tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

SnappyUtils.cpp (2080B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
      5 * You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #include "SnappyUtils.h"
      8 
      9 #include <stddef.h>
     10 
     11 #include "mozilla/Assertions.h"
     12 #include "mozilla/CheckedInt.h"
     13 #include "mozilla/fallible.h"
     14 #include "nsDebug.h"
     15 #include "nsString.h"
     16 #include "snappy/snappy.h"
     17 
     18 namespace mozilla::dom {
     19 
     20 static_assert(SNAPPY_VERSION == 0x010202);
     21 
     22 bool SnappyCompress(const nsACString& aSource, nsACString& aDest) {
     23  MOZ_ASSERT(!aSource.IsVoid());
     24 
     25  size_t uncompressedLength = aSource.Length();
     26 
     27  if (uncompressedLength <= 16) {
     28    aDest.SetIsVoid(true);
     29    return true;
     30  }
     31 
     32  size_t compressedLength = snappy::MaxCompressedLength(uncompressedLength);
     33 
     34  if (NS_WARN_IF(!aDest.SetLength(compressedLength, fallible))) {
     35    return false;
     36  }
     37 
     38  snappy::RawCompress(aSource.BeginReading(), uncompressedLength,
     39                      aDest.BeginWriting(), &compressedLength);
     40 
     41  if (compressedLength >= uncompressedLength) {
     42    aDest.SetIsVoid(true);
     43    return true;
     44  }
     45 
     46  if (NS_WARN_IF(!aDest.SetLength(compressedLength, fallible))) {
     47    return false;
     48  }
     49 
     50  return true;
     51 }
     52 
     53 bool SnappyUncompress(const nsACString& aSource, nsACString& aDest) {
     54  MOZ_ASSERT(!aSource.IsVoid());
     55 
     56  const char* compressed = aSource.BeginReading();
     57 
     58  auto compressedLength = static_cast<size_t>(aSource.Length());
     59 
     60  size_t uncompressedLength = 0u;
     61  if (!snappy::GetUncompressedLength(compressed, compressedLength,
     62                                     &uncompressedLength)) {
     63    return false;
     64  }
     65 
     66  CheckedUint32 checkedLength(uncompressedLength);
     67  if (!checkedLength.isValid()) {
     68    return false;
     69  }
     70 
     71  aDest.SetLength(checkedLength.value());
     72 
     73  if (!snappy::RawUncompress(compressed, compressedLength,
     74                             aDest.BeginWriting())) {
     75    return false;
     76  }
     77 
     78  return true;
     79 }
     80 
     81 }  // namespace mozilla::dom