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 "base/rand_util.h" 8 #include "base/strings/stringprintf.h" 9 10 namespace base { 11 12 std::string GenerateGUID() { 13 uint64 sixteen_bytes[2] = { base::RandUint64(), base::RandUint64() }; 14 15 // Set the GUID to version 4 as described in RFC 4122, section 4.4. 16 // The format of GUID version 4 must be xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, 17 // where y is one of [8, 9, A, B]. 18 19 // Clear the version bits and set the version to 4: 20 sixteen_bytes[0] &= 0xffffffffffff0fffULL; 21 sixteen_bytes[0] |= 0x0000000000004000ULL; 22 23 // Set the two most significant bits (bits 6 and 7) of the 24 // clock_seq_hi_and_reserved to zero and one, respectively: 25 sixteen_bytes[1] &= 0x3fffffffffffffffULL; 26 sixteen_bytes[1] |= 0x8000000000000000ULL; 27 28 return RandomDataToGUIDString(sixteen_bytes); 29 } 30 31 // TODO(cmasone): Once we're comfortable this works, migrate Windows code to 32 // use this as well. 33 std::string RandomDataToGUIDString(const uint64 bytes[2]) { 34 return StringPrintf("%08X-%04X-%04X-%04X-%012llX", 35 static_cast<unsigned int>(bytes[0] >> 32), 36 static_cast<unsigned int>((bytes[0] >> 16) & 0x0000ffff), 37 static_cast<unsigned int>(bytes[0] & 0x0000ffff), 38 static_cast<unsigned int>(bytes[1] >> 48), 39 bytes[1] & 0x0000ffffffffffffULL); 40 } 41 42 } // namespace guid 43