1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/guid.h" 6 7 #include <stdint.h> 8 9 #include "base/rand_util.h" 10 #include "base/strings/stringprintf.h" 11 12 namespace base { 13 14 std::string GenerateGUID() { 15 uint64_t sixteen_bytes[2] = {base::RandUint64(), base::RandUint64()}; 16 17 // Set the GUID to version 4 as described in RFC 4122, section 4.4. 18 // The format of GUID version 4 must be xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, 19 // where y is one of [8, 9, A, B]. 20 21 // Clear the version bits and set the version to 4: 22 sixteen_bytes[0] &= 0xffffffffffff0fffULL; 23 sixteen_bytes[0] |= 0x0000000000004000ULL; 24 25 // Set the two most significant bits (bits 6 and 7) of the 26 // clock_seq_hi_and_reserved to zero and one, respectively: 27 sixteen_bytes[1] &= 0x3fffffffffffffffULL; 28 sixteen_bytes[1] |= 0x8000000000000000ULL; 29 30 return RandomDataToGUIDString(sixteen_bytes); 31 } 32 33 // TODO(cmasone): Once we're comfortable this works, migrate Windows code to 34 // use this as well. 35 std::string RandomDataToGUIDString(const uint64_t bytes[2]) { 36 return StringPrintf("%08X-%04X-%04X-%04X-%012llX", 37 static_cast<unsigned int>(bytes[0] >> 32), 38 static_cast<unsigned int>((bytes[0] >> 16) & 0x0000ffff), 39 static_cast<unsigned int>(bytes[0] & 0x0000ffff), 40 static_cast<unsigned int>(bytes[1] >> 48), 41 bytes[1] & 0x0000ffffffffffffULL); 42 } 43 44 } // namespace base 45
