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Linux/fs/squashfs/lz4_wrapper.c

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  1 /*
  2  * Copyright (c) 2013, 2014
  3  * Phillip Lougher <phillip@squashfs.org.uk>
  4  *
  5  * This work is licensed under the terms of the GNU GPL, version 2. See
  6  * the COPYING file in the top-level directory.
  7  */
  8 
  9 #include <linux/buffer_head.h>
 10 #include <linux/mutex.h>
 11 #include <linux/slab.h>
 12 #include <linux/vmalloc.h>
 13 #include <linux/lz4.h>
 14 
 15 #include "squashfs_fs.h"
 16 #include "squashfs_fs_sb.h"
 17 #include "squashfs.h"
 18 #include "decompressor.h"
 19 #include "page_actor.h"
 20 
 21 #define LZ4_LEGACY      1
 22 
 23 struct lz4_comp_opts {
 24         __le32 version;
 25         __le32 flags;
 26 };
 27 
 28 struct squashfs_lz4 {
 29         void *input;
 30         void *output;
 31 };
 32 
 33 
 34 static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
 35         void *buff, int len)
 36 {
 37         struct lz4_comp_opts *comp_opts = buff;
 38 
 39         /* LZ4 compressed filesystems always have compression options */
 40         if (comp_opts == NULL || len < sizeof(*comp_opts))
 41                 return ERR_PTR(-EIO);
 42 
 43         if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
 44                 /* LZ4 format currently used by the kernel is the 'legacy'
 45                  * format */
 46                 ERROR("Unknown LZ4 version\n");
 47                 return ERR_PTR(-EINVAL);
 48         }
 49 
 50         return NULL;
 51 }
 52 
 53 
 54 static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
 55 {
 56         int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
 57         struct squashfs_lz4 *stream;
 58 
 59         stream = kzalloc(sizeof(*stream), GFP_KERNEL);
 60         if (stream == NULL)
 61                 goto failed;
 62         stream->input = vmalloc(block_size);
 63         if (stream->input == NULL)
 64                 goto failed2;
 65         stream->output = vmalloc(block_size);
 66         if (stream->output == NULL)
 67                 goto failed3;
 68 
 69         return stream;
 70 
 71 failed3:
 72         vfree(stream->input);
 73 failed2:
 74         kfree(stream);
 75 failed:
 76         ERROR("Failed to initialise LZ4 decompressor\n");
 77         return ERR_PTR(-ENOMEM);
 78 }
 79 
 80 
 81 static void lz4_free(void *strm)
 82 {
 83         struct squashfs_lz4 *stream = strm;
 84 
 85         if (stream) {
 86                 vfree(stream->input);
 87                 vfree(stream->output);
 88         }
 89         kfree(stream);
 90 }
 91 
 92 
 93 static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
 94         struct buffer_head **bh, int b, int offset, int length,
 95         struct squashfs_page_actor *output)
 96 {
 97         struct squashfs_lz4 *stream = strm;
 98         void *buff = stream->input, *data;
 99         int avail, i, bytes = length, res;
100 
101         for (i = 0; i < b; i++) {
102                 avail = min(bytes, msblk->devblksize - offset);
103                 memcpy(buff, bh[i]->b_data + offset, avail);
104                 buff += avail;
105                 bytes -= avail;
106                 offset = 0;
107                 put_bh(bh[i]);
108         }
109 
110         res = LZ4_decompress_safe(stream->input, stream->output,
111                 length, output->length);
112 
113         if (res < 0)
114                 return -EIO;
115 
116         bytes = res;
117         data = squashfs_first_page(output);
118         buff = stream->output;
119         while (data) {
120                 if (bytes <= PAGE_SIZE) {
121                         memcpy(data, buff, bytes);
122                         break;
123                 }
124                 memcpy(data, buff, PAGE_SIZE);
125                 buff += PAGE_SIZE;
126                 bytes -= PAGE_SIZE;
127                 data = squashfs_next_page(output);
128         }
129         squashfs_finish_page(output);
130 
131         return res;
132 }
133 
134 const struct squashfs_decompressor squashfs_lz4_comp_ops = {
135         .init = lz4_init,
136         .comp_opts = lz4_comp_opts,
137         .free = lz4_free,
138         .decompress = lz4_uncompress,
139         .id = LZ4_COMPRESSION,
140         .name = "lz4",
141         .supported = 1
142 };
143 

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