Track permissions as bytes

[workingjubilee]

Because we expect certain inputs, we don't need chars. The code also doesn't need to validate exact lengths. This reduces the generated code size slightly.

I have some more exciting experiments which I am hoping may take off more in final Rust binaries, but which increase the intermediate rlib by more, so this is the only unequivocal win.

[ChrisDenton]

This looks great to me.

I take it perms aren't actually used anywhere except the test atm? I guess I'm wondering why we store all this stuff when only address and pathname appear to be used? Unless I'm missing something.

[workingjubilee]

We need to parse up to the pathname anyways, in order to be confident the parse is correct. However, once we have done so, we can simply discard this information, yes. I experimented with doing that but the generated rlib got bigger, surprisingly, and I figured it might reduce the final built and optimized size, but that required shoving it inside the stdlib and actually building a binary to test so I deferred that.

[workingjubilee]

I'm going to hold onto this PR since it almost certainly should result in a (small) final-binary diff until either @Kobzol or myself fix the CI check so graciously added, apologies for the noise.

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 512760B Updated binary size: 513184B Difference: +424B (0.08%)

[workingjubilee]

That sounds unlikely!

[workingjubilee]

However, more importantly: it sounds! Thanks, @Kobzol!

[Kobzol]

Did you expect a larger increase? Currently we just compile a hello world program with panic!() with -O. We could try other things, like -Copt-level=s or strip.

[workingjubilee]

I expected a decrease, actually! Let me tinker with the build settings, then.

[workingjubilee]

First pass: Let's try my hypothesis that discarding all the fields will decrease the built size.

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513528B Difference: +400B (0.08%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513528B Difference: +400B (0.08%)

[workingjubilee]

Okay, opt-level doesn't make a difference, but 24 bytes less means I am on to something! Maybe!

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513520B Difference: +392B (0.08%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513720B Difference: +592B (0.12%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 515056B Difference: +1928B (0.38%)

[workingjubilee]

well that backfired lmao.

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513208B Difference: +80B (0.02%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 514040B Difference: +912B (0.18%)

[workingjubilee]

WHAT.

[workingjubilee]

"zero-cost abstractions" MY ASS.

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513896B Difference: +768B (0.15%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513752B Difference: +624B (0.12%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513200B Difference: +72B (0.01%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513928B Difference: +800B (0.16%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513712B Difference: +584B (0.11%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513712B Difference: +584B (0.11%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513712B Difference: +584B (0.11%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513200B Difference: +72B (0.01%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513200B Difference: +72B (0.01%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513216B Difference: +88B (0.02%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513216B Difference: +88B (0.02%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 513208B Difference: +80B (0.02%)

[github-actions[bot]]

Below is the size of a hello-world Rust program linked with libstd with backtrace.

Original binary size: 513128B Updated binary size: 515184B Difference: +2056B (0.40%)