1 #include <u.h>
2 #include <libc.h>
3 #include <flate.h>
4 #include "zlib.h"
5 
6 typedef struct Block	Block;
7 
8 struct Block
9 {
10 	uchar	*pos;
11 	uchar	*limit;
12 };
13 
14 static int
15 blgetc(void *vb)
16 {
17 	Block *b;
18 
19 	b = vb;
20 	if(b->pos >= b->limit)
21 		return -1;
22 	return *b->pos++;
23 }
24 
25 static int
26 blwrite(void *vb, void *buf, int n)
27 {
28 	Block *b;
29 
30 	b = vb;
31 
32 	if(n > b->limit - b->pos)
33 		n = b->limit - b->pos;
34 	memmove(b->pos, buf, n);
35 	b->pos += n;
36 	return n;
37 }
38 
39 int
40 inflatezlibblock(uchar *dst, int dsize, uchar *src, int ssize)
41 {
42 	Block bd, bs;
43 	int ok;
44 
45 	if(ssize < 6)
46 		return FlateInputFail;
47 
48 	if(((src[0] << 8) | src[1]) % 31)
49 		return FlateCorrupted;
50 	if((src[0] & ZlibMeth) != ZlibDeflate
51 	|| (src[0] & ZlibCInfo) > ZlibWin32k)
52 		return FlateCorrupted;
53 
54 	bs.pos = src + 2;
55 	bs.limit = src + ssize - 6;
56 
57 	bd.pos = dst;
58 	bd.limit = dst + dsize;
59 
60 	ok = inflate(&bd, blwrite, &bs, blgetc);
61 	if(ok != FlateOk)
62 		return ok;
63 
64 	if(adler32(1, dst, bs.pos - dst) != ((bs.pos[0] << 24) | (bs.pos[1] << 16) | (bs.pos[2] << 8) | bs.pos[3]))
65 		return FlateCorrupted;
66 
67 	return bd.pos - dst;
68 }