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297a3646c2
xemu/scripts/qapi-commands.py
Markus Armbruster 297a3646c2 qapi: Replace uncommon use of the error API by the common one 
We commonly use the error API like this:

    err = NULL;
    foo(..., &err);
    if (err) {
        goto out;
    }
    bar(..., &err);

Every error source is checked separately.  The second function is only
called when the first one succeeds.  Both functions are free to pass
their argument to error_set().  Because error_set() asserts no error
has been set, this effectively means they must not be called with an
error set.

The qapi-generated code uses the error API differently:

    // *errp was initialized to NULL somewhere up the call chain
    frob(..., errp);
    gnat(..., errp);

Errors accumulate in *errp: first error wins, subsequent errors get
dropped.  To make this work, the second function does nothing when
called with an error set.  Requires non-null errp, or else the second
function can't see the first one fail.

This usage has also bled into visitor tests, and two device model
object property getters rtc_get_date() and balloon_stats_get_all().

With the "accumulate" technique, you need fewer error checks in
callers, and buy that with an error check in every callee.  Can be
nice.

However, mixing the two techniques is confusing.  You can't use the
"accumulate" technique with functions designed for the "check
separately" technique.  You can use the "check separately" technique
with functions designed for the "accumulate" technique, but then
error_set() can't catch you setting an error more than once.

Standardize on the "check separately" technique for now, because it's
overwhelmingly prevalent.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-05-15 14:00:46 -04:00

488 lines
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#
# QAPI command marshaller generator
#
# Copyright IBM, Corp. 2011
# Copyright (C) 2014 Red Hat, Inc.
#
# Authors:
# Anthony Liguori <aliguori@us.ibm.com>
# Michael Roth <mdroth@linux.vnet.ibm.com>
# Markus Armbruster <armbru@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2.
# See the COPYING file in the top-level directory.
from ordereddict import OrderedDict
from qapi import *
import re
import sys
import os
import getopt
import errno
def type_visitor(name):
if type(name) == list:
return 'visit_type_%sList' % name[0]
else:
return 'visit_type_%s' % name
def generate_command_decl(name, args, ret_type):
arglist=""
for argname, argtype, optional, structured in parse_args(args):
argtype = c_type(argtype)
if argtype == "char *":
argtype = "const char *"
if optional:
arglist += "bool has_%s, " % c_var(argname)
arglist += "%s %s, " % (argtype, c_var(argname))
return mcgen('''
%(ret_type)s qmp_%(name)s(%(args)sError **errp);
''',
ret_type=c_type(ret_type), name=c_fun(name), args=arglist).strip()
def gen_err_check(errvar):
if errvar:
return mcgen('''
if (local_err) {
goto out;
}
''')
return ''
def gen_sync_call(name, args, ret_type, indent=0):
ret = ""
arglist=""
retval=""
if ret_type:
retval = "retval = "
for argname, argtype, optional, structured in parse_args(args):
if optional:
arglist += "has_%s, " % c_var(argname)
arglist += "%s, " % (c_var(argname))
push_indent(indent)
ret = mcgen('''
%(retval)sqmp_%(name)s(%(args)s&local_err);
''',
name=c_fun(name), args=arglist, retval=retval).rstrip()
if ret_type:
ret += "\n" + gen_err_check('local_err')
ret += "\n" + mcgen(''''
%(marshal_output_call)s
''',
marshal_output_call=gen_marshal_output_call(name, ret_type)).rstrip()
pop_indent(indent)
return ret.rstrip()
def gen_marshal_output_call(name, ret_type):
if not ret_type:
return ""
return "qmp_marshal_output_%s(retval, ret, &local_err);" % c_fun(name)
def gen_visitor_input_containers_decl(args, obj):
ret = ""
push_indent()
if len(args) > 0:
ret += mcgen('''
QmpInputVisitor *mi = qmp_input_visitor_new_strict(%(obj)s);
QapiDeallocVisitor *md;
Visitor *v;
''',
obj=obj)
pop_indent()
return ret.rstrip()
def gen_visitor_input_vars_decl(args):
ret = ""
push_indent()
for argname, argtype, optional, structured in parse_args(args):
if optional:
ret += mcgen('''
bool has_%(argname)s = false;
''',
argname=c_var(argname))
if c_type(argtype).endswith("*"):
ret += mcgen('''
%(argtype)s %(argname)s = NULL;
''',
argname=c_var(argname), argtype=c_type(argtype))
else:
ret += mcgen('''
%(argtype)s %(argname)s;
''',
argname=c_var(argname), argtype=c_type(argtype))
pop_indent()
return ret.rstrip()
def gen_visitor_input_block(args, dealloc=False):
ret = ""
errparg = '&local_err'
errarg = 'local_err'
if len(args) == 0:
return ret
push_indent()
if dealloc:
errparg = 'NULL'
errarg = None;
ret += mcgen('''
qmp_input_visitor_cleanup(mi);
md = qapi_dealloc_visitor_new();
v = qapi_dealloc_get_visitor(md);
''')
else:
ret += mcgen('''
v = qmp_input_get_visitor(mi);
''')
for argname, argtype, optional, structured in parse_args(args):
if optional:
ret += mcgen('''
visit_optional(v, &has_%(c_name)s, "%(name)s", %(errp)s);
''',
c_name=c_var(argname), name=argname, errp=errparg)
ret += gen_err_check(errarg)
ret += mcgen('''
if (has_%(c_name)s) {
''',
c_name=c_var(argname))
push_indent()
ret += mcgen('''
%(visitor)s(v, &%(c_name)s, "%(name)s", %(errp)s);
''',
c_name=c_var(argname), name=argname, argtype=argtype,
visitor=type_visitor(argtype), errp=errparg)
ret += gen_err_check(errarg)
if optional:
pop_indent()
ret += mcgen('''
}
''')
if dealloc:
ret += mcgen('''
qapi_dealloc_visitor_cleanup(md);
''')
pop_indent()
return ret.rstrip()
def gen_marshal_output(name, args, ret_type, middle_mode):
if not ret_type:
return ""
ret = mcgen('''
static void qmp_marshal_output_%(c_name)s(%(c_ret_type)s ret_in, QObject **ret_out, Error **errp)
{
Error *local_err = NULL;
QmpOutputVisitor *mo = qmp_output_visitor_new();
QapiDeallocVisitor *md;
Visitor *v;
v = qmp_output_get_visitor(mo);
%(visitor)s(v, &ret_in, "unused", &local_err);
if (local_err) {
goto out;
}
*ret_out = qmp_output_get_qobject(mo);
out:
error_propagate(errp, local_err);
qmp_output_visitor_cleanup(mo);
md = qapi_dealloc_visitor_new();
v = qapi_dealloc_get_visitor(md);
%(visitor)s(v, &ret_in, "unused", NULL);
qapi_dealloc_visitor_cleanup(md);
}
''',
c_ret_type=c_type(ret_type), c_name=c_fun(name),
visitor=type_visitor(ret_type))
return ret
def gen_marshal_input_decl(name, args, ret_type, middle_mode):
if middle_mode:
return 'int qmp_marshal_input_%s(Monitor *mon, const QDict *qdict, QObject **ret)' % c_fun(name)
else:
return 'static void qmp_marshal_input_%s(QDict *args, QObject **ret, Error **errp)' % c_fun(name)
def gen_marshal_input(name, args, ret_type, middle_mode):
hdr = gen_marshal_input_decl(name, args, ret_type, middle_mode)
ret = mcgen('''
%(header)s
{
Error *local_err = NULL;
''',
header=hdr)
if middle_mode:
ret += mcgen('''
QDict *args = (QDict *)qdict;
''')
if ret_type:
if c_type(ret_type).endswith("*"):
retval = " %s retval = NULL;" % c_type(ret_type)
else:
retval = " %s retval;" % c_type(ret_type)
ret += mcgen('''
%(retval)s
''',
retval=retval)
if len(args) > 0:
ret += mcgen('''
%(visitor_input_containers_decl)s
%(visitor_input_vars_decl)s
%(visitor_input_block)s
''',
visitor_input_containers_decl=gen_visitor_input_containers_decl(args, "QOBJECT(args)"),
visitor_input_vars_decl=gen_visitor_input_vars_decl(args),
visitor_input_block=gen_visitor_input_block(args))
else:
ret += mcgen('''
(void)args;
''')
ret += mcgen('''
%(sync_call)s
''',
sync_call=gen_sync_call(name, args, ret_type, indent=4))
if re.search('^ *goto out\\;', ret, re.MULTILINE):
ret += mcgen('''
out:
''')
if not middle_mode:
ret += mcgen('''
error_propagate(errp, local_err);
''')
ret += mcgen('''
%(visitor_input_block_cleanup)s
''',
visitor_input_block_cleanup=gen_visitor_input_block(args,
dealloc=True))
if middle_mode:
ret += mcgen('''
if (local_err) {
qerror_report_err(local_err);
error_free(local_err);
return -1;
}
return 0;
''')
else:
ret += mcgen('''
return;
''')
ret += mcgen('''
}
''')
return ret
def option_value_matches(opt, val, cmd):
if opt in cmd and cmd[opt] == val:
return True
return False
def gen_registry(commands):
registry=""
push_indent()
for cmd in commands:
options = 'QCO_NO_OPTIONS'
if option_value_matches('success-response', 'no', cmd):
options = 'QCO_NO_SUCCESS_RESP'
registry += mcgen('''
qmp_register_command("%(name)s", qmp_marshal_input_%(c_name)s, %(opts)s);
''',
name=cmd['command'], c_name=c_fun(cmd['command']),
opts=options)
pop_indent()
ret = mcgen('''
static void qmp_init_marshal(void)
{
%(registry)s
}
qapi_init(qmp_init_marshal);
''',
registry=registry.rstrip())
return ret
def gen_command_decl_prologue(header, guard, prefix=""):
ret = mcgen('''
/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
/*
* schema-defined QAPI function prototypes
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#ifndef %(guard)s
#define %(guard)s
#include "%(prefix)sqapi-types.h"
#include "qapi/qmp/qdict.h"
#include "qapi/error.h"
''',
header=basename(header), guard=guardname(header), prefix=prefix)
return ret
def gen_command_def_prologue(prefix="", proxy=False):
ret = mcgen('''
/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
/*
* schema-defined QMP->QAPI command dispatch
*
* Copyright IBM, Corp. 2011
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu-common.h"
#include "qemu/module.h"
#include "qapi/qmp/qerror.h"
#include "qapi/qmp/types.h"
#include "qapi/qmp/dispatch.h"
#include "qapi/visitor.h"
#include "qapi/qmp-output-visitor.h"
#include "qapi/qmp-input-visitor.h"
#include "qapi/dealloc-visitor.h"
#include "%(prefix)sqapi-types.h"
#include "%(prefix)sqapi-visit.h"
''',
prefix=prefix)
if not proxy:
ret += '#include "%sqmp-commands.h"' % prefix
return ret + "\n\n"
try:
opts, args = getopt.gnu_getopt(sys.argv[1:], "chp:i:o:m",
["source", "header", "prefix=",
"input-file=", "output-dir=",
"type=", "middle"])
except getopt.GetoptError, err:
print str(err)
sys.exit(1)
output_dir = ""
prefix = ""
dispatch_type = "sync"
c_file = 'qmp-marshal.c'
h_file = 'qmp-commands.h'
middle_mode = False
do_c = False
do_h = False
for o, a in opts:
if o in ("-p", "--prefix"):
prefix = a
elif o in ("-i", "--input-file"):
input_file = a
elif o in ("-o", "--output-dir"):
output_dir = a + "/"
elif o in ("-t", "--type"):
dispatch_type = a
elif o in ("-m", "--middle"):
middle_mode = True
elif o in ("-c", "--source"):
do_c = True
elif o in ("-h", "--header"):
do_h = True
if not do_c and not do_h:
do_c = True
do_h = True
c_file = output_dir + prefix + c_file
h_file = output_dir + prefix + h_file
def maybe_open(really, name, opt):
if really:
return open(name, opt)
else:
import StringIO
return StringIO.StringIO()
try:
os.makedirs(output_dir)
except os.error, e:
if e.errno != errno.EEXIST:
raise
exprs = parse_schema(input_file)
commands = filter(lambda expr: expr.has_key('command'), exprs)
commands = filter(lambda expr: not expr.has_key('gen'), commands)
if dispatch_type == "sync":
fdecl = maybe_open(do_h, h_file, 'w')
fdef = maybe_open(do_c, c_file, 'w')
ret = gen_command_decl_prologue(header=basename(h_file), guard=guardname(h_file), prefix=prefix)
fdecl.write(ret)
ret = gen_command_def_prologue(prefix=prefix)
fdef.write(ret)
for cmd in commands:
arglist = []
ret_type = None
if cmd.has_key('data'):
arglist = cmd['data']
if cmd.has_key('returns'):
ret_type = cmd['returns']
ret = generate_command_decl(cmd['command'], arglist, ret_type) + "\n"
fdecl.write(ret)
if ret_type:
ret = gen_marshal_output(cmd['command'], arglist, ret_type, middle_mode) + "\n"
fdef.write(ret)
if middle_mode:
fdecl.write('%s;\n' % gen_marshal_input_decl(cmd['command'], arglist, ret_type, middle_mode))
ret = gen_marshal_input(cmd['command'], arglist, ret_type, middle_mode) + "\n"
fdef.write(ret)
fdecl.write("\n#endif\n");
if not middle_mode:
ret = gen_registry(commands)
fdef.write(ret)
fdef.flush()
fdef.close()
fdecl.flush()
fdecl.close()
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