121 lines
2.7 KiB
C
121 lines
2.7 KiB
C
/*
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* procfs2.c - create a "file" in /proc
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*/
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#include <linux/kernel.h> /* We're doing kernel work */
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#include <linux/module.h> /* Specifically, a module */
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#include <linux/proc_fs.h> /* Necessary because we use the proc fs */
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#include <linux/uaccess.h> /* for copy_from_user */
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#include <linux/version.h>
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
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#define HAVE_PROC_OPS
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#endif
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#define PROCFS_MAX_SIZE 1024
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#define PROCFS_NAME "buffer1k"
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/**
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* This structure hold information about the /proc file
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*
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*/
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static struct proc_dir_entry *Our_Proc_File;
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/**
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* The buffer used to store character for this module
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*
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*/
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static char procfs_buffer[PROCFS_MAX_SIZE];
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/**
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* The size of the buffer
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*
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*/
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static unsigned long procfs_buffer_size = 0;
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/**
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* This function is called then the /proc file is read
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*
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*/
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ssize_t procfile_read(struct file *filePointer,
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char *buffer,
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size_t buffer_length,
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loff_t *offset)
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{
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char s[13] = "HelloWorld!\n";
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int len = sizeof(s);
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ssize_t ret = len;
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if (*offset >= len || copy_to_user(buffer, s, len)) {
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pr_info("copy_to_user failed\n");
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ret = 0;
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} else {
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pr_info("procfile read %s\n", filePointer->f_path.dentry->d_name.name);
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*offset += len;
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}
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return ret;
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}
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/**
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* This function is called with the /proc file is written
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*
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*/
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static ssize_t procfile_write(struct file *file,
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const char *buff,
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size_t len,
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loff_t *off)
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{
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procfs_buffer_size = len;
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if (procfs_buffer_size > PROCFS_MAX_SIZE)
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procfs_buffer_size = PROCFS_MAX_SIZE;
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if (copy_from_user(procfs_buffer, buff, procfs_buffer_size))
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return -EFAULT;
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procfs_buffer[procfs_buffer_size] = '\0';
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return procfs_buffer_size;
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}
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#ifdef HAVE_PROC_OPS
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static const struct proc_ops proc_file_fops = {
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.proc_read = procfile_read,
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.proc_write = procfile_write,
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};
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#else
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static const struct file_operations proc_file_fops = {
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.read = procfile_read,
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.write = procfile_write,
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};
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#endif
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/**
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*This function is called when the module is loaded
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*
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*/
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int init_module()
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{
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Our_Proc_File = proc_create(PROCFS_NAME, 0644, NULL, &proc_file_fops);
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if (NULL == Our_Proc_File) {
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proc_remove(Our_Proc_File);
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pr_alert("Error:Could not initialize /proc/%s\n", PROCFS_NAME);
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return -ENOMEM;
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}
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pr_info("/proc/%s created\n", PROCFS_NAME);
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return 0;
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}
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/**
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*This function is called when the module is unloaded
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*
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*/
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void cleanup_module()
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{
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proc_remove(Our_Proc_File);
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pr_info("/proc/%s removed\n", PROCFS_NAME);
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}
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MODULE_LICENSE("GPL");
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