Linux-2.6.12-rc2
[linux-2.6.git] / fs / cramfs / uncompress.c
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
23 static z_stream stream;
24 static int initialized;
25
26 /* Returns length of decompressed data. */
27 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
28 {
29         int err;
30
31         stream.next_in = src;
32         stream.avail_in = srclen;
33
34         stream.next_out = dst;
35         stream.avail_out = dstlen;
36
37         err = zlib_inflateReset(&stream);
38         if (err != Z_OK) {
39                 printk("zlib_inflateReset error %d\n", err);
40                 zlib_inflateEnd(&stream);
41                 zlib_inflateInit(&stream);
42         }
43
44         err = zlib_inflate(&stream, Z_FINISH);
45         if (err != Z_STREAM_END)
46                 goto err;
47         return stream.total_out;
48
49 err:
50         printk("Error %d while decompressing!\n", err);
51         printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
52         return 0;
53 }
54
55 int cramfs_uncompress_init(void)
56 {
57         if (!initialized++) {
58                 stream.workspace = vmalloc(zlib_inflate_workspacesize());
59                 if ( !stream.workspace ) {
60                         initialized = 0;
61                         return -ENOMEM;
62                 }
63                 stream.next_in = NULL;
64                 stream.avail_in = 0;
65                 zlib_inflateInit(&stream);
66         }
67         return 0;
68 }
69
70 int cramfs_uncompress_exit(void)
71 {
72         if (!--initialized) {
73                 zlib_inflateEnd(&stream);
74                 vfree(stream.workspace);
75         }
76         return 0;
77 }