[v0.3] When does `DescriptorFlags` get checked?

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
32/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
linux, rust, wasm
Domain
operating-systems

Research direction

Start by reading the WASIp1 test in crates/test-programs/src/bin/preview1_file_write.rs and the adapter path in crates/wasi-preview1-component-adapter/src/lib.rs. Compare the observed write-via-stream behavior with the DescriptorFlags expectation and determine whether the issue needs a defined semantic decision or an implementation change, with the existing file-write test indicating completion.

Written by the indexing model from the issue text.

Description

P-filesystem

In Wasmtime we have a WASIp1 test that asserts when a file is opened for reading only that writing to it fails. This is then additionally tested on WASIp2 via the WASIp1-to-WASIp2 adapter which bottoms out here. I've noticed that currently the way Wasmtime is implemented write-via-stream succeeds, but then a 0-length write to that stream fails with EBADF on Linux at least.

I don't believe that this was conscious behavior and it just happened to fall out of WASIp1 tests, but I wanted to get something on-the-record here as well. Should write-via-stream check the DescriptorFlags that the file was opened with and reject the call right then-and-there? Or does failure only happen when a write happens? (I assume the former, but wanted to check)

Dominant language
Rust
Stars
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Forks
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Avg merge
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Merged PRs (30d)
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