include_guard "run_process_output"

template run_process_output {
    alias(@_arg0) command;
    
    # We collect the results here.
    var(@false) succeeded;
    value("") output;
    
    Do {
        # Start child process.
        sys.start_process(command, "r", ["keep_stderr":"true"]) proc;
        If (proc.is_error) {
            _do->break();
        };
        
        # Get read pipe handle.
        proc->read_pipe() read_pipe;
        If (read_pipe.is_error) {
            _do->break();
        };
        
        # Read all contents.
        backtrack_point() read_again;
        read_pipe->read() read;
        If (read.not_eof) {
            output->append(read);
            read_again->go();
        };
        
        # Wait for the process to terminate.
        proc->wait() wait;
        val_different(wait.exit_status, "0") not_ok;
        If (not_ok) {
            _do->break();
        };
        
        # Assume success.
        succeeded->set(@true);
    };
}