Load libraries in breadth-first order

This patch fixes the problem with symbol search order
  for dlsym(RTLD_DEFAULT/RTLD_NEXT, .) by loading libraries
  and ld_preloads in correct order.

Bug: https://code.google.com/p/android/issues/detail?id=74255
Change-Id: I4cf84c70dbaabe99310230dfda12385ae5401859

libc/private/ScopeGuard.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2014 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 SCOPE_GUARD_H
+#define SCOPE_GUARD_H
+
+// TODO: include explicit std::move when it becomes available
+template<typename F>
+class ScopeGuard {
+ public:
+  ScopeGuard(F f) : f_(f), active_(true) {}
+
+  ScopeGuard(ScopeGuard&& that) : f_(that.f_), active_(that.active_) {
+    that.active_ = false;
+  }
+
+  ~ScopeGuard() {
+    if (active_) {
+      f_();
+    }
+  }
+
+  void disable() {
+    active_ = false;
+  }
+ private:
+  F f_;
+  bool active_;
+
+  ScopeGuard() = delete;
+  ScopeGuard(const ScopeGuard&) = delete;
+  ScopeGuard& operator=(const ScopeGuard&) = delete;
+};
+
+template<typename T>
+ScopeGuard<T> create_scope_guard(T f) {
+  return ScopeGuard<T>(f);
+}
+
+#endif  // SCOPE_GUARD_H

libc/private/UniquePtr.h

@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2010 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 UNIQUE_PTR_H_included
+#define UNIQUE_PTR_H_included
+
+// Default deleter for pointer types.
+template <typename T>
+struct DefaultDelete {
+    enum { type_must_be_complete = sizeof(T) };
+    DefaultDelete() {}
+    void operator()(T* p) const {
+        delete p;
+    }
+};
+
+// Default deleter for array types.
+template <typename T>
+struct DefaultDelete<T[]> {
+    enum { type_must_be_complete = sizeof(T) };
+    void operator()(T* p) const {
+        delete[] p;
+    }
+};
+
+// A smart pointer that deletes the given pointer on destruction.
+// Equivalent to C++0x's std::unique_ptr (a combination of boost::scoped_ptr
+// and boost::scoped_array).
+// Named to be in keeping with Android style but also to avoid
+// collision with any other implementation, until we can switch over
+// to unique_ptr.
+// Use thus:
+//   UniquePtr<C> c(new C);
+template <typename T, typename D = DefaultDelete<T> >
+class UniquePtr {
+public:
+    // Construct a new UniquePtr, taking ownership of the given raw pointer.
+    explicit UniquePtr(T* ptr = nullptr) : mPtr(ptr) { }
+
+    UniquePtr(UniquePtr<T, D>&& that) {
+      mPtr = that.mPtr;
+      that.mPtr = nullptr;
+    }
+
+    ~UniquePtr() {
+        reset();
+    }
+
+    // Accessors.
+    T& operator*() const { return *mPtr; }
+    T* operator->() const { return mPtr; }
+    T* get() const { return mPtr; }
+
+    // Returns the raw pointer and hands over ownership to the caller.
+    // The pointer will not be deleted by UniquePtr.
+    T* release() __attribute__((warn_unused_result)) {
+        T* result = mPtr;
+        mPtr = nullptr;
+        return result;
+    }
+
+    // Takes ownership of the given raw pointer.
+    // If this smart pointer previously owned a different raw pointer, that
+    // raw pointer will be freed.
+    void reset(T* ptr = nullptr) {
+        if (ptr != mPtr) {
+            D()(mPtr);
+            mPtr = ptr;
+        }
+    }
+
+private:
+    // The raw pointer.
+    T* mPtr;
+
+    // Comparing unique pointers is probably a mistake, since they're unique.
+    template <typename T2> bool operator==(const UniquePtr<T2>& p) const = delete;
+    template <typename T2> bool operator!=(const UniquePtr<T2>& p) const = delete;
+
+    // Disallow copy and assignment.
+    UniquePtr(const UniquePtr&) = delete;
+    void operator=(const UniquePtr&) = delete;
+};
+
+// Partial specialization for array types. Like std::unique_ptr, this removes
+// operator* and operator-> but adds operator[].
+template <typename T, typename D>
+class UniquePtr<T[], D> {
+public:
+    explicit UniquePtr(T* ptr = NULL) : mPtr(ptr) {
+    }
+    UniquePtr(UniquePtr<T, D>&& that) {
+      mPtr = that.mPtr;
+      that.mPtr = nullptr;
+    }
+
+    ~UniquePtr() {
+        reset();
+    }
+
+    T& operator[](size_t i) const {
+        return mPtr[i];
+    }
+    T* get() const { return mPtr; }
+
+    T* release() __attribute__((warn_unused_result)) {
+        T* result = mPtr;
+        mPtr = NULL;
+        return result;
+    }
+
+    void reset(T* ptr = NULL) {
+        if (ptr != mPtr) {
+            D()(mPtr);
+            mPtr = ptr;
+        }
+    }
+
+private:
+    T* mPtr;
+
+    // Disallow copy and assignment.
+    UniquePtr(const UniquePtr&) = delete;
+    void operator=(const UniquePtr&) = delete;
+};
+
+#endif  // UNIQUE_PTR_H_included