NAME
proc_dir_entry, proc_register, proc_register_dynamic,
proc_unregister - register entries in the /proc filesystem.
SYNOPSIS
#include <linux/proc_fs.h>
struct proc_dir_entry * child);
int proc_register(struct proc_dir_entry * parent,
int proc_unregister(struct proc_dir_entry * parent, int
inode));
struct proc_dir_entry * child);
int proc_register_dynamic(struct proc_dir_entry * parent,
DESCRIPTION
The proc_register functions add file or directory entries to
the /proc file system. They associate processing routines
with each node of the /proc tree. The structure
proc_dir_entry is defined as
struct proc_dir_entry {
unsigned short low_ino;
unsigned short namelen;
const char *name;
mode_t mode;
nlink_t nlink;
uid_t uid;
gid_t gid;
unsigned long size;
struct inode_operations * ops;
int (*get_info)(char *buffer, char **start,
off_t offset, int length, int unused);
void (*fill_inode)(struct inode *);
struct proc_dir_entry *next, *parent, *subdir;
void *data;
};
low_ino The inode number of this directory entry. For
proc_register this number should be unique within
the /proc filesystem, values are defined in
<linux/proc_fs.h>. For proc_register_dynamic the
inode number is dynamically assigned.
namelen The length of the name, excluding the trailing null.
name The name of this node.
mode The node's type and permissions. Drawn from
<linux/stat.h>.
nlink Number of links to the node. Initialise to 2 if
mode includes S_IFDIR, 1 otherwise.
uid The uid that owns the node, normally 0.
gid The gid that owns the node. normally 0.
size Sets the size of the node, the value will appear as
the inode size in listings and be returned by stat.
Unless you really need a size, set this to zero.
ops Defines the set of inode operations to perform for
your /proc node. For a directory node, use
&proc_dir_inode_operations unless you have special
requirements. For a leaf node, set to NULL unless
you have special requirements.
get_info
If defined, this proc is called when the node is
read. Should be NULL for directory nodes. NOTE: If
you need to return large amounts of data, the proc
must return the data in chunks and reposition itself
on the next call, using the offset variable. See
ip_masq_procinfo for example code with large output.
fill_inode
Dynamically fill in the inode characteristics during
directory operations. Not normally required and set
to NULL. See proc_pid_fill_inode for example code.
next, parent, subdir
Maintained by /proc routines. Initial value is
irrelevant, set to NULL.
data An opaque pointer which can be used by proc handlers
to pass local data around. Set to whatever you like
when calling proc_register, normally NULL. This
pointer is copied into the inode u.ip_generic field
(by proc_get_inode) so it is available to any proc
routines that are passed an inode.
proc_register adds the child as a node under the parent.
proc_register_dynamic dynamically assigns an inode number
then adds the child as a node under the parent.
proc_unregister scans the inode list under the parent for
the specified inode number and removes the matching entry.
RETURN VALUE
proc_register always returns 0.
proc_register_dynamic returns 0 for success or -EAGAIN if
there are no free dynamic inode numbers.
proc_unregister returns 0 for success or -EINVAL if the node
was not found.
SEE ALSO
proc_net_register(9), proc_net_unregister(9),
proc_scsi_register(9),
AUTHOR
Keith Owens <kaos@ocs.com.au>
BUGS
The uniqueness of /proc inode numbers is assumed, not
enforced. It is possible to add two nodes with the same
inode number.