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/bio.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 bio * bio,int offset,int length,struct squashfs_page_actor * output)52 static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
53 	struct bio *bio, int offset, int length,
54 	struct squashfs_page_actor *output)
55 {
56 	struct bvec_iter_all iter_all = {};
57 	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
58 	int zlib_init = 0, error = 0;
59 	z_stream *stream = strm;
60 
61 	stream->avail_out = PAGE_SIZE;
62 	stream->next_out = squashfs_first_page(output);
63 	stream->avail_in = 0;
64 
65 	if (IS_ERR(stream->next_out)) {
66 		error = PTR_ERR(stream->next_out);
67 		goto finish;
68 	}
69 
70 	for (;;) {
71 		int zlib_err;
72 
73 		if (stream->avail_in == 0) {
74 			const void *data;
75 			int avail;
76 
77 			if (!bio_next_segment(bio, &iter_all)) {
78 				/* Z_STREAM_END must be reached. */
79 				error = -EIO;
80 				break;
81 			}
82 
83 			avail = min(length, ((int)bvec->bv_len) - offset);
84 			data = bvec_virt(bvec);
85 			length -= avail;
86 			stream->next_in = data + offset;
87 			stream->avail_in = avail;
88 			offset = 0;
89 		}
90 
91 		if (stream->avail_out == 0) {
92 			stream->next_out = squashfs_next_page(output);
93 			if (IS_ERR(stream->next_out)) {
94 				error = PTR_ERR(stream->next_out);
95 				break;
96 			} else if (stream->next_out != NULL)
97 				stream->avail_out = PAGE_SIZE;
98 		}
99 
100 		if (!zlib_init) {
101 			zlib_err = zlib_inflateInit(stream);
102 			if (zlib_err != Z_OK) {
103 				error = -EIO;
104 				break;
105 			}
106 			zlib_init = 1;
107 		}
108 
109 		zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
110 		if (zlib_err == Z_STREAM_END)
111 			break;
112 		if (zlib_err != Z_OK) {
113 			error = -EIO;
114 			break;
115 		}
116 	}
117 
118 finish:
119 	squashfs_finish_page(output);
120 
121 	if (!error)
122 		if (zlib_inflateEnd(stream) != Z_OK)
123 			error = -EIO;
124 
125 	return error ? error : stream->total_out;
126 }
127 
128 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
129 	.init = zlib_init,
130 	.free = zlib_free,
131 	.decompress = zlib_uncompress,
132 	.id = ZLIB_COMPRESSION,
133 	.name = "zlib",
134 	.alloc_buffer = 1,
135 	.supported = 1
136 };
137 
138