// The version of this program that appeared in the first and second
// printings did not comply with the proposed rules for passing
// pointers between Go and C, described here:
// The rules forbid a C function like bz2compress from storing 'in'
// and 'out' (pointers to variables allocated by Go) into the Go
// variable 's', even temporarily.
// The version below, which appears in the third printing, has been
// corrected. To comply with the rules, the bz_stream variable must
// be allocated by C code. We have introduced two C functions,
// bz2alloc and bz2free, to allocate and free instances of the
// bz_stream type. Also, we have changed bz2compress so that before
// it returns, it clears the fields of the bz_stream that contain
// pointers to Go variables.