bzip2.c

// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/

// See page 362.
//
// 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:
// https://github.com/golang/proposal/blob/master/design/12416-cgo-pointers.md
//
// The version below, which appears in the third printing,
// has been corrected.  See bzip2.go for explanation.

//!+
/* This file is gopl.io/ch13/bzip/bzip2.c,         */
/* a simple wrapper for libbzip2 suitable for cgo. */
#include <bzlib.h>

int bz2compress(bz_stream *s, int action,
                char *in, unsigned *inlen, char *out, unsigned *outlen) {
  s->next_in = in;
  s->avail_in = *inlen;
  s->next_out = out;
  s->avail_out = *outlen;
  int r = BZ2_bzCompress(s, action);
  *inlen -= s->avail_in;
  *outlen -= s->avail_out;
  s->next_in = s->next_out = NULL;
  return r;
}

//!-