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// dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*-
// Copyright 2007, 2008 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 <map>
#include "elfcpp.h"
#include "elfcpp_swap.h"
#include "dwarf.h"
#include "reloc.h"
namespace gold
{
template<int size, bool big_endian>
class Track_relocs;
struct LineStateMachine;
// 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 header_num; // which file-list to use (i.e. which .o file are we in)
int file_num; // a pointer into files_
int line_num; // the line number in the source file
// 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; }
};
// This class is used to read the line information from the debugging
// section of an object file.
class Dwarf_line_info
{
public:
Dwarf_line_info()
{ }
virtual
~Dwarf_line_info()
{ }
// 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)
{ return do_addr2line(shndx, offset); }
// A helper function for a single addr2line lookup. It uses
// parameters() to figure out the size and endianness. This is less
// efficient than using the templatized size and endianness, so only
// call this from an un-templatized context.
static std::string
one_addr2line(Object* object, unsigned int shndx, off_t offset);
private:
virtual std::string
do_addr2line(unsigned int shndx, off_t offset) = 0;
};
template<int size, bool big_endian>
class Sized_dwarf_line_info : public Dwarf_line_info
{
public:
// Initializes a .debug_line reader for a given object file.
// If SHNDX is specified and non-negative, only read the debug
// information that pertains to the specified section.
Sized_dwarf_line_info(Object* object, off_t read_shndx = -1U);
private:
std::string
do_addr2line(unsigned int shndx, off_t offset);
// Start processing line info, and populates the offset_map_.
// If SHNDX is non-negative, only store debug information that
// pertains to the specified section.
void
read_line_mappings(Object*, off_t shndx);
// Reads the relocation section associated with .debug_line and
// stores relocation information in reloc_map_.
void
read_relocs(Object*);
// Looks in the symtab to see what section a symbol is in.
unsigned int
symbol_section(Object*, unsigned int sym,
typename elfcpp::Elf_types<size>::Elf_Addr* value,
bool* is_ordinary);
// Reads the DWARF2/3 header for this line info. Each takes as input
// a starting buffer position, and returns the ending position.
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. If shndx is non-negative,
// discard all line information that doesn't pertain to the given
// section.
const unsigned char*
read_lines(const unsigned char* lineptr, off_t shndx);
// 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(const unsigned char* start,
struct LineStateMachine* lsm, size_t* len);
// Some parts of processing differ depending on whether the input
// was a .o file or not.
bool input_is_relobj();
// If we saw anything amiss while parsing, we set this to false.
// Then addr2line will always fail (rather than return possibly-
// corrupt data).
bool data_valid_;
// 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* buffer_end_;
// This has relocations that point into buffer.
Track_relocs<size, big_endian> track_relocs_;
// This is used to figure out what section to apply a relocation to.
const unsigned char* symtab_buffer_;
section_size_type symtab_buffer_size_;
// Holds the directories and files as we see them. We have an array
// of directory-lists, one for each .o file we're reading (usually
// there will just be one, but there may be more if input is a .so).
std::vector<std::vector<std::string> > directories_;
// The first part is an index into directories_, the second the filename.
std::vector<std::vector< std::pair<int, std::string> > > files_;
// An index into the current directories_ and files_ vectors.
int current_header_index_;
// A sorted map from offset of the relocation target to the shndx
// and addend for the relocation.
typedef std::map<typename elfcpp::Elf_types<size>::Elf_Addr,
std::pair<unsigned int,
typename elfcpp::Elf_types<size>::Elf_Swxword> >
Reloc_map;
Reloc_map reloc_map_;
// 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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