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// -*- 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>
// The DwarfLineToModule class accepts line number information from a
// DWARF parser and adds it to a google_breakpad::Module. The Module
// can write that data out as a Breakpad symbol file.
#ifndef COMMON_LINUX_DWARF_LINE_TO_MODULE_H
#define COMMON_LINUX_DWARF_LINE_TO_MODULE_H
#include <string>
#include "common/module.h"
#include "common/dwarf/dwarf2reader.h"
#include "common/using_std_string.h"
namespace google_breakpad {
// A class for producing a vector of google_breakpad::Module::Line
// instances from parsed DWARF line number data.
//
// An instance of this class can be provided as a handler to a
// dwarf2reader::LineInfo DWARF line number information parser. The
// handler accepts source location information from the parser and
// uses it to produce a vector of google_breakpad::Module::Line
// objects, referring to google_breakpad::Module::File objects added
// to a particular google_breakpad::Module.
//
// GNU toolchain omitted sections support:
// ======================================
//
// Given the right options, the GNU toolchain will omit unreferenced
// functions from the final executable. Unfortunately, when it does so, it
// does not remove the associated portions of the DWARF line number
// program; instead, it gives the DW_LNE_set_address instructions referring
// to the now-deleted code addresses of zero. Given this input, the DWARF
// line parser will call AddLine with a series of lines starting at address
// zero. For example, here is the output from 'readelf -wl' for a program
// with four functions, the first three of which have been omitted:
//
// Line Number Statements:
// Extended opcode 2: set Address to 0x0
// Advance Line by 14 to 15
// Copy
// Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16
// Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18
// Advance PC by 2 to 0xd
// Extended opcode 1: End of Sequence
//
// Extended opcode 2: set Address to 0x0
// Advance Line by 14 to 15
// Copy
// Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 16
// Special opcode 119: advance Address by 8 to 0xb and Line by 2 to 18
// Advance PC by 2 to 0xd
// Extended opcode 1: End of Sequence
//
// Extended opcode 2: set Address to 0x0
// Advance Line by 19 to 20
// Copy
// Special opcode 48: advance Address by 3 to 0x3 and Line by 1 to 21
// Special opcode 76: advance Address by 5 to 0x8 and Line by 1 to 22
// Advance PC by 2 to 0xa
// Extended opcode 1: End of Sequence
//
// Extended opcode 2: set Address to 0x80483a4
// Advance Line by 23 to 24
// Copy
// Special opcode 202: advance Address by 14 to 0x80483b2 and Line by 1 to 25
// Special opcode 76: advance Address by 5 to 0x80483b7 and Line by 1 to 26
// Advance PC by 6 to 0x80483bd
// Extended opcode 1: End of Sequence
//
// Instead of collecting runs of lines describing code that is not there,
// we try to recognize and drop them. Since the linker doesn't explicitly
// distinguish references to dropped sections from genuine references to
// code at address zero, we must use a heuristic. We have chosen:
//
// - If a line starts at address zero, omit it. (On the platforms
// breakpad targets, it is extremely unlikely that there will be code
// at address zero.)
//
// - If a line starts immediately after an omitted line, omit it too.
class DwarfLineToModule: public dwarf2reader::LineInfoHandler {
public:
// As the DWARF line info parser passes us line records, add source
// files to MODULE, and add all lines to the end of LINES. LINES
// need not be empty. If the parser hands us a zero-length line, we
// omit it. If the parser hands us a line that extends beyond the
// end of the address space, we clip it. It's up to our client to
// sort out which lines belong to which functions; we don't add them
// to any particular function in MODULE ourselves.
DwarfLineToModule(Module *module, vector<Module::Line> *lines)
: module_(module),
lines_(lines),
highest_file_number_(-1),
omitted_line_end_(0),
warned_bad_file_number_(false),
warned_bad_directory_number_(false) { }
~DwarfLineToModule() { }
void DefineDir(const string &name, uint32 dir_num);
void DefineFile(const string &name, int32 file_num,
uint32 dir_num, uint64 mod_time,
uint64 length);
void AddLine(uint64 address, uint64 length,
uint32 file_num, uint32 line_num, uint32 column_num);
private:
typedef std::map<uint32, string> DirectoryTable;
typedef std::map<uint32, Module::File *> FileTable;
// The module we're contributing debugging info to. Owned by our
// client.
Module *module_;
// The vector of lines we're accumulating. Owned by our client.
//
// In a Module, as in a breakpad symbol file, lines belong to
// specific functions, but DWARF simply assigns lines to addresses;
// one must infer the line/function relationship using the
// functions' beginning and ending addresses. So we can't add these
// to the appropriate function from module_ until we've read the
// function info as well. Instead, we accumulate lines here, and let
// whoever constructed this sort it all out.
vector<Module::Line> *lines_;
// A table mapping directory numbers to paths.
DirectoryTable directories_;
// A table mapping file numbers to Module::File pointers.
FileTable files_;
// The highest file number we've seen so far, or -1 if we've seen
// none. Used for dynamically defined file numbers.
int32 highest_file_number_;
// This is the ending address of the last line we omitted, or zero if we
// didn't omit the previous line. It is zero before we have received any
// AddLine calls.
uint64 omitted_line_end_;
// True if we've warned about:
bool warned_bad_file_number_; // bad file numbers
bool warned_bad_directory_number_; // bad directory numbers
};
} // namespace google_breakpad
#endif // COMMON_LINUX_DWARF_LINE_TO_MODULE_H
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