scripts: qmp-shell: Expand support for QMP expressions

This includes support for [] expressions, single-quotes in
QMP expressions (which is not strictly a part of JSON), and
the ability to use "True", "False" and "None" literals instead
of JSON's equivalent true, false, and null literals.

qmp-shell currently allows you to describe values as
JSON expressions:
key={"key":{"key2":"val"}}

But it does not currently support arrays, which are needed
for serializing and deserializing transactions:
key=[{"type":"drive-backup","data":{...}}]

qmp-shell also only currently accepts doubly quoted strings
as-per JSON spec, but QMP allows single quotes.

Lastly, python allows you to utilize "True" or "False" as
boolean literals, but JSON expects "true" or "false". Expand
qmp-shell to allow the user to type either, converting to the
correct type.

As a consequence of the above, the key=val parsing is also improved
to give better error messages if a key=val token is not provided.

CAVEAT: The parser is still extremely rudimentary and does not
expect to find spaces in {} nor [] expressions. This patch does
not improve this functionality.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Kashyap Chamarthy <kchamart@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
John Snow 2015-04-29 15:14:02 -04:00 committed by Luiz Capitulino
parent a7430a0bad
commit 6092c3ecc4
1 changed files with 47 additions and 16 deletions

View File

@ -32,6 +32,7 @@
import qmp
import json
import ast
import readline
import sys
import pprint
@ -51,6 +52,19 @@ class QMPShellError(Exception):
class QMPShellBadPort(QMPShellError):
pass
class FuzzyJSON(ast.NodeTransformer):
'''This extension of ast.NodeTransformer filters literal "true/false/null"
values in an AST and replaces them by proper "True/False/None" values that
Python can properly evaluate.'''
def visit_Name(self, node):
if node.id == 'true':
node.id = 'True'
if node.id == 'false':
node.id = 'False'
if node.id == 'null':
node.id = '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):
@ -88,23 +102,40 @@ class QMPShell(qmp.QEMUMonitorProtocol):
# clearing everything as it doesn't seem to matter
readline.set_completer_delims('')
def __parse_value(self, val):
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:
st = ast.parse(val, mode='eval')
return ast.literal_eval(FuzzyJSON().visit(st))
except SyntaxError:
pass
except ValueError:
pass
return val
def __cli_expr(self, tokens, parent):
for arg in tokens:
opt = arg.split('=')
try:
if(len(opt) > 2):
opt[1] = '='.join(opt[1:])
value = int(opt[1])
except ValueError:
if opt[1] == 'true':
value = True
elif opt[1] == 'false':
value = False
elif opt[1].startswith('{'):
value = json.loads(opt[1])
else:
value = opt[1]
optpath = opt[0].split('.')
(key, _, val) = arg.partition('=')
if not val:
raise QMPShellError("Expected a key=value pair, got '%s'" % arg)
value = self.__parse_value(val)
optpath = key.split('.')
curpath = []
for p in optpath[:-1]:
curpath.append(p)
@ -117,7 +148,7 @@ class QMPShell(qmp.QEMUMonitorProtocol):
if type(parent[optpath[-1]]) is dict:
raise QMPShellError('Cannot use "%s" as both leaf and non-leaf key' % '.'.join(curpath))
else:
raise QMPShellError('Cannot set "%s" multiple times' % opt[0])
raise QMPShellError('Cannot set "%s" multiple times' % key)
parent[optpath[-1]] = value
def __build_cmd(self, cmdline):