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// script.h -- handle linker scripts for gold -*- C++ -*-
// Copyright 2006, 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.
// We implement a subset of the original GNU ld linker script language
// for compatibility. The goal is not to implement the entire
// language. It is merely to implement enough to handle common uses.
// In particular we need to handle /usr/lib/libc.so on a typical
// GNU/Linux system, and we want to handle linker scripts used by the
// Linux kernel build.
#ifndef GOLD_SCRIPT_H
#define GOLD_SCRIPT_H
#include <vector>
namespace gold
{
class General_options;
class Command_line;
class Symbol_table;
class Layout;
class Input_argument;
class Input_objects;
class Input_group;
class Input_file;
class Target;
class Task_token;
class Workqueue;
// This class represents an expression in a linker script.
class Expression
{
protected:
// These should only be created by child classes.
Expression()
{ }
public:
virtual ~Expression()
{ }
// Return the value of the expression.
uint64_t
eval(const Symbol_table*, const Layout*);
protected:
struct Expression_eval_info;
public:
// Compute the value of the expression (implemented by child class).
// This is public rather than protected because it is called
// directly by children of Expression on other Expression objects.
virtual uint64_t
value(const Expression_eval_info*) = 0;
private:
// May not be copied.
Expression(const Expression&);
Expression& operator=(const Expression&);
};
// We can read a linker script in two different contexts: when
// initially parsing the command line, and when we find an input file
// which is actually a linker script. Also some of the data which can
// be set by a linker script can also be set via command line options
// like -e and --defsym. This means that we have a type of data which
// can be set both during command line option parsing and while
// reading input files. We store that data in an instance of this
// object. We will keep pointers to that instance in both the
// Command_line and Layout objects.
class Script_options
{
public:
Script_options();
// The entry address.
const char*
entry() const
{ return this->entry_.empty() ? NULL : this->entry_.c_str(); }
// Set the entry address.
void
set_entry(const char* entry, size_t length)
{ this->entry_.assign(entry, length); }
// Add a symbol to be defined. These are for symbol definitions
// which appear outside of a SECTIONS clause.
void
add_symbol_assignment(const char* name, size_t length, Expression* value,
bool provided, bool hidden)
{
this->symbol_assignments_.push_back(Symbol_assignment(name, length, value,
provided, hidden));
}
// Define a symbol from the command line.
bool
define_symbol(const char* definition);
// Add all symbol definitions to the symbol table.
void
add_symbols_to_table(Symbol_table*, const Target*);
// Finalize the symbol values.
void
finalize_symbols(Symbol_table*, const Layout*);
private:
// We keep a list of symbol assignments.
struct Symbol_assignment
{
// Symbol name.
std::string name;
// Expression to assign to symbol.
Expression* value;
// Whether the assignment should be provided (only set if there is
// an undefined reference to the symbol.
bool provide;
// Whether the assignment should be hidden.
bool hidden;
// The entry in the symbol table.
Symbol* sym;
Symbol_assignment(const char* namea, size_t lengtha, Expression* valuea,
bool providea, bool hiddena)
: name(namea, lengtha), value(valuea), provide(providea),
hidden(hiddena), sym(NULL)
{ }
};
typedef std::vector<Symbol_assignment> Symbol_assignments;
template<int size>
void
sized_finalize_symbols(Symbol_table*, const Layout*);
// The entry address. This will be empty if not set.
std::string entry_;
// Symbols to set.
Symbol_assignments symbol_assignments_;
};
// FILE was found as an argument on the command line, but was not
// recognized as an ELF file. Try to read it as a script. We've
// already read BYTES of data into P. Return true if the file was
// handled. This has to handle /usr/lib/libc.so on a GNU/Linux
// system.
bool
read_input_script(Workqueue*, const General_options&, Symbol_table*, Layout*,
Dirsearch*, Input_objects*, Input_group*,
const Input_argument*, Input_file*, const unsigned char* p,
off_t bytes, Task_token* this_blocker,
Task_token* next_blocker);
// FILE was found as an argument to --script (-T).
// Read it as a script, and execute its contents immediately.
bool
read_commandline_script(const char* filename, Command_line*);
} // End namespace gold.
#endif // !defined(GOLD_SCRIPT_H)
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