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1 /*
2  * Copyright (C) 2012 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ART_RUNTIME_ELF_FILE_H_
18 #define ART_RUNTIME_ELF_FILE_H_
19 
20 #include <memory>
21 #include <string>
22 
23 #include "base/macros.h"
24 // Explicitly include our own elf.h to avoid Linux and other dependencies.
25 #include "./elf.h"
26 #include "os.h"
27 
28 namespace art {
29 template <typename ElfTypes>
30 class ElfFileImpl;
31 
32 // Explicitly instantiated in elf_file.cc
33 typedef ElfFileImpl<ElfTypes32> ElfFileImpl32;
34 typedef ElfFileImpl<ElfTypes64> ElfFileImpl64;
35 
36 // Used for compile time and runtime for ElfFile access. Because of
37 // the need for use at runtime, cannot directly use LLVM classes such as
38 // ELFObjectFile.
39 class ElfFile {
40  public:
41   static ElfFile* Open(File* file, bool writable, bool program_header_only, std::string* error_msg,
42                        uint8_t* requested_base = nullptr);  // TODO: move arg to before error_msg.
43   // Open with specific mmap flags, Always maps in the whole file, not just the
44   // program header sections.
45   static ElfFile* Open(File* file, int mmap_prot, int mmap_flags, std::string* error_msg);
46   ~ElfFile();
47 
48   // Load segments into memory based on PT_LOAD program headers
49   bool Load(bool executable, std::string* error_msg);
50 
51   const uint8_t* FindDynamicSymbolAddress(const std::string& symbol_name) const;
52 
53   size_t Size() const;
54 
55   // The start of the memory map address range for this ELF file.
56   uint8_t* Begin() const;
57 
58   // The end of the memory map address range for this ELF file.
59   uint8_t* End() const;
60 
61   const File& GetFile() const;
62 
63   bool GetSectionOffsetAndSize(const char* section_name, uint64_t* offset, uint64_t* size);
64 
65   uint64_t FindSymbolAddress(unsigned section_type,
66                              const std::string& symbol_name,
67                              bool build_map);
68 
69   bool GetLoadedSize(size_t* size, std::string* error_msg) const;
70 
71   // Strip an ELF file of unneeded debugging information.
72   // Returns true on success, false on failure.
73   static bool Strip(File* file, std::string* error_msg);
74 
75   // Fixup an ELF file so that that oat header will be loaded at oat_begin.
76   // Returns true on success, false on failure.
77   static bool Fixup(File* file, uint64_t oat_data_begin);
78 
79   bool Fixup(uint64_t base_address);
80 
Is64Bit()81   bool Is64Bit() const {
82     return elf64_.get() != nullptr;
83   }
84 
GetImpl32()85   ElfFileImpl32* GetImpl32() const {
86     return elf32_.get();
87   }
88 
GetImpl64()89   ElfFileImpl64* GetImpl64() const {
90     return elf64_.get();
91   }
92 
93  private:
94   explicit ElfFile(ElfFileImpl32* elf32);
95   explicit ElfFile(ElfFileImpl64* elf64);
96 
97   const std::unique_ptr<ElfFileImpl32> elf32_;
98   const std::unique_ptr<ElfFileImpl64> elf64_;
99 
100   DISALLOW_COPY_AND_ASSIGN(ElfFile);
101 };
102 
103 }  // namespace art
104 
105 #endif  // ART_RUNTIME_ELF_FILE_H_
106