memstream.cpp

/*
 * libopenraw - memstream.cpp
 *
 * Copyright (C) 2007-2018 Hubert Figuière
 *
 * This library is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see
 * <http://www.gnu.org/licenses/>.
 */
 
 
#include <string.h>
#include <stdio.h>
 
#include <libopenraw/consts.h>
#include <libopenraw/debug.h>
 
#include "memstream.hpp"
#include "trace.hpp"
 
using namespace Debug;
 
namespace OpenRaw {
namespace IO {
 
MemStream::MemStream(const uint8_t* ptr, size_t s)
  : Stream(""),
    m_ptr(ptr),
    m_size(s),
    m_current(nullptr)
{
}
 
or_error MemStream::open()
{
  m_current = m_ptr;
  return OR_ERROR_NONE;
}
 
 
int MemStream::close()
{
  m_current = nullptr;
  return 0;
}
 
int MemStream::seek(off_t offset, int whence)
{
  int newpos = 0;
//          LOGDBG1("MemStream::seek %ld bytes - whence = %d", offset, whence);
  // TODO check bounds
  if (m_current == nullptr) {
    // TODO set error code
    return -1;
  }
  switch (whence)
  {
  case SEEK_SET:
    m_current = m_ptr + offset;
    newpos = offset;
    break;
  case SEEK_END:
    m_current = m_ptr + m_size + offset;
    newpos = m_size + offset;
    break;
  case SEEK_CUR:
    m_current += offset;
    newpos = (m_current - m_ptr);
    break;
  default:
    return -1;
    break;
  }
  return newpos;
}
 
 
int MemStream::read(void *buf, size_t count)
{
  if ((m_current == nullptr) || (m_ptr == nullptr)) {
    LOGDBG1("MemStream::failed\n");
    return -1;
  }
 
  const uint8_t* end = m_ptr + m_size;
  if ((off_t)count > (end - m_current)) {
    count = end - m_current;
    // TODO set EOF
  }
  memcpy(buf, m_current, count);
  m_current += count;
  return count;
}
 
 
off_t MemStream::filesize()
{
  return m_size;
}
 
}
}
/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0))
  tab-width:2
  c-basic-offset:2
  indent-tabs-mode:nil
  fill-column:80
  End:
*/