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/* 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 CustomElf_h
#define CustomElf_h
#include "ElfLoader.h"
#include "BaseElf.h"
#include "Logging.h"
#include "Elfxx.h"
/**
* Library Handle class for ELF libraries we don't let the system linker
* handle.
*/
class CustomElf : public BaseElf, private ElfLoader::link_map {
friend class ElfLoader;
friend class SEGVHandler;
public:
/**
* Returns a new CustomElf using the given file descriptor to map ELF
* content. The file descriptor ownership is stolen, and it will be closed
* in CustomElf's destructor if an instance is created, or by the Load
* method otherwise. The path corresponds to the file descriptor, and flags
* are the same kind of flags that would be given to dlopen(), though
* currently, none are supported and the behaviour is more or less that of
* RTLD_GLOBAL | RTLD_BIND_NOW.
*/
static already_AddRefed<LibHandle> Load(Mappable* mappable, const char* path,
int flags);
/**
* Inherited from LibHandle/BaseElf
*/
virtual ~CustomElf();
protected:
virtual Mappable* GetMappable() const;
public:
/**
* Returns the instance, casted as BaseElf. (short of a better way to do
* this without RTTI)
*/
virtual BaseElf* AsBaseElf() { return this; }
private:
/**
* Scan dependent libraries to find the address corresponding to the
* given symbol name. This is used to find symbols that are undefined
* in the Elf object.
*/
void* GetSymbolPtrInDeps(const char* symbol) const;
/**
* Private constructor
*/
CustomElf(Mappable* mappable, const char* path)
: BaseElf(path, mappable),
link_map(),
init(0),
fini(0),
initialized(false),
has_text_relocs(false) {}
/**
* Loads an Elf segment defined by the given PT_LOAD header.
* Returns whether this succeeded or failed.
*/
bool LoadSegment(const Elf::Phdr* pt_load) const;
/**
* 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);
/**
* Apply .rel.dyn/.rela.dyn relocations.
* Returns whether this succeeded or failed.
*/
bool Relocate();
/**
* Apply .rel.plt/.rela.plt relocations.
* Returns whether this succeeded or failed.
*/
bool RelocateJumps();
/**
* Call initialization functions (.init/.init_array)
* Returns true;
*/
bool CallInit();
/**
* Call destructor functions (.fini_array/.fini)
* Returns whether this succeeded or failed.
*/
void CallFini();
/**
* Call a function given a pointer to its location.
*/
void CallFunction(void* ptr) const {
/* C++ doesn't allow direct conversion between pointer-to-object
* and pointer-to-function. */
union {
void* ptr;
void (*func)(void);
} f;
f.ptr = ptr;
DEBUG_LOG("%s: Calling function @%p", GetPath(), ptr);
f.func();
}
/**
* Call a function given a an address relative to the library base
*/
void CallFunction(Elf::Addr addr) const { return CallFunction(GetPtr(addr)); }
/* List of dependent libraries */
std::vector<RefPtr<LibHandle> > dependencies;
/* List of .rel.dyn/.rela.dyn relocations */
Array<Elf::Reloc> relocations;
/* List of .rel.plt/.rela.plt relocation */
Array<Elf::Reloc> jumprels;
/* Relative address of the initialization and destruction functions
* (.init/.fini) */
Elf::Addr init, fini;
/* List of initialization and destruction functions
* (.init_array/.fini_array) */
Array<void*> init_array, fini_array;
bool initialized;
bool has_text_relocs;
};
#endif /* CustomElf_h */