xz_wrapper.c

  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
 24struct squashfs_xz {
 25	struct xz_dec *state;
 26	struct xz_buf buf;
 27};
 28
 29struct disk_comp_opts {
 30	__le32 dictionary_size;
 31	__le32 flags;
 32};
 33
 34struct comp_opts {
 35	int dict_size;
 36};
 37
 38static 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
 74out:
 75	kfree(opts);
 76out2:
 77	return ERR_PTR(err);
 78}
 79
 80
 81static 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
102failed:
103	ERROR("Failed to initialise xz decompressor\n");
104	return ERR_PTR(err);
105}
106
107
108static 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
119static 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
181finish:
182	squashfs_finish_page(output);
183
184	return error ? error : total + stream->buf.out_pos;
185}
186
187const 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};