Add new cfg linux_time_bits64 corresponding to __USE_TIME_BITS64 #4148

snogge · 2024-11-25T23:38:31Z

Description

Add a new cfg linux_time_bits64 -- corresponding to the kernels __USE_TIME_BITS64 -- with some associated changes as a base for 64bit time_t support for glibc and musl

Sources

https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/socket.h#L157
https://github.com/torvalds/linux/blob/master/arch/mips/include/uapi/asm/socket.h#L164
https://github.com/torvalds/linux/blob/master/arch/powerpc/include/uapi/asm/socket.h

https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/resource.h#L58
https://github.com/torvalds/linux/blob/master/arch/mips/include/uapi/asm/resource.h#L31

https://github.com/torvalds/linux/blob/master/include/uapi/linux/input.h#L28

https://github.com/torvalds/linux/blob/master/include/uapi/linux/time.h#L17

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

rustbot · 2024-11-25T23:38:35Z

r? @tgross35

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tgross35 · 2024-11-25T23:59:05Z

Thanks! I'll need to double check the definitions but at first glance this looks good.

Could you add an internal env RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64 in build.rs to set this config? Then here

libc/ci/verify-build.sh

Line 67 in 42e5708

add

if [ "$os" = "linux" ]; then
    RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64=1 $cmd
fi

So we make sure the build is correct in CI

src/unix/linux_like/linux/arch/generic/mod.rs

build.rs

tgross35 · 2024-11-26T00:14:37Z

Also FYI there is a large edition refactor coming #4132 so this will probably wind up with conflicts in the near future.

src/unix/mod.rs

tgross35 · 2024-11-26T00:34:45Z

src/unix/linux_like/linux/mod.rs

    pub struct input_event {
-        pub time: ::timeval,
+        #[cfg(any(target_pointer_width = "64", not(linux_time_bits64)))]
+        pub input_event_sec: ::time_t,
+        #[cfg(all(target_pointer_width = "32", linux_time_bits64))]
+        pub input_event_sec: ::c_ulong,
+
+        #[cfg(any(target_pointer_width = "64", not(linux_time_bits64)))]
+        pub input_event_usec: ::suseconds_t,
+        #[cfg(all(target_pointer_width = "32", linux_time_bits64))]
+        pub input_event_usec: ::c_ulong,
+
+        #[cfg(target_arch = "sparc64")]
+        _pad1: ::c_int,


I think that we should leave the pub time: ::timeval for #[cfg(any(target_pointer_width = "64", not(linux_time_bits64)))] to minimize breakage. Maybe it's better to leave time or __sec+__usec as the fields, then make input_event_u?sec methods on the struct.

Also I believe sparc64 needs __usec/input_event_usec to be a c_uint rather than c_ulong.

I choose the current struct based on the discussion starting here #3175 (review) . The input_event_X members are the platform independent way of referring to these members, even if I cannot find any documentation for this.
We can exclude the input_event change from this PR for now if we need to discuss this further,

And suseconds_t is i32 on sparc64 for glibc. As far as I can tell none of the other libc's support sparc64.

Thanks for the information, that reasoning makes sense. Agreed that we should make this change but I would like to be able to backport this PR (so users can start experimenting before commiting to 1.0) so I don't think we should make this change now. Would it be possible to:

Leave time with the cfg mentioned in Add new cfg linux_time_bits64 corresponding to __USE_TIME_BITS64 #4148 (comment)

Just put the conflicting input_event_* in a block comment with a FIXME(1.0): ... so we make this change before that release

I think we should mark time deprecated at some point but I am hesitant to do that without a migration path, so this can be revisited later.

snogge · 2024-11-26T19:30:58Z

I think I've addressed most of your comments. I did not change the input_event struct as I think the current version is the most compatible one.

bors · 2024-11-27T00:27:13Z

☔ The latest upstream changes (presumably #4132) made this pull request unmergeable. Please resolve the merge conflicts.

snogge · 2024-11-28T15:08:00Z

The PR has been rebased on main, including the mentioned refactor in #4132 .

tgross35 · 2024-11-30T07:08:46Z

Thanks for the changes, I'll double check this within the next couple of days (the recent MSRV bump and edition change have been pretty time consuming in this repo).

tgross35 · 2024-12-06T23:07:44Z

One last request to defer the time field change until later and then this looks great to me.

linux_time_bits64 will be used to match __USE_TIME_BITS64 in the uapi headers. The environment variable RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64 can be used by callers to enable the linux_time_bits64 config.

The actual values may be different on 32bit archs with and without __USE_TIME_BITS64

snogge · 2024-12-09T10:06:44Z

I've updated input_event as I think you meant.

struct timeval has to be updated at least for glibc with _TIME_BITS=64.

tgross35

Looks great, thanks for the changes! You can run ./ci/style.sh to fix whatever the failure is.

rustbot assigned tgross35 Nov 25, 2024

rustbot added O-linux O-mips O-unix S-waiting-on-review labels Nov 25, 2024

snogge mentioned this pull request Nov 25, 2024

Switch to 64 bit file and time APIs on GNU libc for 32bit systems #3175

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tgross35 reviewed Nov 26, 2024

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tgross35 reviewed Nov 26, 2024

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rustbot added the A-CI Area: CI-related items label Nov 26, 2024

snogge force-pushed the linux_time_bits64 branch 3 times, most recently from e38313d to 34378b5 Compare November 26, 2024 19:29

snogge force-pushed the linux_time_bits64 branch from 34378b5 to 2cb283e Compare November 28, 2024 15:06

tgross35 added the stable-nominated This PR should be considered for cherry-pick to libc's stable release branch label Dec 6, 2024

snogge added 3 commits December 9, 2024 11:05

build.rs: Add linux_time_bits64 to ALLOWED_CFGS

5453fe6

linux_time_bits64 will be used to match __USE_TIME_BITS64 in the uapi headers. The environment variable RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64 can be used by callers to enable the linux_time_bits64 config.

linux: Set SO_TIMESTAMP* and SO_RCVTIMEO and SO_SNDTIMEO

616d546

The actual values may be different on 32bit archs with and without __USE_TIME_BITS64

linux: Set RLIM_INFINITY for 32bit mips with __USE_TIME_BITS64

125b4f7

snogge force-pushed the linux_time_bits64 branch from 2cb283e to 7572399 Compare December 9, 2024 10:05

linux: Update struct input_event for __USE_TIME_BITS64

7413e22

unix: Add FIXME(time) for struct timeval

c201302

struct timeval has to be updated at least for glibc with _TIME_BITS=64.

tgross35 approved these changes Dec 9, 2024

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snogge force-pushed the linux_time_bits64 branch from 7572399 to c201302 Compare December 9, 2024 10:09

tgross35 enabled auto-merge December 9, 2024 10:10

tgross35 added this pull request to the merge queue Dec 9, 2024

Merged via the queue into rust-lang:main with commit 3b458ff Dec 9, 2024
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Add new cfg linux_time_bits64 corresponding to __USE_TIME_BITS64 #4148

Add new cfg linux_time_bits64 corresponding to __USE_TIME_BITS64 #4148

snogge commented Nov 25, 2024

rustbot commented Nov 25, 2024

tgross35 commented Nov 25, 2024 •

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Add new cfg linux_time_bits64 corresponding to __USE_TIME_BITS64 #4148

Add new cfg linux_time_bits64 corresponding to __USE_TIME_BITS64 #4148

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snogge commented Nov 25, 2024

Description

Sources

Checklist

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