, 2026 06:47

tgross35 mentioned this pull request Apr 22, 2026

fix(newlib): update stat struct to match official headers #5061

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xbjfk force-pushed the stat-timespec branch from b0859fb to 1ae80a9 Compare April 26, 2026 10:36

tgross35 added this to the 1.0 milestone Jun 19, 2026

tgross35 added the stable-declined This change is breaking, difficult to backport, low priority, or otherwise not relevant for 0.2 label Jun 19, 2026

tgross35 reviewed Jun 19, 2026

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tgross35 mentioned this pull request Jun 22, 2026

fuchsia: clean up module #5127

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maurer approved these changes Jul 20, 2026

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tgross35 mentioned this pull request Aug 11, 2026

android 32 bits fix stat struct proposal. #3286

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rustbot added O-bsd O-dragonfly O-freebsd O-gnu O-linux O-linux-like O-mips O-musl O-powerpc O-redox O-riscv O-solarish O-sparc O-unix O-wasi O-x86 labels Oct 5, 2026

xbjfk force-pushed the stat-timespec branch from 23644fa to f3d4ad7 Compare October 5, 2026 06:19

xbjfk added 10 commits October 5, 2026 06:20

FreeBSD: change struct stat/stat64 times to timespec

3462e1e

Source: https://github.com/freebsd/freebsd-src/blob/ced74610217ff0be071e4614c64a4ff66c40bc6b/sys/sys/stat.h#L157

DragonflyBSD: change struct stat/stat64 times to timespec

2830915

Source: https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/stat.h

OpenBSD: change struct stat/stat64 times to timespec

b594901

Source: https://github.com/openbsd/src/blob/976c316f788ad8622366f6452e787413e76fede1/sys/sys/stat.h#L53

NetBSD: change struct stat/stat64 times to timespec

6f757fb

Source: https://github.com/NetBSD/src/blob/c802b18990b9adaa6593241cd6a8b3bf4ce9753d/sys/sys/stat.h#L67

Redox: change struct stat/stat64 times to timespec

28600ba

Source: https://github.com/redox-os/relibc/blob/30cc2de953d5dfe319b9e0d5755ec6437c88e307/src/header/sys_stat/mod.rs#L73-L75

GNU: change struct stat/stat64 times to timespec

466542c

Souce: https://man7.org/linux/man-pages/man3/stat.3type.html

uClibc: change struct stat/stat64 times to timespec

6fb09ce

Source: https://github.com/wbx-github/uclibc-ng/blob/3dcc84c74ece048b62c992edceab9cce54446f57/libc/sysdeps/linux/common-generic/bits/stat.h#L32

Android: change struct stat/stat64 times to timespec

bfe707b

SOURCE: https://cs.android.com/android/platform/superproject/main/+/main:bionic/libc/include/sys/stat.h;l=44?ss=android%2Fplatform%2Fsuperproject%2Fmain

musl: change struct stat/stat64 times to timespec

a3489fb

SOURCE: https://github.com/kraj/musl/blob/8cb84492b0245d70b2cd0edd523e2b55c7ad67a9/arch/generic/bits/stat.h#L14

libc-test: Linux: remove test workaround for inlined timespec

f3d4ad7

They have all been fixed.

	pub st_atime: time64_t,
	pub st_mtime: time64_t,
	pub st_ctime: time64_t,

	pub st_atime: crate::time_t,
	pub st_spare1: c_long,
	pub st_mtime: crate::time_t,
	pub st_spare2: c_long,
	pub st_ctime: crate::time_t,
	pub st_spare3: c_long,

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