third_party/WebKit/Source/platform/UUID.cpp

/*
* Copyright (C) 2010 Google Inc. All rights reserved.
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* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
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*     * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "platform/UUID.h"

#include "wtf/CryptographicallyRandomNumber.h"
#include "wtf/HexNumber.h"
#include "wtf/text/StringBuilder.h"

namespace blink {

String createCanonicalUUIDString()
{
    unsigned randomData[4];
    cryptographicallyRandomValues(reinterpret_cast<unsigned char*>(randomData), sizeof(randomData));

    // Format as Version 4 UUID.
    StringBuilder builder;
    builder.reserveCapacity(36);
    appendUnsignedAsHexFixedSize(randomData[0], builder, 8, Lowercase);
    builder.append('-');
    appendUnsignedAsHexFixedSize(randomData[1] >> 16, builder, 4, Lowercase);
    builder.appendLiteral("-4");
    appendUnsignedAsHexFixedSize(randomData[1] & 0x00000fff, builder, 3, Lowercase);
    builder.append('-');
    appendUnsignedAsHexFixedSize((randomData[2] >> 30) | 0x8, builder, 1, Lowercase);
    appendUnsignedAsHexFixedSize((randomData[2] >> 16) & 0x00000fff, builder, 3, Lowercase);
    builder.append('-');
    appendUnsignedAsHexFixedSize(randomData[2] & 0x0000ffff, builder, 4, Lowercase);
    appendUnsignedAsHexFixedSize(randomData[3], builder, 8, Lowercase);
    return builder.toString();
}

static bool isLowercaseHex(char c)
{
    return (('0' <= c && c <= '9') || ('a' <= c && c <= 'f'));
}

bool isValidUUID(const String& uuid)
{
    // 32 digits + 4 hyphens = 36 characters.
    if (uuid.length() != 36)
        return false;

    for (size_t i = 0; i < uuid.length(); i++) {
        if (i == 8 || i == 13 || i == 18 || i == 23) {
            if (uuid[i] != '-')
                return false;
        } else {
            if (!isLowercaseHex(uuid[i]))
                return false;
        }
    }

    return true;
}

} // namespace blink