block: Use JSON null instead of "" to disable backing file

[qemu.git] / tests / qemu-iotests / common.qemu

#!/bin/bash
#
# This allows for launching of multiple QEMU instances, with independent
# communication possible to each instance.
#
# Each instance can choose, at launch, to use either the QMP or the
# HMP (monitor) interface.
#
# All instances are cleaned up via _cleanup_qemu, including killing the
# running qemu instance.
#
# Copyright (C) 2014 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/>.
#

QEMU_COMM_TIMEOUT=10

QEMU_FIFO_IN="${QEMU_TEST_DIR}/qmp-in-$$"
QEMU_FIFO_OUT="${QEMU_TEST_DIR}/qmp-out-$$"

QEMU_HANDLE=0

# If bash version is >= 4.1, these will be overwritten and dynamic
# file descriptor values assigned.
_out_fd=3
_in_fd=4

# Wait for expected QMP response from QEMU.  Will time out
# after 10 seconds, which counts as failure.
#
# Override QEMU_COMM_TIMEOUT for a timeout different than the
# default 10 seconds
#
# $1: The handle to use
# $2+ All remaining arguments comprise the string to search for
#    in the response.
#
# If $silent is set to anything but an empty string, then
# response is not echoed out.
function _timed_wait_for()
{
    local h=${1}
    shift

    QEMU_STATUS[$h]=0
    while read -t ${QEMU_COMM_TIMEOUT} resp <&${QEMU_OUT[$h]}
    do
        if [ -z "${silent}" ]; then
            echo "${resp}" | _filter_testdir | _filter_qemu \
                           | _filter_qemu_io | _filter_qmp | _filter_hmp
        fi
        grep -q "${*}" < <(echo ${resp})
        if [ $? -eq 0 ]; then
            return
        fi
    done
    QEMU_STATUS[$h]=-1
    if [ -z "${qemu_error_no_exit}" ]; then
        echo "Timeout waiting for ${*} on handle ${h}"
        exit 1  # Timeout means the test failed
    fi
}


# Sends QMP or HMP command to QEMU, and waits for the expected response
#
# $1:       QEMU handle to use
# $2:       String of the QMP command to send
# ${@: -1}  (Last string passed)
#             String that the QEMU response should contain. If it is a null
#             string, do not wait for a response
#
# Set qemu_cmd_repeat to the number of times to repeat the cmd
# until either timeout, or a response.  If it is not set, or <=0,
# then the command is only sent once.
#
# If $qemu_error_no_exit is set, then even if the expected response
# is not seen, we will not exit.  $QEMU_STATUS[$1] will be set it -1 in
# that case.
function _send_qemu_cmd()
{
    local h=${1}
    local count=1
    local cmd=
    local use_error=${qemu_error_no_exit}
    shift

    if [ ${qemu_cmd_repeat} -gt 0 ] 2>/dev/null; then
        count=${qemu_cmd_repeat}
        use_error="no"
    fi
    # This array element extraction is done to accommodate pathnames with spaces
    cmd=${@: 1:${#@}-1}
    shift $(($# - 1))

    while [ ${count} -gt 0 ]
    do
        echo "${cmd}" >&${QEMU_IN[${h}]}
        if [ -n "${1}" ]; then
            qemu_error_no_exit=${use_error} _timed_wait_for ${h} "${1}"
            if [ ${QEMU_STATUS[$h]} -eq 0 ]; then
                return
            fi
        fi
        let count--;
    done
    if [ ${QEMU_STATUS[$h]} -ne 0 ] && [ -z "${qemu_error_no_exit}" ]; then
        echo "Timeout waiting for ${1} on handle ${h}"
        exit 1 #Timeout means the test failed
    fi
}


# Launch a QEMU process.
#
# Input parameters:
# $qemu_comm_method: set this variable to 'monitor' (case insensitive)
#                    to use the QEMU HMP monitor for communication.
#                    Otherwise, the default of QMP is used.
# $keep_stderr: Set this variable to 'y' to keep QEMU's stderr output on stderr.
#               If this variable is empty, stderr will be redirected to stdout.
# Returns:
# $QEMU_HANDLE: set to a handle value to communicate with this QEMU instance.
#
function _launch_qemu()
{
    local comm=
    local fifo_out=
    local fifo_in=

    if (shopt -s nocasematch; [[ "${qemu_comm_method}" == "monitor" ]])
    then
        comm="-monitor stdio"
    else
        local qemu_comm_method="qmp"
        comm="-monitor none -qmp stdio"
    fi

    fifo_out=${QEMU_FIFO_OUT}_${_QEMU_HANDLE}
    fifo_in=${QEMU_FIFO_IN}_${_QEMU_HANDLE}
    mkfifo "${fifo_out}"
    mkfifo "${fifo_in}"

    object_options=
    if [ -n "$IMGKEYSECRET" ]; then
        object_options="--object secret,id=keysec0,data=$IMGKEYSECRET"
    fi

    if [ -z "$keep_stderr" ]; then
        QEMU_NEED_PID='y'\
        ${QEMU} ${object_options} -nographic -serial none ${comm} "${@}" >"${fifo_out}" \
                                                       2>&1 \
                                                       <"${fifo_in}" &
    elif [ "$keep_stderr" = "y" ]; then
        QEMU_NEED_PID='y'\
        ${QEMU} ${object_options} -nographic -serial none ${comm} "${@}" >"${fifo_out}" \
                                                       <"${fifo_in}" &
    else
        exit 1
    fi

    if [[ "${BASH_VERSINFO[0]}" -ge "5" ||
        ("${BASH_VERSINFO[0]}" -ge "4"  &&  "${BASH_VERSINFO[1]}" -ge "1") ]]
    then
        # bash >= 4.1 required for automatic fd
        exec {_out_fd}<"${fifo_out}"
        exec {_in_fd}>"${fifo_in}"
    else
        let _out_fd++
        let _in_fd++
        eval "exec ${_out_fd}<'${fifo_out}'"
        eval "exec ${_in_fd}>'${fifo_in}'"
    fi

    QEMU_OUT[${_QEMU_HANDLE}]=${_out_fd}
    QEMU_IN[${_QEMU_HANDLE}]=${_in_fd}
    QEMU_STATUS[${_QEMU_HANDLE}]=0

    if [ "${qemu_comm_method}" == "qmp" ]
    then
        # Don't print response, since it has version information in it
        silent=yes _timed_wait_for ${_QEMU_HANDLE} "capabilities"
    fi
    QEMU_HANDLE=${_QEMU_HANDLE}
    let _QEMU_HANDLE++
}


# Silenty kills the QEMU process
#
# If $wait is set to anything other than the empty string, the process will not
# be killed but only waited for, and any output will be forwarded to stdout. If
# $wait is empty, the process will be killed and all output will be suppressed.
function _cleanup_qemu()
{
    # QEMU_PID[], QEMU_IN[], QEMU_OUT[] all use same indices
    for i in "${!QEMU_OUT[@]}"
    do
        local QEMU_PID
        if [ -f "${QEMU_TEST_DIR}/qemu-${i}.pid" ]; then
            read QEMU_PID < "${QEMU_TEST_DIR}/qemu-${i}.pid"
            rm -f "${QEMU_TEST_DIR}/qemu-${i}.pid"
            if [ -z "${wait}" ] && [ -n "${QEMU_PID}" ]; then
                kill -KILL ${QEMU_PID} 2>/dev/null
            fi
            if [ -n "${QEMU_PID}" ]; then
                wait ${QEMU_PID} 2>/dev/null # silent kill
            fi
        fi

        if [ -n "${wait}" ]; then
            cat <&${QEMU_OUT[$i]} | _filter_testdir | _filter_qemu \
                                  | _filter_qemu_io | _filter_qmp | _filter_hmp
        fi
        rm -f "${QEMU_FIFO_IN}_${i}" "${QEMU_FIFO_OUT}_${i}"
        eval "exec ${QEMU_IN[$i]}<&-"   # close file descriptors
        eval "exec ${QEMU_OUT[$i]}<&-"

        unset QEMU_IN[$i]
        unset QEMU_OUT[$i]
    done
}