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// Copyright (c) 2006, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "linux/handler/guid_generator.h"
#include <assert.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
//
// GUIDGenerator
//
// This class is used to generate random GUID.
// Currently use random number to generate a GUID since Linux has
// no native GUID generator. This should be OK since we don't expect
// crash to happen very offen.
//
class GUIDGenerator {
public:
static uint16_t BytesToUInt16(const uint8_t bytes[]) {
return ((uint16_t) bytes[1] << 8) | ((uint16_t) bytes[0]);
}
// The last field in a GUID is 48 bits long so we're converting only 6 bytes
static uint64_t BytesToUInt48(const uint8_t bytes[]) {
return ((uint64_t) bytes[0] << 40) | ((uint64_t) bytes[1] << 32) |
((uint64_t) bytes[2] << 24) | ((uint64_t) bytes[3] << 16) |
((uint64_t) bytes[4] << 8) | (uint64_t) bytes[5];
}
static void UInt32ToBytes(uint8_t bytes[], uint32_t n) {
bytes[0] = n & 0xff;
bytes[1] = (n >> 8) & 0xff;
bytes[2] = (n >> 16) & 0xff;
bytes[3] = (n >> 24) & 0xff;
}
static bool CreateGUID(GUID *guid) {
InitOnce();
guid->data1 = random();
guid->data2 = (uint16_t)(random());
guid->data3 = (uint16_t)(random());
UInt32ToBytes(&guid->data4[0], random());
UInt32ToBytes(&guid->data4[4], random());
return true;
}
private:
static void InitOnce() {
pthread_once(&once_control, &InitOnceImpl);
}
static void InitOnceImpl() {
srandom(time(NULL));
}
static pthread_once_t once_control;
};
pthread_once_t GUIDGenerator::once_control = PTHREAD_ONCE_INIT;
bool CreateGUID(GUID *guid) {
return GUIDGenerator::CreateGUID(guid);
}
// Parse guid to string.
bool GUIDToString(const GUID *guid, char *buf, size_t buf_len) {
// Should allow more space the the max length of GUID.
assert(buf_len > kGUIDStringLength);
int num = snprintf(buf, buf_len, kGUIDFormatString,
guid->data1, guid->data2, guid->data3,
GUIDGenerator::BytesToUInt16(&(guid->data4[0])),
GUIDGenerator::BytesToUInt48(&(guid->data4[2])));
if (num != kGUIDStringLength)
return false;
buf[num] = '\0';
return true;
}