Add KeyBuffer

Android.mk

@@ -10,7 +10,9 @@ LOCAL_CFLAGS += \
     -Wno-unused-parameter \
     -Wno-comment
 
-LOCAL_SRC_FILES += Keymaster4.cpp
+LOCAL_SRC_FILES += \
+    KeyBuffer.cpp \
+    Keymaster4.cpp
 LOCAL_SHARED_LIBRARIES += \
     [email protected] \
     libkeymaster4support

KeyBuffer.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#include "KeyBuffer.h"
+
+#include <algorithm>
+#include <cstring>
+
+namespace android {
+namespace vold {
+
+KeyBuffer operator+(KeyBuffer&& lhs, const KeyBuffer& rhs) {
+    std::copy(rhs.begin(), rhs.end(), std::back_inserter(lhs));
+    return std::move(lhs);
+}
+
+KeyBuffer operator+(KeyBuffer&& lhs, const char* rhs) {
+    std::copy(rhs, rhs + strlen(rhs), std::back_inserter(lhs));
+    return std::move(lhs);
+}
+
+}  // namespace vold
+}  // namespace android
+

KeyBuffer.h

@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2017 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 ANDROID_VOLD_KEYBUFFER_H
+#define ANDROID_VOLD_KEYBUFFER_H
+
+#include <cstring>
+#include <memory>
+#include <vector>
+
+namespace android {
+namespace vold {
+
+/**
+ * Variant of memset() that should never be optimized away. Borrowed from keymaster code.
+ */
+#ifdef __clang__
+#define OPTNONE __attribute__((optnone))
+#else  // not __clang__
+#define OPTNONE __attribute__((optimize("O0")))
+#endif  // not __clang__
+inline OPTNONE void* memset_s(void* s, int c, size_t n) {
+    if (!s)
+        return s;
+    return memset(s, c, n);
+}
+#undef OPTNONE
+
+// Allocator that delegates useful work to standard one but zeroes data before deallocating.
+class ZeroingAllocator : public std::allocator<char> {
+    public:
+    void deallocate(pointer p, size_type n)
+    {
+        memset_s(p, 0, n);
+        std::allocator<char>::deallocate(p, n);
+    }
+};
+
+// Char vector that zeroes memory when deallocating.
+using KeyBuffer = std::vector<char, ZeroingAllocator>;
+
+// Convenience methods to concatenate key buffers.
+KeyBuffer operator+(KeyBuffer&& lhs, const KeyBuffer& rhs);
+KeyBuffer operator+(KeyBuffer&& lhs, const char* rhs);
+
+}  // namespace vold
+}  // namespace android
+
+#endif
+