/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <flate.h>#include "zlib.h" typedef struct ZRead	ZRead; struct ZRead{	ulong	adler;	void	*rr;	int	(*r)(void*, void*, int);}; static intzlread(void *vzr, void *buf, int n){	ZRead *zr; 	zr = vzr;	n = (*zr->r)(zr->rr, buf, n);	if(n <= 0)		return n;	zr->adler = adler32(zr->adler, buf, n);	return n;} intdeflatezlib(void *wr, int (*w)(void*, void*, int), void *rr, int (*r)(void*, void*, int), int level, int debug){	ZRead zr;	uchar buf[4];	int ok; 	buf[0] = ZlibDeflate | ZlibWin32k; 	/* bogus zlib encoding of compression level */	buf[1] = ((level > 2) + (level > 5) + (level > 8)) << 6; 	/* header check field */	buf[1] |= 31 - ((buf[0] << 8) | buf[1]) % 31;	if((*w)(wr, buf, 2) != 2)		return FlateOutputFail; 	zr.rr = rr;	zr.r = r;	zr.adler = 1;	ok = deflate(wr, w, &zr, zlread, level, debug);	if(ok != FlateOk)		return ok; 	buf[0] = zr.adler >> 24;	buf[1] = zr.adler >> 16;	buf[2] = zr.adler >> 8;	buf[3] = zr.adler;	if((*w)(wr, buf, 4) != 4)		return FlateOutputFail; 	return FlateOk;}