Stream.cpp

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/*
 * 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.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
 
#include <Stream.h>
 
#include <cstdio>  /* printf */
#include <cstring> /* memcpy */
 
static const char *msg_error_seek = "DDS: trying to seek beyond end of stream (corrupt file?)";
static const char *msg_error_read = "DDS: trying to read beyond end of stream (corrupt file?)";
 
inline bool is_read_within_bounds(const Stream &mem, unsigned int cnt)
{
  if (mem.pos >= mem.size) {
    /* No more data remained in the memory buffer. */
    return false;
  }
 
  if (cnt > mem.size - mem.pos) {
    /* Reading past the memory bounds. */
    return false;
  }
 
  return true;
}
 
unsigned int Stream::seek(unsigned int p)
{
  if (p > size) {
    set_failed(msg_error_seek);
  }
  else {
    pos = p;
  }
 
  return pos;
}
 
unsigned int mem_read(Stream &mem, unsigned long long &i)
{
  if (!is_read_within_bounds(mem, 8)) {
    mem.set_failed(msg_error_seek);
    return 0;
  }
  memcpy(&i, mem.mem + mem.pos, 8); /* @@ todo: make sure little endian */
  mem.pos += 8;
  return 8;
}
 
unsigned int mem_read(Stream &mem, unsigned int &i)
{
  if (!is_read_within_bounds(mem, 4)) {
    mem.set_failed(msg_error_read);
    return 0;
  }
  memcpy(&i, mem.mem + mem.pos, 4); /* @@ todo: make sure little endian */
  mem.pos += 4;
  return 4;
}
 
unsigned int mem_read(Stream &mem, unsigned short &i)
{
  if (!is_read_within_bounds(mem, 2)) {
    mem.set_failed(msg_error_read);
    return 0;
  }
  memcpy(&i, mem.mem + mem.pos, 2); /* @@ todo: make sure little endian */
  mem.pos += 2;
  return 2;
}
 
unsigned int mem_read(Stream &mem, unsigned char &i)
{
  if (!is_read_within_bounds(mem, 1)) {
    mem.set_failed(msg_error_read);
    return 0;
  }
  i = (mem.mem + mem.pos)[0];
  mem.pos += 1;
  return 1;
}
 
unsigned int mem_read(Stream &mem, unsigned char *i, unsigned int cnt)
{
  if (!is_read_within_bounds(mem, cnt)) {
    mem.set_failed(msg_error_read);
    return 0;
  }
  memcpy(i, mem.mem + mem.pos, cnt);
  mem.pos += cnt;
  return cnt;
}
 
void Stream::set_failed(const char *msg)
{
  if (!failed) {
    puts(msg);
    failed = true;
  }
}