LXR linux/fs/squashfs/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#include <linux/buffer_head.h>
  15
  16#include "squashfs_fs.h"
  17#include "squashfs_fs_sb.h"
  18#include "decompressor.h"
  19#include "squashfs.h"
  20#include "page_actor.h"
  21
  22/*
  23 * This file (and decompressor.h) implements a decompressor framework for
  24 * Squashfs, allowing multiple decompressors to be easily supported
  25 */
  26
  27static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
  28        NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
  29};
  30
  31#ifndef CONFIG_SQUASHFS_LZ4
  32static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
  33        NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
  34};
  35#endif
  36
  37#ifndef CONFIG_SQUASHFS_LZO
  38static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
  39        NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
  40};
  41#endif
  42
  43#ifndef CONFIG_SQUASHFS_XZ
  44static const struct squashfs_decompressor squashfs_xz_comp_ops = {
  45        NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
  46};
  47#endif
  48
  49#ifndef CONFIG_SQUASHFS_ZLIB
  50static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
  51        NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
  52};
  53#endif
  54
  55#ifndef CONFIG_SQUASHFS_ZSTD
  56static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
  57        NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
  58};
  59#endif
  60
  61static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  62        NULL, NULL, NULL, NULL, 0, "unknown", 0
  63};
  64
  65static const struct squashfs_decompressor *decompressor[] = {
  66        &squashfs_zlib_comp_ops,
  67        &squashfs_lz4_comp_ops,
  68        &squashfs_lzo_comp_ops,
  69        &squashfs_xz_comp_ops,
  70        &squashfs_lzma_unsupported_comp_ops,
  71        &squashfs_zstd_comp_ops,
  72        &squashfs_unknown_comp_ops
  73};
  74
  75
  76const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
  77{
  78        int i;
  79
  80        for (i = 0; decompressor[i]->id; i++)
  81                if (id == decompressor[i]->id)
  82                        break;
  83
  84        return decompressor[i];
  85}
  86
  87
  88static void *get_comp_opts(struct super_block *sb, unsigned short flags)
  89{
  90        struct squashfs_sb_info *msblk = sb->s_fs_info;
  91        void *buffer = NULL, *comp_opts;
  92        struct squashfs_page_actor *actor = NULL;
  93        int length = 0;
  94
  95        /*
  96         * Read decompressor specific options from file system if present
  97         */
  98        if (SQUASHFS_COMP_OPTS(flags)) {
  99                buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 100                if (buffer == NULL) {
 101                        comp_opts = ERR_PTR(-ENOMEM);
 102                        goto out;
 103                }
 104
 105                actor = squashfs_page_actor_init(&buffer, 1, 0);
 106                if (actor == NULL) {
 107                        comp_opts = ERR_PTR(-ENOMEM);
 108                        goto out;
 109                }
 110
 111                length = squashfs_read_data(sb,
 112                        sizeof(struct squashfs_super_block), 0, NULL, actor);
 113
 114                if (length < 0) {
 115                        comp_opts = ERR_PTR(length);
 116                        goto out;
 117                }
 118        }
 119
 120        comp_opts = squashfs_comp_opts(msblk, buffer, length);
 121
 122out:
 123        kfree(actor);
 124        kfree(buffer);
 125        return comp_opts;
 126}
 127
 128
 129void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
 130{
 131        struct squashfs_sb_info *msblk = sb->s_fs_info;
 132        void *stream, *comp_opts = get_comp_opts(sb, flags);
 133
 134        if (IS_ERR(comp_opts))
 135                return comp_opts;
 136
 137        stream = squashfs_decompressor_create(msblk, comp_opts);
 138        if (IS_ERR(stream))
 139                kfree(comp_opts);
 140
 141        return stream;
 142}
 143