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// dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*-
// Copyright 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#ifndef GOLD_DWARF_READER_H
#define GOLD_DWARF_READER_H
#include <vector>
#include "elfcpp_swap.h"
#include "dwarf.h"
namespace gold
{
struct LineStateMachine;
// This class is used to read the line information from the debugging
// section of an object file.
class Dwarf_line_info
{
public:
// Initializes a .debug_line reader. Buffer and buffer length point
// to the beginning and length of the line information to read.
// Reader is a ByteReader class that has the endianness set
// properly.
Dwarf_line_info(const unsigned char* buffer, off_t buffer_length)
: buffer_(buffer), buffer_end_(buffer + buffer_length),
directories_(1), files_(1)
{ }
// Start processing line info, and populates the offset_map_.
template<int size, bool big_endian>
void
read_line_mappings()
{
while (buffer_ < buffer_end_)
{
const unsigned char* lineptr = buffer_;
lineptr = this->read_header_prolog<size, big_endian>(lineptr);
lineptr = this->read_header_tables(lineptr);
lineptr = this->read_lines(size, big_endian, lineptr);
buffer_ = lineptr;
}
finalize_line_number_map();
}
// Given a section number and an offset, returns the associated
// file and line-number, as a string: "file:lineno". If unable
// to do the mapping, returns the empty string. You must call
// read_line_mappings() before calling this function.
std::string
addr2line(unsigned int shndx, off_t offset);
private:
// Reads the DWARF2/3 header for this line info. Each takes as input
// a starting buffer position, and returns the ending position.
template<int size, bool big_endian>
const unsigned char*
read_header_prolog(const unsigned char* lineptr);
const unsigned char*
read_header_tables(const unsigned char* lineptr);
// Reads the DWARF2/3 line information.
const unsigned char*
read_lines(int size, bool big_endian, const unsigned char* lineptr);
// Process a single line info opcode at START using the state
// machine at LSM. Return true if we should define a line using the
// current state of the line state machine. Place the length of the
// opcode in LEN.
bool
process_one_opcode(int size, bool big_endian,
const unsigned char* start,
struct LineStateMachine* lsm, size_t* len);
// Called after all line number have been read, to ready
// line_number_map_ for calls to addr2line().
void
finalize_line_number_map();
// A DWARF2/3 line info header. This is not the same size as in the
// actual file, as the one in the file may have a 32 bit or 64 bit
// lengths.
struct Dwarf_line_infoHeader
{
off_t total_length;
int version;
off_t prologue_length;
int min_insn_length; // insn stands for instructin
bool default_is_stmt; // stmt stands for statement
signed char line_base;
int line_range;
unsigned char opcode_base;
std::vector<unsigned char> std_opcode_lengths;
int offset_size;
} header_;
// buffer is the buffer for our line info, starting at exactly where
// the line info to read is.
const unsigned char* buffer_;
const unsigned char* const buffer_end_;
// Holds the directories and files as we see them.
std::vector<std::string> directories_;
// The first part is an index into directories_, the second the filename.
std::vector< std::pair<int, std::string> > files_;
// We can't do better than to keep the offsets in a sorted vector.
// Here, offset is the key, and file_num/line_num is the value.
struct Offset_to_lineno_entry
{
off_t offset;
int file_num; // a pointer into files_
int line_num;
// Offsets are unique within a section, so that's a sufficient sort key.
bool operator<(const Offset_to_lineno_entry& that) const
{ return this->offset < that.offset; }
};
// We have a vector of offset->lineno entries for every input section.
typedef Unordered_map<unsigned int, std::vector<Offset_to_lineno_entry> >
Lineno_map;
Lineno_map line_number_map_;
};
} // End namespace gold.
#endif // !defined(GOLD_DWARF_READER_H)
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