1#! /usr/bin/env python3
2"""Generate coroutine wrappers for block subsystem.
3
4The program parses one or several concatenated c files from stdin,
5searches for functions with the 'co_wrapper' specifier
6and generates corresponding wrappers on stdout.
7
8Usage: block-coroutine-wrapper.py generated-file.c FILE.[ch]...
9
10Copyright (c) 2020 Virtuozzo International GmbH.
11
12This program is free software; you can redistribute it and/or modify
13it under the terms of the GNU General Public License as published by
14the Free Software Foundation; either version 2 of the License, or
15(at your option) any later version.
16
17This program is distributed in the hope that it will be useful,
18but WITHOUT ANY WARRANTY; without even the implied warranty of
19MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20GNU General Public License for more details.
21
22You should have received a copy of the GNU General Public License
23along with this program.  If not, see <http://www.gnu.org/licenses/>.
24"""
25
26import sys
27import re
28from typing import Iterator
29
30
31def gen_header():
32    copyright = re.sub('^.*Copyright', 'Copyright', __doc__, flags=re.DOTALL)
33    copyright = re.sub('^(?=.)', ' * ', copyright.strip(), flags=re.MULTILINE)
34    copyright = re.sub('^$', ' *', copyright, flags=re.MULTILINE)
35    return f"""\
36/*
37 * File is generated by scripts/block-coroutine-wrapper.py
38 *
39{copyright}
40 */
41
42#include "qemu/osdep.h"
43#include "block/coroutines.h"
44#include "block/block-gen.h"
45#include "block/block_int.h"\
46"""
47
48
49class ParamDecl:
50    param_re = re.compile(r'(?P<decl>'
51                          r'(?P<type>.*[ *])'
52                          r'(?P<name>[a-z][a-z0-9_]*)'
53                          r')')
54
55    def __init__(self, param_decl: str) -> None:
56        m = self.param_re.match(param_decl.strip())
57        if m is None:
58            raise ValueError(f'Wrong parameter declaration: "{param_decl}"')
59        self.decl = m.group('decl')
60        self.type = m.group('type')
61        self.name = m.group('name')
62
63
64class FuncDecl:
65    def __init__(self, return_type: str, name: str, args: str,
66                 variant: str) -> None:
67        self.return_type = return_type.strip()
68        self.name = name.strip()
69        self.struct_name = snake_to_camel(self.name)
70        self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
71        self.create_only_co = 'mixed' not in variant
72
73        subsystem, subname = self.name.split('_', 1)
74        self.co_name = f'{subsystem}_co_{subname}'
75
76        t = self.args[0].type
77        if t == 'BlockDriverState *':
78            ctx = 'bdrv_get_aio_context(bs)'
79        elif t == 'BdrvChild *':
80            ctx = 'bdrv_get_aio_context(child->bs)'
81        elif t == 'BlockBackend *':
82            ctx = 'blk_get_aio_context(blk)'
83        else:
84            ctx = 'qemu_get_aio_context()'
85        self.ctx = ctx
86
87    def gen_list(self, format: str) -> str:
88        return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
89
90    def gen_block(self, format: str) -> str:
91        return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
92
93
94# Match wrappers declared with a co_wrapper mark
95func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
96                          r'\s*co_wrapper'
97                          r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
98                          r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
99                          r'\((?P<args>[^)]*)\);$', re.MULTILINE)
100
101
102def func_decl_iter(text: str) -> Iterator:
103    for m in func_decl_re.finditer(text):
104        yield FuncDecl(return_type=m.group('return_type'),
105                       name=m.group('wrapper_name'),
106                       args=m.group('args'),
107                       variant=m.group('variant'))
108
109
110def snake_to_camel(func_name: str) -> str:
111    """
112    Convert underscore names like 'some_function_name' to camel-case like
113    'SomeFunctionName'
114    """
115    words = func_name.split('_')
116    words = [w[0].upper() + w[1:] for w in words]
117    return ''.join(words)
118
119
120def create_mixed_wrapper(func: FuncDecl) -> str:
121    """
122    Checks if we are already in coroutine
123    """
124    name = func.co_name
125    struct_name = func.struct_name
126    return f"""\
127{func.return_type} {func.name}({ func.gen_list('{decl}') })
128{{
129    if (qemu_in_coroutine()) {{
130        return {name}({ func.gen_list('{name}') });
131    }} else {{
132        {struct_name} s = {{
133            .poll_state.ctx = {func.ctx},
134            .poll_state.in_progress = true,
135
136{ func.gen_block('            .{name} = {name},') }
137        }};
138
139        s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
140
141        bdrv_poll_co(&s.poll_state);
142        return s.ret;
143    }}
144}}"""
145
146
147def create_co_wrapper(func: FuncDecl) -> str:
148    """
149    Assumes we are not in coroutine, and creates one
150    """
151    name = func.co_name
152    struct_name = func.struct_name
153    return f"""\
154{func.return_type} {func.name}({ func.gen_list('{decl}') })
155{{
156    {struct_name} s = {{
157        .poll_state.ctx = {func.ctx},
158        .poll_state.in_progress = true,
159
160{ func.gen_block('        .{name} = {name},') }
161    }};
162    assert(!qemu_in_coroutine());
163
164    s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
165
166    bdrv_poll_co(&s.poll_state);
167    return s.ret;
168}}"""
169
170
171def gen_wrapper(func: FuncDecl) -> str:
172    assert not '_co_' in func.name
173
174    name = func.co_name
175    struct_name = func.struct_name
176
177    creation_function = create_mixed_wrapper
178    if func.create_only_co:
179        creation_function = create_co_wrapper
180
181    return f"""\
182/*
183 * Wrappers for {name}
184 */
185
186typedef struct {struct_name} {{
187    BdrvPollCo poll_state;
188    {func.return_type} ret;
189{ func.gen_block('    {decl};') }
190}} {struct_name};
191
192static void coroutine_fn {name}_entry(void *opaque)
193{{
194    {struct_name} *s = opaque;
195
196    s->ret = {name}({ func.gen_list('s->{name}') });
197    s->poll_state.in_progress = false;
198
199    aio_wait_kick();
200}}
201
202{creation_function(func)}"""
203
204
205def gen_wrappers(input_code: str) -> str:
206    res = ''
207    for func in func_decl_iter(input_code):
208        res += '\n\n\n'
209        res += gen_wrapper(func)
210
211    return res
212
213
214if __name__ == '__main__':
215    if len(sys.argv) < 3:
216        exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
217
218    with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
219        f_out.write(gen_header())
220        for fname in sys.argv[2:]:
221            with open(fname, encoding='utf-8') as f_in:
222                f_out.write(gen_wrappers(f_in.read()))
223                f_out.write('\n')
224