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DEFINITIONS
This source file includes following definitions.
- devpts_remount
- devpts_show_options
- devpts_fill_super
- devpts_get_sb
- devpts_new_index
- devpts_kill_index
- devpts_pty_new
- devpts_get_tty
- devpts_pty_kill
- init_devpts_fs
- exit_devpts_fs
/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/devpts/inode.c
*
* Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/tty.h>
#include <linux/mutex.h>
#include <linux/idr.h>
#include <linux/devpts_fs.h>
#include <linux/parser.h>
#include <linux/fsnotify.h>
#include <linux/seq_file.h>
#define DEVPTS_SUPER_MAGIC 0x1cd1
#define DEVPTS_DEFAULT_MODE 0600
#define PTMX_MINOR 2
extern int pty_limit; /* Config limit on Unix98 ptys */
static DEFINE_IDA(allocated_ptys);
static DEFINE_MUTEX(allocated_ptys_lock);
static struct vfsmount *devpts_mnt;
static struct dentry *devpts_root;
static struct {
int setuid;
int setgid;
uid_t uid;
gid_t gid;
umode_t mode;
} config = {.mode = DEVPTS_DEFAULT_MODE};
enum {
Opt_uid, Opt_gid, Opt_mode,
Opt_err
};
static const match_table_t tokens = {
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
{Opt_err, NULL}
};
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
char *p;
config.setuid = 0;
config.setgid = 0;
config.uid = 0;
config.gid = 0;
config.mode = DEVPTS_DEFAULT_MODE;
while ((p = strsep(&data, ",")) != NULL) {
substring_t args[MAX_OPT_ARGS];
int token;
int option;
if (!*p)
continue;
token = match_token(p, tokens, args);
switch (token) {
case Opt_uid:
if (match_int(&args[0], &option))
return -EINVAL;
config.uid = option;
config.setuid = 1;
break;
case Opt_gid:
if (match_int(&args[0], &option))
return -EINVAL;
config.gid = option;
config.setgid = 1;
break;
case Opt_mode:
if (match_octal(&args[0], &option))
return -EINVAL;
config.mode = option & S_IALLUGO;
break;
default:
printk(KERN_ERR "devpts: called with bogus options\n");
return -EINVAL;
}
}
return 0;
}
static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
if (config.setuid)
seq_printf(seq, ",uid=%u", config.uid);
if (config.setgid)
seq_printf(seq, ",gid=%u", config.gid);
seq_printf(seq, ",mode=%03o", config.mode);
return 0;
}
static const struct super_operations devpts_sops = {
.statfs = simple_statfs,
.remount_fs = devpts_remount,
.show_options = devpts_show_options,
};
static int
devpts_fill_super(struct super_block *s, void *data, int silent)
{
struct inode * inode;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->s_magic = DEVPTS_SUPER_MAGIC;
s->s_op = &devpts_sops;
s->s_time_gran = 1;
inode = new_inode(s);
if (!inode)
goto fail;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_blocks = 0;
inode->i_uid = inode->i_gid = 0;
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inode->i_nlink = 2;
devpts_root = s->s_root = d_alloc_root(inode);
if (s->s_root)
return 0;
printk("devpts: get root dentry failed\n");
iput(inode);
fail:
return -ENOMEM;
}
static int devpts_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
}
static struct file_system_type devpts_fs_type = {
.owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
.kill_sb = kill_anon_super,
};
/*
* The normal naming convention is simply /dev/pts/<number>; this conforms
* to the System V naming convention
*/
int devpts_new_index(struct inode *ptmx_inode)
{
int index;
int ida_ret;
retry:
if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
return -ENOMEM;
}
mutex_lock(&allocated_ptys_lock);
ida_ret = ida_get_new(&allocated_ptys, &index);
if (ida_ret < 0) {
mutex_unlock(&allocated_ptys_lock);
if (ida_ret == -EAGAIN)
goto retry;
return -EIO;
}
if (index >= pty_limit) {
ida_remove(&allocated_ptys, index);
mutex_unlock(&allocated_ptys_lock);
return -EIO;
}
mutex_unlock(&allocated_ptys_lock);
return index;
}
void devpts_kill_index(struct inode *ptmx_inode, int idx)
{
mutex_lock(&allocated_ptys_lock);
ida_remove(&allocated_ptys, idx);
mutex_unlock(&allocated_ptys_lock);
}
int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
{
int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
struct tty_driver *driver = tty->driver;
dev_t device = MKDEV(driver->major, driver->minor_start+number);
struct dentry *dentry;
struct inode *inode = new_inode(devpts_mnt->mnt_sb);
char s[12];
/* We're supposed to be given the slave end of a pty */
BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
if (!inode)
return -ENOMEM;
inode->i_ino = number+2;
inode->i_uid = config.setuid ? config.uid : current->fsuid;
inode->i_gid = config.setgid ? config.gid : current->fsgid;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
init_special_inode(inode, S_IFCHR|config.mode, device);
inode->i_private = tty;
tty->driver_data = inode;
sprintf(s, "%d", number);
mutex_lock(&devpts_root->d_inode->i_mutex);
dentry = d_alloc_name(devpts_root, s);
if (!IS_ERR(dentry)) {
d_add(dentry, inode);
fsnotify_create(devpts_root->d_inode, dentry);
}
mutex_unlock(&devpts_root->d_inode->i_mutex);
return 0;
}
struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
{
BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
return (struct tty_struct *)pts_inode->i_private;
return NULL;
}
void devpts_pty_kill(struct tty_struct *tty)
{
struct inode *inode = tty->driver_data;
struct dentry *dentry;
BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
mutex_lock(&devpts_root->d_inode->i_mutex);
dentry = d_find_alias(inode);
if (dentry && !IS_ERR(dentry)) {
inode->i_nlink--;
d_delete(dentry);
dput(dentry);
}
mutex_unlock(&devpts_root->d_inode->i_mutex);
}
static int __init init_devpts_fs(void)
{
int err = register_filesystem(&devpts_fs_type);
if (!err) {
devpts_mnt = kern_mount(&devpts_fs_type);
if (IS_ERR(devpts_mnt))
err = PTR_ERR(devpts_mnt);
}
return err;
}
static void __exit exit_devpts_fs(void)
{
unregister_filesystem(&devpts_fs_type);
mntput(devpts_mnt);
}
module_init(init_devpts_fs)
module_exit(exit_devpts_fs)
MODULE_LICENSE("GPL");