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