gecko-dev/xpcom/base/nsUUIDGenerator.cpp

193 строки
5.6 KiB
C++

/* -*- Mode: C++; tab-width: 50; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* mozilla.org
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Vladimir Vukicevic <vladimir@pobox.com> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#if defined(XP_WIN)
#include <windows.h>
#include <objbase.h>
#elif defined(XP_MACOSX)
#include <CoreFoundation/CoreFoundation.h>
#else
#include <stdlib.h>
#include "prrng.h"
#endif
#include "nsMemory.h"
#include "nsAutoLock.h"
#include "nsUUIDGenerator.h"
NS_IMPL_THREADSAFE_ISUPPORTS1(nsUUIDGenerator, nsIUUIDGenerator)
nsUUIDGenerator::nsUUIDGenerator()
: mLock(nsnull)
{
}
nsUUIDGenerator::~nsUUIDGenerator()
{
if (mLock) {
PR_DestroyLock(mLock);
}
}
nsresult
nsUUIDGenerator::Init()
{
mLock = PR_NewLock();
NS_ENSURE_TRUE(mLock, NS_ERROR_OUT_OF_MEMORY);
// We're a service, so we're guaranteed that Init() is not going
// to be reentered while we're inside Init().
#if !defined(XP_WIN) && !defined(XP_MACOSX)
/* initialize random number generator using NSPR random noise */
unsigned int seed;
PRSize bytes = 0;
while (bytes < sizeof(seed)) {
PRSize nbytes = PR_GetRandomNoise(((unsigned char *)&seed)+bytes,
sizeof(seed)-bytes);
if (nbytes == 0) {
return NS_ERROR_FAILURE;
}
bytes += nbytes;
}
/* Initialize a new RNG state, and immediately switch
* back to the previous one -- we want to use mState
* only for our own calls to random().
*/
mSavedState = initstate(seed, mState, sizeof(mState));
setstate(mSavedState);
mRBytes = 4;
#ifdef RAND_MAX
if ((unsigned long) RAND_MAX < (unsigned long)0xffffffff)
mRBytes = 3;
if ((unsigned long) RAND_MAX < (unsigned long)0x00ffffff)
mRBytes = 2;
if ((unsigned long) RAND_MAX < (unsigned long)0x0000ffff)
mRBytes = 1;
if ((unsigned long) RAND_MAX < (unsigned long)0x000000ff)
return NS_ERROR_FAILURE;
#endif
#endif /* non XP_WIN and non XP_MACOSX */
return NS_OK;
}
NS_IMETHODIMP
nsUUIDGenerator::GenerateUUID(nsID** ret)
{
nsID *id = static_cast<nsID*>(NS_Alloc(sizeof(nsID)));
if (id == nsnull)
return NS_ERROR_OUT_OF_MEMORY;
nsresult rv = GenerateUUIDInPlace(id);
if (NS_FAILED(rv)) {
NS_Free(id);
return rv;
}
*ret = id;
return rv;
}
NS_IMETHODIMP
nsUUIDGenerator::GenerateUUIDInPlace(nsID* id)
{
// The various code in this method is probably not threadsafe, so lock
// across the whole method.
nsAutoLock lock(mLock);
#if defined(XP_WIN)
HRESULT hr = CoCreateGuid((GUID*)id);
if (NS_FAILED(hr))
return NS_ERROR_FAILURE;
#elif defined(XP_MACOSX)
CFUUIDRef uuid = CFUUIDCreate(kCFAllocatorDefault);
if (!uuid)
return NS_ERROR_FAILURE;
CFUUIDBytes bytes = CFUUIDGetUUIDBytes(uuid);
memcpy(id, &bytes, sizeof(nsID));
CFRelease(uuid);
#else /* not windows or OS X; generate randomness using random(). */
/* XXX we should be saving the return of setstate here and switching
* back to it; instead, we use the value returned when we called
* initstate, since older glibc's have broken setstate() return values
*/
setstate(mState);
PRSize bytesLeft = sizeof(nsID);
while (bytesLeft > 0) {
long rval = random();
PRUint8 *src = (PRUint8*)&rval;
// We want to grab the mRBytes least significant bytes of rval, since
// mRBytes less than sizeof(rval) means the high bytes are 0.
#ifdef IS_BIG_ENDIAN
src += sizeof(rval) - mRBytes;
#endif
PRUint8 *dst = ((PRUint8*) id) + (sizeof(nsID) - bytesLeft);
PRSize toWrite = (bytesLeft < mRBytes ? bytesLeft : mRBytes);
for (PRSize i = 0; i < toWrite; i++)
dst[i] = src[i];
bytesLeft -= toWrite;
}
/* Put in the version */
id->m2 &= 0x0fff;
id->m2 |= 0x4000;
/* Put in the variant */
id->m3[0] &= 0x3f;
id->m3[0] |= 0x80;
/* Restore the previous RNG state */
setstate(mSavedState);
#endif
return NS_OK;
}