gecko-dev/xpcom/base/nsUUIDGenerator.cpp

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 *
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 * 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)
 *
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
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#ifdef XP_WIN
#include <windows.h>
#include <objbase.h>
#else
#include <stdlib.h>
#endif

#include <nsMemory.h>

#include "nsUUIDGenerator.h"

#include "prrng.h"

NS_IMPL_ISUPPORTS1(nsUUIDGenerator, nsIUUIDGenerator)

nsUUIDGenerator::nsUUIDGenerator()
    : mInitialized(PR_FALSE)
{
}

nsresult
nsUUIDGenerator::Init()
{
#ifndef XP_WIN
    /* 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;
    }

    initstate(seed, mState, sizeof(mState));

    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 */

    mInitialized = PR_TRUE;
    return NS_OK;
}

NS_IMETHODIMP
nsUUIDGenerator::GenerateUUID(nsID** ret)
{
    nsID *id = NS_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)
{
    if (!mInitialized) {
        nsresult rv = Init();
        if (NS_FAILED(rv))
            return rv;
    }

#ifdef XP_WIN
    HRESULT hr = CoCreateGuid((GUID*)id);
    if (NS_FAILED(hr))
        return NS_ERROR_FAILURE;
#else /* non-windows; generate randomness using random(). */
    PRSize bytesLeft = sizeof(nsID);
    while (bytesLeft > 0) {
        long rval = random();

        PRUint8 *src = (PRUint8*)&rval;
#ifdef IS_LITTLE_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;
#endif

    return NS_OK;
}