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        self.graph_wrlock = 'bdrv_wrlock' in variant
75
76        self.wrapper_type = wrapper_type
77
78        if wrapper_type == 'co':
79            if self.graph_wrlock:
80                raise ValueError(f"co function can't be wrlock: {self.name}")
81            subsystem, subname = self.name.split('_', 1)
82            self.target_name = f'{subsystem}_co_{subname}'
83        else:
84            assert wrapper_type == 'no_co'
85            subsystem, co_infix, subname = self.name.split('_', 2)
86            if co_infix != 'co':
87                raise ValueError(f"Invalid no_co function name: {self.name}")
88            if not self.create_only_co:
89                raise ValueError(f"no_co function can't be mixed: {self.name}")
90            if self.graph_rdlock and self.graph_wrlock:
91                raise ValueError("function can't be both rdlock and wrlock: "
92                                 f"{self.name}")
93            self.target_name = f'{subsystem}_{subname}'
94
95        self.get_result = 's->ret = '
96        self.ret = 'return s.ret;'
97        self.co_ret = 'return '
98        self.return_field = self.return_type + " ret;"
99        if self.return_type == 'void':
100            self.get_result = ''
101            self.ret = ''
102            self.co_ret = ''
103            self.return_field = ''
104
105    def gen_ctx(self, prefix: str = '') -> str:
106        t = self.args[0].type
107        name = self.args[0].name
108        if t == 'BlockDriverState *':
109            return f'bdrv_get_aio_context({prefix}{name})'
110        elif t == 'BdrvChild *':
111            return f'bdrv_get_aio_context({prefix}{name}->bs)'
112        elif t == 'BlockBackend *':
113            return f'blk_get_aio_context({prefix}{name})'
114        else:
115            return 'qemu_get_aio_context()'
116
117    def gen_list(self, format: str) -> str:
118        return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
119
120    def gen_block(self, format: str) -> str:
121        return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
122
123
124# Match wrappers declared with a co_wrapper mark
125func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
126                          r'(\s*coroutine_fn)?'
127                          r'\s*(?P<wrapper_type>(no_)?co)_wrapper'
128                          r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
129                          r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
130                          r'\((?P<args>[^)]*)\);$', re.MULTILINE)
131
132
133def func_decl_iter(text: str) -> Iterator:
134    for m in func_decl_re.finditer(text):
135        yield FuncDecl(wrapper_type=m.group('wrapper_type'),
136                       return_type=m.group('return_type'),
137                       name=m.group('wrapper_name'),
138                       args=m.group('args'),
139                       variant=m.group('variant'))
140
141
142def snake_to_camel(func_name: str) -> str:
143    """
144    Convert underscore names like 'some_function_name' to camel-case like
145    'SomeFunctionName'
146    """
147    words = func_name.split('_')
148    words = [w[0].upper() + w[1:] for w in words]
149    return ''.join(words)
150
151
152def create_mixed_wrapper(func: FuncDecl) -> str:
153    """
154    Checks if we are already in coroutine
155    """
156    name = func.target_name
157    struct_name = func.struct_name
158    graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
159
160    return f"""\
161{func.return_type} {func.name}({ func.gen_list('{decl}') })
162{{
163    if (qemu_in_coroutine()) {{
164        {graph_assume_lock}
165        {func.co_ret}{name}({ func.gen_list('{name}') });
166    }} else {{
167        {struct_name} s = {{
168            .poll_state.ctx = qemu_get_current_aio_context(),
169            .poll_state.in_progress = true,
170
171{ func.gen_block('            .{name} = {name},') }
172        }};
173
174        s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
175
176        bdrv_poll_co(&s.poll_state);
177        {func.ret}
178    }}
179}}"""
180
181
182def create_co_wrapper(func: FuncDecl) -> str:
183    """
184    Assumes we are not in coroutine, and creates one
185    """
186    name = func.target_name
187    struct_name = func.struct_name
188    return f"""\
189{func.return_type} {func.name}({ func.gen_list('{decl}') })
190{{
191    {struct_name} s = {{
192        .poll_state.ctx = qemu_get_current_aio_context(),
193        .poll_state.in_progress = true,
194
195{ func.gen_block('        .{name} = {name},') }
196    }};
197    assert(!qemu_in_coroutine());
198
199    s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
200
201    bdrv_poll_co(&s.poll_state);
202    {func.ret}
203}}"""
204
205
206def gen_co_wrapper(func: FuncDecl) -> str:
207    assert not '_co_' in func.name
208    assert func.wrapper_type == 'co'
209
210    name = func.target_name
211    struct_name = func.struct_name
212
213    graph_lock=''
214    graph_unlock=''
215    if func.graph_rdlock:
216        graph_lock='    bdrv_graph_co_rdlock();'
217        graph_unlock='    bdrv_graph_co_rdunlock();'
218
219    creation_function = create_mixed_wrapper
220    if func.create_only_co:
221        creation_function = create_co_wrapper
222
223    return f"""\
224/*
225 * Wrappers for {name}
226 */
227
228typedef struct {struct_name} {{
229    BdrvPollCo poll_state;
230    {func.return_field}
231{ func.gen_block('    {decl};') }
232}} {struct_name};
233
234static void coroutine_fn {name}_entry(void *opaque)
235{{
236    {struct_name} *s = opaque;
237
238{graph_lock}
239    {func.get_result}{name}({ func.gen_list('s->{name}') });
240{graph_unlock}
241    s->poll_state.in_progress = false;
242
243    aio_wait_kick();
244}}
245
246{creation_function(func)}"""
247
248
249def gen_no_co_wrapper(func: FuncDecl) -> str:
250    assert '_co_' in func.name
251    assert func.wrapper_type == 'no_co'
252
253    name = func.target_name
254    struct_name = func.struct_name
255
256    graph_lock=''
257    graph_unlock=''
258    if func.graph_rdlock:
259        graph_lock='    bdrv_graph_rdlock_main_loop();'
260        graph_unlock='    bdrv_graph_rdunlock_main_loop();'
261    elif func.graph_wrlock:
262        graph_lock='    bdrv_graph_wrlock();'
263        graph_unlock='    bdrv_graph_wrunlock();'
264
265    return f"""\
266/*
267 * Wrappers for {name}
268 */
269
270typedef struct {struct_name} {{
271    Coroutine *co;
272    {func.return_field}
273{ func.gen_block('    {decl};') }
274}} {struct_name};
275
276static void {name}_bh(void *opaque)
277{{
278    {struct_name} *s = opaque;
279
280{graph_lock}
281    {func.get_result}{name}({ func.gen_list('s->{name}') });
282{graph_unlock}
283
284    aio_co_wake(s->co);
285}}
286
287{func.return_type} coroutine_fn {func.name}({ func.gen_list('{decl}') })
288{{
289    {struct_name} s = {{
290        .co = qemu_coroutine_self(),
291{ func.gen_block('        .{name} = {name},') }
292    }};
293    assert(qemu_in_coroutine());
294
295    aio_bh_schedule_oneshot(qemu_get_aio_context(), {name}_bh, &s);
296    qemu_coroutine_yield();
297
298    {func.ret}
299}}"""
300
301
302def gen_wrappers(input_code: str) -> str:
303    res = ''
304    for func in func_decl_iter(input_code):
305        res += '\n\n\n'
306        if func.wrapper_type == 'co':
307            res += gen_co_wrapper(func)
308        else:
309            res += gen_no_co_wrapper(func)
310
311    return res
312
313
314if __name__ == '__main__':
315    if len(sys.argv) < 3:
316        exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
317
318    with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
319        f_out.write(gen_header())
320        for fname in sys.argv[2:]:
321            with open(fname, encoding='utf-8') as f_in:
322                f_out.write(gen_wrappers(f_in.read()))
323                f_out.write('\n')
324