| /* |
| * Copyright 2017 The Abseil Authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * https://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| // Allow dynamic symbol lookup for in-memory Elf images. |
| |
| #ifndef ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_ |
| #define ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_ |
| |
| // Including this will define the __GLIBC__ macro if glibc is being |
| // used. |
| #include <climits> |
| |
| // Maybe one day we can rewrite this file not to require the elf |
| // symbol extensions in glibc, but for right now we need them. |
| #ifdef ABSL_HAVE_ELF_MEM_IMAGE |
| #error ABSL_HAVE_ELF_MEM_IMAGE cannot be directly set |
| #endif |
| |
| #if defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) && \ |
| !defined(__asmjs__) && !defined(__wasm__) |
| #define ABSL_HAVE_ELF_MEM_IMAGE 1 |
| #endif |
| |
| #if ABSL_HAVE_ELF_MEM_IMAGE |
| |
| #include <link.h> // for ElfW |
| |
| namespace absl { |
| namespace debugging_internal { |
| |
| // An in-memory ELF image (may not exist on disk). |
| class ElfMemImage { |
| private: |
| // Sentinel: there could never be an elf image at &kInvalidBaseSentinel. |
| static const int kInvalidBaseSentinel; |
| |
| public: |
| // Sentinel: there could never be an elf image at this address. |
| static constexpr const void *const kInvalidBase = |
| static_cast<const void*>(&kInvalidBaseSentinel); |
| |
| // 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_ != nullptr; } |
| 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 is non-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 is non-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 debugging_internal |
| } // namespace absl |
| |
| #endif // ABSL_HAVE_ELF_MEM_IMAGE |
| |
| #endif // ABSL_DEBUGGING_INTERNAL_ELF_MEM_IMAGE_H_ |