Line data    Source code

       1             : // Copyright (c) 2006, Google Inc.
       2             : // All rights reserved.
       3             : //
       4             : // Redistribution and use in source and binary forms, with or without
       5             : // modification, are permitted provided that the following conditions are
       6             : // met:
       7             : //
       8             : //     * Redistributions of source code must retain the above copyright
       9             : // notice, this list of conditions and the following disclaimer.
      10             : //     * Redistributions in binary form must reproduce the above
      11             : // copyright notice, this list of conditions and the following disclaimer
      12             : // in the documentation and/or other materials provided with the
      13             : // distribution.
      14             : //     * Neither the name of Google Inc. nor the names of its
      15             : // contributors may be used to endorse or promote products derived from
      16             : // this software without specific prior written permission.
      17             : //
      18             : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      19             : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      20             : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      21             : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
      22             : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      23             : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
      24             : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      25             : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      26             : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      27             : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
      28             : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      29             : 
      30             : #include "linux/handler/guid_generator.h"
      31             : 
      32             : #include <assert.h>
      33             : #include <pthread.h>
      34             : #include <stdio.h>
      35             : #include <stdlib.h>
      36             : #include <time.h>
      37             : #include <unistd.h>
      38             : 
      39             : //
      40             : // GUIDGenerator
      41             : //
      42             : // This class is used to generate random GUID.
      43             : // Currently use random number to generate a GUID since Linux has
      44             : // no native GUID generator. This should be OK since we don't expect
      45             : // crash to happen very offen.
      46             : //
      47             : class GUIDGenerator {
      48             :  public:
      49           0 :   static uint16_t BytesToUInt16(const uint8_t bytes[]) {
      50           0 :     return ((uint16_t) bytes[1] << 8) | ((uint16_t) bytes[0]);
      51             :   }
      52             : 
      53             :   // The last field in a GUID is 48 bits long so we're converting only 6 bytes
      54           0 :   static uint64_t BytesToUInt48(const uint8_t bytes[]) {
      55           0 :     return ((uint64_t) bytes[0] << 40) | ((uint64_t) bytes[1] << 32) |
      56           0 :            ((uint64_t) bytes[2] << 24) | ((uint64_t) bytes[3] << 16) |
      57           0 :            ((uint64_t) bytes[4] << 8)  | (uint64_t) bytes[5];
      58             :   }
      59             : 
      60           0 :   static void UInt32ToBytes(uint8_t bytes[], uint32_t n) {
      61           0 :     bytes[0] = n & 0xff;
      62           0 :     bytes[1] = (n >> 8) & 0xff;
      63           0 :     bytes[2] = (n >> 16) & 0xff;
      64           0 :     bytes[3] = (n >> 24) & 0xff;
      65           0 :   }
      66             : 
      67           0 :   static bool CreateGUID(GUID *guid) {
      68           0 :     InitOnce();
      69           0 :     guid->data1 = random();
      70           0 :     guid->data2 = (uint16_t)(random());
      71           0 :     guid->data3 = (uint16_t)(random());
      72           0 :     UInt32ToBytes(&guid->data4[0], random());
      73           0 :     UInt32ToBytes(&guid->data4[4], random());
      74           0 :     return true;
      75             :   }
      76             : 
      77             :  private:
      78           0 :   static void InitOnce() {
      79           0 :     pthread_once(&once_control, &InitOnceImpl);
      80           0 :   }
      81             : 
      82           0 :   static void InitOnceImpl() {
      83           0 :     srandom(time(NULL));
      84           0 :   }
      85             : 
      86             :   static pthread_once_t once_control;
      87             : };
      88             : 
      89             : pthread_once_t GUIDGenerator::once_control = PTHREAD_ONCE_INIT;
      90             : 
      91           0 : bool CreateGUID(GUID *guid) {
      92           0 :   return GUIDGenerator::CreateGUID(guid);
      93             : }
      94             : 
      95             : // Parse guid to string.
      96           0 : bool GUIDToString(const GUID *guid, char *buf, size_t buf_len) {
      97             :   // Should allow more space the the max length of GUID.
      98           0 :   assert(buf_len > kGUIDStringLength);
      99           0 :   int num = snprintf(buf, buf_len, kGUIDFormatString,
     100           0 :                      guid->data1, guid->data2, guid->data3,
     101           0 :                      GUIDGenerator::BytesToUInt16(&(guid->data4[0])),
     102           0 :                      GUIDGenerator::BytesToUInt48(&(guid->data4[2])));
     103           0 :   if (num != kGUIDStringLength)
     104           0 :     return false;
     105             : 
     106           0 :   buf[num] = '\0';
     107           0 :   return true;
     108             : }