* and may be truncated if the buffer is too small.
*
* @param s the read-only AVIOContext
* @param buf buffer to store the read line
* @param maxlen size of the buffer
* @return the length of the string written in the buffer, not including the
* and may be truncated if the buffer is too small.
*
* @param s the read-only AVIOContext
* @param buf buffer to store the read line
* @param maxlen size of the buffer
* @return the length of the string written in the buffer, not including the