static void jas_stream_initbuf(jas_stream_t *stream, int bufmode, char *buf,
  int bufsize)
{
	/* If this function is being called, the buffer should not have been
	  initialized yet. */
	assert(!stream->bufbase_);

	if (bufmode != JAS_STREAM_UNBUF) {
		/* The full- or line-buffered mode is being employed. */
		if (!buf) {
			/* The caller has not specified a buffer to employ, so allocate
			  one. */
			if ((stream->bufbase_ = jas_malloc(JAS_STREAM_BUFSIZE +
			  JAS_STREAM_MAXPUTBACK))) {
				stream->bufmode_ |= JAS_STREAM_FREEBUF;
				stream->bufsize_ = JAS_STREAM_BUFSIZE;
			} else {
				/* The buffer allocation has failed.  Resort to unbuffered
				  operation. */
				stream->bufbase_ = stream->tinybuf_;
				stream->bufsize_ = 1;
			}
		} else {
			/* The caller has specified a buffer to employ. */
			/* The buffer must be large enough to accommodate maximum
			  putback. */
			assert(bufsize > JAS_STREAM_MAXPUTBACK);
			stream->bufbase_ = JAS_CAST(jas_uchar *, buf);
			stream->bufsize_ = bufsize - JAS_STREAM_MAXPUTBACK;
		}
	} else {
		/* The unbuffered mode is being employed. */
		/* A buffer should not have been supplied by the caller. */
		assert(!buf);
		/* Use a trivial one-character buffer. */
		stream->bufbase_ = stream->tinybuf_;
		stream->bufsize_ = 1;
	}
	stream->bufstart_ = &stream->bufbase_[JAS_STREAM_MAXPUTBACK];
	stream->ptr_ = stream->bufstart_;
	stream->cnt_ = 0;
	stream->bufmode_ |= bufmode & JAS_STREAM_BUFMODEMASK;
}
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.