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
blgetc(void * vb)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
blwrite(void * vb,void * buf,int n)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
inflatezlibblock(uchar * dst,int dsize,uchar * src,int ssize)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 }
69