diff options
Diffstat (limited to 'lib/xz/xz_dec_test.c')
-rw-r--r-- | lib/xz/xz_dec_test.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/lib/xz/xz_dec_test.c b/lib/xz/xz_dec_test.c new file mode 100644 index 0000000000..da28a19d6c --- /dev/null +++ b/lib/xz/xz_dec_test.c @@ -0,0 +1,220 @@ +/* + * 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"); |