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/*
* Copyright (c) 2016-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
*/
/* DO_XXH should be 32 or 64 for xxh32 and xxh64 respectively */
#define DO_XXH 0
/* DO_CRC should be 0 or 1 */
#define DO_CRC 0
/* Buffer size */
#define BUFFER_SIZE 4096
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#if DO_XXH
#include <linux/xxhash.h>
#endif
#if DO_CRC
#include <linux/crc32.h>
#endif
/* Device name to pass to register_chrdev(). */
#define DEVICE_NAME "xxhash_test"
/* Dynamically allocated device major number */
static int device_major;
/*
* We reuse the same hash state, and thus can hash only one
* file at a time.
*/
static bool device_is_open;
static uint64_t total_length;
#if (DO_XXH == 32)
#define xxh_state xxh32_state
#define xxh_reset xxh32_reset
#define xxh_update xxh32_update
#define xxh_digest xxh32_digest
#define XXH_FORMAT "XXH32 = 0x%x"
#elif (DO_XXH == 64)
#define xxh_state xxh64_state
#define xxh_reset xxh64_reset
#define xxh_update xxh64_update
#define xxh_digest xxh64_digest
#define XXH_FORMAT "XXH64 = 0x%llx"
#elif DO_XXH
#error "Invalid value of DO_XXH"
#endif
#if DO_XXH
/* XXH state */
static struct xxh_state state;
#endif /* DO_XXH */
#if DO_CRC
static uint32_t crc;
#endif /* DO_CRC */
/*
* Input buffer used to put data coming from userspace.
*/
static uint8_t buffer_in[BUFFER_SIZE];
static int xxhash_test_open(struct inode *i, struct file *f)
{
if (device_is_open)
return -EBUSY;
device_is_open = true;
total_length = 0;
#if DO_XXH
xxh_reset(&state, 0);
#endif
#if DO_CRC
crc = 0xFFFFFFFF;
#endif
printk(KERN_INFO DEVICE_NAME ": opened\n");
return 0;
}
static int xxhash_test_release(struct inode *i, struct file *f)
{
device_is_open = false;
printk(KERN_INFO DEVICE_NAME ": total_len = %llu\n", total_length);
#if DO_XXH
printk(KERN_INFO DEVICE_NAME ": " XXH_FORMAT "\n", xxh_digest(&state));
#endif
#if DO_CRC
printk(KERN_INFO DEVICE_NAME ": CRC32 = 0x%08x\n", ~crc);
#endif
printk(KERN_INFO DEVICE_NAME ": closed\n");
return 0;
}
/*
* Hash the data given to us from userspace.
*/
static ssize_t xxhash_test_write(struct file *file, const char __user *buf,
size_t size, loff_t *pos)
{
size_t remaining = size;
while (remaining > 0) {
#if DO_XXH
int ret;
#endif
size_t const copy_size = min(remaining, sizeof(buffer_in));
if (copy_from_user(buffer_in, buf, copy_size))
return -EFAULT;
buf += copy_size;
remaining -= copy_size;
total_length += copy_size;
#if DO_XXH
if ((ret = xxh_update(&state, buffer_in, copy_size))) {
printk(KERN_INFO DEVICE_NAME ": xxh failure.");
return ret;
}
#endif
#if DO_CRC
crc = crc32(crc, buffer_in, copy_size);
#endif
}
return size;
}
/* register the character device. */
static int __init xxhash_test_init(void)
{
static const struct file_operations fileops = {
.owner = THIS_MODULE,
.open = &xxhash_test_open,
.release = &xxhash_test_release,
.write = &xxhash_test_write
};
device_major = register_chrdev(0, DEVICE_NAME, &fileops);
if (device_major < 0) {
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 data "
"to it.\n", device_major);
return 0;
}
static void __exit xxhash_test_exit(void)
{
unregister_chrdev(device_major, DEVICE_NAME);
printk(KERN_INFO DEVICE_NAME ": module unloaded\n");
}
module_init(xxhash_test_init);
module_exit(xxhash_test_exit);
MODULE_DESCRIPTION("XXHash tester");
MODULE_VERSION("1.0");
MODULE_LICENSE("Dual BSD/GPL");
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