scripts/qapi-visit.py

#
# QAPI visitor generator
#
# Copyright IBM, Corp. 2011
# Copyright (C) 2014-2015 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

implicit_structs_seen = set()
struct_fields_seen = set()

def generate_visit_implicit_struct(type):
    if type in implicit_structs_seen:
        return ''
    implicit_structs_seen.add(type)
    ret = ''
    if type not in struct_fields_seen:
        # Need a forward declaration
        ret += mcgen('''

static void visit_type_%(c_type)s_fields(Visitor *m, %(c_type)s **obj, Error **errp);
''',
                     c_type=type_name(type))

    ret += mcgen('''

static void visit_type_implicit_%(c_type)s(Visitor *m, %(c_type)s **obj, Error **errp)
{
    Error *err = NULL;

    visit_start_implicit_struct(m, (void **)obj, sizeof(%(c_type)s), &err);
    if (!err) {
        visit_type_%(c_type)s_fields(m, obj, errp);
        visit_end_implicit_struct(m, &err);
    }
    error_propagate(errp, err);
}
''',
                 c_type=type_name(type))
    return ret

def generate_visit_struct_fields(name, members, base = None):
    struct_fields_seen.add(name)

    ret = ''

    if base:
        ret += generate_visit_implicit_struct(base)

    ret += mcgen('''

static void visit_type_%(name)s_fields(Visitor *m, %(name)s **obj, Error **errp)
{
    Error *err = NULL;

''',
                 name=c_name(name))
    push_indent()

    if base:
        ret += mcgen('''
visit_type_implicit_%(type)s(m, &(*obj)->%(c_name)s, &err);
if (err) {
    goto out;
}
''',
                     type=type_name(base), c_name=c_name('base'))

    for argname, argentry, optional in parse_args(members):
        if optional:
            ret += mcgen('''
visit_optional(m, &(*obj)->has_%(c_name)s, "%(name)s", &err);
if (!err && (*obj)->has_%(c_name)s) {
''',
                         c_name=c_name(argname), name=argname)
            push_indent()

        ret += mcgen('''
visit_type_%(type)s(m, &(*obj)->%(c_name)s, "%(name)s", &err);
''',
                     type=type_name(argentry), c_name=c_name(argname),
                     name=argname)

        if optional:
            pop_indent()
            ret += mcgen('''
}
''')
        ret += mcgen('''
if (err) {
    goto out;
}
''')

    pop_indent()
    if re.search('^ *goto out\\;', ret, re.MULTILINE):
        ret += mcgen('''

out:
''')
    ret += mcgen('''
    error_propagate(errp, err);
}
''')
    return ret


def generate_visit_struct_body(name):
    # FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
    # *obj, but then visit_type_FOO_fields() fails, we should clean up *obj
    # rather than leaving it non-NULL. As currently written, the caller must
    # call qapi_free_FOO() to avoid a memory leak of the partial FOO.
    ret = mcgen('''
    Error *err = NULL;

    visit_start_struct(m, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), &err);
    if (!err) {
        if (*obj) {
            visit_type_%(c_name)s_fields(m, obj, errp);
        }
        visit_end_struct(m, &err);
    }
    error_propagate(errp, err);
''',
                name=name, c_name=c_name(name))

    return ret

def generate_visit_struct(expr):

    name = expr['struct']
    members = expr['data']
    base = expr.get('base')

    ret = generate_visit_struct_fields(name, members, base)

    ret += mcgen('''

void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **errp)
{
''',
                 name=c_name(name))

    ret += generate_visit_struct_body(name)

    ret += mcgen('''
}
''')
    return ret

def generate_visit_list(name):
    return mcgen('''

void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, Error **errp)
{
    Error *err = NULL;
    GenericList *i, **prev;

    visit_start_list(m, name, &err);
    if (err) {
        goto out;
    }

    for (prev = (GenericList **)obj;
         !err && (i = visit_next_list(m, prev, &err)) != NULL;
         prev = &i) {
        %(name)sList *native_i = (%(name)sList *)i;
        visit_type_%(name)s(m, &native_i->value, NULL, &err);
    }

    error_propagate(errp, err);
    err = NULL;
    visit_end_list(m, &err);
out:
    error_propagate(errp, err);
}
''',
                name=type_name(name))

def generate_visit_enum(name):
    return mcgen('''

void visit_type_%(c_name)s(Visitor *m, %(c_name)s *obj, const char *name, Error **errp)
{
    visit_type_enum(m, (int *)obj, %(c_name)s_lookup, "%(name)s", name, errp);
}
''',
                 c_name=c_name(name), name=name)

def generate_visit_alternate(name, members):
    ret = mcgen('''

void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **errp)
{
    Error *err = NULL;

    visit_start_implicit_struct(m, (void**) obj, sizeof(%(name)s), &err);
    if (err) {
        goto out;
    }
    visit_get_next_type(m, (int*) &(*obj)->kind, %(name)s_qtypes, name, &err);
    if (err) {
        goto out_end;
    }
    switch ((*obj)->kind) {
''',
                name=c_name(name))

    # For alternate, always use the default enum type automatically generated
    # as name + 'Kind'
    disc_type = c_name(name) + 'Kind'

    for key in members:
        assert (members[key] in builtin_types.keys()
            or find_struct(members[key])
            or find_union(members[key])
            or find_enum(members[key])), "Invalid alternate member"

        enum_full_value = c_enum_const(disc_type, key)
        ret += mcgen('''
    case %(enum_full_value)s:
        visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, name, &err);
        break;
''',
                enum_full_value = enum_full_value,
                c_type = type_name(members[key]),
                c_name = c_name(key))

    ret += mcgen('''
    default:
        abort();
    }
out_end:
    error_propagate(errp, err);
    err = NULL;
    visit_end_implicit_struct(m, &err);
out:
    error_propagate(errp, err);
}
''')

    return ret


def generate_visit_union(expr):

    name = expr['union']
    members = expr['data']

    base = expr.get('base')
    discriminator = expr.get('discriminator')

    enum_define = discriminator_find_enum_define(expr)
    if enum_define:
        # Use the enum type as discriminator
        ret = ""
        disc_type = c_name(enum_define['enum_name'])
    else:
        # There will always be a discriminator in the C switch code, by default
        # it is an enum type generated silently
        ret = generate_visit_enum(name + 'Kind')
        disc_type = c_name(name) + 'Kind'

    if base:
        assert discriminator
        base_fields = find_struct(base)['data'].copy()
        del base_fields[discriminator]
        ret += generate_visit_struct_fields(name, base_fields)

    if discriminator:
        for key in members:
            ret += generate_visit_implicit_struct(members[key])

    ret += mcgen('''

void visit_type_%(c_name)s(Visitor *m, %(c_name)s **obj, const char *name, Error **errp)
{
    Error *err = NULL;

    visit_start_struct(m, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), &err);
    if (err) {
        goto out;
    }
    if (*obj) {
''',
                 c_name=c_name(name), name=name)

    if base:
        ret += mcgen('''
        visit_type_%(name)s_fields(m, obj, &err);
        if (err) {
            goto out_obj;
        }
''',
                     name=c_name(name))

    if not discriminator:
        tag = 'kind'
        disc_key = "type"
    else:
        tag = discriminator
        disc_key = discriminator
    ret += mcgen('''
        visit_type_%(disc_type)s(m, &(*obj)->%(c_tag)s, "%(disc_key)s", &err);
        if (err) {
            goto out_obj;
        }
        if (!visit_start_union(m, !!(*obj)->data, &err) || err) {
            goto out_obj;
        }
        switch ((*obj)->%(c_tag)s) {
''',
                 disc_type = disc_type,
                 c_tag=c_name(tag),
                 disc_key = disc_key)

    for key in members:
        if not discriminator:
            fmt = 'visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, "data", &err);'
        else:
            fmt = 'visit_type_implicit_%(c_type)s(m, &(*obj)->%(c_name)s, &err);'

        enum_full_value = c_enum_const(disc_type, key)
        ret += mcgen('''
        case %(enum_full_value)s:
            ''' + fmt + '''
            break;
''',
                enum_full_value = enum_full_value,
                c_type=type_name(members[key]),
                c_name=c_name(key))

    ret += mcgen('''
        default:
            abort();
        }
out_obj:
        error_propagate(errp, err);
        err = NULL;
        visit_end_union(m, !!(*obj)->data, &err);
        error_propagate(errp, err);
        err = NULL;
    }
    visit_end_struct(m, &err);
out:
    error_propagate(errp, err);
}
''')

    return ret

def generate_declaration(name, builtin_type=False):
    ret = ""
    if not builtin_type:
        name = c_name(name)
        ret += mcgen('''

void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **errp);
''',
                     name=name)

    ret += mcgen('''
void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, Error **errp);
''',
                 name=name)

    return ret

def generate_enum_declaration(name):
    ret = mcgen('''
void visit_type_%(name)sList(Visitor *m, %(name)sList **obj, const char *name, Error **errp);
''',
                name=c_name(name))

    return ret

def generate_decl_enum(name):
    return mcgen('''

void visit_type_%(name)s(Visitor *m, %(name)s *obj, const char *name, Error **errp);
''',
                 name=c_name(name))

do_builtins = False

(input_file, output_dir, do_c, do_h, prefix, opts) = \
    parse_command_line("b", ["builtins"])

for o, a in opts:
    if o in ("-b", "--builtins"):
        do_builtins = True

c_comment = '''
/*
 * schema-defined QAPI visitor functions
 *
 * 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.
 *
 */
'''
h_comment = '''
/*
 * schema-defined QAPI visitor functions
 *
 * 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.
 *
 */
'''

(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
                            'qapi-visit.c', 'qapi-visit.h',
                            c_comment, h_comment)

fdef.write(mcgen('''
#include "qemu-common.h"
#include "%(prefix)sqapi-visit.h"
''',
                 prefix = prefix))

fdecl.write(mcgen('''
#include "qapi/visitor.h"
#include "%(prefix)sqapi-types.h"

''',
                  prefix=prefix))

exprs = QAPISchema(input_file).get_exprs()

# to avoid header dependency hell, we always generate declarations
# for built-in types in our header files and simply guard them
fdecl.write(guardstart("QAPI_VISIT_BUILTIN_VISITOR_DECL"))
for typename in builtin_types.keys():
    fdecl.write(generate_declaration(typename, builtin_type=True))
fdecl.write(guardend("QAPI_VISIT_BUILTIN_VISITOR_DECL"))

# ...this doesn't work for cases where we link in multiple objects that
# have the functions defined, so we use -b option to provide control
# over these cases
if do_builtins:
    for typename in builtin_types.keys():
        fdef.write(generate_visit_list(typename))

for expr in exprs:
    if expr.has_key('struct'):
        ret = generate_visit_struct(expr)
        ret += generate_visit_list(expr['struct'])
        fdef.write(ret)

        ret = generate_declaration(expr['struct'])
        fdecl.write(ret)
    elif expr.has_key('union'):
        ret = generate_visit_union(expr)
        ret += generate_visit_list(expr['union'])
        fdef.write(ret)

        enum_define = discriminator_find_enum_define(expr)
        ret = ""
        if not enum_define:
            ret = generate_decl_enum('%sKind' % expr['union'])
        ret += generate_declaration(expr['union'])
        fdecl.write(ret)
    elif expr.has_key('alternate'):
        ret = generate_visit_alternate(expr['alternate'], expr['data'])
        ret += generate_visit_list(expr['alternate'])
        fdef.write(ret)

        ret = generate_decl_enum('%sKind' % expr['alternate'])
        ret += generate_declaration(expr['alternate'])
        fdecl.write(ret)
    elif expr.has_key('enum'):
        ret = generate_visit_list(expr['enum'])
        ret += generate_visit_enum(expr['enum'])
        fdef.write(ret)

        ret = generate_decl_enum(expr['enum'])
        ret += generate_enum_declaration(expr['enum'])
        fdecl.write(ret)

close_output(fdef, fdecl)