mirror of
https://github.com/sysprog21/lkmpg.git
synced 2024-11-22 11:43:41 +08:00
39a313dc20
To make sure the behavior of the read and write operations are correct with offset, update it each time. Also, since it is using the offset, modify the part of read for removing unnecessary variable.
99 lines
2.6 KiB
C
99 lines
2.6 KiB
C
/*
|
|
* procfs2.c - create a "file" in /proc
|
|
*/
|
|
|
|
#include <linux/kernel.h> /* We're doing kernel work */
|
|
#include <linux/module.h> /* Specifically, a module */
|
|
#include <linux/proc_fs.h> /* Necessary because we use the proc fs */
|
|
#include <linux/uaccess.h> /* for copy_from_user */
|
|
#include <linux/version.h>
|
|
|
|
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
|
|
#define HAVE_PROC_OPS
|
|
#endif
|
|
|
|
#define PROCFS_MAX_SIZE 1024
|
|
#define PROCFS_NAME "buffer1k"
|
|
|
|
/* This structure hold information about the /proc file */
|
|
static struct proc_dir_entry *our_proc_file;
|
|
|
|
/* The buffer used to store character for this module */
|
|
static char procfs_buffer[PROCFS_MAX_SIZE];
|
|
|
|
/* The size of the buffer */
|
|
static unsigned long procfs_buffer_size = 0;
|
|
|
|
/* This function is called then the /proc file is read */
|
|
static ssize_t procfile_read(struct file *filePointer, char __user *buffer,
|
|
size_t buffer_length, loff_t *offset)
|
|
{
|
|
char s[13] = "HelloWorld!\n";
|
|
int len = sizeof(s);
|
|
ssize_t ret = len;
|
|
|
|
if (*offset >= len || copy_to_user(buffer, s, len)) {
|
|
pr_info("copy_to_user failed\n");
|
|
ret = 0;
|
|
} else {
|
|
pr_info("procfile read %s\n", filePointer->f_path.dentry->d_name.name);
|
|
*offset += len;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* This function is called with the /proc file is written. */
|
|
static ssize_t procfile_write(struct file *file, const char __user *buff,
|
|
size_t len, loff_t *off)
|
|
{
|
|
procfs_buffer_size = len;
|
|
if (procfs_buffer_size > PROCFS_MAX_SIZE)
|
|
procfs_buffer_size = PROCFS_MAX_SIZE;
|
|
|
|
if (copy_from_user(procfs_buffer, buff, procfs_buffer_size))
|
|
return -EFAULT;
|
|
|
|
procfs_buffer[procfs_buffer_size & (PROCFS_MAX_SIZE - 1)] = '\0';
|
|
*off += procfs_buffer_size;
|
|
pr_info("procfile write %s\n", procfs_buffer);
|
|
|
|
return procfs_buffer_size;
|
|
}
|
|
|
|
#ifdef HAVE_PROC_OPS
|
|
static const struct proc_ops proc_file_fops = {
|
|
.proc_read = procfile_read,
|
|
.proc_write = procfile_write,
|
|
};
|
|
#else
|
|
static const struct file_operations proc_file_fops = {
|
|
.read = procfile_read,
|
|
.write = procfile_write,
|
|
};
|
|
#endif
|
|
|
|
static int __init procfs2_init(void)
|
|
{
|
|
our_proc_file = proc_create(PROCFS_NAME, 0644, NULL, &proc_file_fops);
|
|
if (NULL == our_proc_file) {
|
|
proc_remove(our_proc_file);
|
|
pr_alert("Error:Could not initialize /proc/%s\n", PROCFS_NAME);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
pr_info("/proc/%s created\n", PROCFS_NAME);
|
|
return 0;
|
|
}
|
|
|
|
static void __exit procfs2_exit(void)
|
|
{
|
|
proc_remove(our_proc_file);
|
|
pr_info("/proc/%s removed\n", PROCFS_NAME);
|
|
}
|
|
|
|
module_init(procfs2_init);
|
|
module_exit(procfs2_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|