net/spdy/spdy_prefixed_buffer_reader.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/spdy/spdy_prefixed_buffer_reader.h"
   6
   7 #include "base/logging.h"
   8
   9 namespace net {
  10
  11 SpdyPrefixedBufferReader::SpdyPrefixedBufferReader(
  12     const char* prefix,
  13     size_t prefix_length,
  14     const char* suffix,
  15     size_t suffix_length)
  16     : prefix_(prefix),
  17       suffix_(suffix),
  18       prefix_length_(prefix_length),
  19       suffix_length_(suffix_length) {}
  20
  21 size_t SpdyPrefixedBufferReader::Available() {
  22   return prefix_length_ + suffix_length_;
  23 }
  24
  25 bool SpdyPrefixedBufferReader::ReadN(size_t count, char* out) {
  26   if (Available() < count)
  27     return false;
  28
  29   if (prefix_length_ >= count) {
  30     // Read is fully satisfied by the prefix.
  31     std::copy(prefix_, prefix_ + count, out);
  32     prefix_ += count;
  33     prefix_length_ -= count;
  34     return true;
  35   } else if (prefix_length_ != 0) {
  36     // Read is partially satisfied by the prefix.
  37     out = std::copy(prefix_, prefix_ + prefix_length_, out);
  38     count -= prefix_length_;
  39     prefix_length_ = 0;
  40     // Fallthrough to suffix read.
  41   }
  42   DCHECK(suffix_length_ >= count);
  43   // Read is satisfied by the suffix.
  44   std::copy(suffix_, suffix_ + count, out);
  45   suffix_ += count;
  46   suffix_length_ -= count;
  47   return true;
  48 }
  49
  50 bool SpdyPrefixedBufferReader::ReadN(size_t count,
  51                                      SpdyPinnableBufferPiece* out) {
  52   if (Available() < count)
  53     return false;
  54
  55   out->storage_.reset();
  56   out->length_ = count;
  57
  58   if (prefix_length_ >= count) {
  59     // Read is fully satisfied by the prefix.
  60     out->buffer_ = prefix_;
  61     prefix_ += count;
  62     prefix_length_ -= count;
  63     return true;
  64   } else if (prefix_length_ != 0) {
  65     // Read is only partially satisfied by the prefix. We need to allocate
  66     // contiguous storage as the read spans the prefix & suffix.
  67     out->storage_.reset(new char[count]);
  68     out->buffer_ = out->storage_.get();
  69     ReadN(count, out->storage_.get());
  70     return true;
  71   } else {
  72     DCHECK(suffix_length_ >= count);
  73     // Read is fully satisfied by the suffix.
  74     out->buffer_ = suffix_;
  75     suffix_ += count;
  76     suffix_length_ -= count;
  77     return true;
  78   }
  79 }
  80
  81 }  // namespace net