base/transformadapter.cc

/*
 * libjingle
 * Copyright 2004--2005, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "talk/base/transformadapter.h"

#include <string.h>

#include "talk/base/common.h"

namespace talk_base {

///////////////////////////////////////////////////////////////////////////////

TransformAdapter::TransformAdapter(StreamInterface * stream,
                                   TransformInterface * transform,
                                   bool direction_read)
    : StreamAdapterInterface(stream), transform_(transform),
      direction_read_(direction_read), state_(ST_PROCESSING), len_(0) {
}

TransformAdapter::~TransformAdapter() {
  TransformAdapter::Close();
  delete transform_;
}

StreamResult
TransformAdapter::Read(void * buffer, size_t buffer_len,
                       size_t * read, int * error) {
  if (!direction_read_)
    return SR_EOS;

  while (state_ != ST_ERROR) {
    if (state_ == ST_COMPLETE)
      return SR_EOS;

    // Buffer more data
    if ((state_ == ST_PROCESSING) && (len_ < sizeof(buffer_))) {
      size_t subread;
      StreamResult result = StreamAdapterInterface::Read(
                              buffer_ + len_,
                              sizeof(buffer_) - len_,
                              &subread,
                              &error_);
      if (result == SR_BLOCK) {
        return SR_BLOCK;
      } else if (result == SR_ERROR) {
        state_ = ST_ERROR;
        break;
      } else if (result == SR_EOS) {
        state_ = ST_FLUSHING;
      } else {
        len_ += subread;
      }
    }

    // Process buffered data
    size_t in_len = len_;
    size_t out_len = buffer_len;
    StreamResult result = transform_->Transform(buffer_, &in_len,
                                                buffer, &out_len,
                                                (state_ == ST_FLUSHING));
    ASSERT(result != SR_BLOCK);
    if (result == SR_EOS) {
      // Note: Don't signal SR_EOS this iteration, unless out_len is zero
      state_ = ST_COMPLETE;
    } else if (result == SR_ERROR) {
      state_ = ST_ERROR;
      error_ = -1; // TODO: propagate error
      break;
    } else if ((out_len == 0) && (state_ == ST_FLUSHING)) {
      // If there is no output AND no more input, then something is wrong
      state_ = ST_ERROR;
      error_ = -1; // TODO: better error code?
      break;
    }

    len_ -= in_len;
    if (len_ > 0)
      memmove(buffer_, buffer_ + in_len, len_);

    if (out_len == 0)
      continue;

    if (read)
      *read = out_len;
    return SR_SUCCESS;
  }

  if (error)
    *error = error_;
  return SR_ERROR;
}

StreamResult
TransformAdapter::Write(const void * data, size_t data_len,
                        size_t * written, int * error) {
  if (direction_read_)
    return SR_EOS;

  size_t bytes_written = 0;
  while (state_ != ST_ERROR) {
    if (state_ == ST_COMPLETE)
      return SR_EOS;

    if (len_ < sizeof(buffer_)) {
      // Process buffered data
      size_t in_len = data_len;
      size_t out_len = sizeof(buffer_) - len_;
      StreamResult result = transform_->Transform(data, &in_len,
                                                  buffer_ + len_, &out_len,
                                                  (state_ == ST_FLUSHING));

      ASSERT(result != SR_BLOCK);
      if (result == SR_EOS) {
        // Note: Don't signal SR_EOS this iteration, unless no data written
        state_ = ST_COMPLETE;
      } else if (result == SR_ERROR) {
        ASSERT(false); // When this happens, think about what should be done
        state_ = ST_ERROR;
        error_ = -1; // TODO: propagate error
        break;
      }

      len_ = out_len;
      bytes_written = in_len;
    }

    size_t pos = 0;
    while (pos < len_) {
      size_t subwritten;
      StreamResult result = StreamAdapterInterface::Write(buffer_ + pos,
                                                          len_ - pos,
                                                          &subwritten,
                                                          &error_);
      if (result == SR_BLOCK) {
        ASSERT(false); // TODO: we should handle this
        return SR_BLOCK;
      } else if (result == SR_ERROR) {
        state_ = ST_ERROR;
        break;
      } else if (result == SR_EOS) {
        state_ = ST_COMPLETE;
        break;
      }

      pos += subwritten;
    }

    len_ -= pos;
    if (len_ > 0)
      memmove(buffer_, buffer_ + pos, len_);

    if (bytes_written == 0)
      continue;

    if (written)
      *written = bytes_written;
    return SR_SUCCESS;
  }

  if (error)
    *error = error_;
  return SR_ERROR;
}

void
TransformAdapter::Close() {
  if (!direction_read_ && (state_ == ST_PROCESSING)) {
    state_ = ST_FLUSHING;
    do {
      Write(0, 0, NULL, NULL);
    } while (state_ == ST_FLUSHING);
  }
  state_ = ST_COMPLETE;
  StreamAdapterInterface::Close();
}

} // namespace talk_base