text: /*
   * Copyright (C) 2012 The Android Open Source Project
   *
   * 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
   *
   *      http://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.
   */
  
  #ifndef ART_RUNTIME_ELF_FILE_H_
  #define ART_RUNTIME_ELF_FILE_H_
  
  #include <museum/5.0.0/external/libcxx/map>
  #include <museum/5.0.0/external/libcxx/memory>
  #include <museum/5.0.0/external/libcxx/vector>
  
  #include <museum/5.0.0/art/runtime/base/unix_file/fd_file.h>
  #include <museum/5.0.0/art/runtime/globals.h>
  #include <museum/5.0.0/art/runtime/elf_utils.h>
  #include <museum/5.0.0/art/runtime/mem_map.h>
  #include <museum/5.0.0/art/runtime/os.h>
  
  namespace facebook { namespace museum { namespace MUSEUM_VERSION { namespace art {
  
  // Interface to GDB JIT for backtrace information.
  extern "C" {
    struct JITCodeEntry;
  }
  
  
  // Used for compile time and runtime for ElfFile access. Because of
  // the need for use at runtime, cannot directly use LLVM classes such as
  // ELFObjectFile.
  class ElfFile {
   public:
    static ElfFile* Open(File* file, bool writable, bool program_header_only, std::string* error_msg);
    // Open with specific mmap flags, Always maps in the whole file, not just the
    // program header sections.
    static ElfFile* Open(File* file, int mmap_prot, int mmap_flags, std::string* error_msg);
    ~ElfFile();
  
    // Load segments into memory based on PT_LOAD program headers
  
    const File& GetFile() const {
      return *file_;
    }
  
    byte* Begin() const {
      return map_->Begin();
    }
  
    byte* End() const {
      return map_->End();
    }
  
    size_t Size() const {
      return map_->Size();
    }
  
    Elf32_Ehdr& GetHeader() const;
  
    Elf32_Word GetProgramHeaderNum() const;
    Elf32_Phdr* GetProgramHeader(Elf32_Word) const;
  
    Elf32_Word GetSectionHeaderNum() const;
    Elf32_Shdr* GetSectionHeader(Elf32_Word) const;
    Elf32_Shdr* FindSectionByType(Elf32_Word type) const;
    Elf32_Shdr* FindSectionByName(const std::string& name) const;
  
    Elf32_Shdr* GetSectionNameStringSection() const;
  
    // Find .dynsym using .hash for more efficient lookup than FindSymbolAddress.
    const byte* FindDynamicSymbolAddress(const std::string& symbol_name) const;
  
    Elf32_Word GetSymbolNum(Elf32_Shdr&) const;
    Elf32_Sym* GetSymbol(Elf32_Word section_type, Elf32_Word i) const;
  
    // Find address of symbol in specified table, returning 0 if it is
    // not found. See FindSymbolByName for an explanation of build_map.
    Elf32_Addr FindSymbolAddress(Elf32_Word section_type,
                                 const std::string& symbol_name,
                                 bool build_map);
  
    // Lookup a string given string section and offset. Returns nullptr for
    // special 0 offset.
    const char* GetString(Elf32_Shdr&, Elf32_Word) const;
  
    Elf32_Word GetDynamicNum() const;
    Elf32_Dyn& GetDynamic(Elf32_Word) const;
  
    Elf32_Word GetRelNum(Elf32_Shdr&) const;
    Elf32_Rel& GetRel(Elf32_Shdr&, Elf32_Word) const;
  
    Elf32_Word GetRelaNum(Elf32_Shdr&) const;
    Elf32_Rela& GetRela(Elf32_Shdr&, Elf32_Word) const;
  
    // Returns the expected size when the file is loaded at runtime
    size_t GetLoadedSize() const;
  
    // Load segments into memory based on PT_LOAD program headers.
    // executable is true at run time, false at compile time.
    bool Load(bool executable, std::string* error_msg);
  
   private:
    ElfFile(File* file, bool writable, bool program_header_only);
  
    bool Setup(int prot, int flags, std::string* error_msg);
  
    bool SetMap(MemMap* map, std::string* error_msg);
  
    byte* GetProgramHeadersStart() const;
    byte* GetSectionHeadersStart() const;
    Elf32_Phdr& GetDynamicProgramHeader() const;
    Elf32_Dyn* GetDynamicSectionStart() const;
    Elf32_Sym* GetSymbolSectionStart(Elf32_Word section_type) const;
    const char* GetStringSectionStart(Elf32_Word section_type) const;
    Elf32_Rel* GetRelSectionStart(Elf32_Shdr&) const;
    Elf32_Rela* GetRelaSectionStart(Elf32_Shdr&) const;
    Elf32_Word* GetHashSectionStart() const;
    Elf32_Word GetHashBucketNum() const;
    Elf32_Word GetHashChainNum() const;
    Elf32_Word GetHashBucket(size_t i, bool* ok) const;
    Elf32_Word GetHashChain(size_t i, bool* ok) const;
  
    typedef std::map<std::string, Elf32_Sym*> SymbolTable;
    SymbolTable** GetSymbolTable(Elf32_Word section_type);
  
    bool ValidPointer(const byte* start) const;
  
    const Elf32_Sym* FindDynamicSymbol(const std::string& symbol_name) const;
  
    // Check that certain sections and their dependencies exist.
    bool CheckSectionsExist(std::string* error_msg) const;
  
    // Check that the link of the first section links to the second section.
    bool CheckSectionsLinked(const byte* source, const byte* target) const;
  
    // Check whether the offset is in range, and set to target to Begin() + offset if OK.
    bool CheckAndSet(Elf32_Off offset, const char* label, byte** target, std::string* error_msg);
  
    // Find symbol in specified table, returning nullptr if it is not found.
    //
    // If build_map is true, builds a map to speed repeated access. The
    // map does not included untyped symbol values (aka STT_NOTYPE)
    // since they can contain duplicates. If build_map is false, the map
    // will be used if it was already created. Typically build_map
    // should be set unless only a small number of symbols will be
    // looked up.
    Elf32_Sym* FindSymbolByName(Elf32_Word section_type,
                                const std::string& symbol_name,
                                bool build_map);
  
    Elf32_Phdr* FindProgamHeaderByType(Elf32_Word type) const;
  
    Elf32_Dyn* FindDynamicByType(Elf32_Sword type) const;
    Elf32_Word FindDynamicValueByType(Elf32_Sword type) const;
  
    // Lookup a string by section type. Returns nullptr for special 0 offset.
    const char* GetString(Elf32_Word section_type, Elf32_Word) const;
  
    const File* const file_;
    const bool writable_;
    const bool program_header_only_;
  
    // ELF header mapping. If program_header_only_ is false, will
    // actually point to the entire elf file.
    std::unique_ptr<MemMap> map_;
    Elf32_Ehdr* header_;
    std::vector<MemMap*> segments_;
  
    // Pointer to start of first PT_LOAD program segment after Load()
    // when program_header_only_ is true.
    byte* base_address_;
  
    // The program header should always available but use GetProgramHeadersStart() to be sure.
    byte* program_headers_start_;
  
    // Conditionally available values. Use accessors to ensure they exist if they are required.
    byte* section_headers_start_;
    Elf32_Phdr* dynamic_program_header_;
    Elf32_Dyn* dynamic_section_start_;
    Elf32_Sym* symtab_section_start_;
    Elf32_Sym* dynsym_section_start_;
    char* strtab_section_start_;
    char* dynstr_section_start_;
    Elf32_Word* hash_section_start_;
  
    SymbolTable* symtab_symbol_table_;
    SymbolTable* dynsym_symbol_table_;
  
    // Support for GDB JIT
    byte* jit_elf_image_;
    JITCodeEntry* jit_gdb_entry_;
    std::unique_ptr<ElfFile> gdb_file_mapping_;
    void GdbJITSupport();
  };
  
  } } } } // namespace facebook::museum::MUSEUM_VERSION::art
  
  #endif  // ART_RUNTIME_ELF_FILE_H_
  