/* * 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");