// dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*-

// dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*-

// Copyright (C) 2007-2024 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <[email protected]>.

// 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 <limits.h>
#include <sys/types.h>

#include "elfcpp.h"
#include "elfcpp_swap.h"
#include "dwarf.h"
#include "reloc.h"

namespace gold
{

class Dwarf_info_reader;
struct LineStateMachine;

// This class is used to extract the section index and offset of
// the target of a relocation for a given offset within the section.

class Elf_reloc_mapper
{
public:
Elf_reloc_mapper()
{ }

virtual
~Elf_reloc_mapper()
{ }

// Initialize the relocation tracker for section RELOC_SHNDX.
bool
initialize(unsigned int reloc_shndx, unsigned int reloc_type)
{ return this->do_initialize(reloc_shndx, reloc_type); }

// Return the next reloc_offset.
off_t
next_offset()
{ return this->do_next_offset(); }

// Advance to the next relocation past OFFSET.
void
advance(off_t offset)
{ this->do_advance(offset); }

// Return the section index and offset within the section of the target
// of the relocation for RELOC_OFFSET in the referring section.
unsigned int
get_reloc_target(off_t reloc_offset, off_t* target_offset)
{ return this->do_get_reloc_target(reloc_offset, target_offset); }

// Checkpoint the current position in the reloc section.
uint64_t
checkpoint() const
{ return this->do_checkpoint(); }

// Reset the current position to the CHECKPOINT.
void
reset(uint64_t checkpoint)
{ this->do_reset(checkpoint); }

protected:
virtual bool
do_initialize(unsigned int, unsigned int) = 0;

// Return the next reloc_offset.
virtual off_t
do_next_offset() = 0;

// Advance to the next relocation past OFFSET.
virtual void
do_advance(off_t offset) = 0;

virtual unsigned int
do_get_reloc_target(off_t reloc_offset, off_t* target_offset) = 0;

// Checkpoint the current position in the reloc section.
virtual uint64_t
do_checkpoint() const = 0;

// Reset the current position to the CHECKPOINT.
virtual void
do_reset(uint64_t checkpoint) = 0;
};

template<int size, bool big_endian>
class Sized_elf_reloc_mapper : public Elf_reloc_mapper
{
public:
Sized_elf_reloc_mapper(Object* object, const unsigned char* symtab,
off_t symtab_size)
: object_(object), symtab_(symtab), symtab_size_(symtab_size),
reloc_type_(0), track_relocs_()
{ }

protected:
bool
do_initialize(unsigned int reloc_shndx, unsigned int reloc_type);

// Return the next reloc_offset.
virtual off_t
do_next_offset()
{ return this->track_relocs_.next_offset(); }

// Advance to the next relocation past OFFSET.
virtual void
do_advance(off_t offset)
{ this->track_relocs_.advance(offset); }

unsigned int
do_get_reloc_target(off_t reloc_offset, off_t* target_offset);

// Checkpoint the current position in the reloc section.
uint64_t
do_checkpoint() const
{ return this->track_relocs_.checkpoint(); }

// Reset the current position to the CHECKPOINT.
void
do_reset(uint64_t checkpoint)
{ this->track_relocs_.reset(checkpoint); }

private:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;

// Return the section index of symbol SYMNDX, and copy its value to *VALUE.
// Set *IS_ORDINARY true if the section index is an ordinary section index.
unsigned int
symbol_section(unsigned int symndx, Address* value, bool* is_ordinary);

// The object file.
Object* object_;
// The ELF symbol table.
const unsigned char* symtab_;
// The size of the ELF symbol table.
off_t symtab_size_;
// Type of the relocation section (SHT_REL or SHT_RELA).
unsigned int reloc_type_;
// Relocations for the referring section.
Track_relocs<size, big_endian> track_relocs_;
};

// This class is used to read the abbreviations table from the
// .debug_abbrev section of the object file.

class Dwarf_abbrev_table
{
public:
// An attribute list entry.
struct Attribute
{
Attribute(unsigned int a, unsigned int f, int c)
: attr(a), form(f), implicit_const(c)
{ }
unsigned int attr;
unsigned int form;
int implicit_const;
};

// An abbrev code entry.
struct Abbrev_code
{
Abbrev_code(unsigned int t, bool hc)
: tag(t), has_children(hc), has_sibling_attribute(false), attributes()
{
this->attributes.reserve(10);
}

void
add_attribute(unsigned int attr, unsigned int form, int implicit_const)
{
this->attributes.push_back(Attribute(attr, form, implicit_const));
}

// The DWARF tag.
unsigned int tag;
// True if the DIE has children.
bool has_children : 1;
// True if the DIE has a sibling attribute.
bool has_sibling_attribute : 1;
// The list of attributes and forms.
std::vector<Attribute> attributes;
};

Dwarf_abbrev_table()
: abbrev_shndx_(0), abbrev_offset_(0), buffer_(NULL), buffer_end_(NULL),
owns_buffer_(false), buffer_pos_(NULL), high_abbrev_codes_()
{
memset(this->low_abbrev_codes_, 0, sizeof(this->low_abbrev_codes_));
}

~Dwarf_abbrev_table()
{
if (this->owns_buffer_ && this->buffer_ != NULL)
delete[] this->buffer_;
this->clear_abbrev_codes();
}

// Read the abbrev table from an object file.
bool
read_abbrevs(Relobj* object,
unsigned int abbrev_shndx,
off_t abbrev_offset)
{
// If we've already read this abbrev table, return immediately.
if (this->abbrev_shndx_ > 0
&& this->abbrev_shndx_ == abbrev_shndx
&& this->abbrev_offset_ == abbrev_offset)
return true;
return this->do_read_abbrevs(object, abbrev_shndx, abbrev_offset);
}

// Return the abbrev code entry for CODE. This is a fast path for
// abbrev codes that are in the direct lookup table. If not found
// there, we call do_get_abbrev() to do the hard work.
const Abbrev_code*
get_abbrev(unsigned int code)
{
if (code < this->low_abbrev_code_max_
&& this->low_abbrev_codes_[code] != NULL)
return this->low_abbrev_codes_[code];
return this->do_get_abbrev(code);
}

private:
// Read the abbrev table from an object file.
bool
do_read_abbrevs(Relobj* object,
unsigned int abbrev_shndx,
off_t abbrev_offset);

// Lookup the abbrev code entry for CODE.
const Abbrev_code*
do_get_abbrev(unsigned int code);

// Store an abbrev code entry for CODE.
void
store_abbrev(unsigned int code, const Abbrev_code* entry)
{
if (code < this->low_abbrev_code_max_)
this->low_abbrev_codes_[code] = entry;
else
this->high_abbrev_codes_[code] = entry;
}

// Clear the abbrev code table and release the memory it uses.
void
clear_abbrev_codes();

typedef Unordered_map<unsigned int, const Abbrev_code*> Abbrev_code_table;

// The section index of the current abbrev table.
unsigned int abbrev_shndx_;
// The offset within the section of the current abbrev table.
off_t abbrev_offset_;
// The buffer containing the .debug_abbrev section.
const unsigned char* buffer_;
const unsigned char* buffer_end_;
// True if this object owns the buffer and needs to delete it.
bool owns_buffer_;
// Pointer to the current position in the buffer.
const unsigned char* buffer_pos_;
// The table of abbrev codes.
// We use a direct-lookup array for low abbrev codes,
// and store the rest in a hash table.
static const unsigned int low_abbrev_code_max_ = 256;
const Abbrev_code* low_abbrev_codes_[low_abbrev_code_max_];
Abbrev_code_table high_abbrev_codes_;
};

// A DWARF range list. The start and end offsets are relative
// to the input section SHNDX. Each range must lie entirely
// within a single section.

class Dwarf_range_list
{
public:
struct Range
{
Range(unsigned int a_shndx, off_t a_start, off_t a_end)
: shndx(a_shndx), start(a_start), end(a_end)
{ }

unsigned int shndx;
off_t start;
off_t end;
};

Dwarf_range_list()
: range_list_()
{ }

void
add(unsigned int shndx, off_t start, off_t end)
{ this->range_list_.push_back(Range(shndx, start, end)); }

size_t
size() const
{ return this->range_list_.size(); }

const Range&
operator[](off_t i) const
{ return this->range_list_[i]; }

private:
std::vector<Range> range_list_;
};

// This class is used to read the ranges table from the
// .debug_ranges section of the object file.

class Dwarf_ranges_table
{
public:
Dwarf_ranges_table(Dwarf_info_reader* dwinfo)
: dwinfo_(dwinfo), ranges_shndx_(0), ranges_buffer_(NULL),
ranges_buffer_end_(NULL), owns_ranges_buffer_(false),
ranges_reloc_mapper_(NULL), reloc_type_(0), output_section_offset_(0)
{ }

~Dwarf_ranges_table()
{
if (this->owns_ranges_buffer_ && this->ranges_buffer_ != NULL)
delete[] this->ranges_buffer_;
if (this->ranges_reloc_mapper_ != NULL)
delete this->ranges_reloc_mapper_;
}

// Fetch the contents of the ranges table from an object file.
bool
read_ranges_table(Relobj* object,
const unsigned char* symtab,
off_t symtab_size,
unsigned int ranges_shndx,
unsigned int version);

// Read the DWARF 2/3/4 range table.
Dwarf_range_list*
read_range_list(Relobj* object,
const unsigned char* symtab,
off_t symtab_size,
unsigned int address_size,
unsigned int ranges_shndx,
off_t ranges_offset);

// Read the DWARF 5 rnglists table.
Dwarf_range_list*
read_range_list_v5(Relobj* object,
const unsigned char* symtab,
off_t symtab_size,
unsigned int address_size,
unsigned int ranges_shndx,
off_t ranges_offset);

// Look for a relocation at offset OFF in the range table,
// and return the section index and offset of the target.
unsigned int
lookup_reloc(off_t off, off_t* target_off);

private:
// The Dwarf_info_reader, for reading data.
Dwarf_info_reader* dwinfo_;
// The section index of the ranges table.
unsigned int ranges_shndx_;
// The buffer containing the .debug_ranges section.
const unsigned char* ranges_buffer_;
const unsigned char* ranges_buffer_end_;
// True if this object owns the buffer and needs to delete it.
bool owns_ranges_buffer_;
// Relocation mapper for the .debug_ranges section.
Elf_reloc_mapper* ranges_reloc_mapper_;
// Type of the relocation section (SHT_REL or SHT_RELA).
unsigned int reloc_type_;
// For incremental update links, this will hold the offset of the
// input section within the output section. Offsets read from
// relocated data will be relative to the output section, and need
// to be corrected before reading data from the input section.
uint64_t output_section_offset_;
};

// This class is used to read the pubnames and pubtypes tables from the
// .debug_pubnames and .debug_pubtypes sections of the object file.

class Dwarf_pubnames_table
{
public:
Dwarf_pubnames_table(Dwarf_info_reader* dwinfo, bool is_pubtypes)
: dwinfo_(dwinfo), buffer_(NULL), buffer_end_(NULL), owns_buffer_(false),
offset_size_(0), pinfo_(NULL), end_of_table_(NULL),
is_pubtypes_(is_pubtypes), is_gnu_style_(false),
unit_length_(0), cu_offset_(0)
{ }

~Dwarf_pubnames_table()
{
if (this->owns_buffer_ && this->buffer_ != NULL)
delete[] this->buffer_;
}

// Read the pubnames section from the object file, using the symbol
// table for relocating it.
bool
read_section(Relobj* object, const unsigned char* symbol_table,
off_t symtab_size);

// Read the header for the set at OFFSET.
bool
read_header(off_t offset);

// Return the offset to the cu within the info or types section.
off_t
cu_offset()
{ return this->cu_offset_; }

// Return the size of this subsection of the table. The unit length
// doesn't include the size of its own field.
off_t
subsection_size()
{ return this->unit_length_; }

// Read the next name from the set. If the pubname table is gnu-style,
// FLAG_BYTE is set to the high-byte of a gdb_index version 7 cu_index.
const char*
next_name(uint8_t* flag_byte);

private:
// The Dwarf_info_reader, for reading data.
Dwarf_info_reader* dwinfo_;
// The buffer containing the .debug_ranges section.
const unsigned char* buffer_;
const unsigned char* buffer_end_;
// True if this object owns the buffer and needs to delete it.
bool owns_buffer_;
// The size of a DWARF offset for the current set.
unsigned int offset_size_;
// The current position within the buffer.
const unsigned char* pinfo_;
// The end of the current pubnames table.
const unsigned char* end_of_table_;
// TRUE if this is a .debug_pubtypes section.
bool is_pubtypes_;
// Gnu-style pubnames table. This style has an extra flag byte between the
// offset and the name, and is used for generating version 7 of gdb-index.
bool is_gnu_style_;
// Fields read from the header.
uint64_t unit_length_;
off_t cu_offset_;

// Track relocations for this table so we can find the CUs that
// correspond to the subsections.
Elf_reloc_mapper* reloc_mapper_;
// Type of the relocation section (SHT_REL or SHT_RELA).
unsigned int reloc_type_;
};

// This class represents a DWARF Debug Info Entry (DIE).

class Dwarf_die
{
public:
// An attribute value.
struct Attribute_value
{
unsigned int attr;
unsigned int form;
union
{
int64_t intval;
uint64_t uintval;
const char* stringval;
const unsigned char* blockval;
off_t refval;
} val;
union
{
// Section index for reference forms.
unsigned int shndx;
// Block length for block forms.
unsigned int blocklen;
} aux;
};

// A list of attribute values.
typedef std::vector<Attribute_value> Attributes;

Dwarf_die(Dwarf_info_reader* dwinfo,
off_t die_offset,
Dwarf_die* parent);

// Return the DWARF tag for this DIE.
unsigned int
tag() const
{
if (this->abbrev_code_ == NULL)
return 0;
return this->abbrev_code_->tag;
}

// Return true if this DIE has children.
bool
has_children() const
{
gold_assert(this->abbrev_code_ != NULL);
return this->abbrev_code_->has_children;
}

// Return true if this DIE has a sibling attribute.
bool
has_sibling_attribute() const
{
gold_assert(this->abbrev_code_ != NULL);
return this->abbrev_code_->has_sibling_attribute;
}

// Return the value of attribute ATTR.
const Attribute_value*
attribute(unsigned int attr);

// Return the value of the DW_AT_name attribute.
const char*
name()
{
if (this->name_ == NULL)
this->set_name();
return this->name_;
}

// Return the value of the DW_AT_linkage_name
// or DW_AT_MIPS_linkage_name attribute.
const char*
linkage_name()
{
if (this->linkage_name_ == NULL)
this->set_linkage_name();
return this->linkage_name_;
}

// Return the value of the DW_AT_specification attribute.
off_t
specification()
{
if (!this->attributes_read_)
this->read_attributes();
return this->specification_;
}

// Return the value of the DW_AT_abstract_origin attribute.
off_t
abstract_origin()
{
if (!this->attributes_read_)
this->read_attributes();
return this->abstract_origin_;
}

// Return the value of attribute ATTR as a string.
const char*
string_attribute(unsigned int attr);

// Return the value of attribute ATTR as an integer.
int64_t
int_attribute(unsigned int attr);

// Return the value of attribute ATTR as an unsigned integer.
uint64_t
uint_attribute(unsigned int attr);

// Return the value of attribute ATTR as a reference.
off_t
ref_attribute(unsigned int attr, unsigned int* shndx);

// Return the value of attribute ATTR as a address.
off_t
address_attribute(unsigned int attr, unsigned int* shndx);

// Return the value of attribute ATTR as a flag.
bool
flag_attribute(unsigned int attr)
{ return this->int_attribute(attr) != 0; }

// Return true if this DIE is a declaration.
bool
is_declaration()
{ return this->flag_attribute(elfcpp::DW_AT_declaration); }

// Return the parent of this DIE.
Dwarf_die*
parent() const
{ return this->parent_; }

// Return the offset of this DIE.
off_t
offset() const
{ return this->die_offset_; }

// Return the offset of this DIE's first child.
off_t
child_offset();

// Set the offset of this DIE's next sibling.
void
set_sibling_offset(off_t sibling_offset)
{ this->sibling_offset_ = sibling_offset; }

// Return the offset of this DIE's next sibling.
off_t
sibling_offset();

private:
typedef Dwarf_abbrev_table::Abbrev_code Abbrev_code;

// Read all the attributes of the DIE.
bool
read_attributes();

// Set the name of the DIE if present.
void
set_name();

// Set the linkage name if present.
void
set_linkage_name();

// Skip all the attributes of the DIE and return the offset
// of the next DIE.
off_t
skip_attributes();

// The Dwarf_info_reader, for reading attributes.
Dwarf_info_reader* dwinfo_;
// The parent of this DIE.
Dwarf_die* parent_;
// Offset of this DIE within its compilation unit.
off_t die_offset_;
// Offset of the first attribute, relative to the beginning of the DIE.
off_t attr_offset_;
// Offset of the first child, relative to the compilation unit.
off_t child_offset_;
// Offset of the next sibling, relative to the compilation unit.
off_t sibling_offset_;
// The abbreviation table entry.
const Abbrev_code* abbrev_code_;
// The list of attributes.
Attributes attributes_;
// True if the attributes have been read.
bool attributes_read_;
// The following fields hold common attributes to avoid a linear
// search through the attribute list.
// The DIE name (DW_AT_name).
const char* name_;
// Offset of the name in the string table (for DW_FORM_strp).
off_t name_off_;
// The linkage name (DW_AT_linkage_name or DW_AT_MIPS_linkage_name).
const char* linkage_name_;
// Offset of the linkage name in the string table (for DW_FORM_strp).
off_t linkage_name_off_;
// Section index of the string table (for DW_FORM_strp).
unsigned int string_shndx_;
// The value of a DW_AT_specification attribute.
off_t specification_;
// The value of a DW_AT_abstract_origin attribute.
off_t abstract_origin_;
};

// This class is used to read the debug info from the .debug_info
// or .debug_types sections. This is a base class that implements
// the generic parsing of the compilation unit header and DIE
// structure. The parse() method parses the entire section, and
// calls the various visit_xxx() methods for each header. Clients
// should derive a new class from this one and implement the
// visit_compilation_unit() and visit_type_unit() functions.
// IS_TYPE_UNIT is true if we are reading from a .debug_types section,
// which is used only in DWARF 4. For DWARF 5, it will be false,
// and we will determine whether it's a type init when we parse the
// header.

class Dwarf_info_reader
{
public:
Dwarf_info_reader(bool is_type_unit,
Relobj* object,
const unsigned char* symtab,
off_t symtab_size,
unsigned int shndx,
unsigned int reloc_shndx,
unsigned int reloc_type)
: object_(object), symtab_(symtab),
symtab_size_(symtab_size), shndx_(shndx), reloc_shndx_(reloc_shndx),
reloc_type_(reloc_type), abbrev_shndx_(0), string_shndx_(0),
buffer_(NULL), buffer_end_(NULL), cu_offset_(0), cu_length_(0),
offset_size_(0), address_size_(0), cu_version_(0),
abbrev_table_(), ranges_table_(this),
reloc_mapper_(NULL), string_buffer_(NULL), string_buffer_end_(NULL),
owns_string_buffer_(false), string_output_section_offset_(0)
{
// For DWARF 4, we infer the unit type from the section name.
// For DWARF 5, we will read this from the unit header.
this->unit_type_ =
(is_type_unit ? elfcpp::DW_UT_type : elfcpp::DW_UT_compile);
}

virtual
~Dwarf_info_reader()
{
if (this->reloc_mapper_ != NULL)
delete this->reloc_mapper_;
if (this->owns_string_buffer_ && this->string_buffer_ != NULL)
delete[] this->string_buffer_;
}

bool
is_type_unit() const
{
return (this->unit_type_ == elfcpp::DW_UT_type
|| this->unit_type_ == elfcpp::DW_UT_split_type);
}

// Begin parsing the debug info. This calls visit_compilation_unit()
// or visit_type_unit() for each compilation or type unit found in the
// section, and visit_die() for each top-level DIE.
void
parse();

// Return the abbrev code entry for a CODE.
const Dwarf_abbrev_table::Abbrev_code*
get_abbrev(unsigned int code)
{ return this->abbrev_table_.get_abbrev(code); }

// Return a pointer to the DWARF info buffer at OFFSET.
const unsigned char*
buffer_at_offset(off_t offset) const
{
const unsigned char* p = this->buffer_ + this->cu_offset_ + offset;
if (this->check_buffer(p + 1))
return p;
return NULL;
}

// Read a possibly unaligned integer of SIZE.
template <int valsize>
inline typename elfcpp::Valtype_base<valsize>::Valtype
read_from_pointer(const unsigned char* source);

// Read a possibly unaligned integer of SIZE. Update SOURCE after read.
template <int valsize>
inline typename elfcpp::Valtype_base<valsize>::Valtype
read_from_pointer(const unsigned char** source);

inline typename elfcpp::Valtype_base<32>::Valtype
read_3bytes_from_pointer(const unsigned char** source);

// Look for a relocation at offset ATTR_OFF in the dwarf info,
// and return the section index and offset of the target.
unsigned int
lookup_reloc(off_t attr_off, off_t* target_off);

// Return a string from the DWARF string table.
const char*
get_string(off_t str_off, unsigned int string_shndx);

// Return the size of a DWARF offset.
unsigned int
offset_size() const
{ return this->offset_size_; }

// Return the size of an address.
unsigned int
address_size() const
{ return this->address_size_; }

// Return the size of a DW_FORM_ref_addr.
// In DWARF v2, this was the size of an address; in DWARF v3 and later,
// it is the size of an DWARF offset.
unsigned int
ref_addr_size() const
{ return this->cu_version_ > 2 ? this->offset_size_ : this->address_size_; }

// Set the section index of the .debug_abbrev section.
// We use this if there are no relocations for the .debug_info section.
// If not set, the code parse() routine will search for the section by name.
void
set_abbrev_shndx(unsigned int abbrev_shndx)
{ this->abbrev_shndx_ = abbrev_shndx; }

// Return a pointer to the object file's ELF symbol table.
const unsigned char*
symtab() const
{ return this->symtab_; }

// Return the size of the object file's ELF symbol table.
off_t
symtab_size() const
{ return this->symtab_size_; }

// Return the offset of the current compilation unit.
off_t
cu_offset() const
{ return this->cu_offset_; }

protected:
// Begin parsing the debug info. This calls visit_compilation_unit()
// or visit_type_unit() for each compilation or type unit found in the
// section, and visit_die() for each top-level DIE.
template<bool big_endian>
void
do_parse();

// The following methods are hooks that are meant to be implemented
// by a derived class. A default, do-nothing, implementation of
// each is provided for this base class.

// Visit a compilation unit.
virtual void
visit_compilation_unit(off_t cu_offset, off_t cu_length, Dwarf_die* root_die);

// Visit a type unit.
virtual void
visit_type_unit(off_t tu_offset, off_t tu_length, off_t type_offset,
uint64_t signature, Dwarf_die* root_die);

// Read the range table.
Dwarf_range_list*
read_range_list(unsigned int ranges_shndx, off_t ranges_offset)
{
if (this->cu_version_ < 5)
return this->ranges_table_.read_range_list(this->object_,
this->symtab_,
this->symtab_size_,
this->address_size_,
ranges_shndx,
ranges_offset);
else
return this->ranges_table_.read_range_list_v5(this->object_,
this->symtab_,
this->symtab_size_,
this->address_size_,
ranges_shndx,
ranges_offset);
}

// Return the object.
Relobj*
object() const
{ return this->object_; }

// Checkpoint the relocation tracker.
uint64_t
get_reloc_checkpoint() const
{ return this->reloc_mapper_->checkpoint(); }

// Reset the relocation tracker to the CHECKPOINT.
void
reset_relocs(uint64_t checkpoint)
{ this->reloc_mapper_->reset(checkpoint); }

private:
// Print a warning about a corrupt debug section.
void
warn_corrupt_debug_section() const;

// Check that P is within the bounds of the current section.
bool
check_buffer(const unsigned char* p) const
{
if (p > this->buffer_ + this->cu_offset_ + this->cu_length_)
{
this->warn_corrupt_debug_section();
return false;
}
return true;
}

// Read the DWARF string table.
bool
read_string_table(unsigned int string_shndx)
{
// If we've already read this string table, return immediately.
if (this->string_shndx_ > 0 && this->string_shndx_ == string_shndx)
return true;
if (string_shndx == 0 && this->string_shndx_ > 0)
return true;
return this->do_read_string_table(string_shndx);
}

bool
do_read_string_table(unsigned int string_shndx);

// The unit type (DW_UT_xxx).
unsigned int unit_type_;
// The object containing the .debug_info or .debug_types input section.
Relobj* object_;
// The ELF symbol table.
const unsigned char* symtab_;
// The size of the ELF symbol table.
off_t symtab_size_;
// Index of the .debug_info or .debug_types section.
unsigned int shndx_;
// Index of the relocation section.
unsigned int reloc_shndx_;
// Type of the relocation section (SHT_REL or SHT_RELA).
unsigned int reloc_type_;
// Index of the .debug_abbrev section (0 if not known).
unsigned int abbrev_shndx_;
// Index of the .debug_str section.
unsigned int string_shndx_;
// The buffer for the debug info.
const unsigned char* buffer_;
const unsigned char* buffer_end_;
// Offset of the current compilation unit.
off_t cu_offset_;
// Length of the current compilation unit.
off_t cu_length_;
// Size of a DWARF offset for the current compilation unit.
unsigned int offset_size_;
// Size of an address for the target architecture.
unsigned int address_size_;
// Compilation unit version number.
unsigned int cu_version_;
// Abbreviations table for current compilation unit.
Dwarf_abbrev_table abbrev_table_;
// Ranges table for the current compilation unit.
Dwarf_ranges_table ranges_table_;
// Relocation mapper for the section.
Elf_reloc_mapper* reloc_mapper_;
// The buffer for the debug string table.
const char* string_buffer_;
const char* string_buffer_end_;
// True if this object owns the buffer and needs to delete it.
bool owns_string_buffer_;
// For incremental update links, this will hold the offset of the
// input .debug_str section within the output section. Offsets read
// from relocated data will be relative to the output section, and need
// to be corrected before reading data from the input section.
uint64_t string_output_section_offset_;
};

// 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)
// A pointer into files_.
unsigned int file_num : sizeof(int) * CHAR_BIT - 1;
// True if this was the last entry for the current offset, meaning
// it's the line that actually applies.
unsigned int last_line_for_offset : 1;
// The line number in the source file. -1 to indicate end-of-function.
int line_num;

// This sorts by offsets first, and then puts the correct line to
// report for a given offset at the beginning of the run of equal
// offsets (so that asking for 1 line gives the best answer). This
// is not a total ordering.
bool operator<(const Offset_to_lineno_entry& that) const
{
if (this->offset != that.offset)
return this->offset < that.offset;
// Note the '>' which makes this sort 'true' first.
return this->last_line_for_offset > that.last_line_for_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. If
// 'other_lines' is non-NULL, fills that in with other line
// numbers assigned to the same offset.
std::string
addr2line(unsigned int shndx, off_t offset,
std::vector<std::string>* other_lines)
{ return this->do_addr2line(shndx, offset, other_lines); }

// A helper function for a single addr2line lookup. It also keeps a
// cache of the last CACHE_SIZE Dwarf_line_info objects it created;
// set to 0 not to cache at all. The larger CACHE_SIZE is, the more
// chance this routine won't have to re-create a Dwarf_line_info
// object for its addr2line computation; such creations are slow.
// NOTE: Not thread-safe, so only call from one thread at a time.
static std::string
one_addr2line(Object* object, unsigned int shndx, off_t offset,
size_t cache_size, std::vector<std::string>* other_lines);

// This reclaims all the memory that one_addr2line may have cached.
// Use this when you know you will not be calling one_addr2line again.
static void
clear_addr2line_cache();

private:
virtual std::string
do_addr2line(unsigned int shndx, off_t offset,
std::vector<std::string>* other_lines) = 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, unsigned int read_shndx = -1U);

virtual
~Sized_dwarf_line_info()
{
if (this->buffer_start_ != NULL)
delete[] this->buffer_start_;
if (this->str_buffer_start_ != NULL)
delete[] this->str_buffer_start_;
}

private:
std::string
do_addr2line(unsigned int shndx, off_t offset,
std::vector<std::string>* other_lines);

// Formats a file and line number to a string like "dirname/filename:lineno".
std::string
format_file_lineno(const Offset_to_lineno_entry& lineno) const;

// 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(unsigned int shndx);

// Reads the relocation section associated with .debug_line and
// stores relocation information in reloc_map_.
void
read_relocs();

// Reads the DWARF 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_v2(const unsigned char* lineptr);

const unsigned char*
read_header_tables_v5(const unsigned char* lineptr);

// Reads the DWARF 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, const unsigned char* endptr,
unsigned int 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;
int address_size;
off_t prologue_length;
int min_insn_length; // insn stands for instruction
int max_ops_per_insn; // Added in DWARF-4.
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_;
// If the buffer was allocated temporarily, and therefore must be
// deallocated in the dtor, this contains a pointer to the start
// of the buffer.
const unsigned char* buffer_start_;

// str_buffer is the buffer for the line table strings.
const unsigned char* str_buffer_;
const unsigned char* str_buffer_end_;
// If the buffer was allocated temporarily, and therefore must be
// deallocated in the dtor, this contains a pointer to the start
// of the buffer.
const unsigned char* str_buffer_start_;

// Pointer to the end of the header_length field (aka prologue_length).
const unsigned char* end_of_header_length_;

// Pointer to the end of the current compilation unit.
const unsigned char* end_of_unit_;

// This has relocations that point into buffer.
Sized_elf_reloc_mapper<size, big_endian>* reloc_mapper_;
// The type of the reloc section in track_relocs_--SHT_REL or SHT_RELA.
unsigned int track_relocs_type_;

// 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<off_t, std::pair<unsigned int, off_t> >
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)