wasmtime has a different output depending on whether it is run normally or through a pipe (for example, tail).

Test Case

See the wasm.test file here:
wasm-test.zip

Steps to Reproduce

Normal case:

$ wasmtime run test.wasm
line written using C puts
hello world!

Output is redirected to a pipe:

$ wasmtime run test.wasm | tail
line written using C puts

For comparison, I tested the same thing in wasmer and it has the correct (first) output in both cases.

Expected Results

Output should be the same, regardless of where stdout is redirected.

Actual Results

The last line is somehow lost when stdout is redirected to a pipe (in this case, passing it to tail but I've also seen this issue when running from inside Go os/exec).

Versions and Environment

Wasmtime version or commit: wasmtime-cli 17.0.0

Operating system: Linux (Fedora Asahi)

Architecture: aarch64

Extra Info

This is a relatively big test case, I can try to make it smaller if needed.
For example, I've found it reproducible using fwrite("test\n", 5, 1, stdout);.