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https://gitlab.winehq.org/wine/wine-gecko.git
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81 lines
2.9 KiB
C++
81 lines
2.9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "XiphExtradata.h"
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namespace mozilla {
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bool XiphHeadersToExtradata(MediaByteBuffer* aCodecSpecificConfig,
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const nsTArray<const unsigned char*>& aHeaders,
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const nsTArray<size_t>& aHeaderLens)
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{
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size_t nheaders = aHeaders.Length();
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if (!nheaders || nheaders > 255) return false;
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aCodecSpecificConfig->AppendElement(nheaders - 1);
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for (size_t i = 0; i < nheaders - 1; i++) {
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size_t headerLen;
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for (headerLen = aHeaderLens[i]; headerLen >= 255; headerLen -= 255) {
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aCodecSpecificConfig->AppendElement(255);
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}
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aCodecSpecificConfig->AppendElement(headerLen);
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}
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for (size_t i = 0; i < nheaders; i++) {
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aCodecSpecificConfig->AppendElements(aHeaders[i], aHeaderLens[i]);
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}
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return true;
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}
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bool XiphExtradataToHeaders(nsTArray<unsigned char*>& aHeaders,
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nsTArray<size_t>& aHeaderLens,
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unsigned char* aData,
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size_t aAvailable)
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{
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size_t total = 0;
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if (aAvailable < 1) {
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return false;
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}
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aAvailable--;
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int nHeaders = *aData++ + 1;
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for (int i = 0; i < nHeaders - 1; i++) {
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size_t headerLen = 0;
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for (;;) {
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// After this test, we know that (aAvailable - total > headerLen) and
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// (headerLen >= 0) so (aAvailable - total > 0). The loop decrements
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// aAvailable by 1 and total remains fixed, so we know that in the next
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// iteration (aAvailable - total >= 0). Thus (aAvailable - total) can
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// never underflow.
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if (aAvailable - total <= headerLen) {
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return false;
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}
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// Since we know (aAvailable > total + headerLen), this can't overflow
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// unless total is near 0 and both aAvailable and headerLen are within
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// 255 bytes of the maximum representable size. However, that is
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// impossible, since we would have had to have gone through this loop
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// more than 255 times to make headerLen that large, and thus decremented
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// aAvailable more than 255 times.
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headerLen += *aData;
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aAvailable--;
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if (*aData++ != 255) break;
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}
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// And this check ensures updating total won't cause (aAvailable - total)
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// to underflow.
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if (aAvailable - total < headerLen) {
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return false;
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}
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aHeaderLens.AppendElement(headerLen);
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// Since we know aAvailable >= total + headerLen, this can't overflow.
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total += headerLen;
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}
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aHeaderLens.AppendElement(aAvailable - total);
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for (int i = 0; i < nHeaders; i++) {
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aHeaders.AppendElement(aData);
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aData += aHeaderLens[i];
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}
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return true;
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}
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} // namespace mozilla
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