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464da0f9c2
In order to avoid adding more dlsym overhead than there already is, resolve symbols directly in the library containing the linker. (GetSymbolPtr is essentially free ; dlsym makes the system linker compule a ElfHash itself, and that's quite expensive to do on all symbols) This also paves the way for direct symbol resolution in all system libraries.
94 lines
2.4 KiB
C++
94 lines
2.4 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 BaseElf_h
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#define BaseElf_h
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#include "ElfLoader.h"
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#include "Elfxx.h"
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/**
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* Base class for ELF libraries. This class includes things that will be
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* common between SystemElfs and CustomElfs.
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*/
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class BaseElf: public LibHandle
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{
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public:
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/**
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* Hash function for symbol lookup, as defined in ELF standard for System V.
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*/
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static unsigned long Hash(const char *symbol);
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/**
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* Returns the address corresponding to the given symbol name (with a
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* pre-computed hash).
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*/
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void *GetSymbolPtr(const char *symbol, unsigned long hash) const;
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/**
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* Returns a pointer to the Elf Symbol in the Dynamic Symbol table
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* corresponding to the given symbol name (with a pre-computed hash).
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*/
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const Elf::Sym *GetSymbol(const char *symbol, unsigned long hash) const;
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BaseElf(const char *path)
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: LibHandle(path) { }
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protected:
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/**
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* Inherited from LibHandle. Those are temporary and are not supposed to
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* be used.
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*/
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virtual void *GetSymbolPtr(const char *symbol) const { return NULL; };
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virtual bool Contains(void *addr) const { return false; };
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virtual void *GetBase() const { return GetPtr(0); }
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#ifdef __ARM_EABI__
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virtual const void *FindExidx(int *pcount) const { return NULL; };
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#endif
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virtual Mappable *GetMappable() const { return NULL; };
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public:
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/* private: */
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/**
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* Returns a pointer relative to the base address where the library is
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* loaded.
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*/
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void *GetPtr(const Elf::Addr offset) const
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{
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if (reinterpret_cast<void *>(offset) > base)
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return reinterpret_cast<void *>(offset);
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return base + offset;
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}
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/**
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* Like the above, but returns a typed (const) pointer
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*/
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template <typename T>
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const T *GetPtr(const Elf::Addr offset) const
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{
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if (reinterpret_cast<void *>(offset) > base)
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return reinterpret_cast<const T *>(offset);
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return reinterpret_cast<const T *>(base + offset);
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}
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/* Base address where the library is loaded */
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MappedPtr base;
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/* Buckets and chains for the System V symbol hash table */
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Array<Elf::Word> buckets;
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UnsizedArray<Elf::Word> chains;
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/* protected: */
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/* String table */
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Elf::Strtab strtab;
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/* Symbol table */
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UnsizedArray<Elf::Sym> symtab;
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};
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#endif /* BaseElf_h */
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