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. */
cramfs_uncompress_block(void * dst,int dstlen,void * src,int srclen)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 
cramfs_uncompress_init(void)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 
cramfs_uncompress_exit(void)74 void cramfs_uncompress_exit(void)
75 {
76 	if (!--initialized) {
77 		zlib_inflateEnd(&stream);
78 		vfree(stream.workspace);
79 	}
80 }
81