1// SPDX-License-Identifier: GPL-2.0
2#include <linux/zlib.h>
3
4/* bits taken from ppc */
5
6extern void *avail_ram, *end_avail;
7void gunzip(void *dst, int dstlen, unsigned char *src, int *lenp);
8
9static void exit(void)
10{
11  for (;;);
12}
13
14static void *zalloc(unsigned int size)
15{
16        void *p = avail_ram;
17
18        size = (size + 7) & -8;
19        avail_ram += size;
20        if (avail_ram > end_avail) {
21                //puts("oops... out of memory\n");
22                //pause();
23                exit ();
24        }
25        return p;
26}
27
28#define HEAD_CRC        2
29#define EXTRA_FIELD     4
30#define ORIG_NAME       8
31#define COMMENT         0x10
32#define RESERVED        0xe0
33
34#define DEFLATED        8
35
36void gunzip (void *dst, int dstlen, unsigned char *src, int *lenp)
37{
38	z_stream s;
39	int r, i, flags;
40
41        /* skip header */
42        i = 10;
43        flags = src[3];
44        if (src[2] != DEFLATED || (flags & RESERVED) != 0) {
45                //puts("bad gzipped data\n");
46                exit();
47        }
48        if ((flags & EXTRA_FIELD) != 0)
49                i = 12 + src[10] + (src[11] << 8);
50        if ((flags & ORIG_NAME) != 0)
51                while (src[i++] != 0)
52                        ;
53        if ((flags & COMMENT) != 0)
54                while (src[i++] != 0)
55                        ;
56        if ((flags & HEAD_CRC) != 0)
57                i += 2;
58        if (i >= *lenp) {
59                //puts("gunzip: ran out of data in header\n");
60                exit();
61        }
62
63	s.workspace = zalloc(zlib_inflate_workspacesize());
64        r = zlib_inflateInit2(&s, -MAX_WBITS);
65        if (r != Z_OK) {
66                //puts("inflateInit2 returned "); puthex(r); puts("\n");
67                exit();
68        }
69        s.next_in = src + i;
70        s.avail_in = *lenp - i;
71        s.next_out = dst;
72        s.avail_out = dstlen;
73        r = zlib_inflate(&s, Z_FINISH);
74        if (r != Z_OK && r != Z_STREAM_END) {
75                //puts("inflate returned "); puthex(r); puts("\n");
76                exit();
77        }
78        *lenp = s.next_out - (unsigned char *) dst;
79        zlib_inflateEnd(&s);
80}
81
82