mirror of https://github.com/tLDP/LDP
115 lines
2.5 KiB
C
115 lines
2.5 KiB
C
/**
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* procfs2.c - create a "file" in /proc
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*
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*/
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#include <linux/module.h> /* Specifically, a module */
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#include <linux/kernel.h> /* We're doing kernel work */
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#include <linux/proc_fs.h> /* Necessary because we use the proc fs */
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#include <asm/uaccess.h> /* for copy_from_user */
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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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int
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procfile_read(char *buffer,
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char **buffer_location,
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off_t offset, int buffer_length, int *eof, void *data)
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{
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int ret;
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printk(KERN_INFO "procfile_read (/proc/%s) called\n", PROCFS_NAME);
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if (offset > 0) {
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/* we have finished to read, return 0 */
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ret = 0;
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} else {
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/* fill the buffer, return the buffer size */
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memcpy(buffer, procfs_buffer, procfs_buffer_size);
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ret = procfs_buffer_size;
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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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int procfile_write(struct file *file, const char *buffer, unsigned long count,
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void *data)
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{
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/* get buffer size */
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procfs_buffer_size = count;
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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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}
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/* write data to the buffer */
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if ( copy_from_user(procfs_buffer, buffer, procfs_buffer_size) ) {
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return -EFAULT;
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}
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return procfs_buffer_size;
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}
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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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/* create the /proc file */
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Our_Proc_File = create_proc_entry(PROCFS_NAME, 0644, NULL);
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if (Our_Proc_File == NULL) {
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remove_proc_entry(PROCFS_NAME, &proc_root);
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printk(KERN_ALERT "Error: Could not initialize /proc/%s\n",
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PROCFS_NAME);
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return -ENOMEM;
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}
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Our_Proc_File->read_proc = procfile_read;
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Our_Proc_File->write_proc = procfile_write;
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Our_Proc_File->owner = THIS_MODULE;
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Our_Proc_File->mode = S_IFREG | S_IRUGO;
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Our_Proc_File->uid = 0;
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Our_Proc_File->gid = 0;
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Our_Proc_File->size = 37;
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printk(KERN_INFO "/proc/%s created\n", PROCFS_NAME);
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return 0; /* everything is ok */
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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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remove_proc_entry(PROCFS_NAME, &proc_root);
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printk(KERN_INFO "/proc/%s removed\n", PROCFS_NAME);
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}
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