#!/usr/bin/env bash
# -*- shell-script-mode -*-
#
# Helpers for NBD server related config
#
# Copyright (C) 2018 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

nbd_unix_socket="${TEST_DIR}/qemu-nbd.sock"
nbd_tcp_addr="127.0.0.1"
nbd_pid_file="${TEST_DIR}/qemu-nbd.pid"
nbd_stderr_fifo="${TEST_DIR}/qemu-nbd.fifo"

# If bash version is >= 4.1, this will be overwritten by a dynamically
# assigned file descriptor value.
nbd_fifo_fd=10

nbd_server_stop()
{
    local NBD_PID
    if [ -f "$nbd_pid_file" ]; then
        read NBD_PID < "$nbd_pid_file"
        rm -f "$nbd_pid_file"
        if [ -n "$NBD_PID" ]; then
            kill "$NBD_PID"
        fi
    fi
    rm -f "$nbd_unix_socket" "$nbd_stderr_fifo"
}

nbd_server_start_unix_socket()
{
    nbd_server_stop
    $QEMU_NBD -v -t -k "$nbd_unix_socket" --fork "$@"
}

nbd_server_start_tcp_socket()
{
    nbd_server_stop

    mkfifo "$nbd_stderr_fifo"
    for ((port = 10809; port <= 10909; port++))
    do
        # Redirect stderr to FIFO, so we can later decide whether we
        # want to read it or to redirect it to our stderr, depending
        # on whether the command fails or not
        $QEMU_NBD -v -t -b $nbd_tcp_addr -p $port --fork "$@" \
            2> "$nbd_stderr_fifo" &

        # Taken from common.qemu
        if [[ "${BASH_VERSINFO[0]}" -ge "5" ||
            ("${BASH_VERSINFO[0]}" -ge "4" && "${BASH_VERSINFO[1]}" -ge "1") ]]
        then
            exec {nbd_fifo_fd}<"$nbd_stderr_fifo"
        else
            let _nbd_fifo_fd++
            eval "exec ${_nbd_fifo_fd}<'$nbd_stderr_fifo'"
        fi
        wait $!

        if test $? == 0
        then
            # Success, redirect qemu-nbd's stderr to our stderr
            nbd_tcp_port=$port
            (cat <&$nbd_fifo_fd >&2) &
            eval "exec $nbd_fifo_fd>&-"
            return
        fi

        # Failure, read the output
        output=$(cat <&$nbd_fifo_fd)
        eval "exec $nbd_fifo_fd>&-"

        if ! echo "$output" | grep -q "Address already in use"
        then
            # Unknown error, print it
            echo "$output" >&2
            rm -f "$nbd_stderr_fifo"
            exit 1
        fi
    done

    echo "Cannot find free TCP port for nbd in range 10809-10909"
    rm -f "$nbd_stderr_fifo"
    exit 1
}