block: qemu-iotests - add common.qemu, for bash-controlled qemu tests

This creates some common functions for bash language qemu-iotests
to control, and communicate with, a running QEMU process.

4 functions are introduced:

    1. _launch_qemu()
        This launches the QEMU process(es), and sets up the file
        descriptors and fifos for communication.  You can choose to
        launch each QEMU process listening for either QMP or HMP
        monitor.  You can call this function multiple times, and
        save the handle returned from each.  The returned handle is
        in $QEMU_HANDLE.  You must copy this value.

Commands 2 and 3 use the handle received from _launch_qemu(), to talk
to the appropriate process.

    2. _send_qemu_cmd()
        Sends a command string, specified by $2, to QEMU.  If $3 is
        non-NULL, _send_qemu_cmd() will wait to receive $3 as a
        required result string from QEMU.  Failure to receive $3 will
        cause the test to fail.  The command can optionally be retried
        $qemu_cmd_repeat number of times.  Set $qemu_error_no_exit
        to not force the test the fail on exit; in this case,
        $QEMU_STATUS[$1] will be set to -1 on failure.

    3. _timed_wait_for()
        Waits for a response, for up to a default of 10 seconds.  If
        $2 is not seen in that time (anywhere in the response), then
        the test fails.  Primarily used by _send_qemu_cmd, but could
        be useful standalone, as well.  To prevent automatic exit
        (and therefore test failure), set $qemu_error_no_exit to a
        non-NULL value.  If $silent is a non-NULL value, then output
        to stdout will be suppressed.

    4. _cleanup_qemu()
        Kills the running QEMU processes, and removes the fifos.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

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="${TEST_DIR}/qmp-in-$$"
+QEMU_FIFO_OUT="${TEST_DIR}/qmp-out-$$"
+
+QEMU_PID=
+_QEMU_HANDLE=0
+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 "${resp}" | _filter_testdir | _filter_qemu \
+                           | _filter_qemu_io | _filter_qmp
+        fi
+        grep -q "${*}" < <(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 accomodate 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.
+# 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}"
+
+    "${QEMU}" -nographic -serial none ${comm} -machine accel=qtest "${@}" 2>&1 \
+                                                                >"${fifo_out}" \
+                                                                <"${fifo_in}" &
+    QEMU_PID[${_QEMU_HANDLE}]=$!
+
+    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
+function _cleanup_qemu()
+{
+    # QEMU_PID[], QEMU_IN[], QEMU_OUT[] all use same indices
+    for i in "${!QEMU_OUT[@]}"
+    do
+        kill -KILL ${QEMU_PID[$i]} 2>/dev/null
+        wait ${QEMU_PID[$i]} 2>/dev/null # silent kill
+        rm -f "${QEMU_FIFO_IN}_${i}" "${QEMU_FIFO_OUT}_${i}"
+        eval "exec ${QEMU_IN[$i]}<&-"   # close file descriptors
+        eval "exec ${QEMU_OUT[$i]}<&-"
+    done
+}