LXR linux/fs/squashfs/xz

   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
  24struct squashfs_xz {
  25        struct xz_dec *state;
  26        struct xz_buf buf;
  27};
  28
  29struct disk_comp_opts {
  30        __le32 dictionary_size;
  31        __le32 flags;
  32};
  33
  34struct comp_opts {
  35        int dict_size;
  36};
  37
  38static 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
  74out:
  75        kfree(opts);
  76out2:
  77        return ERR_PTR(err);
  78}
  79
  80
  81static 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
 102failed:
 103        ERROR("Failed to initialise xz decompressor\n");
 104        return ERR_PTR(err);
 105}
 106
 107
 108static 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
 119static 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 = bvec_virt(bvec);
 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
 179const 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};
 188