// Copyright (c) 2008, Google Inc. // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // --- // Author: Paul Pluzhnikov // // Allow dynamic symbol lookup for in-memory Elf images. #ifndef BASE_ELF_MEM_IMAGE_H_ #define BASE_ELF_MEM_IMAGE_H_ #include <config.h> #ifdef HAVE_FEATURES_H #include <features.h> // for __GLIBC__ #endif // Maybe one day we can rewrite this file not to require the elf // symbol extensions in glibc, but for right now we need them. #if defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) #define HAVE_ELF_MEM_IMAGE 1 #include <stdlib.h> #include <link.h> // for ElfW namespace base { // An in-memory ELF image (may not exist on disk). class ElfMemImage { public: // Sentinel: there could never be an elf image at this address. static const void *const kInvalidBase; // Information about a single vdso symbol. // All pointers are into .dynsym, .dynstr, or .text of the VDSO. // Do not free() them or modify through them. struct SymbolInfo { const char *name; // E.g. "__vdso_getcpu" const char *version; // E.g. "LINUX_2.6", could be "" // for unversioned symbol. const void *address; // Relocated symbol address. const ElfW(Sym) *symbol; // Symbol in the dynamic symbol table. }; // Supports iteration over all dynamic symbols. class SymbolIterator { public: friend class ElfMemImage; const SymbolInfo *operator->() const; const SymbolInfo &operator*() const; SymbolIterator& operator++(); bool operator!=(const SymbolIterator &rhs) const; bool operator==(const SymbolIterator &rhs) const; private: SymbolIterator(const void *const image, int index); void Update(int incr); SymbolInfo info_; int index_; const void *const image_; }; explicit ElfMemImage(const void *base); void Init(const void *base); bool IsPresent() const { return ehdr_ != NULL; } const ElfW(Phdr)* GetPhdr(int index) const; const ElfW(Sym)* GetDynsym(int index) const; const ElfW(Versym)* GetVersym(int index) const; const ElfW(Verdef)* GetVerdef(int index) const; const ElfW(Verdaux)* GetVerdefAux(const ElfW(Verdef) *verdef) const; const char* GetDynstr(ElfW(Word) offset) const; const void* GetSymAddr(const ElfW(Sym) *sym) const; const char* GetVerstr(ElfW(Word) offset) const; int GetNumSymbols() const; SymbolIterator begin() const; SymbolIterator end() const; // Look up versioned dynamic symbol in the image. // Returns false if image is not present, or doesn't contain given // symbol/version/type combination. // If info_out != NULL, additional details are filled in. bool LookupSymbol(const char *name, const char *version, int symbol_type, SymbolInfo *info_out) const; // Find info about symbol (if any) which overlaps given address. // Returns true if symbol was found; false if image isn't present // or doesn't have a symbol overlapping given address. // If info_out != NULL, additional details are filled in. bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const; private: const ElfW(Ehdr) *ehdr_; const ElfW(Sym) *dynsym_; const ElfW(Versym) *versym_; const ElfW(Verdef) *verdef_; const ElfW(Word) *hash_; const char *dynstr_; size_t strsize_; size_t verdefnum_; ElfW(Addr) link_base_; // Link-time base (p_vaddr of first PT_LOAD). }; } // namespace base #endif // __ELF__ and __GLIBC__ and !__native_client__ #endif // BASE_ELF_MEM_IMAGE_H_