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1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Squashfs - a compressed read only filesystem for Linux
4  *
5  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
6  * Phillip Lougher <phillip@squashfs.org.uk>
7  *
8  * zlib_wrapper.c
9  */
10 
11 
12 #include <linux/mutex.h>
13 #include <linux/buffer_head.h>
14 #include <linux/slab.h>
15 #include <linux/zlib.h>
16 #include <linux/vmalloc.h>
17 
18 #include "squashfs_fs.h"
19 #include "squashfs_fs_sb.h"
20 #include "squashfs.h"
21 #include "decompressor.h"
22 #include "page_actor.h"
23 
zlib_init(struct squashfs_sb_info * dummy,void * buff)24 static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
25 {
26 	z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
27 	if (stream == NULL)
28 		goto failed;
29 	stream->workspace = vmalloc(zlib_inflate_workspacesize());
30 	if (stream->workspace == NULL)
31 		goto failed;
32 
33 	return stream;
34 
35 failed:
36 	ERROR("Failed to allocate zlib workspace\n");
37 	kfree(stream);
38 	return ERR_PTR(-ENOMEM);
39 }
40 
41 
zlib_free(void * strm)42 static void zlib_free(void *strm)
43 {
44 	z_stream *stream = strm;
45 
46 	if (stream)
47 		vfree(stream->workspace);
48 	kfree(stream);
49 }
50 
51 
zlib_uncompress(struct squashfs_sb_info * msblk,void * strm,struct buffer_head ** bh,int b,int offset,int length,struct squashfs_page_actor * output)52 static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
53 	struct buffer_head **bh, int b, int offset, int length,
54 	struct squashfs_page_actor *output)
55 {
56 	int zlib_err, zlib_init = 0, k = 0;
57 	z_stream *stream = strm;
58 
59 	stream->avail_out = PAGE_SIZE;
60 	stream->next_out = squashfs_first_page(output);
61 	stream->avail_in = 0;
62 
63 	do {
64 		if (stream->avail_in == 0 && k < b) {
65 			int avail = min(length, msblk->devblksize - offset);
66 			length -= avail;
67 			stream->next_in = bh[k]->b_data + offset;
68 			stream->avail_in = avail;
69 			offset = 0;
70 		}
71 
72 		if (stream->avail_out == 0) {
73 			stream->next_out = squashfs_next_page(output);
74 			if (stream->next_out != NULL)
75 				stream->avail_out = PAGE_SIZE;
76 		}
77 
78 		if (!zlib_init) {
79 			zlib_err = zlib_inflateInit(stream);
80 			if (zlib_err != Z_OK) {
81 				squashfs_finish_page(output);
82 				goto out;
83 			}
84 			zlib_init = 1;
85 		}
86 
87 		zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
88 
89 		if (stream->avail_in == 0 && k < b)
90 			put_bh(bh[k++]);
91 	} while (zlib_err == Z_OK);
92 
93 	squashfs_finish_page(output);
94 
95 	if (zlib_err != Z_STREAM_END)
96 		goto out;
97 
98 	zlib_err = zlib_inflateEnd(stream);
99 	if (zlib_err != Z_OK)
100 		goto out;
101 
102 	if (k < b)
103 		goto out;
104 
105 	return stream->total_out;
106 
107 out:
108 	for (; k < b; k++)
109 		put_bh(bh[k]);
110 
111 	return -EIO;
112 }
113 
114 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
115 	.init = zlib_init,
116 	.free = zlib_free,
117 	.decompress = zlib_uncompress,
118 	.id = ZLIB_COMPRESSION,
119 	.name = "zlib",
120 	.supported = 1
121 };
122 
123