Unify descriptor managment into LiteBox core#722
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jaybosamiya-ms merged 15 commits intomainfrom Mar 17, 2026
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These were intended to eventually be public, but were locked down in the past. Now that things are a bit more stable, we can actually make these public.
This was a non-trivial change since it required migrating a bunch of code up to actually use raw FDs everywhere, but this should make the next commit (hopefully) simpler to read.
This gets rid of the `__Unused`, but introduces some clippy things to be cleaned up, but I wanted to keep this particular commit quite "obvious" on its own to see in the diff.
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🤖 SemverChecks 🤖 No breaking API changes detected Note: this does not mean API is unchanged, or even that there are no breaking changes; simply, none of the detections triggered. |
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Feel free to resolve my last comment and merge this PR when you are ready.
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The descriptor unification in #722 lost the min_fd support for F_DUPFD. do_dup() always allocated at the lowest available fd (ignoring min_fd), then a post-hoc check failed because the allocated fd was below min_fd, returning EMFILE. For example, /bin/sh calling fcntl(3, F_DUPFD, 10) would get fd 4 allocated, then fail with 'Too many open files'. Add fd_into_raw_integer_at_or_above() to RawDescriptorStorage and thread min_fd through do_dup_inner so F_DUPFD allocates at fd >= min_fd.
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This PR fully eliminates the descriptor table indirection we had in the shim, now relying entirely on the LiteBox core to manage file descriptors both for raw FDs as well as the typed FDs.
To do this, I've made the following changes at the core litebox crate:
liteboxcrates to defineFdEnabledSubsystems, as a stabilized interfaceEntryHandleinterface, that allows entry-specific locking outsideliteboxwithout maintaining a full descriptor table lockAt the shim, roughly it boils down to "remove
Descriptors+Descriptor" and deal with the consequences. The changes are quite extensive but are not particularly insightful in any major way. I did clean up a few bugs along the way where (say) rlimits might not have been adhered to, or if two descriptors are made and the second one hit an rlimit issue, then there could have been a leak, etc.Despite removing a chunk of code, some other code did get a tiny bit more bloated, but the level of indirection is smaller. I think we can further clean this up by removing some of the redundancy, but I think merging this in sooner than that is probably the better move, thus I've opened the PR in the current state.
Related: #31