+/** \brief read from block file (may call exit)
+ \param bf block file handle
+ \param no block no (first block is 0, second is 1..)
+ \param offset offset within block to be read
+ \param nbytes number of bytes to read (0 for whole block)
+ \param buf raw bytes with content (at least nbytes of size)
+ \retval 1 whole block could be read
+ \retval 0 whole block could not be read
+ */
+YAZ_EXPORT
+int bf_read(BFile bf, zint no, int offset, int nbytes, void *buf);
+