I spent a while to sort out some integer results of the bzdecompress, so maybe it'll be useful for somebody else also...
(Constants from the sources.)
#define BZ_OK                0
#define BZ_RUN_OK            1
#define BZ_FLUSH_OK          2
#define BZ_FINISH_OK         3
#define BZ_STREAM_END        4
#define BZ_SEQUENCE_ERROR    (-1)
#define BZ_PARAM_ERROR       (-2)
#define BZ_MEM_ERROR         (-3)
#define BZ_DATA_ERROR        (-4)
#define BZ_DATA_ERROR_MAGIC  (-5)
#define BZ_IO_ERROR          (-6)
#define BZ_UNEXPECTED_EOF    (-7)
#define BZ_OUTBUFF_FULL      (-8)
#define BZ_CONFIG_ERROR      (-9)