proc_dir_entry(9) /proc Functions proc_dir_entry(9)NAME
proc_dir_entry, proc_register, proc_register_dynamic, proc_unregister-
register entries in the /proc filesystem.
SYNOPSIS
#include <linux/proc_fs.h>
int proc_register(struct proc_dir_entry * parent,
struct proc_dir_entry * child);
int proc_unregister(struct proc_dir_entry * parent, int inode);
int proc_register_dynamic(struct proc_dir_entry * parent,
struct proc_dir_entry * child);
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 ALSOproc_net_register(9), proc_net_unregister(9), proc_scsi_register(9),
proc_scsi_unregister(9), stat(2).
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.
Linux 2.0.30 July 1997 proc_dir_entry(9)
