160 lines
4.0 KiB
C++
160 lines
4.0 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef CustomElf_h
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#define CustomElf_h
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#include "ElfLoader.h"
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#include "BaseElf.h"
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#include "Logging.h"
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#include "Elfxx.h"
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/**
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* Library Handle class for ELF libraries we don't let the system linker
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* handle.
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*/
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class CustomElf: public BaseElf, private ElfLoader::link_map
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{
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friend class ElfLoader;
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friend class SEGVHandler;
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public:
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/**
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* Returns a new CustomElf using the given file descriptor to map ELF
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* content. The file descriptor ownership is stolen, and it will be closed
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* in CustomElf's destructor if an instance is created, or by the Load
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* method otherwise. The path corresponds to the file descriptor, and flags
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* are the same kind of flags that would be given to dlopen(), though
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* currently, none are supported and the behaviour is more or less that of
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* RTLD_GLOBAL | RTLD_BIND_NOW.
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*/
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static already_AddRefed<LibHandle> Load(Mappable *mappable,
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const char *path, int flags);
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/**
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* Inherited from LibHandle/BaseElf
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*/
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virtual ~CustomElf();
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protected:
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virtual Mappable *GetMappable() const;
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public:
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/**
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* Shows some stats about the Mappable instance. The when argument is to be
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* used by the caller to give an identifier of the when the stats call is
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* made.
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*/
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virtual void stats(const char *when) const;
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/**
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* Returns the instance, casted as BaseElf. (short of a better way to do
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* this without RTTI)
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*/
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virtual BaseElf *AsBaseElf() { return this; }
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private:
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/**
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* Scan dependent libraries to find the address corresponding to the
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* given symbol name. This is used to find symbols that are undefined
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* in the Elf object.
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*/
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void *GetSymbolPtrInDeps(const char *symbol) const;
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/**
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* Private constructor
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*/
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CustomElf(Mappable *mappable, const char *path)
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: BaseElf(path, mappable)
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, link_map()
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, init(0)
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, fini(0)
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, initialized(false)
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, has_text_relocs(false)
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{ }
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/**
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* Loads an Elf segment defined by the given PT_LOAD header.
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* Returns whether this succeeded or failed.
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*/
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bool LoadSegment(const Elf::Phdr *pt_load) const;
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/**
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* Initializes the library according to information found in the given
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* PT_DYNAMIC header.
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* Returns whether this succeeded or failed.
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*/
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bool InitDyn(const Elf::Phdr *pt_dyn);
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/**
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* Apply .rel.dyn/.rela.dyn relocations.
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* Returns whether this succeeded or failed.
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*/
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bool Relocate();
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/**
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* Apply .rel.plt/.rela.plt relocations.
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* Returns whether this succeeded or failed.
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*/
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bool RelocateJumps();
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/**
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* Call initialization functions (.init/.init_array)
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* Returns true;
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*/
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bool CallInit();
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/**
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* Call destructor functions (.fini_array/.fini)
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* Returns whether this succeeded or failed.
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*/
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void CallFini();
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/**
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* Call a function given a pointer to its location.
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*/
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void CallFunction(void *ptr) const
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{
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/* C++ doesn't allow direct conversion between pointer-to-object
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* and pointer-to-function. */
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union {
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void *ptr;
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void (*func)(void);
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} f;
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f.ptr = ptr;
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DEBUG_LOG("%s: Calling function @%p", GetPath(), ptr);
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f.func();
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}
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/**
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* Call a function given a an address relative to the library base
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*/
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void CallFunction(Elf::Addr addr) const
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{
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return CallFunction(GetPtr(addr));
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}
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/* List of dependent libraries */
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std::vector<RefPtr<LibHandle> > dependencies;
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/* List of .rel.dyn/.rela.dyn relocations */
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Array<Elf::Reloc> relocations;
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/* List of .rel.plt/.rela.plt relocation */
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Array<Elf::Reloc> jumprels;
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/* Relative address of the initialization and destruction functions
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* (.init/.fini) */
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Elf::Addr init, fini;
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/* List of initialization and destruction functions
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* (.init_array/.fini_array) */
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Array<void *> init_array, fini_array;
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bool initialized;
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bool has_text_relocs;
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};
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#endif /* CustomElf_h */
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