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/thirdparty/breakpad/common/dwarf_line_to_module.h

http://github.com/tomahawk-player/tomahawk
C++ Header | 179 lines | 35 code | 20 blank | 124 comment | 0 complexity | 811be83cb5a323d7ac2aa68b3fc55277 MD5 | raw file
  1// -*- mode: c++ -*-
  2
  3// Copyright (c) 2010 Google Inc.
  4// All rights reserved.
  5//
  6// Redistribution and use in source and binary forms, with or without
  7// modification, are permitted provided that the following conditions are
  8// met:
  9//
 10//     * Redistributions of source code must retain the above copyright
 11// notice, this list of conditions and the following disclaimer.
 12//     * Redistributions in binary form must reproduce the above
 13// copyright notice, this list of conditions and the following disclaimer
 14// in the documentation and/or other materials provided with the
 15// distribution.
 16//     * Neither the name of Google Inc. nor the names of its
 17// contributors may be used to endorse or promote products derived from
 18// this software without specific prior written permission.
 19//
 20// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 21// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 22// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 23// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 24// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 25// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 26// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 27// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 28// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 29// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 30// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 31
 32// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
 33
 34// The DwarfLineToModule class accepts line number information from a
 35// DWARF parser and adds it to a google_breakpad::Module. The Module
 36// can write that data out as a Breakpad symbol file.
 37
 38#ifndef COMMON_LINUX_DWARF_LINE_TO_MODULE_H
 39#define COMMON_LINUX_DWARF_LINE_TO_MODULE_H
 40
 41#include "common/module.h"
 42#include "common/dwarf/dwarf2reader.h"
 43
 44namespace google_breakpad {
 45
 46// A class for producing a vector of google_breakpad::Module::Line
 47// instances from parsed DWARF line number data.  
 48//
 49// An instance of this class can be provided as a handler to a
 50// dwarf2reader::LineInfo DWARF line number information parser. The
 51// handler accepts source location information from the parser and
 52// uses it to produce a vector of google_breakpad::Module::Line
 53// objects, referring to google_breakpad::Module::File objects added
 54// to a particular google_breakpad::Module.
 55//
 56// GNU toolchain omitted sections support:
 57// ======================================
 58//
 59// Given the right options, the GNU toolchain will omit unreferenced
 60// functions from the final executable. Unfortunately, when it does so, it
 61// does not remove the associated portions of the DWARF line number
 62// program; instead, it gives the DW_LNE_set_address instructions referring
 63// to the now-deleted code addresses of zero. Given this input, the DWARF
 64// line parser will call AddLine with a series of lines starting at address
 65// zero. For example, here is the output from 'readelf -wl' for a program
 66// with four functions, the first three of which have been omitted:
 67//
 68//   Line Number Statements:
 69//    Extended opcode 2: set Address to 0x0
 70//    Advance Line by 14 to 15
 71//    Copy
 72//    Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16
 73//    Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18
 74//    Advance PC by 2 to 0xd
 75//    Extended opcode 1: End of Sequence
 76// 
 77//    Extended opcode 2: set Address to 0x0
 78//    Advance Line by 14 to 15
 79//    Copy
 80//    Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16
 81//    Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18
 82//    Advance PC by 2 to 0xd
 83//    Extended opcode 1: End of Sequence
 84// 
 85//    Extended opcode 2: set Address to 0x0
 86//    Advance Line by 19 to 20
 87//    Copy
 88//    Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 21
 89//    Special opcode 76: advance Address by 5 to 0x8 and Line by 1 to 22
 90//    Advance PC by 2 to 0xa
 91//    Extended opcode 1: End of Sequence
 92// 
 93//    Extended opcode 2: set Address to 0x80483a4
 94//    Advance Line by 23 to 24
 95//    Copy
 96//    Special opcode 202: advance Address by 14 to 0x80483b2 and Line by 1 to 25
 97//    Special opcode 76: advance Address by 5 to 0x80483b7 and Line by 1 to 26
 98//    Advance PC by 6 to 0x80483bd
 99//    Extended opcode 1: End of Sequence
100//
101// Instead of collecting runs of lines describing code that is not there,
102// we try to recognize and drop them. Since the linker doesn't explicitly
103// distinguish references to dropped sections from genuine references to
104// code at address zero, we must use a heuristic. We have chosen:
105//
106// - If a line starts at address zero, omit it. (On the platforms
107//   breakpad targets, it is extremely unlikely that there will be code
108//   at address zero.)
109//
110// - If a line starts immediately after an omitted line, omit it too.
111class DwarfLineToModule: public dwarf2reader::LineInfoHandler {
112 public:
113  // As the DWARF line info parser passes us line records, add source
114  // files to MODULE, and add all lines to the end of LINES. LINES
115  // need not be empty. If the parser hands us a zero-length line, we
116  // omit it. If the parser hands us a line that extends beyond the
117  // end of the address space, we clip it. It's up to our client to
118  // sort out which lines belong to which functions; we don't add them
119  // to any particular function in MODULE ourselves.
120  DwarfLineToModule(Module *module, vector<Module::Line> *lines)
121      : module_(module),
122        lines_(lines),
123        highest_file_number_(-1),
124        omitted_line_end_(0),
125        warned_bad_file_number_(false),
126        warned_bad_directory_number_(false) { }
127  
128  ~DwarfLineToModule() { }
129
130  void DefineDir(const std::string &name, uint32 dir_num);
131  void DefineFile(const std::string &name, int32 file_num,
132                  uint32 dir_num, uint64 mod_time,
133                  uint64 length);
134  void AddLine(uint64 address, uint64 length,
135               uint32 file_num, uint32 line_num, uint32 column_num);
136
137 private:
138
139  typedef std::map<uint32, std::string> DirectoryTable;
140  typedef std::map<uint32, Module::File *> FileTable;
141
142  // The module we're contributing debugging info to. Owned by our
143  // client.
144  Module *module_;
145
146  // The vector of lines we're accumulating. Owned by our client.
147  //
148  // In a Module, as in a breakpad symbol file, lines belong to
149  // specific functions, but DWARF simply assigns lines to addresses;
150  // one must infer the line/function relationship using the
151  // functions' beginning and ending addresses. So we can't add these
152  // to the appropriate function from module_ until we've read the
153  // function info as well. Instead, we accumulate lines here, and let
154  // whoever constructed this sort it all out.
155  vector<Module::Line> *lines_;
156
157  // A table mapping directory numbers to paths.
158  DirectoryTable directories_;
159
160  // A table mapping file numbers to Module::File pointers.
161  FileTable files_;
162
163  // The highest file number we've seen so far, or -1 if we've seen
164  // none.  Used for dynamically defined file numbers.
165  int32 highest_file_number_;
166  
167  // This is the ending address of the last line we omitted, or zero if we
168  // didn't omit the previous line. It is zero before we have received any
169  // AddLine calls.
170  uint64 omitted_line_end_;
171
172  // True if we've warned about:
173  bool warned_bad_file_number_; // bad file numbers
174  bool warned_bad_directory_number_; // bad directory numbers
175};
176
177} // namespace google_breakpad
178
179#endif // COMMON_LINUX_DWARF_LINE_TO_MODULE_H