summaryrefslogtreecommitdiffstats
path: root/toolkit/crashreporter/google-breakpad/src/common/stabs_reader.h
blob: 98ee2dd53b405fd7e85358d2b5eb13cd75e795c9 (plain)
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
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
// -*- mode: c++ -*-

// Copyright (c) 2010 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>

// stabs_reader.h: Define StabsReader, a parser for STABS debugging
// information. A description of the STABS debugging format can be
// found at:
//
//    http://sourceware.org/gdb/current/onlinedocs/stabs_toc.html
//
// The comments here assume you understand the format.
//
// This parser can handle big-endian and little-endian data, and the symbol
// values may be either 32 or 64 bits long. It handles both STABS in
// sections (as used on Linux) and STABS appearing directly in an
// a.out-like symbol table (as used in Darwin OS X Mach-O files).

#ifndef COMMON_STABS_READER_H__
#define COMMON_STABS_READER_H__

#include <stddef.h>
#include <stdint.h>

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#ifdef HAVE_MACH_O_NLIST_H
#include <mach-o/nlist.h>
#elif defined(HAVE_A_OUT_H)
#include <a.out.h>
#endif

#include <string>
#include <vector>

#include "common/byte_cursor.h"
#include "common/using_std_string.h"

namespace google_breakpad {

class StabsHandler;

class StabsReader {
 public:
  // Create a reader for the STABS debug information whose .stab section is
  // being traversed by ITERATOR, and whose .stabstr section is referred to
  // by STRINGS. The reader will call the member functions of HANDLER to
  // report the information it finds, when the reader's 'Process' member
  // function is called.
  //
  // BIG_ENDIAN should be true if the entries in the .stab section are in
  // big-endian form, or false if they are in little-endian form.
  //
  // VALUE_SIZE should be either 4 or 8, indicating the size of the 'value'
  // field in each entry in bytes.
  //
  // UNITIZED should be true if the STABS data is stored in units with
  // N_UNDF headers. This is usually the case for STABS stored in sections,
  // like .stab/.stabstr, and usually not the case for STABS stored in the
  // actual symbol table; UNITIZED should be true when parsing Linux stabs,
  // false when parsing Mac OS X STABS. For details, see:
  // http://sourceware.org/gdb/current/onlinedocs/stabs/Stab-Section-Basics.html
  // 
  // Note that, in ELF, the .stabstr section should be found using the
  // 'sh_link' field of the .stab section header, not by name.
  StabsReader(const uint8_t *stab,    size_t stab_size,
              const uint8_t *stabstr, size_t stabstr_size,
              bool big_endian, size_t value_size, bool unitized,
              StabsHandler *handler);

  // Process the STABS data, calling the handler's member functions to
  // report what we find.  While the handler functions return true,
  // continue to process until we reach the end of the section.  If we
  // processed the entire section and all handlers returned true,
  // return true.  If any handler returned false, return false.
  // 
  // This is only meant to be called once per StabsReader instance;
  // resuming a prior processing pass that stopped abruptly isn't supported.
  bool Process();

 private:

  // An class for walking arrays of STABS entries. This isolates the main
  // STABS reader from the exact format (size; endianness) of the entries
  // themselves.
  class EntryIterator {
   public:
    // The contents of a STABS entry, adjusted for the host's endianness,
    // word size, 'struct nlist' layout, and so on.
    struct Entry {
      // True if this iterator has reached the end of the entry array. When
      // this is set, the other members of this structure are not valid.
      bool at_end;

      // The number of this entry within the list.
      size_t index;

      // The current entry's name offset. This is the offset within the
      // current compilation unit's strings, as establish by the N_UNDF entries.
      size_t name_offset;

      // The current entry's type, 'other' field, descriptor, and value.
      unsigned char type;
      unsigned char other;
      short descriptor;
      uint64_t value;
    };

    // Create a EntryIterator walking the entries in BUFFER. Treat the
    // entries as big-endian if BIG_ENDIAN is true, as little-endian
    // otherwise. Assume each entry has a 'value' field whose size is
    // VALUE_SIZE.
    //
    // This would not be terribly clean to extend to other format variations,
    // but it's enough to handle Linux and Mac, and we'd like STABS to die
    // anyway.
    //
    // For the record: on Linux, STABS entry values are always 32 bits,
    // regardless of the architecture address size (don't ask me why); on
    // Mac, they are 32 or 64 bits long. Oddly, the section header's entry
    // size for a Linux ELF .stab section varies according to the ELF class
    // from 12 to 20 even as the actual entries remain unchanged.
    EntryIterator(const ByteBuffer *buffer, bool big_endian, size_t value_size);

    // Move to the next entry. This function's behavior is undefined if
    // at_end() is true when it is called.
    EntryIterator &operator++() { Fetch(); entry_.index++; return *this; }

    // Dereferencing this iterator produces a reference to an Entry structure
    // that holds the current entry's values. The entry is owned by this
    // EntryIterator, and will be invalidated at the next call to operator++.
    const Entry &operator*() const { return entry_; }
    const Entry *operator->() const { return &entry_; }

   private:
    // Read the STABS entry at cursor_, and set entry_ appropriately.
    void Fetch();

    // The size of entries' value field, in bytes.
    size_t value_size_;

    // A byte cursor traversing buffer_.
    ByteCursor cursor_;

    // Values for the entry this iterator refers to.
    Entry entry_;
  };

  // A source line, saved to be reported later.
  struct Line {
    uint64_t address;
    const char *filename;
    int number;
  };

  // Return the name of the current symbol.
  const char *SymbolString();

  // Process a compilation unit starting at symbol_.  Return true
  // to continue processing, or false to abort.
  bool ProcessCompilationUnit();

  // Process a function in current_source_file_ starting at symbol_.
  // Return true to continue processing, or false to abort.
  bool ProcessFunction();

  // Process an exported function symbol.
  // Return true to continue processing, or false to abort.
  bool ProcessExtern();

  // The STABS entries being parsed.
  ByteBuffer entries_;

  // The string section to which the entries refer.
  ByteBuffer strings_;

  // The iterator walking the STABS entries.
  EntryIterator iterator_;

  // True if the data is "unitized"; see the explanation in the comment for
  // StabsReader::StabsReader.
  bool unitized_;

  StabsHandler *handler_;

  // The offset of the current compilation unit's strings within stabstr_.
  size_t string_offset_;

  // The value string_offset_ should have for the next compilation unit,
  // as established by N_UNDF entries.
  size_t next_cu_string_offset_;

  // The current source file name.
  const char *current_source_file_;

  // Mac OS X STABS place SLINE records before functions; we accumulate a
  // vector of these until we see the FUN record, and then report them
  // after the StartFunction call.
  std::vector<Line> queued_lines_;
};

// Consumer-provided callback structure for the STABS reader.  Clients
// of the STABS reader provide an instance of this structure.  The
// reader then invokes the member functions of that instance to report
// the information it finds.
//
// The default definitions of the member functions do nothing, and return
// true so processing will continue.
class StabsHandler {
 public:
  StabsHandler() { }
  virtual ~StabsHandler() { }

  // Some general notes about the handler callback functions:

  // Processing proceeds until the end of the .stabs section, or until
  // one of these functions returns false.

  // The addresses given are as reported in the STABS info, without
  // regard for whether the module may be loaded at different
  // addresses at different times (a shared library, say).  When
  // processing STABS from an ELF shared library, the addresses given
  // all assume the library is loaded at its nominal load address.
  // They are *not* offsets from the nominal load address.  If you
  // want offsets, you must subtract off the library's nominal load
  // address.

  // The arguments to these functions named FILENAME are all
  // references to strings stored in the .stabstr section.  Because
  // both the Linux and Solaris linkers factor out duplicate strings
  // from the .stabstr section, the consumer can assume that if two
  // FILENAME values are different addresses, they represent different
  // file names.
  //
  // Thus, it's safe to use (say) std::map<char *, ...>, which does
  // string address comparisons, not string content comparisons.
  // Since all the strings are in same array of characters --- the
  // .stabstr section --- comparing their addresses produces
  // predictable, if not lexicographically meaningful, results.

  // Begin processing a compilation unit whose main source file is
  // named FILENAME, and whose base address is ADDRESS.  If
  // BUILD_DIRECTORY is non-NULL, it is the name of the build
  // directory in which the compilation occurred.
  virtual bool StartCompilationUnit(const char *filename, uint64_t address,
                                    const char *build_directory) {
    return true;
  }

  // Finish processing the compilation unit.  If ADDRESS is non-zero,
  // it is the ending address of the compilation unit.  If ADDRESS is
  // zero, then the compilation unit's ending address is not
  // available, and the consumer must infer it by other means.
  virtual bool EndCompilationUnit(uint64_t address) { return true; }

  // Begin processing a function named NAME, whose starting address is
  // ADDRESS.  This function belongs to the compilation unit that was
  // most recently started but not ended.
  //
  // Note that, unlike filenames, NAME is not a pointer into the
  // .stabstr section; this is because the name as it appears in the
  // STABS data is followed by type information.  The value passed to
  // StartFunction is the function name alone.
  //
  // In languages that use name mangling, like C++, NAME is mangled.
  virtual bool StartFunction(const string &name, uint64_t address) {
    return true;
  }

  // Finish processing the function.  If ADDRESS is non-zero, it is
  // the ending address for the function.  If ADDRESS is zero, then
  // the function's ending address is not available, and the consumer
  // must infer it by other means.
  virtual bool EndFunction(uint64_t address) { return true; }
  
  // Report that the code at ADDRESS is attributable to line NUMBER of
  // the source file named FILENAME.  The caller must infer the ending
  // address of the line.
  virtual bool Line(uint64_t address, const char *filename, int number) {
    return true;
  }

  // Report that an exported function NAME is present at ADDRESS.
  // The size of the function is unknown.
  virtual bool Extern(const string &name, uint64_t address) {
    return true;
  }

  // Report a warning.  FORMAT is a printf-like format string,
  // specifying how to format the subsequent arguments.
  virtual void Warning(const char *format, ...) = 0;
};

} // namespace google_breakpad

#endif  // COMMON_STABS_READER_H__