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