95 lines
2.4 KiB
C
95 lines
2.4 KiB
C
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/*
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* Copyright 2024 Zoé Cassiopée Gauthier
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*
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* This file is part of Scream.
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*
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* Scream is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scream is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scream. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include <linux/cdev.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#define SCREAM_MAJOR 0
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static loff_t scream_llseek(struct file *, loff_t, int);
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static ssize_t scream_read(struct file *, char __user *, size_t, loff_t *);
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static ssize_t scream_write(struct file *, const char __user *, size_t,
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loff_t *);
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static const struct file_operations scream_fops = {
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.owner = THIS_MODULE,
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.llseek = scream_llseek,
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.read = scream_read,
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.write = scream_write,
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};
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static struct cdev scream_cdev;
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static int scream_major = 0;
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static loff_t scream_llseek(struct file *file, loff_t offset, int orig)
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{
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return file->f_pos = 0;
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}
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static ssize_t scream_read(struct file *file, char __user *buf, size_t count,
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loff_t *ppos)
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{
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char is_capital;
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get_random_bytes(&is_capital, sizeof(is_capital));
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is_capital &= 0xf;
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if (put_user(is_capital == 0 ? 'A' : 'a', buf))
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return -EFAULT;
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return 1;
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}
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static ssize_t scream_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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return count;
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}
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static int __init scream_init(void)
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{
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dev_t dev;
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if (alloc_chrdev_region(&dev, 0, 1, "scream") < 0)
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panic("Couldn't register /dev/scream driver\n");
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scream_major = MAJOR(dev);
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cdev_init(&scream_cdev, &scream_fops);
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scream_cdev.owner = THIS_MODULE;
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scream_cdev.ops = &scream_fops;
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cdev_add(&scream_cdev, MKDEV(scream_major, 0), 1);
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return 0;
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}
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static void __exit scream_cleanup(void)
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{
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cdev_del(&scream_cdev);
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unregister_chrdev_region(MKDEV(scream_major, 0), 1);
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}
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module_init(scream_init);
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module_exit(scream_cleanup);
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MODULE_DESCRIPTION("Character driver to output screaming");
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MODULE_VERSION("1.0");
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MODULE_LICENSE("GPL");
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