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
  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
  26 static 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
  31 static 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
  37 static 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
  43 static 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
  49 static 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
  55 static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
  56         NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
  57 };
  58 #endif
  59
  60 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  61         NULL, NULL, NULL, NULL, 0, "unknown", 0
  62 };
  63
  64 static 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
  75 const 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
  87 static 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
 121 out:
 122         kfree(actor);
 123         kfree(buffer);
 124         return comp_opts;
 125 }
 126
 127
 128 void *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 }