Android: Add chrome-specific dynamic linker.

base/android/linker/crazy_linker/src/crazy_linker_library_view.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_LIBRARY_VIEW_H
+#define CRAZY_LINKER_LIBRARY_VIEW_H
+
+#include "crazy_linker_error.h"
+#include "crazy_linker_util.h"
+
+namespace crazy {
+
+class SharedLibrary;
+
+// A LibraryView is a reference-counted handle to either a
+// crazy::SharedLibrary object or a library handle returned by the system's
+// dlopen() function.
+//
+// It has a name, which is always a base name, because only one
+// library with a given base name can be loaded in the system.
+class LibraryView {
+public:
+  enum {
+    TYPE_NONE   = 0xbaadbaad,
+    TYPE_SYSTEM = 0x2387cef,
+    TYPE_CRAZY  = 0xcdef2387,
+  };
+
+  LibraryView()
+    : type_(TYPE_NONE),
+      crazy_(NULL),
+      system_(NULL),
+      name_(),
+      ref_count_(1) {}
+
+  ~LibraryView();
+
+  bool IsSystem() const { return type_ == TYPE_SYSTEM; }
+
+  bool IsCrazy() const { return type_ == TYPE_CRAZY; }
+
+  void SetSystem(void* system_lib, const char* name) {
+    type_ = TYPE_SYSTEM;
+    system_ = system_lib;
+    name_ = name;
+  }
+
+  void SetCrazy(SharedLibrary* crazy_lib, const char* name) {
+    type_ = TYPE_CRAZY;
+    crazy_ = crazy_lib;
+    name_ = name;
+  }
+
+  const char* GetName() {
+    return name_.c_str();
+  }
+
+  SharedLibrary* GetCrazy() {
+    return IsCrazy() ? crazy_ : NULL;
+  }
+
+  void* GetSystem() {
+    return IsSystem() ? system_ : NULL;
+  }
+
+  void AddRef() {
+    ref_count_++;
+  }
+
+  // Decrement reference count. Returns true iff it reaches 0.
+  // This never destroys the object.
+  bool SafeDeref() {
+    return (--ref_count_ == 0);
+  }
+
+  // Decrement reference count. If it reaches zero, destroy the object.
+  void Deref() {
+    if (SafeDeref())
+      delete this;
+  }
+
+  // Lookup a symbol from this library.
+  // If this is a crazy library, perform a breadth-first search,
+  // for system libraries, use dlsym() instead.
+  void* LookupSymbol(const char* symbol_name);
+
+  // Retrieve library information.
+  bool GetInfo(size_t* load_address,
+               size_t* load_size,
+               size_t* relro_start,
+               size_t* relro_size,
+               int* relro_fd,
+               Error* error);
+
+  // Enable RELRO section sharing. On This moves the RELRO section into
+  // a shareable ashmem region. On success, return true and sets
+  // |*load_address| to the library load address, |*load_size| to its
+  // full load size, |*relro_start| to the start of the RELRO section
+  // in memory, |*relro_size| to its size, and |*relro_fd| to the ashmem
+  // region's file descriptor.
+  // On failure, return false and sets |error| message.
+  bool EnableSharedRelro(Error* error);
+
+  // Use a shared RELRO section from another process. |relro_start|
+  // and |relro_size| are the start and size of the RELRO section,
+  // and |relro_fd| is a file descriptor for the ashmem region.
+  // On success, return true. On failure, return false and sets
+  // |error| message.
+  // NOTE: This function doesn't do anything except return CRAZY_STATUS_OK
+  // if |relro_fd| is negative, or |relro_size| is 0. This shall correspond
+  // to the case where there is no RELRO section in a library.
+  bool UseSharedRelro(size_t relro_start,
+                      size_t relro_size,
+                      int relro_fd,
+                      Error* error);
+
+private:
+  uint32_t type_;
+  SharedLibrary* crazy_;
+  void* system_;
+  String name_;
+  int ref_count_;
+};
+
+}  // namespace crazy
+
+#endif  // CRAZY_LINKER_LIBRARY_VIEW_H