gecko-dev/xpcom/base/nsUUIDGenerator.cpp

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/* -*- Mode: C++; tab-width: 50; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2012-05-21 11:12:37 +00:00
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#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 "nsUUIDGenerator.h"
using namespace mozilla;
NS_IMPL_THREADSAFE_ISUPPORTS1(nsUUIDGenerator, nsIUUIDGenerator)
nsUUIDGenerator::nsUUIDGenerator()
: mLock("nsUUIDGenerator.mLock")
{
}
nsUUIDGenerator::~nsUUIDGenerator()
{
}
nsresult
nsUUIDGenerator::Init()
{
// 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) && !defined(ANDROID)
/* initialize random number generator using NSPR random noise */
unsigned int seed;
size_t bytes = 0;
while (bytes < sizeof(seed)) {
size_t 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 == nullptr)
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.
MutexAutoLock lock(mLock);
#if defined(XP_WIN)
HRESULT hr = CoCreateGuid((GUID*)id);
if (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
*/
#ifndef ANDROID
setstate(mState);
#endif
size_t bytesLeft = sizeof(nsID);
while (bytesLeft > 0) {
#ifdef ANDROID
long rval = arc4random();
const int mRBytes = 4;
#else
long rval = random();
#endif
uint8_t *src = (uint8_t*)&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
uint8_t *dst = ((uint8_t*) id) + (sizeof(nsID) - bytesLeft);
size_t toWrite = (bytesLeft < mRBytes ? bytesLeft : mRBytes);
for (size_t 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;
#ifndef ANDROID
/* Restore the previous RNG state */
setstate(mSavedState);
#endif
#endif
return NS_OK;
}