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1 /*
2 * uncompress.c
3 *
4 * (C) Copyright 1999 Linus Torvalds
5 *
6 * cramfs interfaces to the uncompression library. There's really just
7 * three entrypoints:
8 *
9 * - cramfs_uncompress_init() - called to initialize the thing.
10 * - cramfs_uncompress_exit() - tell me when you're done
11 * - cramfs_uncompress_block() - uncompress a block.
12 *
13 * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
14 * only have one stream, and we'll initialize it only once even if it
15 * then is used by multiple filesystems.
16 */
17
18 #include <linux/kernel.h>
19 #include <linux/errno.h>
20 #include <linux/vmalloc.h>
21 #include <linux/zlib.h>
22 #include <linux/cramfs_fs.h>
23
24 static z_stream stream;
25 static int initialized;
26
27 /* Returns length of decompressed data. */
28 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
29 {
30 int err;
31
32 stream.next_in = src;
33 stream.avail_in = srclen;
34
35 stream.next_out = dst;
36 stream.avail_out = dstlen;
37
38 err = zlib_inflateReset(&stream);
39 if (err != Z_OK) {
40 printk("zlib_inflateReset error %d\n", err);
41 zlib_inflateEnd(&stream);
42 zlib_inflateInit(&stream);
43 }
44
45 err = zlib_inflate(&stream, Z_FINISH);
46 if (err != Z_STREAM_END)
47 goto err;
48 return stream.total_out;
49
50 err:
51 printk("Error %d while decompressing!\n", err);
52 printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
53 return 0;
54 }
55
56 int cramfs_uncompress_init(void)
57 {
58 if (!initialized++) {
59 stream.workspace = vmalloc(zlib_inflate_workspacesize());
60 if ( !stream.workspace ) {
61 initialized = 0;
62 return -ENOMEM;
63 }
64 stream.next_in = NULL;
65 stream.avail_in = 0;
66 zlib_inflateInit(&stream);
67 }
68 return 0;
69 }
70
71 int cramfs_uncompress_exit(void)
72 {
73 if (!--initialized) {
74 zlib_inflateEnd(&stream);
75 vfree(stream.workspace);
76 }
77 return 0;
78 }