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
zlread(void * vzr,void * buf,int n)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
deflatezlib(void * wr,int (* w)(void *,void *,int),void * rr,int (* r)(void *,void *,int),int level,int debug)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 }
61