xz_dec_test.c

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    1 /*
    2  * XZ decoder tester
    3  *
    4  * Author: Lasse Collin <lasse.collin@tukaani.org>
    5  *
    6  * This file has been put into the public domain.
    7  * You can do whatever you want with this file.
    8  */
    9 
   10 #include <linux/kernel.h>
   11 #include <linux/module.h>
   12 #include <linux/fs.h>
   13 #include <linux/uaccess.h>
   14 #include <linux/crc32.h>
   15 #include <linux/xz.h>
   16 
   17 /* Maximum supported dictionary size */
   18 #define DICT_MAX (1 << 20)
   19 
   20 /* Device name to pass to register_chrdev(). */
   21 #define DEVICE_NAME "xz_dec_test"
   22 
   23 /* Dynamically allocated device major number */
   24 static int device_major;
   25 
   26 /*
   27  * We reuse the same decoder state, and thus can decode only one
   28  * file at a time.
   29  */
   30 static bool device_is_open;
   31 
   32 /* XZ decoder state */
   33 static struct xz_dec *state;
   34 
   35 /*
   36  * Return value of xz_dec_run(). We need to avoid calling xz_dec_run() after
   37  * it has returned XZ_STREAM_END, so we make this static.
   38  */
   39 static enum xz_ret ret;
   40 
   41 /*
   42  * Input and output buffers. The input buffer is used as a temporary safe
   43  * place for the data coming from the userspace.
   44  */
   45 static uint8_t buffer_in[1024];
   46 static uint8_t buffer_out[1024];
   47 
   48 /*
   49  * Structure to pass the input and output buffers to the XZ decoder.
   50  * A few of the fields are never modified so we initialize them here.
   51  */
   52 static struct xz_buf buffers = {
   53         .in = buffer_in,
   54         .out = buffer_out,
   55         .out_size = sizeof(buffer_out)
   56 };
   57 
   58 /*
   59  * CRC32 of uncompressed data. This is used to give the user a simple way
   60  * to check that the decoder produces correct output.
   61  */
   62 static uint32_t crc;
   63 
   64 static int xz_dec_test_open(struct inode *i, struct file *f)
   65 {
   66         if (device_is_open)
   67                 return -EBUSY;
   68 
   69         device_is_open = true;
   70 
   71         xz_dec_reset(state);
   72         ret = XZ_OK;
   73         crc = 0xFFFFFFFF;
   74 
   75         buffers.in_pos = 0;
   76         buffers.in_size = 0;
   77         buffers.out_pos = 0;
   78 
   79         printk(KERN_INFO DEVICE_NAME ": opened\n");
   80         return 0;
   81 }
   82 
   83 static int xz_dec_test_release(struct inode *i, struct file *f)
   84 {
   85         device_is_open = false;
   86 
   87         if (ret == XZ_OK)
   88                 printk(KERN_INFO DEVICE_NAME ": input was truncated\n");
   89 
   90         printk(KERN_INFO DEVICE_NAME ": closed\n");
   91         return 0;
   92 }
   93 
   94 /*
   95  * Decode the data given to us from the userspace. CRC32 of the uncompressed
   96  * data is calculated and is printed at the end of successful decoding. The
   97  * uncompressed data isn't stored anywhere for further use.
   98  *
   99  * The .xz file must have exactly one Stream and no Stream Padding. The data
  100  * after the first Stream is considered to be garbage.
  101  */
  102 static ssize_t xz_dec_test_write(struct file *file, const char __user *buf,
  103                                  size_t size, loff_t *pos)
  104 {
  105         size_t remaining;
  106 
  107         if (ret != XZ_OK) {
  108                 if (size > 0)
  109                         printk(KERN_INFO DEVICE_NAME ": %zu bytes of "
  110                                         "garbage at the end of the file\n",
  111                                         size);
  112 
  113                 return -ENOSPC;
  114         }
  115 
  116         printk(KERN_INFO DEVICE_NAME ": decoding %zu bytes of input\n",
  117                         size);
  118 
  119         remaining = size;
  120         while ((remaining > 0 || buffers.out_pos == buffers.out_size)
  121                         && ret == XZ_OK) {
  122                 if (buffers.in_pos == buffers.in_size) {
  123                         buffers.in_pos = 0;
  124                         buffers.in_size = min(remaining, sizeof(buffer_in));
  125                         if (copy_from_user(buffer_in, buf, buffers.in_size))
  126                                 return -EFAULT;
  127 
  128                         buf += buffers.in_size;
  129                         remaining -= buffers.in_size;
  130                 }
  131 
  132                 buffers.out_pos = 0;
  133                 ret = xz_dec_run(state, &buffers);
  134                 crc = crc32(crc, buffer_out, buffers.out_pos);
  135         }
  136 
  137         switch (ret) {
  138         case XZ_OK:
  139                 printk(KERN_INFO DEVICE_NAME ": XZ_OK\n");
  140                 return size;
  141 
  142         case XZ_STREAM_END:
  143                 printk(KERN_INFO DEVICE_NAME ": XZ_STREAM_END, "
  144                                 "CRC32 = 0x%08X\n", ~crc);
  145                 return size - remaining - (buffers.in_size - buffers.in_pos);
  146 
  147         case XZ_MEMLIMIT_ERROR:
  148                 printk(KERN_INFO DEVICE_NAME ": XZ_MEMLIMIT_ERROR\n");
  149                 break;
  150 
  151         case XZ_FORMAT_ERROR:
  152                 printk(KERN_INFO DEVICE_NAME ": XZ_FORMAT_ERROR\n");
  153                 break;
  154 
  155         case XZ_OPTIONS_ERROR:
  156                 printk(KERN_INFO DEVICE_NAME ": XZ_OPTIONS_ERROR\n");
  157                 break;
  158 
  159         case XZ_DATA_ERROR:
  160                 printk(KERN_INFO DEVICE_NAME ": XZ_DATA_ERROR\n");
  161                 break;
  162 
  163         case XZ_BUF_ERROR:
  164                 printk(KERN_INFO DEVICE_NAME ": XZ_BUF_ERROR\n");
  165                 break;
  166 
  167         default:
  168                 printk(KERN_INFO DEVICE_NAME ": Bug detected!\n");
  169                 break;
  170         }
  171 
  172         return -EIO;
  173 }
  174 
  175 /* Allocate the XZ decoder state and register the character device. */
  176 static int __init xz_dec_test_init(void)
  177 {
  178         static const struct file_operations fileops = {
  179                 .owner = THIS_MODULE,
  180                 .open = &xz_dec_test_open,
  181                 .release = &xz_dec_test_release,
  182                 .write = &xz_dec_test_write
  183         };
  184 
  185         state = xz_dec_init(XZ_PREALLOC, DICT_MAX);
  186         if (state == NULL)
  187                 return -ENOMEM;
  188 
  189         device_major = register_chrdev(0, DEVICE_NAME, &fileops);
  190         if (device_major < 0) {
  191                 xz_dec_end(state);
  192                 return device_major;
  193         }
  194 
  195         printk(KERN_INFO DEVICE_NAME ": module loaded\n");
  196         printk(KERN_INFO DEVICE_NAME ": Create a device node with "
  197                         "'mknod " DEVICE_NAME " c %d 0' and write .xz files "
  198                         "to it.\n", device_major);
  199         return 0;
  200 }
  201 
  202 static void __exit xz_dec_test_exit(void)
  203 {
  204         unregister_chrdev(device_major, DEVICE_NAME);
  205         xz_dec_end(state);
  206         printk(KERN_INFO DEVICE_NAME ": module unloaded\n");
  207 }
  208 
  209 module_init(xz_dec_test_init);
  210 module_exit(xz_dec_test_exit);
  211 
  212 MODULE_DESCRIPTION("XZ decompressor tester");
  213 MODULE_VERSION("1.0");
  214 MODULE_AUTHOR("Lasse Collin <lasse.collin@tukaani.org>");
  215 
  216 /*
  217  * This code is in the public domain, but in Linux it's simplest to just
  218  * say it's GPL and consider the authors as the copyright holders.
  219  */
  220 MODULE_LICENSE("GPL");

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FreeBSD/Linux Kernel Cross Reference sys/contrib/xz-embedded/linux/lib/xz/xz_dec_test.c

FreeBSD/Linux Kernel Cross Reference
sys/contrib/xz-embedded/linux/lib/xz/xz_dec_test.c