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fibonacci.c
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fibonacci.c
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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sergey Gerasimov");
static int fibonacci_init(void);
static void fibonacci_exit(void);
static ssize_t read_number(struct file *, char *, size_t, loff_t *, unsigned long long *);
static ssize_t input_read(struct file *, char *, size_t, loff_t *);
static ssize_t input_write(struct file *, const char *, size_t, loff_t *);
static ssize_t result_read(struct file *, char *, size_t, loff_t *);
#define INPUT_NAME "fibonacci_input"
#define RESULT_NAME "fibonacci_result"
#define BUF_SIZE 32
static int input_major = -1;
static int result_major = -1;
static int input_error_code = 0;
static char *input_error_message;
static char buf[BUF_SIZE] = { 0 };
static long n = 0;
static unsigned long long res = 0;
static struct file_operations input_fops = {
.owner = THIS_MODULE,
.read = input_read,
.write = input_write
};
static struct file_operations result_fops = {
.owner = THIS_MODULE,
.read = result_read
};
static int fibonacci_init()
{
input_major = register_chrdev(0, INPUT_NAME, &input_fops);
if (input_major < 0) {
printk("Input device is not created");
fibonacci_exit();
return input_major;
}
result_major = register_chrdev(0, RESULT_NAME, &result_fops);
if (result_major < 0) {
printk("Result device is not created");
fibonacci_exit();
return result_major;
}
return 0;
}
static void fibonacci_exit()
{
if (result_major > 0) {
unregister_chrdev(result_major, RESULT_NAME);
}
if (input_major > 0) {
unregister_chrdev(input_major, INPUT_NAME);
}
}
static ssize_t input_write(struct file *filp, const char *buff, size_t len, loff_t *off)
{
long i;
unsigned long long a;
unsigned long long tmp;
if (len > BUF_SIZE) {
input_error_code = -EINVAL;
input_error_message = "Too long input string";
return input_error_code;
}
if (copy_from_user(buf, buff, len)) {
input_error_code = -EINVAL;
input_error_message = "copy_from_user error";
return input_error_code;
}
if (kstrtol(buf, 10, &n) == -EINVAL) {
input_error_code = -EINVAL;
input_error_message = "Input string is not the number";
return input_error_code;
}
if (n < 0) {
input_error_code = -EINVAL;
input_error_message = "Input number must be non-negative";
return input_error_code;
}
a = 0;
res = 1;
if (n == 0) {
res = 0;
}
for (i = 0; i < n - 1; ++i) {
tmp = res;
res = res + a;
if (res < tmp) {
input_error_code = -EINVAL;
input_error_message = "Too big input number";
return input_error_code;
}
a = tmp;
}
return len;
}
static ssize_t read_number(struct file *filp, char *buff, size_t len, loff_t *off,unsigned long long *num)
{
ssize_t size;
long length;
if (*off != 0) {
return 0;
}
if (input_error_code < 0) {
copy_to_user(buff, input_error_message, strlen(input_error_message));
length = strlen(input_error_message);
*off = length;
return length;
}
snprintf(buf, BUF_SIZE, "%llu", *num);
size = strlen(buf);
if (size >= len) {
return -EINVAL;
}
if (copy_to_user(buff, buf, size)) {
return -EINVAL;
}
*off = size;
return size;
}
static ssize_t input_read(struct file *filp, char *buff, size_t len, loff_t * off)
{
unsigned long long tmp;
tmp = n;
return read_number(filp, buff, len, off, &tmp);
}
static ssize_t result_read(struct file *filp, char *buff, size_t len, loff_t * off)
{
return read_number(filp, buff, len, off, &res);
}
module_init(fibonacci_init);
module_exit(fibonacci_exit);