root/branches/3.00/src/archive_tar_file.cc

/*
 * Copyright (c) 2001, Robert Collins 
 *
 *     This program is free software; you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation; either version 2 of the License, or
 *     (at your option) any later version.
 *
 *     A copy of the GNU General Public License can be found at
 *     http://www.gnu.org/
 *
 * Written by Robert Collins <rbtcollins@hotmail.com>
 *
 */

/* An individual stream from a tar archive. */

#if 0
static const char *cvsid = "\n%%% $Id: archive_tar_file.cc,v 2.8 2004/11/18 01:19:09 maxb Exp $\n";
#endif

#include <errno.h>
#include <algorithm>

#include "zlib/zlib.h"
#include "io_stream.h"
#include "compress.h"
#include "archive.h"
#include "archive_tar.h"
#include "log.h"

archive_tar_file::archive_tar_file (tar_state & newstate):state (newstate)
{
}

archive_tar_file::~archive_tar_file ()
{
  state.header_read = 0;
}

/* Virtual memebrs */
ssize_t archive_tar_file::read (void *buffer, size_t len)
{
  /* how many bytes do we want to give the user */
  int
    want = std::min (len, state.file_length - state.file_offset);
  /* how many do we need to read after that to line up the file pointer */
  int
    roundup = (512 - (want % 512)) % 512;
  if (want)
    {
      ssize_t
        got = state.parent->read (buffer, want);
      char
        throwaway[512];
      ssize_t
        got2 = state.parent->read (throwaway, roundup);
      if (got == want && got2 == roundup)
        {
          state.file_offset += got;
          return got;
        }
      else
        {
          /* unexpected EOF or read error in the tar parent stream */
          /* the user can query the parent for the error */
          state.lasterr = EIO;
          return EIO;
        }
    }
  return 0;
}

/* provide data to (double duh!) */
ssize_t archive_tar_file::write (const void *buffer, size_t len)
{
  /* write not supported */
  return EBADF;
}

/* read data without removing it from the class's internal buffer */
ssize_t archive_tar_file::peek (void *buffer, size_t len)
{
  int
    want = std::min (len, state.file_length - state.file_offset);
  if (want)
    {
      ssize_t
        got = state.parent->peek (buffer, want);
      if (got == want)
        {
          return got;
        }
      else
        {
          /* unexpected EOF or read error in the tar parent stream */
          /* the user can query the parent for the error */
          state.lasterr = EIO;
          return EIO;
        }
    }
  return 0;
}

long
archive_tar_file::tell ()
{
  return state.file_offset;
}

int
archive_tar_file::seek (long where, io_stream_seek_t whence)
{
  /* nothing needs seeking here yet. Implement when needed 
   */
  return -1;
}

/* try guessing this one */
int
archive_tar_file::error ()
{
  return state.lasterr;
}

int
archive_tar_file::get_mtime ()
{
  int mtime;
  sscanf (state.tar_header.mtime, "%o", &mtime);
  return mtime;
}