Man page 9 : xdr_buf_trim

xdr_buf_trim - lop at most « len » bytes off the end of « buf »

void xdr_buf_trim(struct xdr_buf *  buf , unsigned int  len );

buf
    buf to be trimmed

len
    number of bytes to reduce « buf » by

Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note that itAqs possible that weAqll trim less than that amount if the xdr_buf is too small, or if (for instance) itAqs all in the head and the parser has already read too far into it.