gecko/mozglue/linker/BaseElf.h
Mike Hommey 49c12e0023 Bug 1081034 part 2 - Move initialization of self_elf to its own separate class. r=nfroyd
The new class is kind of like SystemElf, but using our linker's own symbol
resolution. This also adds some initialization from ELF program headers that
weren't done previously for self_elf, as well as registration as for CustomElf
instances.
2014-10-16 09:20:06 +09:00

142 lines
3.5 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef BaseElf_h
#define BaseElf_h
#include "ElfLoader.h"
#include "Elfxx.h"
/**
* Base class for ELF libraries. This class includes things that will be
* common between SystemElfs and CustomElfs.
*/
class BaseElf: public LibHandle
{
public:
/**
* Hash function for symbol lookup, as defined in ELF standard for System V.
*/
static unsigned long Hash(const char *symbol);
/**
* Returns the address corresponding to the given symbol name (with a
* pre-computed hash).
*/
void *GetSymbolPtr(const char *symbol, unsigned long hash) const;
/**
* Returns a pointer to the Elf Symbol in the Dynamic Symbol table
* corresponding to the given symbol name (with a pre-computed hash).
*/
const Elf::Sym *GetSymbol(const char *symbol, unsigned long hash) const;
BaseElf(const char *path, Mappable *mappable = nullptr)
: LibHandle(path)
, mappable(mappable)
{
}
protected:
/**
* Inherited from LibHandle. Those are temporary and are not supposed to
* be used.
*/
virtual void *GetSymbolPtr(const char *symbol) const;
virtual bool Contains(void *addr) const;
virtual void *GetBase() const { return GetPtr(0); }
#ifdef __ARM_EABI__
virtual const void *FindExidx(int *pcount) const;
#endif
virtual Mappable *GetMappable() const { return NULL; };
public:
/* private: */
/**
* Returns a pointer relative to the base address where the library is
* loaded.
*/
void *GetPtr(const Elf::Addr offset) const
{
if (reinterpret_cast<void *>(offset) > base)
return reinterpret_cast<void *>(offset);
return base + offset;
}
/**
* Like the above, but returns a typed (const) pointer
*/
template <typename T>
const T *GetPtr(const Elf::Addr offset) const
{
if (reinterpret_cast<void *>(offset) > base)
return reinterpret_cast<const T *>(offset);
return reinterpret_cast<const T *>(base + offset);
}
/* Appropriated Mappable */
/* /!\ we rely on this being nullptr for BaseElf instances, but not
* CustomElf instances. */
mozilla::RefPtr<Mappable> mappable;
/* Base address where the library is loaded */
MappedPtr base;
/* Buckets and chains for the System V symbol hash table */
Array<Elf::Word> buckets;
UnsizedArray<Elf::Word> chains;
/* protected: */
/* String table */
Elf::Strtab strtab;
/* Symbol table */
UnsizedArray<Elf::Sym> symtab;
#ifdef __ARM_EABI__
/* ARM.exidx information used by FindExidx */
Array<uint32_t[2]> arm_exidx;
#endif
};
/**
* Class for ELF libraries that already loaded in memory.
*/
class LoadedElf: public BaseElf
{
public:
/**
* Returns a LoadedElf corresponding to the already loaded ELF
* at the given base address.
*/
static mozilla::TemporaryRef<LibHandle> Create(const char *path,
void *base_addr);
private:
LoadedElf(const char *path)
: BaseElf(path) { }
~LoadedElf()
{
/* Avoid base's destructor unmapping something that doesn't actually
* belong to it. */
base.release();
ElfLoader::Singleton.Forget(this);
}
/**
* Initializes the library according to information found in the given
* PT_DYNAMIC header.
* Returns whether this succeeded or failed.
*/
bool InitDyn(const Elf::Phdr *pt_dyn);
};
#endif /* BaseElf_h */