dom/file/MemoryStreams.cpp

   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 "MemoryStreams.h"
   8
   9 #include "nsStreamUtils.h"
  10
  11 USING_FILE_NAMESPACE
  12
  13 // static
  14 already_AddRefed<MemoryOutputStream>
  15 MemoryOutputStream::Create(uint64_t aSize)
  16 {
  17   NS_ASSERTION(aSize, "Passed zero size!");
  18
  19   NS_ENSURE_TRUE(aSize <= UINT32_MAX, nullptr);
  20
  21   nsRefPtr<MemoryOutputStream> stream = new MemoryOutputStream();
  22
  23   char* dummy;
  24   uint32_t length = stream->mData.GetMutableData(&dummy, aSize, fallible_t());
  25   NS_ENSURE_TRUE(length == aSize, nullptr);
  26
  27   return stream.forget();
  28 }
  29
  30 NS_IMPL_THREADSAFE_ISUPPORTS1(MemoryOutputStream, nsIOutputStream)
  31
  32 NS_IMETHODIMP
  33 MemoryOutputStream::Close()
  34 {
  35   mData.Truncate(mOffset);
  36   return NS_OK;
  37 }
  38
  39 NS_IMETHODIMP
  40 MemoryOutputStream::Write(const char* aBuf, uint32_t aCount, uint32_t* _retval)
  41 {
  42   return WriteSegments(NS_CopySegmentToBuffer, (char*)aBuf, aCount, _retval);
  43 }
  44
  45 NS_IMETHODIMP
  46 MemoryOutputStream::Flush()
  47 {
  48   return NS_OK;
  49 }
  50
  51 NS_IMETHODIMP
  52 MemoryOutputStream::WriteFrom(nsIInputStream* aFromStream, uint32_t aCount,
  53                               uint32_t* _retval)
  54 {
  55   return NS_ERROR_NOT_IMPLEMENTED;
  56 }
  57
  58 NS_IMETHODIMP
  59 MemoryOutputStream::WriteSegments(nsReadSegmentFun aReader, void* aClosure,
  60                                   uint32_t aCount, uint32_t* _retval)
  61 {
  62   NS_ASSERTION(mData.Length() >= mOffset, "Bad stream state!");
  63
  64   uint32_t maxCount = mData.Length() - mOffset;
  65   if (maxCount == 0) {
  66     *_retval = 0;
  67     return NS_OK;
  68   }
  69
  70   if (aCount > maxCount) {
  71     aCount = maxCount;
  72   }
  73
  74   nsresult rv = aReader(this, aClosure, mData.BeginWriting() + mOffset, 0,
  75                         aCount, _retval);
  76   if (NS_SUCCEEDED(rv)) {
  77     NS_ASSERTION(*_retval <= aCount,
  78                  "Reader should not read more than we asked it to read!");
  79     mOffset += *_retval;
  80   }
  81
  82   return NS_OK;
  83 }
  84
  85 NS_IMETHODIMP
  86 MemoryOutputStream::IsNonBlocking(bool* _retval)
  87 {
  88   *_retval = false;
  89   return NS_OK;
  90 }