netwerk/base/SimpleBuffer.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   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 "SimpleBuffer.h"
   8 #include <algorithm>
   9
  10 namespace mozilla {
  11 namespace net {
  12
  13 SimpleBuffer::SimpleBuffer() : mStatus(NS_OK), mAvailable(0) {}
  14
  15 nsresult SimpleBuffer::Write(char *src, size_t len) {
  16   NS_ASSERT_OWNINGTHREAD(SimpleBuffer);
  17   if (NS_FAILED(mStatus)) {
  18     return mStatus;
  19   }
  20
  21   while (len > 0) {
  22     SimpleBufferPage *p = mBufferList.getLast();
  23     if (p && (p->mWriteOffset == SimpleBufferPage::kSimpleBufferPageSize)) {
  24       // no room.. make a new page
  25       p = nullptr;
  26     }
  27     if (!p) {
  28       p = new (fallible) SimpleBufferPage();
  29       if (!p) {
  30         mStatus = NS_ERROR_OUT_OF_MEMORY;
  31         return mStatus;
  32       }
  33       mBufferList.insertBack(p);
  34     }
  35     size_t roomOnPage =
  36         SimpleBufferPage::kSimpleBufferPageSize - p->mWriteOffset;
  37     size_t toWrite = std::min(roomOnPage, len);
  38     memcpy(p->mBuffer + p->mWriteOffset, src, toWrite);
  39     src += toWrite;
  40     len -= toWrite;
  41     p->mWriteOffset += toWrite;
  42     mAvailable += toWrite;
  43   }
  44   return NS_OK;
  45 }
  46
  47 size_t SimpleBuffer::Read(char *dest, size_t maxLen) {
  48   NS_ASSERT_OWNINGTHREAD(SimpleBuffer);
  49   if (NS_FAILED(mStatus)) {
  50     return 0;
  51   }
  52
  53   size_t rv = 0;
  54   for (SimpleBufferPage *p = mBufferList.getFirst(); p && (rv < maxLen);
  55        p = mBufferList.getFirst()) {
  56     size_t avail = p->mWriteOffset - p->mReadOffset;
  57     size_t toRead = std::min(avail, (maxLen - rv));
  58     memcpy(dest + rv, p->mBuffer + p->mReadOffset, toRead);
  59     rv += toRead;
  60     p->mReadOffset += toRead;
  61     if (p->mReadOffset == p->mWriteOffset) {
  62       p->remove();
  63       delete p;
  64     }
  65   }
  66
  67   MOZ_ASSERT(mAvailable >= rv);
  68   mAvailable -= rv;
  69   return rv;
  70 }
  71
  72 size_t SimpleBuffer::Available() {
  73   NS_ASSERT_OWNINGTHREAD(SimpleBuffer);
  74   return NS_SUCCEEDED(mStatus) ? mAvailable : 0;
  75 }
  76
  77 void SimpleBuffer::Clear() {
  78   NS_ASSERT_OWNINGTHREAD(SimpleBuffer);
  79   SimpleBufferPage *p;
  80   while ((p = mBufferList.popFirst())) {
  81     delete p;
  82   }
  83   mAvailable = 0;
  84 }
  85
  86 }  // namespace net
  87 }  // namespace mozilla