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+// Copyright (c) 2011, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// memory_range.h: Define the google_breakpad::MemoryRange class, which
+// is a lightweight wrapper with a pointer and a length to encapsulate
+// a contiguous range of memory.
+
+#ifndef COMMON_MEMORY_RANGE_H_
+#define COMMON_MEMORY_RANGE_H_
+
+#include <stddef.h>
+
+#include "google_breakpad/common/breakpad_types.h"
+
+namespace google_breakpad {
+
+// A lightweight wrapper with a pointer and a length to encapsulate a
+// contiguous range of memory. It provides helper methods for checked
+// access of a subrange of the memory. Its implemementation does not
+// allocate memory or call into libc functions, and is thus safer to use
+// in a crashed environment.
+class MemoryRange {
+ public:
+ MemoryRange() : data_(NULL), length_(0) {}
+
+ MemoryRange(const void* data, size_t length) {
+ Set(data, length);
+ }
+
+ // Returns true if this memory range contains no data.
+ bool IsEmpty() const {
+ // Set() guarantees that |length_| is zero if |data_| is NULL.
+ return length_ == 0;
+ }
+
+ // Resets to an empty range.
+ void Reset() {
+ data_ = NULL;
+ length_ = 0;
+ }
+
+ // Sets this memory range to point to |data| and its length to |length|.
+ void Set(const void* data, size_t length) {
+ data_ = reinterpret_cast<const uint8_t*>(data);
+ // Always set |length_| to zero if |data_| is NULL.
+ length_ = data ? length : 0;
+ }
+
+ // Returns true if this range covers a subrange of |sub_length| bytes
+ // at |sub_offset| bytes of this memory range, or false otherwise.
+ bool Covers(size_t sub_offset, size_t sub_length) const {
+ // The following checks verify that:
+ // 1. sub_offset is within [ 0 .. length_ - 1 ]
+ // 2. sub_offset + sub_length is within
+ // [ sub_offset .. length_ ]
+ return sub_offset < length_ &&
+ sub_offset + sub_length >= sub_offset &&
+ sub_offset + sub_length <= length_;
+ }
+
+ // Returns a raw data pointer to a subrange of |sub_length| bytes at
+ // |sub_offset| bytes of this memory range, or NULL if the subrange
+ // is out of bounds.
+ const void* GetData(size_t sub_offset, size_t sub_length) const {
+ return Covers(sub_offset, sub_length) ? (data_ + sub_offset) : NULL;
+ }
+
+ // Same as the two-argument version of GetData() but uses sizeof(DataType)
+ // as the subrange length and returns an |DataType| pointer for convenience.
+ template <typename DataType>
+ const DataType* GetData(size_t sub_offset) const {
+ return reinterpret_cast<const DataType*>(
+ GetData(sub_offset, sizeof(DataType)));
+ }
+
+ // Returns a raw pointer to the |element_index|-th element of an array
+ // of elements of length |element_size| starting at |sub_offset| bytes
+ // of this memory range, or NULL if the element is out of bounds.
+ const void* GetArrayElement(size_t element_offset,
+ size_t element_size,
+ unsigned element_index) const {
+ size_t sub_offset = element_offset + element_index * element_size;
+ return GetData(sub_offset, element_size);
+ }
+
+ // Same as the three-argument version of GetArrayElement() but deduces
+ // the element size using sizeof(ElementType) and returns an |ElementType|
+ // pointer for convenience.
+ template <typename ElementType>
+ const ElementType* GetArrayElement(size_t element_offset,
+ unsigned element_index) const {
+ return reinterpret_cast<const ElementType*>(
+ GetArrayElement(element_offset, sizeof(ElementType), element_index));
+ }
+
+ // Returns a subrange of |sub_length| bytes at |sub_offset| bytes of
+ // this memory range, or an empty range if the subrange is out of bounds.
+ MemoryRange Subrange(size_t sub_offset, size_t sub_length) const {
+ return Covers(sub_offset, sub_length) ?
+ MemoryRange(data_ + sub_offset, sub_length) : MemoryRange();
+ }
+
+ // Returns a pointer to the beginning of this memory range.
+ const uint8_t* data() const { return data_; }
+
+ // Returns the length, in bytes, of this memory range.
+ size_t length() const { return length_; }
+
+ private:
+ // Pointer to the beginning of this memory range.
+ const uint8_t* data_;
+
+ // Length, in bytes, of this memory range.
+ size_t length_;
+};
+
+} // namespace google_breakpad
+
+#endif // COMMON_MEMORY_RANGE_H_