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diff --git a/security/nss/lib/mozpkix/include/pkix/Input.h b/security/nss/lib/mozpkix/include/pkix/Input.h
new file mode 100644
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+++ b/security/nss/lib/mozpkix/include/pkix/Input.h
@@ -0,0 +1,310 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This code is made available to you under your choice of the following sets
+ * of licensing terms:
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+/* Copyright 2013 Mozilla Contributors
+ *
+ * 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 mozilla_pkix_Input_h
+#define mozilla_pkix_Input_h
+
+#include <algorithm>
+
+#include "mozpkix/Result.h"
+#include "stdint.h"
+
+namespace mozilla {
+namespace pkix {
+
+class Reader;
+
+// An Input is a safety-oriented immutable weak reference to a array of bytes
+// of a known size. The data can only be legally accessed by constructing a
+// Reader object, which guarantees all accesses to the data are memory safe.
+// Neither Input not Reader provide any facilities for modifying the data
+// they reference.
+//
+// Inputs are small and should usually be passed by value, not by reference,
+// though for inline functions the distinction doesn't matter:
+//
+//    Result GoodExample(Input input);
+//    Result BadExample(const Input& input);
+//    Result WorseExample(const uint8_t* input, size_t len);
+//
+// Note that in the example, GoodExample has the same performance
+// characteristics as WorseExample, but with much better safety guarantees.
+class Input final {
+ public:
+  typedef uint16_t size_type;
+
+  // This constructor is useful for inputs that are statically known to be of a
+  // fixed size, e.g.:
+  //
+  //   static const uint8_t EXPECTED_BYTES[] = { 0x00, 0x01, 0x02 };
+  //   const Input expected(EXPECTED_BYTES);
+  //
+  // This is equivalent to (and preferred over):
+  //
+  //   static const uint8_t EXPECTED_BYTES[] = { 0x00, 0x01, 0x02 };
+  //   Input expected;
+  //   Result rv = expected.Init(EXPECTED_BYTES, sizeof EXPECTED_BYTES);
+  template <size_type N>
+  explicit Input(const uint8_t (&aData)[N]) : data(aData), len(N) {}
+
+  // Construct a valid, empty, Init-able Input.
+  Input() : data(nullptr), len(0u) {}
+
+  // This is intentionally not explicit in order to allow value semantics.
+  Input(const Input&) = default;
+
+  // Initialize the input. data must be non-null and len must be less than
+  // 65536. Init may not be called more than once.
+  Result Init(const uint8_t* aData, size_t aLen) {
+    if (this->data) {
+      // already initialized
+      return Result::FATAL_ERROR_INVALID_ARGS;
+    }
+    if (!aData || aLen > 0xffffu) {
+      // input too large
+      return Result::ERROR_BAD_DER;
+    }
+
+    this->data = aData;
+    this->len = aLen;
+
+    return Success;
+  }
+
+  // Initialize the input to be equivalent to the given input. Init may not be
+  // called more than once.
+  //
+  // This is basically operator=, but it wasn't given that name because
+  // normally callers do not check the result of operator=, and normally
+  // operator= can be used multiple times.
+  Result Init(Input other) { return Init(other.data, other.len); }
+
+  // Returns the length of the input.
+  //
+  // Having the return type be size_type instead of size_t avoids the need for
+  // callers to ensure that the result is small enough.
+  size_type GetLength() const { return static_cast<size_type>(len); }
+
+  // Don't use this. It is here because we have some "friend" functions that we
+  // don't want to declare in this header file.
+  const uint8_t* UnsafeGetData() const { return data; }
+
+ private:
+  const uint8_t* data;
+  size_t len;
+
+  void operator=(const Input&) = delete;  // Use Init instead.
+};
+
+inline bool InputsAreEqual(const Input& a, const Input& b) {
+  return a.GetLength() == b.GetLength() &&
+         std::equal(a.UnsafeGetData(), a.UnsafeGetData() + a.GetLength(),
+                    b.UnsafeGetData());
+}
+
+// An Reader is a cursor/iterator through the contents of an Input, designed to
+// maximize safety during parsing while minimizing the performance cost of that
+// safety. In particular, all methods do strict bounds checking to ensure
+// buffer overflows are impossible, and they are all inline so that the
+// compiler can coalesce as many of those checks together as possible.
+//
+// In general, Reader allows for one byte of lookahead and no backtracking.
+// However, the Match* functions internally may have more lookahead.
+class Reader final {
+ public:
+  Reader() : input(nullptr), end(nullptr) {}
+
+  explicit Reader(Input aInput)
+      : input(aInput.UnsafeGetData()),
+        end(aInput.UnsafeGetData() + aInput.GetLength()) {}
+
+  Result Init(Input aInput) {
+    if (this->input) {
+      return Result::FATAL_ERROR_INVALID_ARGS;
+    }
+    this->input = aInput.UnsafeGetData();
+    this->end = aInput.UnsafeGetData() + aInput.GetLength();
+    return Success;
+  }
+
+  bool Peek(uint8_t expectedByte) const {
+    return input < end && *input == expectedByte;
+  }
+
+  Result Read(uint8_t& out) {
+    Result rv = EnsureLength(1);
+    if (rv != Success) {
+      return rv;
+    }
+    out = *input++;
+    return Success;
+  }
+
+  Result Read(uint16_t& out) {
+    Result rv = EnsureLength(2);
+    if (rv != Success) {
+      return rv;
+    }
+    out = *input++;
+    out <<= 8u;
+    out |= *input++;
+    return Success;
+  }
+
+  template <Input::size_type N>
+  bool MatchRest(const uint8_t (&toMatch)[N]) {
+    // Normally we use EnsureLength which compares (input + len < end), but
+    // here we want to be sure that there is nothing following the matched
+    // bytes
+    if (static_cast<size_t>(end - input) != N) {
+      return false;
+    }
+    if (!std::equal(input, end, toMatch)) {
+      return false;
+    }
+    input = end;
+    return true;
+  }
+
+  bool MatchRest(Input toMatch) {
+    // Normally we use EnsureLength which compares (input + len < end), but
+    // here we want to be sure that there is nothing following the matched
+    // bytes
+    size_t remaining = static_cast<size_t>(end - input);
+    if (toMatch.GetLength() != remaining) {
+      return false;
+    }
+    if (!std::equal(input, end, toMatch.UnsafeGetData())) {
+      return false;
+    }
+    input = end;
+    return true;
+  }
+
+  Result Skip(Input::size_type len) {
+    Result rv = EnsureLength(len);
+    if (rv != Success) {
+      return rv;
+    }
+    input += len;
+    return Success;
+  }
+
+  Result Skip(Input::size_type len, Reader& skipped) {
+    Result rv = EnsureLength(len);
+    if (rv != Success) {
+      return rv;
+    }
+    rv = skipped.Init(input, len);
+    if (rv != Success) {
+      return rv;
+    }
+    input += len;
+    return Success;
+  }
+
+  Result Skip(Input::size_type len, /*out*/ Input& skipped) {
+    Result rv = EnsureLength(len);
+    if (rv != Success) {
+      return rv;
+    }
+    rv = skipped.Init(input, len);
+    if (rv != Success) {
+      return rv;
+    }
+    input += len;
+    return Success;
+  }
+
+  void SkipToEnd() { input = end; }
+
+  Result SkipToEnd(/*out*/ Input& skipped) {
+    return Skip(static_cast<Input::size_type>(end - input), skipped);
+  }
+
+  Result EnsureLength(Input::size_type len) {
+    if (static_cast<size_t>(end - input) < len) {
+      return Result::ERROR_BAD_DER;
+    }
+    return Success;
+  }
+
+  bool AtEnd() const { return input == end; }
+
+  class Mark final {
+   public:
+    Mark(const Mark&) = default;  // Intentionally not explicit.
+   private:
+    friend class Reader;
+    Mark(const Reader& aInput, const uint8_t* aMark)
+        : input(aInput), mark(aMark) {}
+    const Reader& input;
+    const uint8_t* const mark;
+    void operator=(const Mark&) = delete;
+  };
+
+  Mark GetMark() const { return Mark(*this, input); }
+
+  Result GetInput(const Mark& mark, /*out*/ Input& item) {
+    if (&mark.input != this || mark.mark > input) {
+      return NotReached("invalid mark", Result::FATAL_ERROR_INVALID_ARGS);
+    }
+    return item.Init(mark.mark,
+                     static_cast<Input::size_type>(input - mark.mark));
+  }
+
+ private:
+  Result Init(const uint8_t* data, Input::size_type len) {
+    if (input) {
+      // already initialized
+      return Result::FATAL_ERROR_INVALID_ARGS;
+    }
+    input = data;
+    end = data + len;
+    return Success;
+  }
+
+  const uint8_t* input;
+  const uint8_t* end;
+
+  Reader(const Reader&) = delete;
+  void operator=(const Reader&) = delete;
+};
+
+inline bool InputContains(const Input& input, uint8_t toFind) {
+  Reader reader(input);
+  for (;;) {
+    uint8_t b;
+    if (reader.Read(b) != Success) {
+      return false;
+    }
+    if (b == toFind) {
+      return true;
+    }
+  }
+}
+}
+}  // namespace mozilla::pkix
+
+#endif  // mozilla_pkix_Input_h