root/fs/squashfs/decompressor.c

DEFINITIONS

1. squashfs_lookup_decompressor
2. get_comp_opts
3. squashfs_decompressor_setup

   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 
  27 static 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
  32 static 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
  38 static 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
  44 static 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
  50 static 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
  56 static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
  57         NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
  58 };
  59 #endif
  60 
  61 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
  62         NULL, NULL, NULL, NULL, 0, "unknown", 0
  63 };
  64 
  65 static 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 
  76 const 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 
  88 static 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 
 122 out:
 123         kfree(actor);
 124         kfree(buffer);
 125         return comp_opts;
 126 }
 127 
 128 
 129 void *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 }