import os
import time

const broken_stdout_child_source = r'
import os

fn main() {
    mut broken := os.pipe() or { panic(err) }
    saved_stdout := os.fd_dup(1)
    defer {
        os.fd_dup2(saved_stdout, 1)
        os.fd_close(saved_stdout)
        broken.close()
    }
    assert os.fd_dup2(broken.read_fd, 1) != -1
    os.fd_close(broken.read_fd)
    broken.read_fd = -1
    println("broken stdout should not hang")
}
'

fn test_println_does_not_hang_on_failed_stdout_write() {
    $if windows {
        return
    }
    child_source_path := os.join_path(os.vtmp_dir(),
        'broken_stdout_child_${time.now().unix_milli()}.v')
    os.write_file(child_source_path, broken_stdout_child_source)!
    defer {
        os.rm(child_source_path) or {}
    }
    mut p := os.new_process(@VEXE)
    p.set_args(['run', child_source_path])
    p.set_redirect_stdio()
    p.run()
    defer {
        if p.is_alive() {
            p.signal_kill()
            p.wait()
        }
        p.close()
    }
    max_wait_iterations := $if s390x || rv64 { 1200 } $else { 300 }
    for _ in 0 .. max_wait_iterations {
        if !p.is_alive() {
            break
        }
        time.sleep(50 * time.millisecond)
    }
    if p.is_alive() {
        p.signal_kill()
        p.wait()
        stdout := p.stdout_slurp()
        stderr := p.stderr_slurp()
        assert false, 'println hung on a failed stdout write\nstdout:\n${stdout}\nstderr:\n${stderr}'
    }
    p.wait()
    stdout := p.stdout_slurp()
    stderr := p.stderr_slurp()
    assert p.code == 0, 'child exited with ${p.code}\nstdout:\n${stdout}\nstderr:\n${stderr}'
    assert stdout == '', stdout
    assert stderr == '', stderr
}