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
  30   if (prefix_length_ >= count) {
  31     // Read is fully satisfied by the prefix.
  32     std::copy(prefix_, prefix_ + count, out);
  33     prefix_ += count;
  34     prefix_length_ -= count;
  35     return true;
  36   } else if (prefix_length_ != 0) {
  37     // Read is partially satisfied by the prefix.
  38     out = std::copy(prefix_, prefix_ + prefix_length_, out);
  39     count -= prefix_length_;
  40     prefix_length_ = 0;
  41     // Fallthrough to suffix read.
  42   }
  43   DCHECK(suffix_length_ >= count);
  44   // Read is satisfied by the suffix.
  45   std::copy(suffix_, suffix_ + count, out);
  46   suffix_ += count;
  47   suffix_length_ -= count;
  48   return true;
  49 }
  50
  51 bool SpdyPrefixedBufferReader::ReadN(size_t count,
  52                                      SpdyPinnableBufferPiece* out) {
  53   if (Available() < count) {
  54     return false;
  55   }
  56
  57   out->storage_.reset();
  58   out->length_ = count;
  59
  60   if (prefix_length_ >= count) {
  61     // Read is fully satisfied by the prefix.
  62     out->buffer_ = prefix_;
  63     prefix_ += count;
  64     prefix_length_ -= count;
  65     return true;
  66   } else if (prefix_length_ != 0) {
  67     // Read is only partially satisfied by the prefix. We need to allocate
  68     // contiguous storage as the read spans the prefix & suffix.
  69     out->storage_.reset(new char[count]);
  70     out->buffer_ = out->storage_.get();
  71     ReadN(count, out->storage_.get());
  72     return true;
  73   } else {
  74     DCHECK(suffix_length_ >= count);
  75     // Read is fully satisfied by the suffix.
  76     out->buffer_ = suffix_;
  77     suffix_ += count;
  78     suffix_length_ -= count;
  79     return true;
  80   }
  81 }
  82
  83 }  // namespace net