tor-browser

The Tor Browser
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ZeroCopyNSIOutputStream.cpp (2208B)

      1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
      2 /* This Source Code Form is subject to the terms of the Mozilla Public
      3 * License, v. 2.0. If a copy of the MPL was not distributed with this
      4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      5 
      6 #include "mozilla/devtools/ZeroCopyNSIOutputStream.h"
      7 
      8 #include "mozilla/DebugOnly.h"
      9 
     10 namespace mozilla {
     11 namespace devtools {
     12 
     13 ZeroCopyNSIOutputStream::ZeroCopyNSIOutputStream(nsCOMPtr<nsIOutputStream>& out)
     14    : out(out), result_(NS_OK), amountUsed(0), writtenCount(0) {
     15  DebugOnly<bool> nonBlocking = false;
     16  MOZ_ASSERT(out->IsNonBlocking(&nonBlocking) == NS_OK);
     17  MOZ_ASSERT(!nonBlocking);
     18 }
     19 
     20 ZeroCopyNSIOutputStream::~ZeroCopyNSIOutputStream() {
     21  if (!failed()) (void)NS_WARN_IF(NS_FAILED(writeBuffer()));
     22 }
     23 
     24 nsresult ZeroCopyNSIOutputStream::writeBuffer() {
     25  if (failed()) return result_;
     26 
     27  if (amountUsed == 0) return NS_OK;
     28 
     29  int32_t amountWritten = 0;
     30  while (amountWritten < amountUsed) {
     31    uint32_t justWritten = 0;
     32 
     33    result_ = out->Write(buffer + amountWritten, amountUsed - amountWritten,
     34                         &justWritten);
     35    if (NS_WARN_IF(NS_FAILED(result_))) return result_;
     36 
     37    amountWritten += justWritten;
     38  }
     39 
     40  writtenCount += amountUsed;
     41  amountUsed = 0;
     42  return NS_OK;
     43 }
     44 
     45 // ZeroCopyOutputStream Interface
     46 
     47 bool ZeroCopyNSIOutputStream::Next(void** data, int* size) {
     48  MOZ_ASSERT(data != nullptr);
     49  MOZ_ASSERT(size != nullptr);
     50 
     51  if (failed()) return false;
     52 
     53  if (amountUsed == BUFFER_SIZE) {
     54    if (NS_FAILED(writeBuffer())) return false;
     55  }
     56 
     57  *data = buffer + amountUsed;
     58  *size = BUFFER_SIZE - amountUsed;
     59  amountUsed = BUFFER_SIZE;
     60  return true;
     61 }
     62 
     63 void ZeroCopyNSIOutputStream::BackUp(int count) {
     64  MOZ_ASSERT(count >= 0, "Cannot back up a negative amount of bytes.");
     65  MOZ_ASSERT(amountUsed == BUFFER_SIZE,
     66             "Can only call BackUp directly after calling Next.");
     67  MOZ_ASSERT(count <= amountUsed,
     68             "Can't back up further than we've given out.");
     69 
     70  amountUsed -= count;
     71 }
     72 
     73 ::google::protobuf::int64 ZeroCopyNSIOutputStream::ByteCount() const {
     74  return writtenCount + amountUsed;
     75 }
     76 
     77 }  // namespace devtools
     78 }  // namespace mozilla