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)