/*
*
* Copyright 1999 Digi International (www.digi.com)
* James Puzzo <jamesp at digi dot com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED; without even the
* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
*/
/*
*
* Filename:
*
* dgrp_common.c
*
* Description:
*
* Definitions of global variables and functions which are either
* shared by the tty, mon, and net drivers; or which cross them
* functionally (like the poller).
*
* Author:
*
* James A. Puzzo
*
*/
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include "dgrp_common.h"
/**
* dgrp_carrier -- check for carrier change state and act
* @ch: struct ch_struct *
*/
void dgrp_carrier(struct ch_struct *ch)
{
struct nd_struct *nd;
int virt_carrier = 0;
int phys_carrier = 0;
/* fix case when the tty has already closed. */
if (!ch)
return;
nd = ch->ch_nd;
if (!nd)
return;
/*
* If we are currently waiting to determine the status of the port,
* we don't yet know the state of the modem lines. As a result,
* we ignore state changes when we are waiting for the modem lines
* to be established. We know, as a result of code in dgrp_net_ops,
* that we will be called again immediately following the reception
* of the status message with the true modem status flags in it.
*/
if (ch->ch_expect & RR_STATUS)
return;
/*
* If CH_HANGUP is set, we gotta keep trying to get all the processes
* that have the port open to close the port.
* So lets just keep sending a hangup every time we get here.
*/
if ((ch->ch_flag & CH_HANGUP) &&
(ch->ch_tun.un_open_count > 0))
tty_hangup(ch->ch_tun.un_tty);
/*
* Compute the effective state of both the physical and virtual
* senses of carrier.
*/
if (ch->ch_s_mlast & DM_CD)
phys_carrier = 1;
if ((ch->ch_s_mlast & DM_CD) ||
(ch->ch_digi.digi_flags & DIGI_FORCEDCD) ||
(ch->ch_flag & CH_CLOCAL))
virt_carrier = 1;
/*
* Test for a VIRTUAL carrier transition to HIGH.
*
* The CH_HANGUP condition is intended to prevent any action
* except for close. As a result, we ignore positive carrier
* transitions during CH_HANGUP.
*/
if (((ch->ch_flag & CH_HANGUP) == 0) &&
((ch->ch_flag & CH_VIRT_CD) == 0) &&
(virt_carrier == 1)) {
/*
* When carrier rises, wake any threads waiting
* for carrier in the open routine.
*/
nd->nd_tx_work = 1;
if (waitqueue_active(&ch->ch_flag_wait))
wake_up_interruptible(&ch->ch_flag_wait);
}
/*
* Test for a PHYSICAL transition to low, so long as we aren't
* currently ignoring physical transitions (which is what "virtual
* carrier" indicates).
*
* The transition of the virtual carrier to low really doesn't
* matter... it really only means "ignore carrier state", not
* "make pretend that carrier is there".
*/
if ((virt_carrier == 0) &&
((ch->ch_flag & CH_PHYS_CD) != 0) &&
(phys_carrier == 0)) {
/*
* When carrier drops:
*
* Do a Hard Hangup if that is called for.
*
* Drop carrier on all open units.
*
* Flush queues, waking up any task waiting in the
* line discipline.
*
* Send a hangup to the control terminal.
*
* Enable all select calls.
*/
nd->nd_tx_work = 1;
ch->ch_flag &= ~(CH_LOW | CH_EMPTY | CH_DRAIN | CH_INPUT);
if (waitqueue_active(&ch->ch_flag_wait))
wake_up_interruptible(&ch->ch_flag_wait);
if (ch->ch_tun.un_open_count > 0)
tty_hangup(ch->ch_tun.un_tty);
if (ch->ch_pun.un_open_count > 0)
tty_hangup(ch->ch_pun.un_tty);
}
/*
* Make sure that our cached values reflect the current reality.
*/
if (virt_carrier == 1)
ch->ch_flag |= CH_VIRT_CD;
else
ch->ch_flag &= ~CH_VIRT_CD;
if (phys_carrier == 1)
ch->ch_flag |= CH_PHYS_CD;
else
ch->ch_flag &= ~CH_PHYS_CD;
}
/**
* dgrp_chk_perm() -- check permissions for net device
* @inode: pointer to inode structure for the net communication device
* @op: operation to be tested
*
* The file permissions and ownerships are tested to determine whether
* the operation "op" is permitted on the file pointed to by the inode.
* Returns 0 if the operation is permitted, -EACCESS otherwise
*/
int dgrp_chk_perm(int mode, int op)
{
if (!uid_eq(GLOBAL_ROOT_UID, current_euid()))
mode >>= 6;
else if (in_egroup_p(GLOBAL_ROOT_GID))
mode >>= 3;
if ((mode & op & 0007) == op)
return 0;
if (capable(CAP_SYS_ADMIN))
return 0;
return -EACCES;
}
/* dgrp_chk_perm wrapper for permission call in struct inode_operations */
int dgrp_inode_permission(struct inode *inode, int op)
{
return dgrp_chk_perm(inode->i_mode, op);
}
