Add offsets.c

net/offsets.c

@@ -0,0 +1,77 @@
+//-------------------------------------------------------------------
+//	offsets.c
+//
+//	This example shows how the 'offsetof' operator can be used
+//	in a module to create a pseudo-file showing the offsets of
+//	member-fields within a kernel data-structure, in this case
+//	offsets for a few members of a 'struct net_device' object.  
+//
+//	NOTE: written and tested with Linux kernel version 2.6.22.5.
+//
+//	programmer: ALLAN CRUSE
+//	written on: 28 JAN 2008
+//-------------------------------------------------------------------
+
+#include <linux/module.h>	// for init_module() 
+#include <linux/proc_fs.h>	// for create_proc_info_entry() 
+#include <linux/netdevice.h>	// for 'struct net_device'
+
+
+char modname[] = "offsets";
+
+
+int my_get_info( char *buf, char **start, off_t off, int count )
+{
+	int	o_name	= offsetof( struct net_device, name );
+	int	o_ifindex = offsetof( struct net_device, ifindex ); 
+	int	o_irq 	= offsetof( struct net_device, irq );
+	int	o_priv	= offsetof( struct net_device, priv );
+	int	o_open	= offsetof( struct net_device, open );
+	int	o_stop	= offsetof( struct net_device, stop );
+	int	o_dev_addr = offsetof( struct net_device, dev_addr );
+	int	o_hwxmit = offsetof( struct net_device, hard_start_xmit );
+	int	len = 0;
+
+	len += sprintf( buf+len, "\n" );
+	len += sprintf( buf+len, " Structure-member offsets in " );
+	len += sprintf( buf+len, "\'struct net_device' objects " );
+	len += sprintf( buf+len, "\n" );
+
+	len += sprintf( buf+len, "\n" );
+	len += sprintf( buf+len, "  offset    member  \n" );
+	len += sprintf( buf+len, " -------------------\n" );
+
+	len += sprintf( buf+len, "  0x%04X    name \n", o_name );
+	len += sprintf( buf+len, "  0x%04X    ifindex \n", o_ifindex );
+	len += sprintf( buf+len, "  0x%04X    dev_addr \n", o_dev_addr );
+	len += sprintf( buf+len, "  0x%04X    irq \n", o_irq );
+	len += sprintf( buf+len, "  0x%04X    priv \n", o_priv );
+	len += sprintf( buf+len, "  0x%04X    open \n", o_open );
+	len += sprintf( buf+len, "  0x%04X    stop \n", o_stop );
+	len += sprintf( buf+len, "  0x%04X    hard_start_xmit \n", o_hwxmit );
+	len += sprintf( buf+len, "\n" );
+
+	return	len;
+}
+
+
+static int __init my_init( void )
+{
+	printk( "<1>\nInstalling \'%s\' module\n", modname );
+
+	create_proc_info_entry( modname, 0, NULL, my_get_info );
+	return	0;  //SUCCESS
+}
+
+
+static void __exit my_exit(void )
+{
+	remove_proc_entry( modname, NULL );
+
+	printk( "<1>Removing \'%s\' module\n", modname );
+}
+
+module_init( my_init );
+module_exit( my_exit );
+MODULE_LICENSE("GPL"); 
+