Fix FIONREAD for pipes

[sbc100]

Fixes: #26711

[kleisauke]

Perhaps we should fix WasmFS while we're here too?:

emscripten/system/lib/wasmfs/syscalls.cpp

Line 1313 in c5059e9

// TODO: Full TTY support. For now this is limited, and matches the old FS.

emscripten/system/lib/wasmfs/syscalls.cpp

Line 1329 in c5059e9

return -EINVAL; // not supported

[sbc100]

Perhaps we should fix WasmFS while we're here too?:

emscripten/system/lib/wasmfs/syscalls.cpp

Line 1313 in c5059e9

// TODO: Full TTY support. For now this is limited, and matches the old FS.

emscripten/system/lib/wasmfs/syscalls.cpp

Line 1329 in c5059e9

return -EINVAL; // not supported

Maybe, but given that the test in question is not yet running under wasmfs that seems like something that can be done a followup?

[kleisauke]

test_pipe_select is missing the @no_wasmfs decorator, so it ends up included in the wasmfs suite as wasmfs.test_pipe_select. Though, that suite is likely not executed in CI or by the emscripten-releases roller, so a follow-up sounds reasonable to me.

[sbc100]

test_pipe_select is missing the @no_wasmfs decorator, so it ends up included in the wasmfs suite as wasmfs.test_pipe_select. Though, that suite is likely not executed in CI or by the emscripten-releases roller, so a follow-up sounds reasonable to me.

Ok, I fixed wasmfs.test_pipe_select and added it to CI