1 #include <u.h>
2 #include <libc.h>
3 #include <flate.h>
4 #include "zlib.h"
5 
6 typedef struct ZRead	ZRead;
7 
8 struct ZRead
9 {
10 	ulong	adler;
11 	void	*rr;
12 	int	(*r)(void*, void*, int);
13 };
14 
15 static int
16 zlread(void *vzr, void *buf, int n)
17 {
18 	ZRead *zr;
19 
20 	zr = vzr;
21 	n = (*zr->r)(zr->rr, buf, n);
22 	if(n <= 0)
23 		return n;
24 	zr->adler = adler32(zr->adler, buf, n);
25 	return n;
26 }
27 
28 int
29 deflatezlib(void *wr, int (*w)(void*, void*, int), void *rr, int (*r)(void*, void*, int), int level, int debug)
30 {
31 	ZRead zr;
32 	uchar buf[4];
33 	int ok;
34 
35 	buf[0] = ZlibDeflate | ZlibWin32k;
36 
37 	/* bogus zlib encoding of compression level */
38 	buf[1] = ((level > 2) + (level > 5) + (level > 8)) << 6;
39 
40 	/* header check field */
41 	buf[1] |= 31 - ((buf[0] << 8) | buf[1]) % 31;
42 	if((*w)(wr, buf, 2) != 2)
43 		return FlateOutputFail;
44 
45 	zr.rr = rr;
46 	zr.r = r;
47 	zr.adler = 1;
48 	ok = deflate(wr, w, &zr, zlread, level, debug);
49 	if(ok != FlateOk)
50 		return ok;
51 
52 	buf[0] = zr.adler >> 24;
53 	buf[1] = zr.adler >> 16;
54 	buf[2] = zr.adler >> 8;
55 	buf[3] = zr.adler;
56 	if((*w)(wr, buf, 4) != 4)
57 		return FlateOutputFail;
58 
59 	return FlateOk;
60 }