1 /* 2 * XZ decoder tester 3 * 4 * Author: Lasse Collin <lasse.collin (at) 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 (at) 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"); 221
