/*
CopyRight GPL 2004 mmc Mike Chirico mchirico@users.sourceforge.net
Created: Sun Mar 14 14:31:32 EST 2004
Updated: Sun Mar 14 17:11:19 EST 2004
Dev home: cpearls/src/development/kernel_module/proc/readwrite
http: http://cvs.sourceforge.net/viewcvs.py/cpearls/cpearls/src/development/kernel_module/proc/readwrite/
This is a sample program that will create proc directories
$ cat /proc/procreadwrite/count
Test count 0
$ cat /proc/procreadwrite/count
Test count 1
$ echo -n "my test data" > /proc/procreadwrite/count
in the WRITE mbuf=->my test data<-
$ cat /proc/procreadwrite/sequence
0
1
2
...
$ dd if=/proc/procreadwrite/sequence of=/tmp/seq count=1024
By default dd uses block of 512 so the size will be 1024*512
NOTES:
unsigned long copy_from_user(void *to, const void *from,
unsigned long count);
Think copy from user to kernel. You'll see this in
the "read...as in read from user"
REFERENCES:
http://www.xenotime.net/linux/doc/seq_file_howto.txt
http://www.xenotime.net/linux/procfs_ex/procseq.c
http://lwn.net/Articles/driver-porting/
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#include <linux/tty.h> /* For the tty declarations */
#include <linux/console.h>
#include <linux/usb.h>
MODULE_AUTHOR ("Mike Chirico");
MODULE_LICENSE ("Dual BSD/GPL"); /* gets rid of that tainting message */
#define MY_MODULE_VERSION "1.3"
#define MODULE_NAME "procreadwrite"
char rbuf[80];
static struct proc_dir_entry *e = NULL;
static struct proc_dir_entry *entry = NULL;
static struct proc_dir_entry *eroot = NULL;
static void *proc_seq_count_start (struct seq_file *s, loff_t * pos);
static void *proc_seq_count_next (struct seq_file *s, void *v, loff_t * pos);
static void proc_seq_count_stop (struct seq_file *s, void *v);
static int proc_seq_count_show (struct seq_file *s, void *v);
static int proc_seq_count_open (struct inode *inode, struct file *file);
static struct seq_operations proc_seq_count_ops = {
.start = proc_seq_count_start,
.next = proc_seq_count_next,
.stop = proc_seq_count_stop,
.show = proc_seq_count_show
};
static void *
proc_seq_count_start (struct seq_file *s, loff_t * pos)
{
loff_t *spos = kmalloc (sizeof (loff_t), GFP_KERNEL);
if (!spos)
return NULL;
*spos = *pos;
return spos;
}
static void *
proc_seq_count_next (struct seq_file *s, void *v, loff_t * pos)
{
loff_t *spos = (loff_t *) v;
*pos = ++(*spos);
return spos;
}
static void
proc_seq_count_stop (struct seq_file *s, void *v)
{
kfree (v);
}
/* This could list the sequence
*
* $cat /proc/procreadwrite/sequence
*
*/
static int
proc_seq_count_show (struct seq_file *s, void *v)
{
loff_t *spos = (loff_t *) v;
seq_printf (s, "%Ld\n", *spos);
return 0;
}
static int
proc_seq_count_open (struct inode *inode, struct file *file)
{
return seq_open (file, &proc_seq_count_ops);
};
static int
proc_procreadwrite_show (struct seq_file *m, void *v)
{
static int count = 0;
char buf[80];
snprintf (buf, 80, " Test count %d \n", count);
seq_puts (m, buf);
count++;
return 0;
}
static int
proc_procreadwrite_open (struct inode *inode, struct file *file)
{
return single_open (file, proc_procreadwrite_show, NULL);
}
/* This is for writing to the tty device
* It's good for debugging.
*
*/
static int
mtty_write (char *text)
{
struct tty_struct *my_tty;
static int null_tty = 0;
/* my_tty = current->tty; */ /* old */
my_tty = current->signal->tty; /* For kernel 2.6.6+ current->tty has been replaced with current->signal->tty */
if (my_tty != NULL)
{
((my_tty->driver)->write) (my_tty, /* The tty itself */
0, /* We don't take the string from user space */
text, /* String */
strlen (text)); /* Length */
/* Currently caller will drive this
((my_tty->driver)->write)(
my_tty,
0,
"\015\012",
2);
*/
}
else
{
null_tty++; /* debug for is calling with no tty...it does nothing at the moment */
}
return strlen (text);
}
/* write is for write to the kernel
echo -n "stuff" /proc/procreadwrite/count
*/
static ssize_t
proc_procreadwrite_write (struct file *file,
const char * buf, size_t size, loff_t * ppos)
{
size_t len = 20;
char mbuf[21];
if (len > size)
len = size;
if (copy_from_user (mbuf, buf, len))
return -EFAULT;
mbuf[len] = '\0';
mtty_write ("in the WRITE mbuf=->");
mtty_write (mbuf);
mtty_write ("<-");
mtty_write ("\015\012"); /* crlf */
return len;
}
static struct file_operations proc_procreadwrite_operations = {
.open = proc_procreadwrite_open,
.read = seq_read,
.write = proc_procreadwrite_write,
.llseek = seq_lseek,
.release = single_release,
};
static struct file_operations proc_seq_count_file_ops = {
.owner = THIS_MODULE,
.open = proc_seq_count_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
static int __init
proc_procreadwrite_init (void)
{
int merr = 0;
eroot = proc_mkdir (MODULE_NAME, NULL);
if (eroot == NULL)
{
merr = -ENOMEM;
return merr;
}
eroot->owner = THIS_MODULE;
e = create_proc_entry ("count", 0666, eroot); /* 0666 everyone can write to this */
if (e)
e->proc_fops = &proc_procreadwrite_operations;
entry = create_proc_entry ("sequence", 0, eroot);
if (entry)
entry->proc_fops = &proc_seq_count_file_ops;
return 0;
}
static void __exit
cleanup_procfs_procreadwrite (void)
{
remove_proc_entry ("count", eroot);
remove_proc_entry ("sequence", eroot);
remove_proc_entry (MODULE_NAME, NULL);
printk (KERN_INFO "%s %s removed\n", MODULE_NAME, MY_MODULE_VERSION);
}
module_init (proc_procreadwrite_init);
module_exit (cleanup_procfs_procreadwrite);
MODULE_DESCRIPTION ("procfs examples procreadwrite");
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Mike Chirico, a father of triplets (all girls) lives outside of
Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters
in Computer Science and Mathematics from Villanova University, and has
worked in computer-related jobs from Wall Street to the University of
Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was
known for his open collaboration with others.
Mike's notes page is souptonuts. For
open source consulting needs, please send an email to
mchirico@gmail.com. All consulting work must include a donation to
SourceForge.net.
