fs/squashfs/zlib_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
   6  * Phillip Lougher <phillip@squashfs.org.uk>
   7  *
   8  * zlib_wrapper.c
   9  */
  10
  11
  12 #include <linux/mutex.h>
  13 #include <linux/bio.h>
  14 #include <linux/slab.h>
  15 #include <linux/zlib.h>
  16 #include <linux/vmalloc.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 static void *zlib_init(struct squashfs_sb_info *dummy, void *buff)
  25 {
  26         z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
  27         if (stream == NULL)
  28                 goto failed;
  29         stream->workspace = vmalloc(zlib_inflate_workspacesize());
  30         if (stream->workspace == NULL)
  31                 goto failed;
  32
  33         return stream;
  34
  35 failed:
  36         ERROR("Failed to allocate zlib workspace\n");
  37         kfree(stream);
  38         return ERR_PTR(-ENOMEM);
  39 }
  40
  41
  42 static void zlib_free(void *strm)
  43 {
  44         z_stream *stream = strm;
  45
  46         if (stream)
  47                 vfree(stream->workspace);
  48         kfree(stream);
  49 }
  50
  51
  52 static int zlib_uncompress(struct squashfs_sb_info *msblk, void *strm,
  53         struct bio *bio, int offset, int length,
  54         struct squashfs_page_actor *output)
  55 {
  56         struct bvec_iter_all iter_all = {};
  57         struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
  58         int zlib_init = 0, error = 0;
  59         z_stream *stream = strm;
  60
  61         stream->avail_out = PAGE_SIZE;
  62         stream->next_out = squashfs_first_page(output);
  63         stream->avail_in = 0;
  64
  65         for (;;) {
  66                 int zlib_err;
  67
  68                 if (stream->avail_in == 0) {
  69                         const void *data;
  70                         int avail;
  71
  72                         if (!bio_next_segment(bio, &iter_all)) {
  73                                 /* Z_STREAM_END must be reached. */
  74                                 error = -EIO;
  75                                 break;
  76                         }
  77
  78                         avail = min(length, ((int)bvec->bv_len) - offset);
  79                         data = bvec_virt(bvec);
  80                         length -= avail;
  81                         stream->next_in = data + offset;
  82                         stream->avail_in = avail;
  83                         offset = 0;
  84                 }
  85
  86                 if (stream->avail_out == 0) {
  87                         stream->next_out = squashfs_next_page(output);
  88                         if (stream->next_out != NULL)
  89                                 stream->avail_out = PAGE_SIZE;
  90                 }
  91
  92                 if (!zlib_init) {
  93                         zlib_err = zlib_inflateInit(stream);
  94                         if (zlib_err != Z_OK) {
  95                                 error = -EIO;
  96                                 break;
  97                         }
  98                         zlib_init = 1;
  99                 }
 100
 101                 zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
 102                 if (zlib_err == Z_STREAM_END)
 103                         break;
 104                 if (zlib_err != Z_OK) {
 105                         error = -EIO;
 106                         break;
 107                 }
 108         }
 109
 110         squashfs_finish_page(output);
 111
 112         if (!error)
 113                 if (zlib_inflateEnd(stream) != Z_OK)
 114                         error = -EIO;
 115
 116         return error ? error : stream->total_out;
 117 }
 118
 119 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 120         .init = zlib_init,
 121         .free = zlib_free,
 122         .decompress = zlib_uncompress,
 123         .id = ZLIB_COMPRESSION,
 124         .name = "zlib",
 125         .supported = 1
 126 };
 127