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/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/devpts/root.c
*
* Copyright 1998 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/errno.h>
#include <linux/stat.h>
#include <linux/param.h>
#include <linux/string.h>
#include "devpts_i.h"
static int devpts_root_readdir(struct file *,void *,filldir_t);
static struct dentry *devpts_root_lookup(struct inode *,struct dentry *);
static int devpts_revalidate(struct dentry *, int);
struct file_operations devpts_root_operations = {
read: generic_read_dir,
readdir: devpts_root_readdir,
};
struct inode_operations devpts_root_inode_operations = {
lookup: devpts_root_lookup,
};
static struct dentry_operations devpts_dentry_operations = {
d_revalidate: devpts_revalidate,
};
/*
* The normal naming convention is simply /dev/pts/<number>; this conforms
* to the System V naming convention
*/
#define genptsname(buf,num) sprintf(buf, "%d", num)
static int devpts_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct inode * inode = filp->f_dentry->d_inode;
struct devpts_sb_info * sbi = SBI(filp->f_dentry->d_inode->i_sb);
off_t nr;
char numbuf[16];
nr = filp->f_pos;
switch(nr)
{
case 0:
if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
return 0;
filp->f_pos = ++nr;
/* fall through */
case 1:
if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
return 0;
filp->f_pos = ++nr;
/* fall through */
default:
while ( nr - 2 < sbi->max_ptys ) {
int ptynr = nr - 2;
if ( sbi->inodes[ptynr] ) {
genptsname(numbuf, ptynr);
if ( filldir(dirent, numbuf, strlen(numbuf), nr, nr, DT_CHR) < 0 )
return 0;
}
filp->f_pos = ++nr;
}
break;
}
return 0;
}
/*
* Revalidate is called on every cache lookup. We use it to check that
* the pty really does still exist. Never revalidate negative dentries;
* for simplicity (fix later?)
*/
static int devpts_revalidate(struct dentry * dentry, int flags)
{
struct devpts_sb_info *sbi;
if ( !dentry->d_inode )
return 0;
sbi = SBI(dentry->d_inode->i_sb);
return ( sbi->inodes[dentry->d_inode->i_ino - 2] == dentry->d_inode );
}
static struct dentry *devpts_root_lookup(struct inode * dir, struct dentry * dentry)
{
struct devpts_sb_info *sbi = SBI(dir->i_sb);
unsigned int entry;
int i;
const char *p;
dentry->d_op = &devpts_dentry_operations;
if ( dentry->d_name.len == 1 && dentry->d_name.name[0] == '0' ) {
entry = 0;
} else if ( dentry->d_name.len < 1 ) {
return NULL;
} else {
p = dentry->d_name.name;
if ( *p < '1' || *p > '9' )
return NULL;
entry = *p++ - '0';
for ( i = dentry->d_name.len-1 ; i ; i-- ) {
unsigned int nentry = *p++ - '0';
if ( nentry > 9 )
return NULL;
if ( entry >= ~0U/10 )
return NULL;
entry = nentry + entry * 10;
}
}
if ( entry >= sbi->max_ptys )
return NULL;
if ( sbi->inodes[entry] )
atomic_inc(&sbi->inodes[entry]->i_count);
d_add(dentry, sbi->inodes[entry]);
return NULL;
}
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