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#include "block/dirty-bitmap.h"
47"""
48
49
50class ParamDecl:
51    param_re = re.compile(r'(?P<decl>'
52                          r'(?P<type>.*[ *])'
53                          r'(?P<name>[a-z][a-z0-9_]*)'
54                          r')')
55
56    def __init__(self, param_decl: str) -> None:
57        m = self.param_re.match(param_decl.strip())
58        if m is None:
59            raise ValueError(f'Wrong parameter declaration: "{param_decl}"')
60        self.decl = m.group('decl')
61        self.type = m.group('type')
62        self.name = m.group('name')
63
64
65class FuncDecl:
66    def __init__(self, wrapper_type: str, return_type: str, name: str,
67                 args: str, variant: str) -> None:
68        self.return_type = return_type.strip()
69        self.name = name.strip()
70        self.struct_name = snake_to_camel(self.name)
71        self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
72        self.create_only_co = 'mixed' not in variant
73        self.graph_rdlock = 'bdrv_rdlock' in variant
74
75        self.wrapper_type = wrapper_type
76
77        if wrapper_type == 'co':
78            subsystem, subname = self.name.split('_', 1)
79            self.target_name = f'{subsystem}_co_{subname}'
80        else:
81            assert wrapper_type == 'no_co'
82            subsystem, co_infix, subname = self.name.split('_', 2)
83            if co_infix != 'co':
84                raise ValueError(f"Invalid no_co function name: {self.name}")
85            if not self.create_only_co:
86                raise ValueError(f"no_co function can't be mixed: {self.name}")
87            if self.graph_rdlock:
88                raise ValueError(f"no_co function can't be rdlock: {self.name}")
89            self.target_name = f'{subsystem}_{subname}'
90
91        t = self.args[0].type
92        if t == 'BlockDriverState *':
93            ctx = 'bdrv_get_aio_context(bs)'
94        elif t == 'BdrvChild *':
95            ctx = 'bdrv_get_aio_context(child->bs)'
96        elif t == 'BlockBackend *':
97            ctx = 'blk_get_aio_context(blk)'
98        else:
99            ctx = 'qemu_get_aio_context()'
100        self.ctx = ctx
101
102        self.get_result = 's->ret = '
103        self.ret = 'return s.ret;'
104        self.co_ret = 'return '
105        self.return_field = self.return_type + " ret;"
106        if self.return_type == 'void':
107            self.get_result = ''
108            self.ret = ''
109            self.co_ret = ''
110            self.return_field = ''
111
112    def gen_list(self, format: str) -> str:
113        return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
114
115    def gen_block(self, format: str) -> str:
116        return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
117
118
119# Match wrappers declared with a co_wrapper mark
120func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
121                          r'(\s*coroutine_fn)?'
122                          r'\s*(?P<wrapper_type>(no_)?co)_wrapper'
123                          r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
124                          r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
125                          r'\((?P<args>[^)]*)\);$', re.MULTILINE)
126
127
128def func_decl_iter(text: str) -> Iterator:
129    for m in func_decl_re.finditer(text):
130        yield FuncDecl(wrapper_type=m.group('wrapper_type'),
131                       return_type=m.group('return_type'),
132                       name=m.group('wrapper_name'),
133                       args=m.group('args'),
134                       variant=m.group('variant'))
135
136
137def snake_to_camel(func_name: str) -> str:
138    """
139    Convert underscore names like 'some_function_name' to camel-case like
140    'SomeFunctionName'
141    """
142    words = func_name.split('_')
143    words = [w[0].upper() + w[1:] for w in words]
144    return ''.join(words)
145
146
147def create_mixed_wrapper(func: FuncDecl) -> str:
148    """
149    Checks if we are already in coroutine
150    """
151    name = func.target_name
152    struct_name = func.struct_name
153    graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
154
155    return f"""\
156{func.return_type} {func.name}({ func.gen_list('{decl}') })
157{{
158    if (qemu_in_coroutine()) {{
159        {graph_assume_lock}
160        {func.co_ret}{name}({ func.gen_list('{name}') });
161    }} else {{
162        {struct_name} s = {{
163            .poll_state.ctx = {func.ctx},
164            .poll_state.in_progress = true,
165
166{ func.gen_block('            .{name} = {name},') }
167        }};
168
169        s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
170
171        bdrv_poll_co(&s.poll_state);
172        {func.ret}
173    }}
174}}"""
175
176
177def create_co_wrapper(func: FuncDecl) -> str:
178    """
179    Assumes we are not in coroutine, and creates one
180    """
181    name = func.target_name
182    struct_name = func.struct_name
183    return f"""\
184{func.return_type} {func.name}({ func.gen_list('{decl}') })
185{{
186    {struct_name} s = {{
187        .poll_state.ctx = {func.ctx},
188        .poll_state.in_progress = true,
189
190{ func.gen_block('        .{name} = {name},') }
191    }};
192    assert(!qemu_in_coroutine());
193
194    s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
195
196    bdrv_poll_co(&s.poll_state);
197    {func.ret}
198}}"""
199
200
201def gen_co_wrapper(func: FuncDecl) -> str:
202    assert not '_co_' in func.name
203    assert func.wrapper_type == 'co'
204
205    name = func.target_name
206    struct_name = func.struct_name
207
208    graph_lock=''
209    graph_unlock=''
210    if func.graph_rdlock:
211        graph_lock='    bdrv_graph_co_rdlock();'
212        graph_unlock='    bdrv_graph_co_rdunlock();'
213
214    creation_function = create_mixed_wrapper
215    if func.create_only_co:
216        creation_function = create_co_wrapper
217
218    return f"""\
219/*
220 * Wrappers for {name}
221 */
222
223typedef struct {struct_name} {{
224    BdrvPollCo poll_state;
225    {func.return_field}
226{ func.gen_block('    {decl};') }
227}} {struct_name};
228
229static void coroutine_fn {name}_entry(void *opaque)
230{{
231    {struct_name} *s = opaque;
232
233{graph_lock}
234    {func.get_result}{name}({ func.gen_list('s->{name}') });
235{graph_unlock}
236    s->poll_state.in_progress = false;
237
238    aio_wait_kick();
239}}
240
241{creation_function(func)}"""
242
243
244def gen_no_co_wrapper(func: FuncDecl) -> str:
245    assert '_co_' in func.name
246    assert func.wrapper_type == 'no_co'
247
248    name = func.target_name
249    struct_name = func.struct_name
250
251    return f"""\
252/*
253 * Wrappers for {name}
254 */
255
256typedef struct {struct_name} {{
257    Coroutine *co;
258    {func.return_field}
259{ func.gen_block('    {decl};') }
260}} {struct_name};
261
262static void {name}_bh(void *opaque)
263{{
264    {struct_name} *s = opaque;
265
266    {func.get_result}{name}({ func.gen_list('s->{name}') });
267
268    aio_co_wake(s->co);
269}}
270
271{func.return_type} coroutine_fn {func.name}({ func.gen_list('{decl}') })
272{{
273    {struct_name} s = {{
274        .co = qemu_coroutine_self(),
275{ func.gen_block('        .{name} = {name},') }
276    }};
277    assert(qemu_in_coroutine());
278
279    aio_bh_schedule_oneshot(qemu_get_aio_context(), {name}_bh, &s);
280    qemu_coroutine_yield();
281
282    {func.ret}
283}}"""
284
285
286def gen_wrappers(input_code: str) -> str:
287    res = ''
288    for func in func_decl_iter(input_code):
289        res += '\n\n\n'
290        if func.wrapper_type == 'co':
291            res += gen_co_wrapper(func)
292        else:
293            res += gen_no_co_wrapper(func)
294
295    return res
296
297
298if __name__ == '__main__':
299    if len(sys.argv) < 3:
300        exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
301
302    with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
303        f_out.write(gen_header())
304        for fname in sys.argv[2:]:
305            with open(fname, encoding='utf-8') as f_in:
306                f_out.write(gen_wrappers(f_in.read()))
307                f_out.write('\n')
308