scripts/block-coroutine-wrapper.py

   1 #! /usr/bin/env python3
   2 """Generate coroutine wrappers for block subsystem.
   3
   4 The program parses one or several concatenated c files from stdin,
   5 searches for functions with the 'generated_co_wrapper' specifier
   6 and generates corresponding wrappers on stdout.
   7
   8 Usage: block-coroutine-wrapper.py generated-file.c FILE.[ch]...
   9
  10 Copyright (c) 2020 Virtuozzo International GmbH.
  11
  12 This program is free software; you can redistribute it and/or modify
  13 it under the terms of the GNU General Public License as published by
  14 the Free Software Foundation; either version 2 of the License, or
  15 (at your option) any later version.
  16
  17 This program is distributed in the hope that it will be useful,
  18 but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 GNU General Public License for more details.
  21
  22 You should have received a copy of the GNU General Public License
  23 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24 """
  25
  26 import sys
  27 import re
  28 from typing import Iterator
  29
  30
  31 def 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
  49 class 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
  64 class FuncDecl:
  65     def __init__(self, return_type: str, name: str, args: str) -> None:
  66         self.return_type = return_type.strip()
  67         self.name = name.strip()
  68         self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
  69
  70     def gen_list(self, format: str) -> str:
  71         return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
  72
  73     def gen_block(self, format: str) -> str:
  74         return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
  75
  76
  77 # Match wrappers declared with a generated_co_wrapper mark
  78 func_decl_re = re.compile(r'^int\s*generated_co_wrapper\s*'
  79                           r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
  80                           r'\((?P<args>[^)]*)\);$', re.MULTILINE)
  81
  82
  83 def func_decl_iter(text: str) -> Iterator:
  84     for m in func_decl_re.finditer(text):
  85         yield FuncDecl(return_type='int',
  86                        name=m.group('wrapper_name'),
  87                        args=m.group('args'))
  88
  89
  90 def snake_to_camel(func_name: str) -> str:
  91     """
  92     Convert underscore names like 'some_function_name' to camel-case like
  93     'SomeFunctionName'
  94     """
  95     words = func_name.split('_')
  96     words = [w[0].upper() + w[1:] for w in words]
  97     return ''.join(words)
  98
  99
 100 def gen_wrapper(func: FuncDecl) -> str:
 101     assert func.name.startswith('bdrv_')
 102     assert not func.name.startswith('bdrv_co_')
 103     assert func.return_type == 'int'
 104     assert func.args[0].type in ['BlockDriverState *', 'BdrvChild *']
 105
 106     name = 'bdrv_co_' + func.name[5:]
 107     bs = 'bs' if func.args[0].type == 'BlockDriverState *' else 'child->bs'
 108     struct_name = snake_to_camel(name)
 109
 110     return f"""\
 111 /*
 112  * Wrappers for {name}
 113  */
 114
 115 typedef struct {struct_name} {{
 116     BdrvPollCo poll_state;
 117 { func.gen_block('    {decl};') }
 118 }} {struct_name};
 119
 120 static void coroutine_fn {name}_entry(void *opaque)
 121 {{
 122     {struct_name} *s = opaque;
 123
 124     s->poll_state.ret = {name}({ func.gen_list('s->{name}') });
 125     s->poll_state.in_progress = false;
 126
 127     aio_wait_kick();
 128 }}
 129
 130 int {func.name}({ func.gen_list('{decl}') })
 131 {{
 132     if (qemu_in_coroutine()) {{
 133         return {name}({ func.gen_list('{name}') });
 134     }} else {{
 135         {struct_name} s = {{
 136             .poll_state.bs = {bs},
 137             .poll_state.in_progress = true,
 138
 139 { func.gen_block('            .{name} = {name},') }
 140         }};
 141
 142         s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 143
 144         return bdrv_poll_co(&s.poll_state);
 145     }}
 146 }}"""
 147
 148
 149 def gen_wrappers(input_code: str) -> str:
 150     res = ''
 151     for func in func_decl_iter(input_code):
 152         res += '\n\n\n'
 153         res += gen_wrapper(func)
 154
 155     return res
 156
 157
 158 if __name__ == '__main__':
 159     if len(sys.argv) < 3:
 160         exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
 161
 162     with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
 163         f_out.write(gen_header())
 164         for fname in sys.argv[2:]:
 165             with open(fname, encoding='utf-8') as f_in:
 166                 f_out.write(gen_wrappers(f_in.read()))
 167                 f_out.write('\n')