fs/squashfs/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
  24 struct squashfs_xz {
  25         struct xz_dec *state;
  26         struct xz_buf buf;
  27 };
  28
  29 struct disk_comp_opts {
  30         __le32 dictionary_size;
  31         __le32 flags;
  32 };
  33
  34 struct comp_opts {
  35         int dict_size;
  36 };
  37
  38 static 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
  74 out:
  75         kfree(opts);
  76 out2:
  77         return ERR_PTR(err);
  78 }
  79
  80
  81 static 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
 102 failed:
 103         ERROR("Failed to initialise xz decompressor\n");
 104         return ERR_PTR(err);
 105 }
 106
 107
 108 static 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
 119 static 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
 135         for (;;) {
 136                 enum xz_ret xz_err;
 137
 138                 if (stream->buf.in_pos == stream->buf.in_size) {
 139                         const void *data;
 140                         int avail;
 141
 142                         if (!bio_next_segment(bio, &iter_all)) {
 143                                 /* XZ_STREAM_END must be reached. */
 144                                 error = -EIO;
 145                                 break;
 146                         }
 147
 148                         avail = min(length, ((int)bvec->bv_len) - offset);
 149                         data = page_address(bvec->bv_page) + bvec->bv_offset;
 150                         length -= avail;
 151                         stream->buf.in = data + offset;
 152                         stream->buf.in_size = avail;
 153                         stream->buf.in_pos = 0;
 154                         offset = 0;
 155                 }
 156
 157                 if (stream->buf.out_pos == stream->buf.out_size) {
 158                         stream->buf.out = squashfs_next_page(output);
 159                         if (stream->buf.out != NULL) {
 160                                 stream->buf.out_pos = 0;
 161                                 total += PAGE_SIZE;
 162                         }
 163                 }
 164
 165                 xz_err = xz_dec_run(stream->state, &stream->buf);
 166                 if (xz_err == XZ_STREAM_END)
 167                         break;
 168                 if (xz_err != XZ_OK) {
 169                         error = -EIO;
 170                         break;
 171                 }
 172         }
 173
 174         squashfs_finish_page(output);
 175
 176         return error ? error : total + stream->buf.out_pos;
 177 }
 178
 179 const struct squashfs_decompressor squashfs_xz_comp_ops = {
 180         .init = squashfs_xz_init,
 181         .comp_opts = squashfs_xz_comp_opts,
 182         .free = squashfs_xz_free,
 183         .decompress = squashfs_xz_uncompress,
 184         .id = XZ_COMPRESSION,
 185         .name = "xz",
 186         .supported = 1
 187 };