qemu/scripts/qmp/qmp-shell

#!/usr/bin/env python3
#
# Low-level QEMU shell on top of QMP.
#
# Copyright (C) 2009, 2010 Red Hat Inc.
#
# Authors:
#  Luiz Capitulino <lcapitulino@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2.  See
# the COPYING file in the top-level directory.
#
# Usage:
#
# Start QEMU with:
#
# # qemu [...] -qmp unix:./qmp-sock,server
#
# Run the shell:
#
# $ qmp-shell ./qmp-sock
#
# Commands have the following format:
#
#    < command-name > [ arg-name1=arg1 ] ... [ arg-nameN=argN ]
#
# For example:
#
# (QEMU) device_add driver=e1000 id=net1
# {u'return': {}}
# (QEMU)
#
# key=value pairs also support Python or JSON object literal subset notations,
# without spaces. Dictionaries/objects {} are supported as are arrays [].
#
#    example-command arg-name1={'key':'value','obj'={'prop':"value"}}
#
# Both JSON and Python formatting should work, including both styles of
# string literal quotes. Both paradigms of literal values should work,
# including null/true/false for JSON and None/True/False for Python.
#
#
# Transactions have the following multi-line format:
#
#    transaction(
#    action-name1 [ arg-name1=arg1 ] ... [arg-nameN=argN ]
#    ...
#    action-nameN [ arg-name1=arg1 ] ... [arg-nameN=argN ]
#    )
#
# One line transactions are also supported:
#
#    transaction( action-name1 ... )
#
# For example:
#
#     (QEMU) transaction(
#     TRANS> block-dirty-bitmap-add node=drive0 name=bitmap1
#     TRANS> block-dirty-bitmap-clear node=drive0 name=bitmap0
#     TRANS> )
#     {"return": {}}
#     (QEMU)
#
# Use the -v and -p options to activate the verbose and pretty-print options,
# which will echo back the properly formatted JSON-compliant QMP that is being
# sent to QEMU, which is useful for debugging and documentation generation.
import argparse
import ast
import json
import os
import re
import readline
import sys
from typing import (
    Iterator,
    List,
    NoReturn,
    Optional,
    Sequence,
)


sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'python'))
from qemu import qmp
from qemu.qmp import QMPMessage


class QMPCompleter:
    # NB: Python 3.9+ will probably allow us to subclass list[str] directly,
    # but pylint as of today does not know that List[str] is simply 'list'.
    def __init__(self) -> None:
        self._matches: List[str] = []

    def append(self, value: str) -> None:
        return self._matches.append(value)

    def complete(self, text: str, state: int) -> Optional[str]:
        for cmd in self._matches:
            if cmd.startswith(text):
                if state == 0:
                    return cmd
                state -= 1
        return None


class QMPShellError(Exception):
    pass


class FuzzyJSON(ast.NodeTransformer):
    """
    This extension of ast.NodeTransformer filters literal "true/false/null"
    values in a Python AST and replaces them by proper "True/False/None" values
    that Python can properly evaluate.
    """

    @classmethod
    def visit_Name(cls,  # pylint: disable=invalid-name
                   node: ast.Name) -> ast.AST:
        if node.id == 'true':
            return ast.Constant(value=True)
        if node.id == 'false':
            return ast.Constant(value=False)
        if node.id == 'null':
            return ast.Constant(value=None)
        return node


# TODO: QMPShell's interface is a bit ugly (eg. _fill_completion() and
#       _execute_cmd()). Let's design a better one.
class QMPShell(qmp.QEMUMonitorProtocol):
    def __init__(self, address: qmp.SocketAddrT,
                 pretty: bool = False, verbose: bool = False):
        super().__init__(address)
        self._greeting: Optional[QMPMessage] = None
        self._completer = QMPCompleter()
        self._transmode = False
        self._actions: List[QMPMessage] = []
        self._histfile = os.path.join(os.path.expanduser('~'),
                                      '.qmp-shell_history')
        self.pretty = pretty
        self.verbose = verbose

    def close(self) -> None:
        # Hook into context manager of parent to save shell history.
        self._save_history()
        super().close()

    def _fill_completion(self) -> None:
        cmds = self.cmd('query-commands')
        if 'error' in cmds:
            return
        for cmd in cmds['return']:
            self._completer.append(cmd['name'])

    def __completer_setup(self) -> None:
        self._completer = QMPCompleter()
        self._fill_completion()
        readline.set_history_length(1024)
        readline.set_completer(self._completer.complete)
        readline.parse_and_bind("tab: complete")
        # NB: default delimiters conflict with some command names
        # (eg. query-), clearing everything as it doesn't seem to matter
        readline.set_completer_delims('')
        try:
            readline.read_history_file(self._histfile)
        except FileNotFoundError:
            pass
        except IOError as err:
            print(f"Failed to read history '{self._histfile}': {err!s}")

    def _save_history(self) -> None:
        try:
            readline.write_history_file(self._histfile)
        except IOError as err:
            print(f"Failed to save history file '{self._histfile}': {err!s}")

    @classmethod
    def __parse_value(cls, val: str) -> object:
        try:
            return int(val)
        except ValueError:
            pass

        if val.lower() == 'true':
            return True
        if val.lower() == 'false':
            return False
        if val.startswith(('{', '[')):
            # Try first as pure JSON:
            try:
                return json.loads(val)
            except ValueError:
                pass
            # Try once again as FuzzyJSON:
            try:
                tree = ast.parse(val, mode='eval')
                transformed = FuzzyJSON().visit(tree)
                return ast.literal_eval(transformed)
            except (SyntaxError, ValueError):
                pass
        return val

    def __cli_expr(self,
                   tokens: Sequence[str],
                   parent: qmp.QMPObject) -> None:
        for arg in tokens:
            (key, sep, val) = arg.partition('=')
            if sep != '=':
                raise QMPShellError(
                    f"Expected a key=value pair, got '{arg!s}'"
                )

            value = self.__parse_value(val)
            optpath = key.split('.')
            curpath = []
            for path in optpath[:-1]:
                curpath.append(path)
                obj = parent.get(path, {})
                if not isinstance(obj, dict):
                    msg = 'Cannot use "{:s}" as both leaf and non-leaf key'
                    raise QMPShellError(msg.format('.'.join(curpath)))
                parent[path] = obj
                parent = obj
            if optpath[-1] in parent:
                if isinstance(parent[optpath[-1]], dict):
                    msg = 'Cannot use "{:s}" as both leaf and non-leaf key'
                    raise QMPShellError(msg.format('.'.join(curpath)))
                raise QMPShellError(f'Cannot set "{key}" multiple times')
            parent[optpath[-1]] = value

    def __build_cmd(self, cmdline: str) -> Optional[QMPMessage]:
        """
        Build a QMP input object from a user provided command-line in the
        following format:

            < command-name > [ arg-name1=arg1 ] ... [ arg-nameN=argN ]
        """
        argument_regex = r'''(?:[^\s"']|"(?:\\.|[^"])*"|'(?:\\.|[^'])*')+'''
        cmdargs = re.findall(argument_regex, cmdline)
        qmpcmd: QMPMessage

        # Transactional CLI entry/exit:
        if cmdargs[0] == 'transaction(':
            self._transmode = True
            cmdargs.pop(0)
        elif cmdargs[0] == ')' and self._transmode:
            self._transmode = False
            if len(cmdargs) > 1:
                msg = 'Unexpected input after close of Transaction sub-shell'
                raise QMPShellError(msg)
            qmpcmd = {
                'execute': 'transaction',
                'arguments': {'actions': self._actions}
            }
            self._actions = list()
            return qmpcmd

        # Nothing to process?
        if not cmdargs:
            return None

        # Parse and then cache this Transactional Action
        if self._transmode:
            finalize = False
            action = {'type': cmdargs[0], 'data': {}}
            if cmdargs[-1] == ')':
                cmdargs.pop(-1)
                finalize = True
            self.__cli_expr(cmdargs[1:], action['data'])
            self._actions.append(action)
            return self.__build_cmd(')') if finalize else None

        # Standard command: parse and return it to be executed.
        qmpcmd = {'execute': cmdargs[0], 'arguments': {}}
        self.__cli_expr(cmdargs[1:], qmpcmd['arguments'])
        return qmpcmd

    def _print(self, qmp_message: object) -> None:
        jsobj = json.dumps(qmp_message,
                           indent=4 if self.pretty else None,
                           sort_keys=self.pretty)
        print(str(jsobj))

    def _execute_cmd(self, cmdline: str) -> bool:
        try:
            qmpcmd = self.__build_cmd(cmdline)
        except Exception as err:
            print('Error while parsing command line: %s' % err)
            print('command format: <command-name> ', end=' ')
            print('[arg-name1=arg1] ... [arg-nameN=argN]')
            return True
        # For transaction mode, we may have just cached the action:
        if qmpcmd is None:
            return True
        if self.verbose:
            self._print(qmpcmd)
        resp = self.cmd_obj(qmpcmd)
        if resp is None:
            print('Disconnected')
            return False
        self._print(resp)
        return True

    def connect(self, negotiate: bool = True) -> None:
        self._greeting = super().connect(negotiate)
        self.__completer_setup()

    def show_banner(self,
                    msg: str = 'Welcome to the QMP low-level shell!') -> None:
        print(msg)
        if not self._greeting:
            print('Connected')
            return
        version = self._greeting['QMP']['version']['qemu']
        print("Connected to QEMU {major}.{minor}.{micro}\n".format(**version))

    @property
    def prompt(self) -> str:
        if self._transmode:
            return 'TRANS> '
        return '(QEMU) '

    def read_exec_command(self) -> bool:
        """
        Read and execute a command.

        @return True if execution was ok, return False if disconnected.
        """
        try:
            cmdline = input(self.prompt)
        except EOFError:
            print()
            return False

        if cmdline == '':
            for event in self.get_events():
                print(event)
            self.clear_events()
            return True

        return self._execute_cmd(cmdline)

    def repl(self) -> Iterator[None]:
        self.show_banner()
        while self.read_exec_command():
            yield
        self.close()


class HMPShell(QMPShell):
    def __init__(self, address: qmp.SocketAddrT,
                 pretty: bool = False, verbose: bool = False):
        super().__init__(address, pretty, verbose)
        self.__cpu_index = 0

    def __cmd_completion(self) -> None:
        for cmd in self.__cmd_passthrough('help')['return'].split('\r\n'):
            if cmd and cmd[0] != '[' and cmd[0] != '\t':
                name = cmd.split()[0]  # drop help text
                if name == 'info':
                    continue
                if name.find('|') != -1:
                    # Command in the form 'foobar|f' or 'f|foobar', take the
                    # full name
                    opt = name.split('|')
                    if len(opt[0]) == 1:
                        name = opt[1]
                    else:
                        name = opt[0]
                self._completer.append(name)
                self._completer.append('help ' + name)  # help completion

    def __info_completion(self) -> None:
        for cmd in self.__cmd_passthrough('info')['return'].split('\r\n'):
            if cmd:
                self._completer.append('info ' + cmd.split()[1])

    def __other_completion(self) -> None:
        # special cases
        self._completer.append('help info')

    def _fill_completion(self) -> None:
        self.__cmd_completion()
        self.__info_completion()
        self.__other_completion()

    def __cmd_passthrough(self, cmdline: str,
                          cpu_index: int = 0) -> QMPMessage:
        return self.cmd_obj({
            'execute': 'human-monitor-command',
            'arguments': {
                'command-line': cmdline,
                'cpu-index': cpu_index
            }
        })

    def _execute_cmd(self, cmdline: str) -> bool:
        if cmdline.split()[0] == "cpu":
            # trap the cpu command, it requires special setting
            try:
                idx = int(cmdline.split()[1])
                if 'return' not in self.__cmd_passthrough('info version', idx):
                    print('bad CPU index')
                    return True
                self.__cpu_index = idx
            except ValueError:
                print('cpu command takes an integer argument')
                return True
        resp = self.__cmd_passthrough(cmdline, self.__cpu_index)
        if resp is None:
            print('Disconnected')
            return False
        assert 'return' in resp or 'error' in resp
        if 'return' in resp:
            # Success
            if len(resp['return']) > 0:
                print(resp['return'], end=' ')
        else:
            # Error
            print('%s: %s' % (resp['error']['class'], resp['error']['desc']))
        return True

    def show_banner(self, msg: str = 'Welcome to the HMP shell!') -> None:
        QMPShell.show_banner(self, msg)


def die(msg: str) -> NoReturn:
    sys.stderr.write('ERROR: %s\n' % msg)
    sys.exit(1)


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument('-H', '--hmp', action='store_true',
                        help='Use HMP interface')
    parser.add_argument('-N', '--skip-negotiation', action='store_true',
                        help='Skip negotiate (for qemu-ga)')
    parser.add_argument('-v', '--verbose', action='store_true',
                        help='Verbose (echo commands sent and received)')
    parser.add_argument('-p', '--pretty', action='store_true',
                        help='Pretty-print JSON')

    default_server = os.environ.get('QMP_SOCKET')
    parser.add_argument('qmp_server', action='store',
                        default=default_server,
                        help='< UNIX socket path | TCP address:port >')

    args = parser.parse_args()
    if args.qmp_server is None:
        parser.error("QMP socket or TCP address must be specified")

    shell_class = HMPShell if args.hmp else QMPShell

    try:
        address = shell_class.parse_address(args.qmp_server)
    except qmp.QMPBadPortError:
        parser.error(f"Bad port number: {args.qmp_server}")
        return  # pycharm doesn't know error() is noreturn

    with shell_class(address, args.pretty, args.verbose) as qemu:
        try:
            qemu.connect(negotiate=not args.skip_negotiation)
        except qmp.QMPConnectError:
            die("Didn't get QMP greeting message")
        except qmp.QMPCapabilitiesError:
            die("Couldn't negotiate capabilities")
        except OSError as err:
            die(f"Couldn't connect to {args.qmp_server}: {err!s}")

        for _ in qemu.repl():
            pass


if __name__ == '__main__':
    main()