xpcom/base/nsUUIDGenerator.cpp

   1 /* -*- Mode: C++; tab-width: 50; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is mozilla.org code.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * mozilla.org
  19  * Portions created by the Initial Developer are Copyright (C) 2005
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *   Vladimir Vukicevic <vladimir@pobox.com> (original author)
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either of the GNU General Public License Version 2 or later (the "GPL"),
  27  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
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  34  * the provisions above, a recipient may use your version of this file under
  35  * the terms of any one of the MPL, the GPL or the LGPL.
  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #if defined(XP_WIN)
  40 #include <windows.h>
  41 #include <objbase.h>
  42 #elif defined(XP_MACOSX)
  43 #include <CoreFoundation/CoreFoundation.h>
  44 #else
  45 #include <stdlib.h>
  46 #include "prrng.h"
  47 #endif
  48
  49 #include "nsMemory.h"
  50
  51 #include "nsAutoLock.h"
  52
  53 #include "nsUUIDGenerator.h"
  54
  55 NS_IMPL_THREADSAFE_ISUPPORTS1(nsUUIDGenerator, nsIUUIDGenerator)
  56
  57 nsUUIDGenerator::nsUUIDGenerator()
  58     : mLock(nsnull)
  59 {
  60 }
  61
  62 nsUUIDGenerator::~nsUUIDGenerator()
  63 {
  64     if (mLock) {
  65         PR_DestroyLock(mLock);
  66     }
  67 }
  68
  69 nsresult
  70 nsUUIDGenerator::Init()
  71 {
  72     mLock = PR_NewLock();
  73
  74     NS_ENSURE_TRUE(mLock, NS_ERROR_OUT_OF_MEMORY);
  75
  76     // We're a service, so we're guaranteed that Init() is not going
  77     // to be reentered while we're inside Init().
  78
  79 #if !defined(XP_WIN) && !defined(XP_MACOSX)
  80     /* initialize random number generator using NSPR random noise */
  81     unsigned int seed;
  82
  83     PRSize bytes = 0;
  84     while (bytes < sizeof(seed)) {
  85         PRSize nbytes = PR_GetRandomNoise(((unsigned char *)&seed)+bytes,
  86                                           sizeof(seed)-bytes);
  87         if (nbytes == 0) {
  88             return NS_ERROR_FAILURE;
  89         }
  90         bytes += nbytes;
  91     }
  92
  93     /* Initialize a new RNG state, and immediately switch
  94      * back to the previous one -- we want to use mState
  95      * only for our own calls to random().
  96      */
  97     mSavedState = initstate(seed, mState, sizeof(mState));
  98     setstate(mSavedState);
  99
 100     mRBytes = 4;
 101 #ifdef RAND_MAX
 102     if ((unsigned long) RAND_MAX < (unsigned long)0xffffffff)
 103         mRBytes = 3;
 104     if ((unsigned long) RAND_MAX < (unsigned long)0x00ffffff)
 105         mRBytes = 2;
 106     if ((unsigned long) RAND_MAX < (unsigned long)0x0000ffff)
 107         mRBytes = 1;
 108     if ((unsigned long) RAND_MAX < (unsigned long)0x000000ff)
 109         return NS_ERROR_FAILURE;
 110 #endif
 111
 112 #endif /* non XP_WIN and non XP_MACOSX */
 113
 114     return NS_OK;
 115 }
 116
 117 NS_IMETHODIMP
 118 nsUUIDGenerator::GenerateUUID(nsID** ret)
 119 {
 120     nsID *id = static_cast<nsID*>(NS_Alloc(sizeof(nsID)));
 121     if (id == nsnull)
 122         return NS_ERROR_OUT_OF_MEMORY;
 123
 124     nsresult rv = GenerateUUIDInPlace(id);
 125     if (NS_FAILED(rv)) {
 126         NS_Free(id);
 127         return rv;
 128     }
 129
 130     *ret = id;
 131     return rv;
 132 }
 133
 134 NS_IMETHODIMP
 135 nsUUIDGenerator::GenerateUUIDInPlace(nsID* id)
 136 {
 137     // The various code in this method is probably not threadsafe, so lock
 138     // across the whole method.
 139     nsAutoLock lock(mLock);
 140
 141 #if defined(XP_WIN)
 142     HRESULT hr = CoCreateGuid((GUID*)id);
 143     if (NS_FAILED(hr))
 144         return NS_ERROR_FAILURE;
 145 #elif defined(XP_MACOSX)
 146     CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
 147     if (!uuid)
 148         return NS_ERROR_FAILURE;
 149
 150     CFUUIDBytes bytes = CFUUIDGetUUIDBytes(uuid);
 151     memcpy(id, &bytes, sizeof(nsID));
 152
 153     CFRelease(uuid);
 154 #else /* not windows or OS X; generate randomness using random(). */
 155     /* XXX we should be saving the return of setstate here and switching
 156      * back to it; instead, we use the value returned when we called
 157      * initstate, since older glibc's have broken setstate() return values
 158      */
 159     setstate(mState);
 160
 161     PRSize bytesLeft = sizeof(nsID);
 162     while (bytesLeft > 0) {
 163         long rval = random();
 164
 165         PRUint8 *src = (PRUint8*)&rval;
 166         // We want to grab the mRBytes least significant bytes of rval, since
 167         // mRBytes less than sizeof(rval) means the high bytes are 0.
 168 #ifdef IS_BIG_ENDIAN
 169         src += sizeof(rval) - mRBytes;
 170 #endif
 171         PRUint8 *dst = ((PRUint8*) id) + (sizeof(nsID) - bytesLeft);
 172         PRSize toWrite = (bytesLeft < mRBytes ? bytesLeft : mRBytes);
 173         for (PRSize i = 0; i < toWrite; i++)
 174             dst[i] = src[i];
 175
 176         bytesLeft -= toWrite;
 177     }
 178
 179     /* Put in the version */
 180     id->m2 &= 0x0fff;
 181     id->m2 |= 0x4000;
 182
 183     /* Put in the variant */
 184     id->m3[0] &= 0x3f;
 185     id->m3[0] |= 0x80;
 186
 187     /* Restore the previous RNG state */
 188     setstate(mSavedState);
 189 #endif
 190
 191     return NS_OK;
 192 }