1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
|
# Copyright 2017 syzkaller project authors. All rights reserved.
# Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
'''
This module provides classes which implement AST traversal in order to extract
items belonging to a struct.
'''
import collections
import logging
from pycparser import c_ast
from .header_preprocessor import HeaderFilePreprocessor
class StructWalkerException(Exception):
pass
class StructWalker(c_ast.NodeVisitor):
'''
Given an ast obtained by parsing a header file, return a hierarchy
dictionary. The ast is expected to be of type pycparser.c_ast.FileAST.
Usage :
>>> import tempfile
>>> t = tempfile.NamedTemporaryFile()
>>> contents = """
... #define STRUCT_SIZE 1337
... struct ARRAY_OF_POINTERS_CONTAINER {
... unsigned int *ptr[10];
... int **n;
... };
... struct ARRAY_CONTAINER {
... int g[10];
... int h[20][30];
... };
... struct REGULAR_STRUCT {
... int x;
... char *y;
... void *ptr;
... };
... struct STRUCT_WITH_STRUCT_PTR {
... struct REGULAR_STRUCT *struct_ptr;
... int z;
... };
... struct STRUCT_WITH_STRUCT_INST {
... struct REGULAR_STRUCT regular_struct_inst;
... int a;
... };
... struct STRUCT_WITH_STRUCT_ARRAY {
... struct REGULAR_STRUCT regular_struct_array[100];
... int b;
... };
... struct STRUCT_WITH_ANONYMOUS_STRUCT {
... struct {
... int g;
... int h;
... int i;
... } anonymous_struct;
... };
... struct STRUCT_WITH_ANONYMOUS_UNION {
... union {
... int t;
... char r[100];
... } anonymous_union;
... };
... struct STRUCT_WITH_STRUCT_ARRAY_SIZE_MACRO {
... struct REGULAR_STRUCT regular_struct_array[STRUCT_SIZE];
... };
... struct STRUCT_WITH_2D_ARRAY_INST {
... struct REGULAR_STRUCT regular_struct_array_2D[10][10];
... };
... struct NESTED_ANONYMOUS_STRUCT {
... struct {
... int x;
... struct {
... int y;
... int z;
... } level_2;
... } level_1;
... };
... """
>>> t.write(contents) ; t.flush()
>>> struct_walker = StructWalker(filenames=[t.name])
>>> local_hierarchy = struct_walker.generate_local_hierarchy()
>>> for k in local_hierarchy:
... print k
... print local_hierarchy[k]
ARRAY_OF_POINTERS_CONTAINER
[('unsigned int*[10]', 'ptr'), ('int**', 'n')]
STRUCT_WITH_STRUCT_ARRAY_SIZE_MACRO
[('struct REGULAR_STRUCT[1337]', 'regular_struct_array')]
STRUCT_WITH_2D_ARRAY_INST
[('struct REGULAR_STRUCT[10][10]', 'regular_struct_array_2D')]
STRUCT_WITH_STRUCT_ARRAY
[('struct REGULAR_STRUCT[100]', 'regular_struct_array'), ('int', 'b')]
NESTED_ANONYMOUS_STRUCT
[('int', 'level_1.x'), ('int', 'level_1.level_2.y'), ('int', 'level_1.level_2.z')]
STRUCT_WITH_ANONYMOUS_STRUCT
[('int', 'anonymous_struct.g'), ('int', 'anonymous_struct.h'), ('int', 'anonymous_struct.i')]
STRUCT_WITH_ANONYMOUS_UNION
[('int', 'anonymous_union.t'), ('char[100]', 'anonymous_union.r')]
STRUCT_WITH_STRUCT_INST
[('struct REGULAR_STRUCT', 'regular_struct_inst'), ('int', 'a')]
ARRAY_CONTAINER
[('int[10]', 'g'), ('int[20][30]', 'h')]
REGULAR_STRUCT
[('int', 'x'), ('char*', 'y'), ('void*', 'ptr')]
STRUCT_WITH_STRUCT_PTR
[('struct REGULAR_STRUCT*', 'struct_ptr'), ('int', 'z')]
'''
def __init__(self, ast=None, filenames=[], include_lines='', loglvl=logging.INFO):
super(StructWalker, self).__init__()
self.ast = ast
self.filenames = filenames
if not filenames and not ast:
raise StructWalkerException('Specify either "filename" or "ast" to create'
'StructParser object')
if not self.ast:
self.ast = HeaderFilePreprocessor(self.filenames, include_lines=include_lines,
loglvl=loglvl).get_ast()
self.include_lines = include_lines
self.local_structs_hierarchy = {}
self._setuplogging(loglvl)
def _setuplogging(self, loglvl):
self.logger = logging.getLogger(self.__class__.__name__)
formatter = logging.Formatter('DEBUG:%(name)s:%(message)s')
sh = logging.StreamHandler()
sh.setFormatter(formatter)
sh.setLevel(loglvl)
self.logger.addHandler(sh)
self.logger.setLevel(loglvl)
def _format_item(self, processed_item):
fmt_type = processed_item['type']
fmt_type = ' '.join(fmt_type)
self.logger.debug('_format_item : %s', processed_item)
if 'is_ptr' in processed_item and 'is_fnptr' not in processed_item:
fmt_type = '%s%s' % (fmt_type, '*' * processed_item['is_ptr'])
if 'is_array' in processed_item and 'array_size' in processed_item:
size_str = str(processed_item['array_size']).replace(', ', '][')
fmt_type = '%s%s' % (fmt_type, size_str)
fmt_identifier = processed_item['identifier']
return [(fmt_type, fmt_identifier)]
def _recursive_process_item(self, item_ast, processed_item, parent):
self.logger.debug('--- _recursive_process_item : %s', type(item_ast))
if isinstance(item_ast, c_ast.Decl):
processed_item['identifier'] = item_ast.name
return self._recursive_process_item(item_ast.type, processed_item, item_ast)
elif isinstance(item_ast, c_ast.TypeDecl):
return self._recursive_process_item(item_ast.type, processed_item, item_ast)
elif isinstance(item_ast, c_ast.IdentifierType):
if len(item_ast.names) > 0:
processed_item['type'] = item_ast.names
return self._format_item(processed_item)
elif (isinstance(item_ast, c_ast.Struct) or
isinstance(item_ast, c_ast.Union)):
if not item_ast.name:
nodename, _items_list = self._traverse_ast(item_ast, toplevel=False)
try:
items_list = [(i[0], '%s.%s' % (parent.declname, i[1])) for i in _items_list]
except AttributeError as e:
self.logger.info('-- Encountered anonymous_struct/anonymous_union with no name')
raise StructWalkerException('Encountered anonymous_struct/anonymous_union with no name')
return items_list
else:
processed_item['type'] = ['struct %s' % (item_ast.name)]
return self._format_item(processed_item)
elif isinstance(item_ast, c_ast.PtrDecl):
if 'is_ptr' not in processed_item:
processed_item['is_ptr'] = 0
processed_item['is_ptr'] = processed_item['is_ptr'] + 1
return self._recursive_process_item(item_ast.type, processed_item, item_ast)
elif isinstance(item_ast, c_ast.ArrayDecl):
processed_item['is_array'] = True
if 'array_size' not in processed_item:
processed_item['array_size'] = []
processed_item['array_size'].append(int(item_ast.dim.value))
return self._recursive_process_item(item_ast.type, processed_item, item_ast)
elif isinstance(item_ast, c_ast.Enum):
processed_item['type'] = ['enum %s' % (item_ast.name)]
return self._format_item(processed_item)
elif isinstance(item_ast, c_ast.FuncDecl):
processed_item['is_fnptr'] = True
processed_item['type'] = ['void (*)()']
return self._format_item(processed_item)
def _traverse_ast(self, node, toplevel=True):
items_list = []
# Argument structs are used as types, hence anonymous top-level
# structs are ignored.
if toplevel and not node.name:
return None
if not node.children():
return None
self.logger.debug('>>> Struct name = %s, coord: %s', node.name, node.coord)
for child in node.children():
item = self._recursive_process_item(child[1], {}, None)
items_list.extend(item)
self.logger.debug('_traverse_ast returns: %s', str((node.name, items_list)))
return (node.name, items_list)
def visit_Struct(self, node, *a):
if node.name in self.local_structs_hierarchy:
self.logger.info('Encountered %s again. Ignoring.', repr(node.name))
return
try:
desc = self._traverse_ast(node)
except StructWalkerException as e:
self.logger.info('-- Exception raised by StructWalkerException in %s,'
'inspect manually.',
repr(node.name))
self.logger.info(str(e))
return
if not desc:
return
struct_name, struct_items = desc
self.local_structs_hierarchy[struct_name] = struct_items
def generate_local_hierarchy(self):
self.visit(self.ast)
return self.local_structs_hierarchy
|
