xref: /openbmc/linux/fs/squashfs/xz_wrapper.c (revision f268eedd)
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, 2010
6  * Phillip Lougher <phillip@squashfs.org.uk>
7  *
8  * xz_wrapper.c
9  */
10 
11 
12 #include <linux/mutex.h>
13 #include <linux/bio.h>
14 #include <linux/slab.h>
15 #include <linux/xz.h>
16 #include <linux/bitops.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 
24 struct squashfs_xz {
25 	struct xz_dec *state;
26 	struct xz_buf buf;
27 };
28 
29 struct disk_comp_opts {
30 	__le32 dictionary_size;
31 	__le32 flags;
32 };
33 
34 struct comp_opts {
35 	int dict_size;
36 };
37 
squashfs_xz_comp_opts(struct squashfs_sb_info * msblk,void * buff,int len)38 static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
39 	void *buff, int len)
40 {
41 	struct disk_comp_opts *comp_opts = buff;
42 	struct comp_opts *opts;
43 	int err = 0, n;
44 
45 	opts = kmalloc(sizeof(*opts), GFP_KERNEL);
46 	if (opts == NULL) {
47 		err = -ENOMEM;
48 		goto out2;
49 	}
50 
51 	if (comp_opts) {
52 		/* check compressor options are the expected length */
53 		if (len < sizeof(*comp_opts)) {
54 			err = -EIO;
55 			goto out;
56 		}
57 
58 		opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
59 
60 		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
61 		n = ffs(opts->dict_size) - 1;
62 		if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
63 						(1 << (n + 1))) {
64 			err = -EIO;
65 			goto out;
66 		}
67 	} else
68 		/* use defaults */
69 		opts->dict_size = max_t(int, msblk->block_size,
70 							SQUASHFS_METADATA_SIZE);
71 
72 	return opts;
73 
74 out:
75 	kfree(opts);
76 out2:
77 	return ERR_PTR(err);
78 }
79 
80 
squashfs_xz_init(struct squashfs_sb_info * msblk,void * buff)81 static void *squashfs_xz_init(struct squashfs_sb_info *msblk, void *buff)
82 {
83 	struct comp_opts *comp_opts = buff;
84 	struct squashfs_xz *stream;
85 	int err;
86 
87 	stream = kmalloc(sizeof(*stream), GFP_KERNEL);
88 	if (stream == NULL) {
89 		err = -ENOMEM;
90 		goto failed;
91 	}
92 
93 	stream->state = xz_dec_init(XZ_PREALLOC, comp_opts->dict_size);
94 	if (stream->state == NULL) {
95 		kfree(stream);
96 		err = -ENOMEM;
97 		goto failed;
98 	}
99 
100 	return stream;
101 
102 failed:
103 	ERROR("Failed to initialise xz decompressor\n");
104 	return ERR_PTR(err);
105 }
106 
107 
squashfs_xz_free(void * strm)108 static void squashfs_xz_free(void *strm)
109 {
110 	struct squashfs_xz *stream = strm;
111 
112 	if (stream) {
113 		xz_dec_end(stream->state);
114 		kfree(stream);
115 	}
116 }
117 
118 
squashfs_xz_uncompress(struct squashfs_sb_info * msblk,void * strm,struct bio * bio,int offset,int length,struct squashfs_page_actor * output)119 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void *strm,
120 	struct bio *bio, int offset, int length,
121 	struct squashfs_page_actor *output)
122 {
123 	struct bvec_iter_all iter_all = {};
124 	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
125 	int total = 0, error = 0;
126 	struct squashfs_xz *stream = strm;
127 
128 	xz_dec_reset(stream->state);
129 	stream->buf.in_pos = 0;
130 	stream->buf.in_size = 0;
131 	stream->buf.out_pos = 0;
132 	stream->buf.out_size = PAGE_SIZE;
133 	stream->buf.out = squashfs_first_page(output);
134 	if (IS_ERR(stream->buf.out)) {
135 		error = PTR_ERR(stream->buf.out);
136 		goto finish;
137 	}
138 
139 	for (;;) {
140 		enum xz_ret xz_err;
141 
142 		if (stream->buf.in_pos == stream->buf.in_size) {
143 			const void *data;
144 			int avail;
145 
146 			if (!bio_next_segment(bio, &iter_all)) {
147 				/* XZ_STREAM_END must be reached. */
148 				error = -EIO;
149 				break;
150 			}
151 
152 			avail = min(length, ((int)bvec->bv_len) - offset);
153 			data = bvec_virt(bvec);
154 			length -= avail;
155 			stream->buf.in = data + offset;
156 			stream->buf.in_size = avail;
157 			stream->buf.in_pos = 0;
158 			offset = 0;
159 		}
160 
161 		if (stream->buf.out_pos == stream->buf.out_size) {
162 			stream->buf.out = squashfs_next_page(output);
163 			if (IS_ERR(stream->buf.out)) {
164 				error = PTR_ERR(stream->buf.out);
165 				break;
166 			} else if (stream->buf.out != NULL) {
167 				stream->buf.out_pos = 0;
168 				total += PAGE_SIZE;
169 			}
170 		}
171 
172 		xz_err = xz_dec_run(stream->state, &stream->buf);
173 		if (xz_err == XZ_STREAM_END)
174 			break;
175 		if (xz_err != XZ_OK) {
176 			error = -EIO;
177 			break;
178 		}
179 	}
180 
181 finish:
182 	squashfs_finish_page(output);
183 
184 	return error ? error : total + stream->buf.out_pos;
185 }
186 
187 const struct squashfs_decompressor squashfs_xz_comp_ops = {
188 	.init = squashfs_xz_init,
189 	.comp_opts = squashfs_xz_comp_opts,
190 	.free = squashfs_xz_free,
191 	.decompress = squashfs_xz_uncompress,
192 	.id = XZ_COMPRESSION,
193 	.name = "xz",
194 	.alloc_buffer = 1,
195 	.supported = 1
196 };
197