Android: Add chrome-specific dynamic linker.

third_party/crazy_linker/crazy_linker/src/crazy_linker_elf_loader.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CRAZY_LINKER_ELF_LOADER_H
+#define CRAZY_LINKER_ELF_LOADER_H
+
+#include "crazy_linker_error.h"
+#include "crazy_linker_system.h"  // For ScopedFileDescriptor
+#include "elf_traits.h"
+
+namespace crazy {
+
+// Helper class used to load an ELF binary in memory.
+//
+// Note that this doesn't not perform any relocation, the purpose
+// of this class is strictly to map all loadable segments from the
+// file to their correct location.
+//
+class ElfLoader {
+public:
+  ElfLoader();
+  ~ElfLoader();
+
+  // Try to load a library at a given address. On failure, this will
+  // update the linker error message and returns false.
+  //
+  // |lib_path| is the full library path, and |wanted_address| should
+  // be the desired load address, or 0 to enable randomization.
+  //
+  // |file_offset| is an offset in the file where the ELF header will
+  // be looked for.
+  //
+  // |wanted_address| is the wanted load address (of the first loadable
+  // segment), or 0 to enable randomization.
+  //
+  // On success, the library's loadable segments will be mapped in
+  // memory with their original protection. However, no further processing
+  // will be performed.
+  //
+  // On failure, returns false and assign an error message to |error|.
+  bool LoadAt(const char* lib_path,
+              off_t file_offset,
+              uintptr_t wanted_address,
+              Error* error);
+
+  // Only call the following functions after a succesfull LoadAt() call.
+
+  size_t phdr_count() { return phdr_num_; }
+  ELF::Addr load_start() { return reinterpret_cast<ELF::Addr>(load_start_); }
+  ELF::Addr load_size() { return load_size_; }
+  ELF::Addr load_bias() { return load_bias_; }
+  const ELF::Phdr* loaded_phdr() { return loaded_phdr_; }
+
+private:
+  FileDescriptor fd_;
+  const char* path_;
+
+  ELF::Ehdr header_;
+  size_t phdr_num_;
+
+  void* phdr_mmap_;        // temporary copy of the program header.
+  ELF::Phdr* phdr_table_;
+  ELF::Addr phdr_size_;    // and its size.
+
+  off_t     file_offset_;
+  void*     wanted_load_address_;
+  void*     load_start_;  // First page of reserved address space.
+  ELF::Addr load_size_;   // Size in bytes of reserved address space.
+  ELF::Addr load_bias_;   // load_bias, add this value to all "vaddr"
+                          // values in the library to get the corresponding
+                          // memory address.
+
+  const ELF::Phdr* loaded_phdr_;  // points to the loaded program header.
+
+  // Individual steps used by ::LoadAt()
+  bool ReadElfHeader(Error* error);
+  bool ReadProgramHeader(Error* error);
+  bool ReserveAddressSpace(Error* error);
+  bool LoadSegments(Error* error);
+  bool FindPhdr(Error* error);
+  bool CheckPhdr(ELF::Addr, Error* error);
+};
+
+}  // namespace crazy
+
+#endif  // CRAZY_LINKER_ELF_LOADER_H