this post was submitted on 29 Sep 2024
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This seems overblown, we've faced these things before.
The straightforward path is adding new calls and structs and leaving the old code in place, then having tests that return -1 for time32_t and seeing what breaks.
It's not pretty, but this is life in the new epoch, gentoo doesn't have it harder than anyone else except when they're trying to rebuild while the transition is happening.
I know nobody wants 2 apis, 1 deprecated, but this is an ancient design decision we have to live with, this is how we live with them.
Ah, the joys of requiring non-standard library calls for apps to function.
The problem is that this approach breaks the C standard library API, which is one of the few things that are actually pretty universal and expected to work on any platform. You don't want to force app developers to support your snowflake OS that doesn't support C.
The current way forward accepted by every other distro is to just recompile everything against the new 64-bit libraries. Unless the compiled software makes weird hardcoded assumptions about sizes of structs (hand-coded assembly might be one somewhat legitimate reason for that, but other distros have been migrating to 64-bit time_t for long enough that this should have been caught already), this fixes the problem entirely for software that can be recompiled.
That leaves just the proprietary software, for which you can either have a separate library path with 32-bit time_t dependencies, or use containers to effectively do the same.
Sneaky edit: why not add new 64-bit APIs to C? Because the C standard never said anything about how to represent time_t. If the chosen implementation is insufficient, it's purely on the platform to fix it. The C17 standard:
Your argument is to have 2 subtly incompatible abis and one day binaries magically break.
You're right it breaks c stdlib, but that's literally the point, libc is broken by design, this is the fix.
No program with time32_t will ever work after 2038, so any compiled that way are broken from compilation.
You're right that the length isn't specified though, the issue is changing types for triplets silently has unfortunate side effects.
If you really want to be clever, mangle the symbols for the functions that handle time so they encode time64 as appropriate, but doing it silently is begging for trouble.
Whereas your argument seems to be to have a special C variant for 32bit Linux - there's no reason to have a special time64_t anywhere else.
Yeah, so what will breaking the ABI do? Break it a bit more?
That's what MUSL libc does, and the result is two subtly incompatible ABIs - statically linked programs are fine, but if a dynamically linked library exports any function with time_t parameter or return value, it will use whatever size was configured at build time and it becomes a part of its ABI. So fixing this properly would require every library that wants to pass time_t values in its API to implement its own name mangling. That's not a reasonable request for a barely used platform (remember, this is just 32bit userland, 64bit was always unaffected).
Great, then we just leave everything alone and say 32-bit user land is broken past 2038, doubt too many people are dying to run 32-bit userland after that, but if they are I can guarantee they'll be running old binaries probably without source.
I might be selfish for saying so, but if anyone set up their mind to run anything on a 32-bit system after 2038, they must care enough to compile themselves, right? Any binaries compiled today will be EOL by then.
I think this is a reasonable assumption, but my experience suggests it will absolutely not be true for a lot of proprietary software.
That being said, that stuff will only be supported on rhel which will bend over backwards to keep it sort of working somehow.