String.write(toFile:atomically:encoding:) fails even with atomically: false only on WasmKit

[kateinoigakukun]

Reproduction steps

$ swift package init --name Check --type executable
$ cat <<EOS > Sources/main.swift
import Foundation
let text="test"
do {
  try text.write(toFile: "test.txt", atomically: false, encoding:.utf8)
} catch {
  print("Error: \(error)")
}
EOS
$ swift build --swift-sdk $SWIFT_SDK_ID
$ wasmkit-cli run --dir . .build/debug/Check.wasm
Error: Error Domain=NSCocoaErrorDomain Code=512 "(null)"UserInfo={NSFilePath=test.txt, NSURL=test.txt -- file:///}

wasmtime run --dir . .build/debug/Check.wasm succeeded without throwing the exception.

[kkebo]

try text.write(toFile: "test.txt", atomically: true, encoding:.utf8)

Probably you meant to write atomically: false?

[kkebo]

This is because WasmKit does not support fd_sync yet.

String.write(toFile:atomically:encoding:) calls fsync here.

In fact, when I deleted this line and ran again, it succeeded in writing to a file without any errors.

[kateinoigakukun]

Thanks, good finding!

[kkebo]

I just implemented fd_sync in #180, but I don't know what kind of test to write for fd_sync...

[kkebo]

I'm not sure that the current test suite includes a test case for fd_sync.

[kateinoigakukun]

I don't think we can easily add such a test case for fd_sync. Let's follow https://github.com/WebAssembly/wasi-testsuite side future updates