61 lines
1.6 KiB
C++
61 lines
1.6 KiB
C++
/* Copyright: (c) Kayne Ruse 2016
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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*
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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*
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* 3. This notice may not be removed or altered from any source
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* distribution.
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*/
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#include "file_hash.hpp"
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#include <fstream>
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//hash a byte array into a 32-bit integer
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unsigned fnv_hash_1a_32(void *key, int len) {
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unsigned char *p = static_cast<unsigned char*>(key);
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unsigned h = 0x811c9dc5;
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for (int i = 0; i < len; i++) {
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h = ( h ^ p[i] ) * 0x01000193;
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}
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return h;
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}
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int getFileHash(std::string fname) {
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std::ifstream is(fname, std::ios::in | std::ios::binary);
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//if the file doesn't exist, return a hash of -1
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if (!is.is_open()) {
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return -1;
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}
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//get the file size
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is.seekg(0, std::ios_base::end);
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int size = is.tellg();
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is.seekg(0);
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//create a buffer of that size
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char buffer[size];
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//load the data
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is.read(buffer, size);
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//cleanup
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is.close();
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//finally, return the hash value
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return fnv_hash_1a_32(buffer, size);
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}
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