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/*
* XZ decoder tester
*
* Author: Lasse Collin <lasse.collin@tukaani.org>
*
* This file has been put into the public domain.
* You can do whatever you want with this file.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/crc32.h>
#include <linux/xz.h>
/* Maximum supported dictionary size */
#define DICT_MAX (1 << 20)
/* Device name to pass to register_chrdev(). */
#define DEVICE_NAME "xz_dec_test"
/* Dynamically allocated device major number */
static int device_major;
/*
* We reuse the same decoder state, and thus can decode only one
* file at a time.
*/
static bool device_is_open;
/* XZ decoder state */
static struct xz_dec *state;
/*
* Return value of xz_dec_run(). We need to avoid calling xz_dec_run() after
* it has returned XZ_STREAM_END, so we make this static.
*/
static enum xz_ret ret;
/*
* Input and output buffers. The input buffer is used as a temporary safe
* place for the data coming from the userspace.
*/
static uint8_t buffer_in[1024];
static uint8_t buffer_out[1024];
/*
* Structure to pass the input and output buffers to the XZ decoder.
* A few of the fields are never modified so we initialize them here.
*/
static struct xz_buf buffers = {
.in = buffer_in,
.out = buffer_out,
.out_size = sizeof(buffer_out)
};
/*
* CRC32 of uncompressed data. This is used to give the user a simple way
* to check that the decoder produces correct output.
*/
static uint32_t crc;
static int xz_dec_test_open(struct inode *i, struct file *f)
{
if (device_is_open)
return -EBUSY;
device_is_open = true;
xz_dec_reset(state);
ret = XZ_OK;
crc = 0xFFFFFFFF;
buffers.in_pos = 0;
buffers.in_size = 0;
buffers.out_pos = 0;
printk(KERN_INFO DEVICE_NAME ": opened\n");
return 0;
}
static int xz_dec_test_release(struct inode *i, struct file *f)
{
device_is_open = false;
if (ret == XZ_OK)
printk(KERN_INFO DEVICE_NAME ": input was truncated\n");
printk(KERN_INFO DEVICE_NAME ": closed\n");
return 0;
}
/*
* Decode the data given to us from the userspace. CRC32 of the uncompressed
* data is calculated and is printed at the end of successful decoding. The
* uncompressed data isn't stored anywhere for further use.
*
* The .xz file must have exactly one Stream and no Stream Padding. The data
* after the first Stream is considered to be garbage.
*/
static ssize_t xz_dec_test_write(struct file *file, const char __user *buf,
size_t size, loff_t *pos)
{
size_t remaining;
if (ret != XZ_OK) {
if (size > 0)
printk(KERN_INFO DEVICE_NAME ": %zu bytes of "
"garbage at the end of the file\n",
size);
return -ENOSPC;
}
printk(KERN_INFO DEVICE_NAME ": decoding %zu bytes of input\n",
size);
remaining = size;
while ((remaining > 0 || buffers.out_pos == buffers.out_size)
&& ret == XZ_OK) {
if (buffers.in_pos == buffers.in_size) {
buffers.in_pos = 0;
buffers.in_size = min(remaining, sizeof(buffer_in));
if (copy_from_user(buffer_in, buf, buffers.in_size))
return -EFAULT;
buf += buffers.in_size;
remaining -= buffers.in_size;
}
buffers.out_pos = 0;
ret = xz_dec_run(state, &buffers);
crc = crc32(crc, buffer_out, buffers.out_pos);
}
switch (ret) {
case XZ_OK:
printk(KERN_INFO DEVICE_NAME ": XZ_OK\n");
return size;
case XZ_STREAM_END:
printk(KERN_INFO DEVICE_NAME ": XZ_STREAM_END, "
"CRC32 = 0x%08X\n", ~crc);
return size - remaining - (buffers.in_size - buffers.in_pos);
case XZ_MEMLIMIT_ERROR:
printk(KERN_INFO DEVICE_NAME ": XZ_MEMLIMIT_ERROR\n");
break;
case XZ_FORMAT_ERROR:
printk(KERN_INFO DEVICE_NAME ": XZ_FORMAT_ERROR\n");
break;
case XZ_OPTIONS_ERROR:
printk(KERN_INFO DEVICE_NAME ": XZ_OPTIONS_ERROR\n");
break;
case XZ_DATA_ERROR:
printk(KERN_INFO DEVICE_NAME ": XZ_DATA_ERROR\n");
break;
case XZ_BUF_ERROR:
printk(KERN_INFO DEVICE_NAME ": XZ_BUF_ERROR\n");
break;
default:
printk(KERN_INFO DEVICE_NAME ": Bug detected!\n");
break;
}
return -EIO;
}
/* Allocate the XZ decoder state and register the character device. */
static int __init xz_dec_test_init(void)
{
static const struct file_operations fileops = {
.owner = THIS_MODULE,
.open = &xz_dec_test_open,
.release = &xz_dec_test_release,
.write = &xz_dec_test_write
};
state = xz_dec_init(XZ_PREALLOC, DICT_MAX);
if (state == NULL)
return -ENOMEM;
device_major = register_chrdev(0, DEVICE_NAME, &fileops);
if (device_major < 0) {
xz_dec_end(state);
return device_major;
}
printk(KERN_INFO DEVICE_NAME ": module loaded\n");
printk(KERN_INFO DEVICE_NAME ": Create a device node with "
"'mknod " DEVICE_NAME " c %d 0' and write .xz files "
"to it.\n", device_major);
return 0;
}
static void __exit xz_dec_test_exit(void)
{
unregister_chrdev(device_major, DEVICE_NAME);
xz_dec_end(state);
printk(KERN_INFO DEVICE_NAME ": module unloaded\n");
}
module_init(xz_dec_test_init);
module_exit(xz_dec_test_exit);
MODULE_DESCRIPTION("XZ decompressor tester");
MODULE_VERSION("1.0");
MODULE_AUTHOR("Lasse Collin <lasse.collin@tukaani.org>");
/*
* This code is in the public domain, but in Linux it's simplest to just
* say it's GPL and consider the authors as the copyright holders.
*/
MODULE_LICENSE("GPL");
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