59 lines
1.2 KiB
C
59 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/debugfs.h>
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#define VALUE "tomoron"
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extern struct dentry *module_dir;
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ssize_t id_read(struct file *f, char __user *buf, size_t len, loff_t *off);
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ssize_t id_write(struct file *f, const char __user *buf, size_t len, loff_t *off);
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int init_id(void);
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static const struct file_operations fops = {
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.owner = THIS_MODULE,
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.read = id_read,
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.write = id_write,
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};
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ssize_t id_read(struct file *f, char __user *buf, size_t len, loff_t *off)
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{
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char msg[] = VALUE;
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pr_info("someone read from the file\n");
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return simple_read_from_buffer(buf, len, off, msg, sizeof(msg) - 1);
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}
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ssize_t id_write(struct file *f, const char __user *buf, size_t len, loff_t *off)
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{
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char kbuf[64];
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if (len > sizeof(kbuf) - 1)
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return -EINVAL;
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if (copy_from_user(kbuf, buf, len))
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return -EINVAL;
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kbuf[len] = '\0';
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if (strcmp(kbuf, VALUE) == 0) {
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pr_info("someone wrote the right string\n");
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return len;
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}
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pr_info("someone wrote the wrong string\n");
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return -EINVAL;
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}
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int init_id(void)
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{
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struct dentry *ret;
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ret = debugfs_create_file("id", 0666, module_dir, NULL, &fops);
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if (IS_ERR(ret))
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return PTR_ERR(ret);
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return 0;
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}
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