Directory write check logic sits better in shim - #1386
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Jay Bosamiya (Microsoft) (jaybosamiya-ms) wants to merge 2 commits into
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Jay Bosamiya (Microsoft) (jaybosamiya-ms) wants to merge 2 commits into
Jay Bosamiya (Microsoft) (jaybosamiya-ms) wants to merge 2 commits into
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Jay Bosamiya (Microsoft) (jaybosamiya-ms)
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September 16, 2026 21:46
Jay Bosamiya (Microsoft) (jaybosamiya-ms)
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September 16, 2026 21:46
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| files | ||
| let file = files | ||
| .fs | ||
| .open(&context, path, flags - OFlags::CLOEXEC, mode) | ||
| .map_err(Errno::from) | ||
| .map_err(Errno::from)?; | ||
| if flags.intersects(OFlags::WRONLY | OFlags::RDWR) | ||
| && !flags.contains(OFlags::PATH) | ||
| && files | ||
| .fs | ||
| .fd_file_status(&file) | ||
| .map_err(Errno::from)? | ||
| .file_type | ||
| == litebox::fs::FileType::Directory | ||
| { | ||
| files.fs.close(&file).unwrap(); | ||
| return Err(Errno::EISDIR); | ||
| } | ||
| Ok(file) |
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Yes, this does mean that any writable open of a file suffers an additional status check, but I think the simplification of the semantics and the unblocking of the Windows side (on ulitebox) is worth this tiny and rare inefficiency. Most programs are not constantly opening+closing writable files: usually the write itself is the bottleneck, so I think this is a reasonable tradeoff to make.
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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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This PR decides to explicitly diverge the LiteBox core file system semantics from POSIX. It is part of the longer-term plan to move away from the
OFlagsand use a more broader-applicable abstraction there anyways. Roughly, POSIX requires thatopenofO_WRONLYor such on a directory should return anEISDIR. However, this is a shim-level concern, and the core should not be concerned with this sort of semantics. Thus, I've moved this decision into the shim.