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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;

}