dom/quota/MemoryOutputStream.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "MemoryOutputStream.h"
   8
   9 #include "nsStreamUtils.h"
  10
  11 namespace mozilla {
  12 namespace dom {
  13 namespace quota {
  14
  15 // static
  16 already_AddRefed<MemoryOutputStream> MemoryOutputStream::Create(
  17     uint64_t aSize) {
  18   MOZ_ASSERT(aSize, "Passed zero size!");
  19
  20   if (NS_WARN_IF(aSize > UINT32_MAX)) {
  21     return nullptr;
  22   }
  23
  24   RefPtr<MemoryOutputStream> stream = new MemoryOutputStream();
  25
  26   if (NS_WARN_IF(!stream->mData.SetLength(aSize, fallible))) {
  27     return nullptr;
  28   }
  29
  30   return stream.forget();
  31 }
  32
  33 NS_IMPL_ISUPPORTS(MemoryOutputStream, nsIOutputStream)
  34
  35 NS_IMETHODIMP
  36 MemoryOutputStream::Close() {
  37   mData.Truncate(mOffset);
  38   return NS_OK;
  39 }
  40
  41 NS_IMETHODIMP
  42 MemoryOutputStream::Write(const char* aBuf, uint32_t aCount,
  43                           uint32_t* _retval) {
  44   return WriteSegments(NS_CopySegmentToBuffer, (char*)aBuf, aCount, _retval);
  45 }
  46
  47 NS_IMETHODIMP
  48 MemoryOutputStream::Flush() { return NS_OK; }
  49
  50 NS_IMETHODIMP
  51 MemoryOutputStream::WriteFrom(nsIInputStream* aFromStream, uint32_t aCount,
  52                               uint32_t* _retval) {
  53   return NS_ERROR_NOT_IMPLEMENTED;
  54 }
  55
  56 NS_IMETHODIMP
  57 MemoryOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
  58                                   uint32_t aCount, uint32_t* _retval) {
  59   MOZ_ASSERT(mData.Length() >= mOffset, "Bad stream state!");
  60
  61   uint32_t maxCount = mData.Length() - mOffset;
  62   if (maxCount == 0) {
  63     *_retval = 0;
  64     return NS_OK;
  65   }
  66
  67   if (aCount > maxCount) {
  68     aCount = maxCount;
  69   }
  70
  71   nsresult rv = aReader(this, aClosure, mData.BeginWriting() + mOffset, 0,
  72                         aCount, _retval);
  73   if (NS_SUCCEEDED(rv)) {
  74     MOZ_ASSERT(*_retval <= aCount,
  75                "Reader should not read more than we asked it to read!");
  76     mOffset += *_retval;
  77   }
  78
  79   return NS_OK;
  80 }
  81
  82 NS_IMETHODIMP
  83 MemoryOutputStream::IsNonBlocking(bool* _retval) {
  84   *_retval = false;
  85   return NS_OK;
  86 }
  87
  88 }  // namespace quota
  89 }  // namespace dom
  90 }  // namespace mozilla