decompressor.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
  6 * Phillip Lougher <phillip@squashfs.org.uk>
  7 *
  8 * decompressor.c
  9 */
 10
 11#include <linux/types.h>
 12#include <linux/mutex.h>
 13#include <linux/slab.h>
 14
 15#include "squashfs_fs.h"
 16#include "squashfs_fs_sb.h"
 17#include "decompressor.h"
 18#include "squashfs.h"
 19#include "page_actor.h"
 20
 21/*
 22 * This file (and decompressor.h) implements a decompressor framework for
 23 * Squashfs, allowing multiple decompressors to be easily supported
 24 */
 25
 26static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
 27	NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
 28};
 29
 30#ifndef CONFIG_SQUASHFS_LZ4
 31static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
 32	NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
 33};
 34#endif
 35
 36#ifndef CONFIG_SQUASHFS_LZO
 37static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
 38	NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
 39};
 40#endif
 41
 42#ifndef CONFIG_SQUASHFS_XZ
 43static const struct squashfs_decompressor squashfs_xz_comp_ops = {
 44	NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
 45};
 46#endif
 47
 48#ifndef CONFIG_SQUASHFS_ZLIB
 49static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 50	NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
 51};
 52#endif
 53
 54#ifndef CONFIG_SQUASHFS_ZSTD
 55static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
 56	NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
 57};
 58#endif
 59
 60static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
 61	NULL, NULL, NULL, NULL, 0, "unknown", 0
 62};
 63
 64static const struct squashfs_decompressor *decompressor[] = {
 65	&squashfs_zlib_comp_ops,
 66	&squashfs_lz4_comp_ops,
 67	&squashfs_lzo_comp_ops,
 68	&squashfs_xz_comp_ops,
 69	&squashfs_lzma_unsupported_comp_ops,
 70	&squashfs_zstd_comp_ops,
 71	&squashfs_unknown_comp_ops
 72};
 73
 74
 75const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
 76{
 77	int i;
 78
 79	for (i = 0; decompressor[i]->id; i++)
 80		if (id == decompressor[i]->id)
 81			break;
 82
 83	return decompressor[i];
 84}
 85
 86
 87static void *get_comp_opts(struct super_block *sb, unsigned short flags)
 88{
 89	struct squashfs_sb_info *msblk = sb->s_fs_info;
 90	void *buffer = NULL, *comp_opts;
 91	struct squashfs_page_actor *actor = NULL;
 92	int length = 0;
 93
 94	/*
 95	 * Read decompressor specific options from file system if present
 96	 */
 97	if (SQUASHFS_COMP_OPTS(flags)) {
 98		buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 99		if (buffer == NULL) {
100			comp_opts = ERR_PTR(-ENOMEM);
101			goto out;
102		}
103
104		actor = squashfs_page_actor_init(&buffer, 1, 0);
105		if (actor == NULL) {
106			comp_opts = ERR_PTR(-ENOMEM);
107			goto out;
108		}
109
110		length = squashfs_read_data(sb,
111			sizeof(struct squashfs_super_block), 0, NULL, actor);
112
113		if (length < 0) {
114			comp_opts = ERR_PTR(length);
115			goto out;
116		}
117	}
118
119	comp_opts = squashfs_comp_opts(msblk, buffer, length);
120
121out:
122	kfree(actor);
123	kfree(buffer);
124	return comp_opts;
125}
126
127
128void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
129{
130	struct squashfs_sb_info *msblk = sb->s_fs_info;
131	void *stream, *comp_opts = get_comp_opts(sb, flags);
132
133	if (IS_ERR(comp_opts))
134		return comp_opts;
135
136	stream = msblk->thread_ops->create(msblk, comp_opts);
137	if (IS_ERR(stream))
138		kfree(comp_opts);
139
140	return stream;
141}