//
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// Copyright (C) 2009 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#ifndef UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_
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#define UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_
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#include <openssl/sha.h>
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#include <unistd.h>
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#include <string>
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#include <vector>
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#include <base/logging.h>
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#include <base/macros.h>
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#include <brillo/secure_blob.h>
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// This class provides a simple wrapper around OpenSSL providing a hash of data
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// passed in.
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// The methods of this class must be called in a very specific order: First the
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// ctor (of course), then 0 or more calls to Update(), then Finalize(), then 0
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// or more calls to raw_hash().
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namespace chromeos_update_engine {
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class HashCalculator {
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public:
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HashCalculator();
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// Update is called with all of the data that should be hashed in order.
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// Update will read |length| bytes of |data|.
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// Returns true on success.
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bool Update(const void* data, size_t length);
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// Updates the hash with up to |length| bytes of data from |file|. If |length|
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// is negative, reads in and updates with the whole file. Returns the number
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// of bytes that the hash was updated with, or -1 on error.
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off_t UpdateFile(const std::string& name, off_t length);
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// Call Finalize() when all data has been passed in. This method tells
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// OpenSSL that no more data will come in.
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// Returns true on success.
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bool Finalize();
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const brillo::Blob& raw_hash() const {
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DCHECK(!raw_hash_.empty()) << "Call Finalize() first";
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return raw_hash_;
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}
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// Gets the current hash context. Note that the string will contain binary
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// data (including \0 characters).
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std::string GetContext() const;
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// Sets the current hash context. |context| must the string returned by a
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// previous HashCalculator::GetContext method call. Returns true on success,
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// and false otherwise.
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bool SetContext(const std::string& context);
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static bool RawHashOfBytes(const void* data,
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size_t length,
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brillo::Blob* out_hash);
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static bool RawHashOfData(const brillo::Blob& data, brillo::Blob* out_hash);
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static off_t RawHashOfFile(const std::string& name,
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off_t length,
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brillo::Blob* out_hash);
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private:
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// If non-empty, the final raw hash. Will only be set to non-empty when
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// Finalize is called.
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brillo::Blob raw_hash_;
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// Init success
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bool valid_;
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// The hash state used by OpenSSL
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SHA256_CTX ctx_;
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DISALLOW_COPY_AND_ASSIGN(HashCalculator);
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};
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} // namespace chromeos_update_engine
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#endif // UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_
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