1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * uncompress.c
4 *
5 * (C) Copyright 1999 Linus Torvalds
6 *
7 * cramfs interfaces to the uncompression library. There's really just
8 * three entrypoints:
9 *
10 * - cramfs_uncompress_init() - called to initialize the thing.
11 * - cramfs_uncompress_exit() - tell me when you're done
12 * - cramfs_uncompress_block() - uncompress a block.
13 *
14 * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We
15 * only have one stream, and we'll initialize it only once even if it
16 * then is used by multiple filesystems.
17 */
18
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/kernel.h>
22 #include <linux/errno.h>
23 #include <linux/vmalloc.h>
24 #include <linux/zlib.h>
25 #include "internal.h"
26
27 static z_stream stream;
28 static int initialized;
29
30 /* Returns length of decompressed data. */
31 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen)
32 {
33 int err;
34
35 stream.next_in = src;
36 stream.avail_in = srclen;
37
38 stream.next_out = dst;
39 stream.avail_out = dstlen;
40
41 err = zlib_inflateReset(&stream);
42 if (err != Z_OK) {
43 pr_err("zlib_inflateReset error %d\n", err);
44 zlib_inflateEnd(&stream);
45 zlib_inflateInit(&stream);
46 }
47
48 err = zlib_inflate(&stream, Z_FINISH);
49 if (err != Z_STREAM_END)
50 goto err;
51 return stream.total_out;
52
53 err:
54 pr_err("Error %d while decompressing!\n", err);
55 pr_err("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
56 return -EIO;
57 }
58
59 int cramfs_uncompress_init(void)
60 {
61 if (!initialized++) {
62 stream.workspace = vmalloc(zlib_inflate_workspacesize());
63 if (!stream.workspace) {
64 initialized = 0;
65 return -ENOMEM;
66 }
67 stream.next_in = NULL;
68 stream.avail_in = 0;
69 zlib_inflateInit(&stream);
70 }
71 return 0;
72 }
73
74 void cramfs_uncompress_exit(void)
75 {
76 if (!--initialized) {
77 zlib_inflateEnd(&stream);
78 vfree(stream.workspace);
79 }
80 }
81
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