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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [drivers/] [char/] [tty_io.c] - Blame information for rev 1765

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/*
 *  linux/drivers/char/tty_io.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */
 
/*
 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
 * or rs-channels. It also implements echoing, cooked mode etc.
 *
 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
 *
 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
 * tty_struct and tty_queue structures.  Previously there was an array
 * of 256 tty_struct's which was statically allocated, and the
 * tty_queue structures were allocated at boot time.  Both are now
 * dynamically allocated only when the tty is open.
 *
 * Also restructured routines so that there is more of a separation
 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
 * the low-level tty routines (serial.c, pty.c, console.c).  This
 * makes for cleaner and more compact code.  -TYT, 9/17/92
 *
 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
 * which can be dynamically activated and de-activated by the line
 * discipline handling modules (like SLIP).
 *
 * NOTE: pay no attention to the line discipline code (yet); its
 * interface is still subject to change in this version...
 * -- TYT, 1/31/92
 *
 * Added functionality to the OPOST tty handling.  No delays, but all
 * other bits should be there.
 *      -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
 *
 * Rewrote canonical mode and added more termios flags.
 *      -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
 *
 * Reorganized FASYNC support so mouse code can share it.
 *      -- ctm@ardi.com, 9Sep95
 *
 * New TIOCLINUX variants added.
 *      -- mj@k332.feld.cvut.cz, 19-Nov-95
 *
 * Restrict vt switching via ioctl()
 *      -- grif@cs.ucr.edu, 5-Dec-95
 *
 * Rewrote init_dev and release_dev to eliminate races.
 *      -- Bill Hawes <whawes@star.net>, June 97
 *
 * Configurable CONSOLE, FRAMEBUFFER, and KEYBOARD
 *      -- Kenneth Albanowski <kjahds@kjahds.com>, '98
 */
 
#include <linux/config.h>
#include <linux/types.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/kd.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/malloc.h>
 
#include <asm/segment.h>
#include <asm/system.h>
#include <asm/bitops.h>
 
#include <linux/scc.h>
#include <linux/fb.h>
 
#include "kbd_kern.h"
#include "vt_kern.h"
#include "selection.h"
 
#ifdef CONFIG_KERNELD
#include <linux/kerneld.h>
#endif
 
#define CONSOLE_DEV MKDEV(TTY_MAJOR,0)
#define TTY_DEV MKDEV(TTYAUX_MAJOR,0)
 
#undef TTY_DEBUG_HANGUP
 
#define TTY_PARANOIA_CHECK
#define CHECK_TTY_COUNT
 
extern void do_blank_screen(int nopowersave);
extern void set_vesa_blanking(const unsigned long arg);
 
struct termios tty_std_termios;         /* for the benefit of tty drivers  */
struct tty_driver *tty_drivers = NULL;  /* linked list of tty drivers */
struct tty_ldisc ldiscs[NR_LDISCS];     /* line disc dispatch table     */
 
/*
 * fg_console is the current virtual console,
 * last_console is the last used one,
 * want_console is the console we want to switch to,
 * kmsg_redirect is the console for kernel messages,
 * redirect is the pseudo-tty that console output
 * is redirected to if asked by TIOCCONS.
 */
int fg_console = 0;
int last_console = 0;
int want_console = -1;
int kmsg_redirect = 0;
struct tty_struct * redirect = NULL;
struct wait_queue * keypress_wait = NULL;
char vt_dont_switch = 0;
 
static void initialize_tty_struct(struct tty_struct *tty);
 
static int tty_read(struct inode *, struct file *, char *, int);
static int tty_write(struct inode *, struct file *, const char *, int);
static int tty_select(struct inode *, struct file *, int, select_table *);
static int tty_open(struct inode *, struct file *);
static void tty_release(struct inode *, struct file *);
static int tty_ioctl(struct inode * inode, struct file * file,
                     unsigned int cmd, unsigned long arg);
static int tty_fasync(struct inode * inode, struct file * filp, int on);
 
extern void reset_palette(int currcons) ;
extern void set_palette(void) ;
 
#ifndef MIN
#define MIN(a,b)        ((a) < (b) ? (a) : (b))
#endif
 
/*
 * These two routines return the name of tty.  tty_name() should NOT
 * be used in interrupt drivers, since it's not re-entrant.  Use
 * _tty_name() instead.
 */
char *_tty_name(struct tty_struct *tty, char *buf)
{
        if (tty)
                sprintf(buf, "%s%d", tty->driver.name,
                        MINOR(tty->device) - tty->driver.minor_start +
                        tty->driver.name_base);
        else
                strcpy(buf, "NULL tty");
        return buf;
}
 
char *tty_name(struct tty_struct *tty)
{
        static char buf[64];
 
        return(_tty_name(tty, buf));
}
 
inline int tty_paranoia_check(struct tty_struct *tty, kdev_t device,
                              const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
        static const char *badmagic =
                "Warning: bad magic number for tty struct (%s) in %s\n";
        static const char *badtty =
                "Warning: null TTY for (%s) in %s\n";
 
        if (!tty) {
                printk(badtty, kdevname(device), routine);
                return 1;
        }
        if (tty->magic != TTY_MAGIC) {
                printk(badmagic, kdevname(device), routine);
                return 1;
        }
#endif
        return 0;
}
 
static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
        struct file *f;
        int i, count = 0;
 
        for (f = first_file, i=0; i<nr_files; i++, f = f->f_next) {
                if (!f->f_count)
                        continue;
                if (f->private_data == tty) {
                        count++;
                }
        }
        if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
            tty->driver.subtype == PTY_TYPE_SLAVE &&
            tty->link && tty->link->count)
                count++;
        if (tty->count != count) {
                printk("Warning: dev (%s) tty->count(%d) != #fd's(%d) in %s\n",
                       kdevname(tty->device), tty->count, count, routine);
                return count;
       }
#endif
        return 0;
}
 
int tty_register_ldisc(int disc, struct tty_ldisc *new_ldisc)
{
        if (disc < N_TTY || disc >= NR_LDISCS)
                return -EINVAL;
 
        if (new_ldisc) {
                ldiscs[disc] = *new_ldisc;
                ldiscs[disc].flags |= LDISC_FLAG_DEFINED;
                ldiscs[disc].num = disc;
        } else
                memset(&ldiscs[disc], 0, sizeof(struct tty_ldisc));
 
        return 0;
}
 
/* Set the discipline of a tty line. */
static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
{
        int     retval = 0;
        struct  tty_ldisc o_ldisc;
 
        if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS))
                return -EINVAL;
#ifdef CONFIG_KERNELD
        /* Eduardo Blanco <ejbs@cs.cs.com.uy> */
        if (!(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED)) {
                char modname [20];
                sprintf(modname, "tty-ldisc-%d", ldisc);
                request_module (modname);
        }
#endif
        if (!(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED))
                return -EINVAL;
 
        if (tty->ldisc.num == ldisc)
                return 0;        /* We are already in the desired discipline */
        o_ldisc = tty->ldisc;
 
        tty_wait_until_sent(tty, 0);
 
        /* Shutdown the current discipline. */
        if (tty->ldisc.close)
                (tty->ldisc.close)(tty);
 
        /* Now set up the new line discipline. */
        tty->ldisc = ldiscs[ldisc];
        tty->termios->c_line = ldisc;
        if (tty->ldisc.open)
                retval = (tty->ldisc.open)(tty);
        if (retval < 0) {
                tty->ldisc = o_ldisc;
                tty->termios->c_line = tty->ldisc.num;
                if (tty->ldisc.open && (tty->ldisc.open(tty) < 0)) {
                        tty->ldisc = ldiscs[N_TTY];
                        tty->termios->c_line = N_TTY;
                        if (tty->ldisc.open) {
                                int r = tty->ldisc.open(tty);
 
                                if (r < 0)
                                        panic("Couldn't open N_TTY ldisc for "
                                              "%s --- error %d.",
                                              tty_name(tty), r);
                        }
                }
        }
        if (tty->ldisc.num != o_ldisc.num && tty->driver.set_ldisc)
                tty->driver.set_ldisc(tty);
        return retval;
}
 
/*
 * This routine returns a tty driver structure, given a device number
 */
struct tty_driver *get_tty_driver(kdev_t device)
{
        int     major, minor;
        struct tty_driver *p;
 
        minor = MINOR(device);
        major = MAJOR(device);
 
        for (p = tty_drivers; p; p = p->next) {
                if (p->major != major)
                        continue;
                if (minor < p->minor_start)
                        continue;
                if (minor >= p->minor_start + p->num)
                        continue;
                return p;
        }
        return NULL;
}
 
/*
 * If we try to write to, or set the state of, a terminal and we're
 * not in the foreground, send a SIGTTOU.  If the signal is blocked or
 * ignored, go ahead and perform the operation.  (POSIX 7.2)
 */
int tty_check_change(struct tty_struct * tty)
{
        if (current->tty != tty)
                return 0;
        if (tty->pgrp <= 0) {
                printk("tty_check_change: tty->pgrp <= 0!\n");
                return 0;
        }
        if (current->pgrp == tty->pgrp)
                return 0;
        if (is_ignored(SIGTTOU))
                return 0;
        if (is_orphaned_pgrp(current->pgrp))
                return -EIO;
        (void) kill_pg(current->pgrp,SIGTTOU,1);
        return -ERESTARTSYS;
}
 
static int hung_up_tty_read(struct inode * inode, struct file * file, char * buf, int count)
{
        return 0;
}
 
static int hung_up_tty_write(struct inode * inode, struct file * file, const char * buf, int count)
{
        return -EIO;
}
 
static int hung_up_tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
{
        return 1;
}
 
static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
                             unsigned int cmd, unsigned long arg)
{
        return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
}
 
static int tty_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
{
        return -ESPIPE;
}
 
static struct file_operations tty_fops = {
        tty_lseek,
        tty_read,
        tty_write,
        NULL,           /* tty_readdir */
        tty_select,
        tty_ioctl,
        NULL,           /* tty_mmap */
        tty_open,
        tty_release,
        NULL,           /* tty_fsync */
        tty_fasync
};
 
static struct file_operations hung_up_tty_fops = {
        tty_lseek,
        hung_up_tty_read,
        hung_up_tty_write,
        NULL,           /* hung_up_tty_readdir */
        hung_up_tty_select,
        hung_up_tty_ioctl,
        NULL,           /* hung_up_tty_mmap */
        NULL,           /* hung_up_tty_open */
        tty_release,    /* hung_up_tty_release */
        NULL,           /* hung_up_tty_fsync  */
        NULL            /* hung_up_tty_fasync */
};
 
void do_tty_hangup(struct tty_struct * tty, struct file_operations *fops)
{
        int i;
        struct file * filp;
        struct task_struct *p;
 
        if (!tty)
                return;
        check_tty_count(tty, "do_tty_hangup");
        for (filp = first_file, i=0; i<nr_files; i++, filp = filp->f_next) {
                if (!filp->f_count)
                        continue;
                if (filp->private_data != tty)
                        continue;
                if (!filp->f_inode)
                        continue;
                if (filp->f_inode->i_rdev == CONSOLE_DEV)
                        continue;
                if (filp->f_op != &tty_fops)
                        continue;
                tty_fasync(filp->f_inode, filp, 0);
                filp->f_op = fops;
        }
 
        if (tty->ldisc.flush_buffer)
                tty->ldisc.flush_buffer(tty);
        if (tty->driver.flush_buffer)
                tty->driver.flush_buffer(tty);
        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
            tty->ldisc.write_wakeup)
                (tty->ldisc.write_wakeup)(tty);
        wake_up_interruptible(&tty->write_wait);
        wake_up_interruptible(&tty->read_wait);
 
        /*
         * Shutdown the current line discipline, and reset it to
         * N_TTY.
         */
        if (tty->ldisc.num != ldiscs[N_TTY].num) {
                if (tty->ldisc.close)
                        (tty->ldisc.close)(tty);
                tty->ldisc = ldiscs[N_TTY];
                tty->termios->c_line = N_TTY;
                if (tty->ldisc.open) {
                        i = (tty->ldisc.open)(tty);
                        if (i < 0)
                                printk("do_tty_hangup: N_TTY open: error %d\n",
                                       -i);
                }
        }
 
        for_each_task(p) {
                if ((tty->session > 0) && (p->session == tty->session) &&
                    p->leader) {
                        send_sig(SIGHUP,p,1);
                        send_sig(SIGCONT,p,1);
                        if (tty->pgrp > 0)
                                p->tty_old_pgrp = tty->pgrp;
                }
                if (p->tty == tty)
                        p->tty = NULL;
        }
        tty->flags = 0;
        tty->session = 0;
        tty->pgrp = -1;
        tty->ctrl_status = 0;
        if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS)
                *tty->termios = tty->driver.init_termios;
        if (tty->driver.hangup)
                (tty->driver.hangup)(tty);
}
 
void tty_hangup(struct tty_struct * tty)
{
#ifdef TTY_DEBUG_HANGUP
        printk("%s hangup...\n", tty_name(tty));
#endif
        do_tty_hangup(tty, &hung_up_tty_fops);
}
 
void tty_vhangup(struct tty_struct * tty)
{
#ifdef TTY_DEBUG_HANGUP
        printk("%s vhangup...\n", tty_name(tty));
#endif
        do_tty_hangup(tty, &hung_up_tty_fops);
}
 
int tty_hung_up_p(struct file * filp)
{
        return (filp->f_op == &hung_up_tty_fops);
}
 
/*
 * This function is typically called only by the session leader, when
 * it wants to disassociate itself from its controlling tty.
 *
 * It performs the following functions:
 *      (1)  Sends a SIGHUP and SIGCONT to the foreground process group
 *      (2)  Clears the tty from being controlling the session
 *      (3)  Clears the controlling tty for all processes in the
 *              session group.
 *
 * The argument on_exit is set to 1 if called when a process is
 * exiting; it is 0 if called by the ioctl TIOCNOTTY.
 */
void disassociate_ctty(int on_exit)
{
        struct tty_struct *tty = current->tty;
        struct task_struct *p;
        int tty_pgrp = -1;
 
        if (tty) {
                tty_pgrp = tty->pgrp;
                if (on_exit && tty->driver.type != TTY_DRIVER_TYPE_PTY)
                        tty_vhangup(tty);
        } else {
                if (current->tty_old_pgrp) {
                        kill_pg(current->tty_old_pgrp, SIGHUP, on_exit);
                        kill_pg(current->tty_old_pgrp, SIGCONT, on_exit);
                }
                return;
        }
        if (tty_pgrp > 0) {
                kill_pg(tty_pgrp, SIGHUP, on_exit);
                if (!on_exit)
                        kill_pg(tty_pgrp, SIGCONT, on_exit);
        }
 
        current->tty_old_pgrp = 0;
        tty->session = 0;
        tty->pgrp = -1;
 
        for_each_task(p)
                if (p->session == current->session)
                        p->tty = NULL;
}
 
#ifdef CONFIG_CONSOLE
/*
 * Sometimes we want to wait until a particular VT has been activated. We
 * do it in a very simple manner. Everybody waits on a single queue and
 * get woken up at once. Those that are satisfied go on with their business,
 * while those not ready go back to sleep. Seems overkill to add a wait
 * to each vt just for this - usually this does nothing!
 */
static struct wait_queue *vt_activate_queue = NULL;
 
/*
 * Sleeps until a vt is activated, or the task is interrupted. Returns
 * 0 if activation, -1 if interrupted.
 */
int vt_waitactive(void)
{
        interruptible_sleep_on(&vt_activate_queue);
        return (current->signal & ~current->blocked) ? -1 : 0;
}
 
#define vt_wake_waitactive() wake_up(&vt_activate_queue)
 
void reset_vc(unsigned int new_console)
{
        vt_cons[new_console]->vc_mode = KD_TEXT;
        kbd_table[new_console].kbdmode = VC_XLATE;
        vt_cons[new_console]->vt_mode.mode = VT_AUTO;
        vt_cons[new_console]->vt_mode.waitv = 0;
        vt_cons[new_console]->vt_mode.relsig = 0;
        vt_cons[new_console]->vt_mode.acqsig = 0;
        vt_cons[new_console]->vt_mode.frsig = 0;
        vt_cons[new_console]->vt_pid = -1;
        vt_cons[new_console]->vt_newvt = -1;
        reset_palette (new_console) ;
}
 
/*
 * Performs the back end of a vt switch
 */
void complete_change_console(unsigned int new_console)
{
        unsigned char old_vc_mode;
 
        if ((new_console == fg_console) || (vt_dont_switch))
                return;
        if (!vc_cons_allocated(new_console))
                return;
        last_console = fg_console;
 
        /*
         * If we're switching, we could be going from KD_GRAPHICS to
         * KD_TEXT mode or vice versa, which means we need to blank or
         * unblank the screen later.
         */
        old_vc_mode = vt_cons[fg_console]->vc_mode;
        update_screen(new_console);
 
        /*
         * If this new console is under process control, send it a signal
         * telling it that it has acquired. Also check if it has died and
         * clean up (similar to logic employed in change_console())
         */
        if (vt_cons[new_console]->vt_mode.mode == VT_PROCESS)
        {
                /*
                 * Send the signal as privileged - kill_proc() will
                 * tell us if the process has gone or something else
                 * is awry
                 */
                if (kill_proc(vt_cons[new_console]->vt_pid,
                              vt_cons[new_console]->vt_mode.acqsig,
                              1) != 0)
                {
                /*
                 * The controlling process has died, so we revert back to
                 * normal operation. In this case, we'll also change back
                 * to KD_TEXT mode. I'm not sure if this is strictly correct
                 * but it saves the agony when the X server dies and the screen
                 * remains blanked due to KD_GRAPHICS! It would be nice to do
                 * this outside of VT_PROCESS but there is no single process
                 * to account for and tracking tty count may be undesirable.
                 */
                        reset_vc(new_console);
                }
        }
 
        /*
         * We do this here because the controlling process above may have
         * gone, and so there is now a new vc_mode
         */
        if (old_vc_mode != vt_cons[new_console]->vc_mode)
        {
                if (vt_cons[new_console]->vc_mode == KD_TEXT)
                        do_unblank_screen();
                else
                        do_blank_screen(1);
        }
 
        /* Set the colour palette for this VT */
        if (vt_cons[new_console]->vc_mode == KD_TEXT)
                set_palette() ;
 
        /*
         * Wake anyone waiting for their VT to activate
         */
        vt_wake_waitactive();
        return;
}
 
/*
 * Performs the front-end of a vt switch
 */
void change_console(unsigned int new_console)
{
        if ((new_console == fg_console) || (vt_dont_switch))
                return;
        if (!vc_cons_allocated(new_console))
                return;
 
        /*
         * If this vt is in process mode, then we need to handshake with
         * that process before switching. Essentially, we store where that
         * vt wants to switch to and wait for it to tell us when it's done
         * (via VT_RELDISP ioctl).
         *
         * We also check to see if the controlling process still exists.
         * If it doesn't, we reset this vt to auto mode and continue.
         * This is a cheap way to track process control. The worst thing
         * that can happen is: we send a signal to a process, it dies, and
         * the switch gets "lost" waiting for a response; hopefully, the
         * user will try again, we'll detect the process is gone (unless
         * the user waits just the right amount of time :-) and revert the
         * vt to auto control.
         */
        if (vt_cons[fg_console]->vt_mode.mode == VT_PROCESS)
        {
                /*
                 * Send the signal as privileged - kill_proc() will
                 * tell us if the process has gone or something else
                 * is awry
                 */
                if (kill_proc(vt_cons[fg_console]->vt_pid,
                              vt_cons[fg_console]->vt_mode.relsig,
                              1) == 0)
                {
                        /*
                         * It worked. Mark the vt to switch to and
                         * return. The process needs to send us a
                         * VT_RELDISP ioctl to complete the switch.
                         */
                        vt_cons[fg_console]->vt_newvt = new_console;
                        return;
                }
 
                /*
                 * The controlling process has died, so we revert back to
                 * normal operation. In this case, we'll also change back
                 * to KD_TEXT mode. I'm not sure if this is strictly correct
                 * but it saves the agony when the X server dies and the screen
                 * remains blanked due to KD_GRAPHICS! It would be nice to do
                 * this outside of VT_PROCESS but there is no single process
                 * to account for and tracking tty count may be undesirable.
                 */
                reset_vc(fg_console);
 
                /*
                 * Fall through to normal (VT_AUTO) handling of the switch...
                 */
        }
 
        /*
         * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
         */
        if (vt_cons[fg_console]->vc_mode == KD_GRAPHICS)
                return;
 
        complete_change_console(new_console);
}
#endif /*CONFIG_CONSOLE*/
 
void wait_for_keypress(void)
{
        sleep_on(&keypress_wait);
}
 
void stop_tty(struct tty_struct *tty)
{
        if (tty->stopped)
                return;
        tty->stopped = 1;
        if (tty->link && tty->link->packet) {
                tty->ctrl_status &= ~TIOCPKT_START;
                tty->ctrl_status |= TIOCPKT_STOP;
                wake_up_interruptible(&tty->link->read_wait);
        }
        if (tty->driver.stop)
                (tty->driver.stop)(tty);
}
 
void start_tty(struct tty_struct *tty)
{
        if (!tty->stopped)
                return;
        tty->stopped = 0;
        if (tty->link && tty->link->packet) {
                tty->ctrl_status &= ~TIOCPKT_STOP;
                tty->ctrl_status |= TIOCPKT_START;
                wake_up_interruptible(&tty->link->read_wait);
        }
        if (tty->driver.start)
                (tty->driver.start)(tty);
        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
            tty->ldisc.write_wakeup)
                (tty->ldisc.write_wakeup)(tty);
        wake_up_interruptible(&tty->write_wait);
}
 
static int tty_read(struct inode * inode, struct file * file, char * buf, int count)
{
        int i;
        struct tty_struct * tty;
 
        tty = (struct tty_struct *)file->private_data;
        if (tty_paranoia_check(tty, inode->i_rdev, "tty_read"))
                return -EIO;
        if (!tty || (tty->flags & (1 << TTY_IO_ERROR)))
                return -EIO;
 
        /* This check not only needs to be done before reading, but also
           whenever read_chan() gets woken up after sleeping, so I've
           moved it to there.  This should only be done for the N_TTY
           line discipline, anyway.  Same goes for write_chan(). -- jlc. */
#if 0
        if ((inode->i_rdev != CONSOLE_DEV) && /* don't stop on /dev/console */
            (tty->pgrp > 0) &&
            (current->tty == tty) &&
            (tty->pgrp != current->pgrp))
                if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp))
                        return -EIO;
                else {
                        (void) kill_pg(current->pgrp, SIGTTIN, 1);
                        return -ERESTARTSYS;
                }
#endif
        if (tty->ldisc.read)
                /* XXX casts are for what kernel-wide prototypes should be. */
                i = (tty->ldisc.read)(tty,file,(unsigned char *)buf,(unsigned int)count);
        else
                i = -EIO;
        if (i > 0)
                inode->i_atime = CURRENT_TIME;
        return i;
}
 
/*
 * Split writes up in sane blocksizes to avoid
 * denial-of-service type attacks
 */
static inline int do_tty_write(
        int (*write)(struct tty_struct *, struct file *, const unsigned char *, unsigned int),
        struct inode *inode,
        struct tty_struct *tty,
        struct file *file,
        const unsigned char *buf,
        unsigned int count)
{
        int ret = 0, written = 0;
 
        for (;;) {
                unsigned int size = PAGE_SIZE*2;
                if (size > count)
                        size = count;
                ret = write(tty, file, buf, size);
                if (ret <= 0)
                        break;
                written += ret;
                buf += ret;
                count -= ret;
                if (!count)
                        break;
                ret = -ERESTARTSYS;
                if (current->signal & ~current->blocked)
                        break;
                if (need_resched)
                        schedule();
        }
        if (written) {
                inode->i_mtime = CURRENT_TIME;
                ret = written;
        }
        return ret;
}
 
 
static int tty_write(struct inode * inode, struct file * file, const char * buf, int count)
{
        int is_console;
        struct tty_struct * tty;
 
        is_console = (inode->i_rdev == CONSOLE_DEV);
 
        if (is_console && redirect)
                tty = redirect;
        else
                tty = (struct tty_struct *)file->private_data;
        if (tty_paranoia_check(tty, inode->i_rdev, "tty_write"))
                return -EIO;
        if (!tty || !tty->driver.write || (tty->flags & (1 << TTY_IO_ERROR)))
                return -EIO;
#if 0
        if (!is_console && L_TOSTOP(tty) && (tty->pgrp > 0) &&
            (current->tty == tty) && (tty->pgrp != current->pgrp)) {
                if (is_orphaned_pgrp(current->pgrp))
                        return -EIO;
                if (!is_ignored(SIGTTOU)) {
                        (void) kill_pg(current->pgrp, SIGTTOU, 1);
                        return -ERESTARTSYS;
                }
        }
#endif
        if (!tty->ldisc.write)
                return -EIO;
        return do_tty_write(tty->ldisc.write,
                inode, tty, file,
                (const unsigned char *)buf,
                (unsigned int)count);
}
 
/* Semaphore to protect creating and releasing a tty */
static struct semaphore tty_sem = MUTEX;
static void down_tty_sem(int index)
{
        down(&tty_sem);
}
static void up_tty_sem(int index)
{
        up(&tty_sem);
}
static void release_mem(struct tty_struct *tty, int idx);
 
/*
 * Rewritten to remove races and properly clean up after a failed open.
 * The new code protects the open with a semaphore, so it's really
 * quite straightforward.  The semaphore locking can probably be
 * relaxed for the (most common) case of reopening a tty.
 */
static int init_dev(kdev_t device, struct tty_struct **ret_tty)
{
        struct tty_struct *tty, *o_tty;
        struct termios *tp, **tp_loc, *o_tp, **o_tp_loc;
        struct termios *ltp, **ltp_loc, *o_ltp, **o_ltp_loc;
        struct tty_driver *driver;
        int retval;
        int idx;
 
        driver = get_tty_driver(device);
        if (!driver)
                return -ENODEV;
 
        idx = MINOR(device) - driver->minor_start;
 
        /*
         * Check whether we need to acquire the tty semaphore to avoid
         * race conditions.  For now, play it safe.
         */
        down_tty_sem(idx);
 
        /* check whether we're reopening an existing tty */
        tty = driver->table[idx];
        if(tty) goto fast_track;
 
        /*
         * First time open is complex, especially for PTY devices.
         * This code guarantees that either everything succeeds and the
         * TTY is ready for operation, or else the table slots are vacated
         * and the allocated memory released.  (Except that the termios
         * and locked termios may be retained.)
         */
 
        o_tty = NULL;
        tp = o_tp = NULL;
        ltp = o_ltp = NULL;
 
        tty = (struct tty_struct*) get_free_page(GFP_KERNEL);
        if(!tty)
                goto fail_no_mem;
        initialize_tty_struct(tty);
        tty->device = device;
        tty->driver = *driver;
 
        tp_loc = &driver->termios[idx];
        if (!*tp_loc) {
                tp = (struct termios *) kmalloc(sizeof(struct termios),
                                                GFP_KERNEL);
                if (!tp)
                        goto free_mem_out;
                *tp = driver->init_termios;
        }
 
        ltp_loc = &driver->termios_locked[idx];
        if (!*ltp_loc) {
                ltp = (struct termios *) kmalloc(sizeof(struct termios),
                                                 GFP_KERNEL);
                if (!ltp)
                        goto free_mem_out;
                memset(ltp, 0, sizeof(struct termios));
        }
 
        if (driver->type == TTY_DRIVER_TYPE_PTY) {
                o_tty = (struct tty_struct *) get_free_page(GFP_KERNEL);
                if (!o_tty)
                        goto free_mem_out;
                initialize_tty_struct(o_tty);
                o_tty->device = (kdev_t) MKDEV(driver->other->major,
                                        driver->other->minor_start + idx);
                o_tty->driver = *driver->other;
 
                o_tp_loc  = &driver->other->termios[idx];
                if (!*o_tp_loc) {
                        o_tp = (struct termios *)
                                kmalloc(sizeof(struct termios), GFP_KERNEL);
                        if (!o_tp)
                                goto free_mem_out;
                        *o_tp = driver->other->init_termios;
                }
 
                o_ltp_loc = &driver->other->termios_locked[idx];
                if (!*o_ltp_loc) {
                        o_ltp = (struct termios *)
                                kmalloc(sizeof(struct termios), GFP_KERNEL);
                        if (!o_ltp)
                                goto free_mem_out;
                        memset(o_ltp, 0, sizeof(struct termios));
                }
 
                /*
                 * Everything allocated ... set up the o_tty structure.
                 */
                driver->other->table[idx] = o_tty;
                if (!*o_tp_loc)
                        *o_tp_loc = o_tp;
                if (!*o_ltp_loc)
                        *o_ltp_loc = o_ltp;
                o_tty->termios = *o_tp_loc;
                o_tty->termios_locked = *o_ltp_loc;
                (*driver->other->refcount)++;
                if (driver->subtype == PTY_TYPE_MASTER)
                        o_tty->count++;
 
                /* Establish the links in both directions */
                tty->link   = o_tty;
                o_tty->link = tty;
        }
 
        /*
         * All structures have been allocated, so now we install them.
         * Failures after this point use release_mem to clean up, so
         * there's no need to null out the local pointers.
         */
        driver->table[idx] = tty;       /* FIXME: this is broken and
        probably causes ^D bug. tty->private_date does not (yet) point
        to a console, if keypress comes now, await armagedon.
 
        also, driver->table is accessed from interrupt for vt case,
        and this does not look like atomic access at all. */
 
        if (!*tp_loc)
                *tp_loc = tp;
        if (!*ltp_loc)
                *ltp_loc = ltp;
        tty->termios = *tp_loc;
        tty->termios_locked = *ltp_loc;
        (*driver->refcount)++;
        tty->count++;
 
        /*
         * Structures all installed ... call the ldisc open routines.
         * If we fail here just call release_mem to clean up.  No need
         * to decrement the use counts, as release_mem doesn't care.
         */
        if (tty->ldisc.open) {
                retval = (tty->ldisc.open)(tty);
                if (retval)
                        goto release_mem_out;
        }
        if (o_tty && o_tty->ldisc.open) {
                retval = (o_tty->ldisc.open)(o_tty);
                if (retval) {
                        if (tty->ldisc.close)
                                (tty->ldisc.close)(tty);
                        goto release_mem_out;
                }
        }
        goto success;
 
        /*
         * This fast open can be used if the tty is already open.
         * No memory is allocated, and the only failures are from
         * attempting to open a closing tty or attempting multiple
         * opens on a pty master.
         */
fast_track:
        retval = -EIO;
        if (test_bit(TTY_CLOSING, &tty->flags))
                goto end_init;
 
        if (driver->type == TTY_DRIVER_TYPE_PTY &&
            driver->subtype == PTY_TYPE_MASTER) {
                /*
                 * special case for PTY masters: only one open permitted,
                 * and the slave side open count is incremented as well.
                 */
                if (tty->count)
                        goto end_init;
                tty->link->count++;
        }
        tty->count++;
        tty->driver = *driver; /* N.B. why do this every time?? */
 
success:
        retval = 0;
        *ret_tty = tty;
 
        /* All paths come through here to release the semaphore */
end_init:
        up_tty_sem(idx);
        return retval;
 
        /* Release locally allocated memory ... nothing placed in slots */
free_mem_out:
        if (o_tp)
                kfree_s(o_tp, sizeof(struct termios));
        if (o_tty)
                free_page((unsigned long) o_tty);
        if (ltp)
                kfree_s(ltp, sizeof(struct termios));
        if (tp)
                kfree_s(tp, sizeof(struct termios));
        free_page((unsigned long) tty);
 
fail_no_mem:
        retval = -ENOMEM;
        goto end_init;
 
        /* call the tty release_mem routine to clean out this slot */
release_mem_out:
        printk("init_dev: ldisc open failed, clearing slot %d\n", idx);
        release_mem(tty, idx);
        goto end_init;
}
 
/*
 * Releases memory associated with a tty structure, and clears out the
 * driver table slots.
 */
static void release_mem(struct tty_struct *tty, int idx)
{
        struct tty_struct *o_tty;
        struct termios *tp;
 
        if ((o_tty = tty->link) != NULL) {
                o_tty->driver.table[idx] = NULL;
                if (o_tty->driver.flags & TTY_DRIVER_RESET_TERMIOS) {
                        tp = o_tty->driver.termios[idx];
                        o_tty->driver.termios[idx] = NULL;
                        kfree_s(tp, sizeof(struct termios));
                }
                o_tty->magic = 0;
                (*o_tty->driver.refcount)--;
                free_page((unsigned long) o_tty);
        }
 
        tty->driver.table[idx] = NULL;
        if (tty->driver.flags & TTY_DRIVER_RESET_TERMIOS) {
                tp = tty->driver.termios[idx];
                tty->driver.termios[idx] = NULL;
                kfree_s(tp, sizeof(struct termios));
        }
        tty->magic = 0;
        (*tty->driver.refcount)--;
        free_page((unsigned long) tty);
}
 
/*
 * Even releasing the tty structures is a tricky business.. We have
 * to be very careful that the structures are all released at the
 * same time, as interrupts might otherwise get the wrong pointers.
 */
static void release_dev(struct file * filp)
{
        struct tty_struct *tty, *o_tty;
        int     pty_master, tty_closing, o_tty_closing, do_sleep;
        int     idx;
 
        tty = (struct tty_struct *)filp->private_data;
        if (tty_paranoia_check(tty, filp->f_inode->i_rdev, "release_dev"))
                return;
 
        check_tty_count(tty, "release_dev");
 
        tty_fasync(filp->f_inode, filp, 0);
 
        idx = MINOR(tty->device) - tty->driver.minor_start;
        pty_master = (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
                      tty->driver.subtype == PTY_TYPE_MASTER);
        o_tty = tty->link;
 
#ifdef TTY_PARANOIA_CHECK
        if (idx < 0 || idx >= tty->driver.num) {
                printk("release_dev: bad idx when trying to free (%s)\n",
                       kdevname(tty->device));
                return;
        }
        if (tty != tty->driver.table[idx]) {
                printk("release_dev: driver.table[%d] not tty for (%s)\n",
                       idx, kdevname(tty->device));
                return;
        }
        if (tty->termios != tty->driver.termios[idx]) {
                printk("release_dev: driver.termios[%d] not termios "
                       "for (%s)\n",
                       idx, kdevname(tty->device));
                return;
        }
        if (tty->termios_locked != tty->driver.termios_locked[idx]) {
                printk("release_dev: driver.termios_locked[%d] not "
                       "termios_locked for (%s)\n",
                       idx, kdevname(tty->device));
                return;
        }
#endif
 
#ifdef TTY_DEBUG_HANGUP
        printk("release_dev of %s (tty count=%d)...", tty_name(tty),
               tty->count);
#endif
 
#ifdef TTY_PARANOIA_CHECK
        if (tty->driver.other) {
                if (o_tty != tty->driver.other->table[idx]) {
                        printk("release_dev: other->table[%d] not o_tty for ("
                               "%s)\n",
                               idx, kdevname(tty->device));
                        return;
                }
                if (o_tty->termios != tty->driver.other->termios[idx]) {
                        printk("release_dev: other->termios[%d] not o_termios "
                               "for (%s)\n",
                               idx, kdevname(tty->device));
                        return;
                }
                if (o_tty->termios_locked !=
                      tty->driver.other->termios_locked[idx]) {
                        printk("release_dev: other->termios_locked[%d] not "
                               "o_termios_locked for (%s)\n",
                               idx, kdevname(tty->device));
                        return;
                }
                if (o_tty->link != tty) {
                        printk("release_dev: bad pty pointers\n");
                        return;
                }
        }
#endif
 
        if (tty->driver.close)
                tty->driver.close(tty, filp);
 
        /*
         * Sanity check: if tty->count is going to zero, there shouldn't be
         * any waiters on tty->read_wait or tty->write_wait.  We test the
         * wait queues and kick everyone out _before_ actually starting to
         * close.  This ensures that we won't block while releasing the tty
         * structure.
         *
         * The test for the o_tty closing is necessary, since the master and
         * slave sides may close in any order.  If the slave side closes out
         * first, its count will be one, since the master side holds an open.
         * Thus this test wouldn't be triggered at the time the slave closes,
         * so we do it now.
         *
         * Note that it's possible for the tty to be opened again while we're
         * flushing out waiters.  By recalculating the closing flags before
         * each iteration we avoid any problems.
         */
        while (1) {
                tty_closing = tty->count <= 1;
                o_tty_closing = o_tty &&
                        (o_tty->count <= (pty_master ? 1 : 0));
                do_sleep = 0;
 
                if (tty_closing) {
                        if (waitqueue_active(&tty->read_wait)) {
                                wake_up(&tty->read_wait);
                                do_sleep++;
                        }
                        if (waitqueue_active(&tty->write_wait)) {
                                wake_up(&tty->write_wait);
                                do_sleep++;
                        }
                }
                if (o_tty_closing) {
                        if (waitqueue_active(&o_tty->read_wait)) {
                                wake_up(&o_tty->read_wait);
                                do_sleep++;
                        }
                        if (waitqueue_active(&o_tty->write_wait)) {
                                wake_up(&o_tty->write_wait);
                                do_sleep++;
                        }
                }
                if (!do_sleep)
                        break;
 
                printk("release_dev: %s: read/write wait queue active!\n",
                       tty_name(tty));
                schedule();
        }
 
        /*
         * The closing flags are now consistent with the open counts on
         * both sides, and we've completed the last operation that could
         * block, so it's safe to proceed with closing.
         */
 
        if (pty_master) {
                if (--o_tty->count < 0) {
                        printk("release_dev: bad pty slave count (%d) for %s\n",
                               o_tty->count, tty_name(o_tty));
                        o_tty->count = 0;
                }
        }
        if (--tty->count < 0) {
                printk("release_dev: bad tty->count (%d) for %s\n",
                       tty->count, tty_name(tty));
                tty->count = 0;
        }
 
        /*
         * Perform some housekeeping before deciding whether to return.
         *
         * Set the TTY_CLOSING flag if this was the last open.  In the
         * case of a pty we may have to wait around for the other side
         * to close, and TTY_CLOSING makes sure we can't be reopened.
         */
        if(tty_closing)
                set_bit(TTY_CLOSING, &tty->flags);
        if(o_tty_closing)
                set_bit(TTY_CLOSING, &o_tty->flags);
 
        /*
         * If _either_ side is closing, make sure there aren't any
         * processes that still think tty or o_tty is their controlling
         * tty.  Also, clear redirect if it points to either tty.
         */
        if (tty_closing || o_tty_closing) {
                struct task_struct *p;
 
                for_each_task(p) {
                        if (p->tty == tty || (o_tty && p->tty == o_tty))
                                p->tty = NULL;
                }
 
                if (redirect == tty || (o_tty && redirect == o_tty))
                        redirect = NULL;
        }
 
        /* check whether both sides are closing ... */
        if (!tty_closing || (o_tty && !o_tty_closing))
                return;
        filp->private_data = 0;
 
#ifdef TTY_DEBUG_HANGUP
        printk("freeing tty structure...");
#endif
 
        /*
         * Shutdown the current line discipline, and reset it to N_TTY.
         * N.B. why reset ldisc when we're releasing the memory??
         */
        if (tty->ldisc.close)
                (tty->ldisc.close)(tty);
        tty->ldisc = ldiscs[N_TTY];
        tty->termios->c_line = N_TTY;
        if (o_tty) {
                if (o_tty->ldisc.close)
                        (o_tty->ldisc.close)(o_tty);
                o_tty->ldisc = ldiscs[N_TTY];
        }
 
        /*
         * Make sure that the tty's task queue isn't activated.  If it
         * is, take it out of the linked list.  The tqueue isn't used by
         * pty's, so skip the test for them.
         */
        if (tty->driver.type != TTY_DRIVER_TYPE_PTY) {
                cli();
                if (tty->flip.tqueue.sync) {
                        struct tq_struct *tq, *prev;
 
                        for (tq=tq_timer, prev=0; tq; prev=tq, tq=tq->next) {
                                if (tq == &tty->flip.tqueue) {
                                        if (prev)
                                                prev->next = tq->next;
                                        else
                                                tq_timer = tq->next;
                                        break;
                                }
                        }
                }
                sti();
        }
 
        /*
         * The release_mem function takes care of the details of clearing
         * the slots and preserving the termios structure.
         */
        release_mem(tty, idx);
}
 
/*
 * tty_open and tty_release keep up the tty count that contains the
 * number of opens done on a tty. We cannot use the inode-count, as
 * different inodes might point to the same tty.
 *
 * Open-counting is needed for pty masters, as well as for keeping
 * track of serial lines: DTR is dropped when the last close happens.
 * (This is not done solely through tty->count, now.  - Ted 1/27/92)
 *
 * The termios state of a pty is reset on first open so that
 * settings don't persist across reuse.
 */
static int tty_open(struct inode * inode, struct file * filp)
{
        struct tty_struct *tty;
        int minor;
        int noctty, retval;
        kdev_t device;
 
retry_open:
        noctty = filp->f_flags & O_NOCTTY;
        device = inode->i_rdev;
        if (device == TTY_DEV) {
                if (!current->tty)
                        return -ENXIO;
                device = current->tty->device;
                /* noctty = 1; */
        }
        if (device == CONSOLE_DEV) {
                device = MKDEV(TTY_MAJOR, fg_console+1);
                noctty = 1;
        }
        minor = MINOR(device);
 
        retval = init_dev(device, &tty);
        if (retval)
                return retval;
        filp->private_data = tty;
        check_tty_count(tty, "tty_open");
        if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
            tty->driver.subtype == PTY_TYPE_MASTER)
                noctty = 1;
#ifdef TTY_DEBUG_HANGUP
        printk("opening %s...", tty_name(tty));
#endif
        if (tty->driver.open)
                retval = tty->driver.open(tty, filp);
        else
                retval = -ENODEV;
 
        if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) && !suser())
                retval = -EBUSY;
 
        if (retval) {
#ifdef TTY_DEBUG_HANGUP
                printk("error %d in opening %s...", retval, tty_name(tty));
#endif
 
                release_dev(filp);
                if (retval != -ERESTARTSYS)
                        return retval;
                if (current->signal & ~current->blocked)
                        return retval;
                schedule();
                /*
                 * Need to reset f_op in case a hangup happened.
                 */
                filp->f_op = &tty_fops;
                goto retry_open;
        }
        if (!noctty &&
            current->leader &&
            !current->tty &&
            tty->session == 0) {
                current->tty = tty;
                current->tty_old_pgrp = 0;
                tty->session = current->session;
                tty->pgrp = current->pgrp;
        }
        return 0;
}
 
static void tty_release(struct inode * inode, struct file * filp)
{
        release_dev(filp);
}
 
static int tty_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
{
        struct tty_struct * tty;
 
        tty = (struct tty_struct *)filp->private_data;
        if (tty_paranoia_check(tty, inode->i_rdev, "tty_select"))
                return 0;
 
        if (tty->ldisc.select)
                return (tty->ldisc.select)(tty, inode, filp, sel_type, wait);
        return 0;
}
 
/*
 * fasync_helper() is used by some character device drivers (mainly mice)
 * to set up the fasync queue. It returns negative on error, 0 if it did
 * no changes and positive if it added/deleted the entry.
 */
int fasync_helper(struct inode * inode, struct file * filp, int on, struct fasync_struct **fapp)
{
        struct fasync_struct *fa, **fp;
        unsigned long flags;
 
        for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
                if (fa->fa_file == filp)
                        break;
        }
 
        if (on) {
                if (fa)
                        return 0;
                fa = (struct fasync_struct *)kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
                if (!fa)
                        return -ENOMEM;
                fa->magic = FASYNC_MAGIC;
                fa->fa_file = filp;
                save_flags(flags);
                cli();
                fa->fa_next = *fapp;
                *fapp = fa;
                restore_flags(flags);
                return 1;
        }
        if (!fa)
                return 0;
        save_flags(flags);
        cli();
        *fp = fa->fa_next;
        restore_flags(flags);
        kfree(fa);
        return 1;
}
 
static int tty_fasync(struct inode * inode, struct file * filp, int on)
{
        struct tty_struct * tty;
        int retval;
 
        tty = (struct tty_struct *)filp->private_data;
        if (tty_paranoia_check(tty, inode->i_rdev, "tty_fasync"))
                return 0;
 
        retval = fasync_helper(inode, filp, on, &tty->fasync);
        if (retval <= 0)
                return retval;
 
        if (on) {
                if (!waitqueue_active(&tty->read_wait))
                        tty->minimum_to_wake = 1;
                if (filp->f_owner.pid == 0) {
                        filp->f_owner.pid = (-tty->pgrp) ? : current->pid;
                        filp->f_owner.uid = current->uid;
                        filp->f_owner.euid = current->euid;
                }
        } else {
                if (!tty->fasync && !waitqueue_active(&tty->read_wait))
                        tty->minimum_to_wake = N_TTY_BUF_SIZE;
        }
        return 0;
}
 
#if 0
/*
 * XXX does anyone use this anymore?!?
 */
static int do_get_ps_info(unsigned long arg)
{
        struct tstruct {
                int flag;
                int present[NR_TASKS];
                struct task_struct tasks[NR_TASKS];
        };
        struct tstruct *ts = (struct tstruct *)arg;
        struct task_struct **p;
        char *c, *d;
        int i, n = 0;
 
        i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct tstruct));
        if (i)
                return i;
        for (p = &FIRST_TASK ; p <= &LAST_TASK ; p++, n++)
                if (*p)
                {
                        c = (char *)(*p);
                        d = (char *)(ts->tasks+n);
                        for (i=0 ; i<sizeof(struct task_struct) ; i++)
                                put_user(*c++, d++);
                        put_user(1, ts->present+n);
                }
                else
                        put_user(0, ts->present+n);
        return(0);
}
#endif
 
static int tty_ioctl(struct inode * inode, struct file * file,
                     unsigned int cmd, unsigned long arg)
{
        int     retval;
        struct tty_struct * tty;
        struct tty_struct * real_tty;
        struct winsize tmp_ws;
        pid_t pgrp;
        unsigned char   ch;
        char    mbz = 0;
 
        tty = (struct tty_struct *)file->private_data;
        if (tty_paranoia_check(tty, inode->i_rdev, "tty_ioctl"))
                return -EINVAL;
 
        if (tty->driver.type == TTY_DRIVER_TYPE_PTY &&
            tty->driver.subtype == PTY_TYPE_MASTER)
                real_tty = tty->link;
        else
                real_tty = tty;
 
        switch (cmd) {
                case TIOCSTI:
                        if ((current->tty != tty) && !suser())
                                return -EPERM;
                        retval = verify_area(VERIFY_READ, (void *) arg, 1);
                        if (retval)
                                return retval;
                        ch = get_user((char *) arg);
                        tty->ldisc.receive_buf(tty, &ch, &mbz, 1);
                        return 0;
                case TIOCGWINSZ:
                        retval = verify_area(VERIFY_WRITE, (void *) arg,
                                             sizeof (struct winsize));
                        if (retval)
                                return retval;
                        memcpy_tofs((struct winsize *) arg, &tty->winsize,
                                    sizeof (struct winsize));
                        return 0;
                case TIOCSWINSZ:
                        retval = verify_area(VERIFY_READ, (void *) arg,
                                             sizeof (struct winsize));
                        if (retval)
                                return retval;
                        memcpy_fromfs(&tmp_ws, (struct winsize *) arg,
                                      sizeof (struct winsize));
                        if (memcmp(&tmp_ws, &tty->winsize,
                                   sizeof(struct winsize))) {
                                if (tty->pgrp > 0)
                                        kill_pg(tty->pgrp, SIGWINCH, 1);
                                if ((real_tty->pgrp != tty->pgrp) &&
                                    (real_tty->pgrp > 0))
                                        kill_pg(real_tty->pgrp, SIGWINCH, 1);
                        }
                        tty->winsize = tmp_ws;
                        real_tty->winsize = tmp_ws;
                        return 0;
                case TIOCCONS:
                        if (tty->driver.type == TTY_DRIVER_TYPE_CONSOLE) {
                                if (!suser())
                                        return -EPERM;
                                redirect = NULL;
                                return 0;
                        }
                        if (redirect)
                                return -EBUSY;
                        redirect = real_tty;
                        return 0;
                case FIONBIO:
                        retval = verify_area(VERIFY_READ, (void *) arg, sizeof(int));
                        if (retval)
                                return retval;
                        arg = get_user((unsigned int *) arg);
                        if (arg)
                                file->f_flags |= O_NONBLOCK;
                        else
                                file->f_flags &= ~O_NONBLOCK;
                        return 0;
                case TIOCEXCL:
                        set_bit(TTY_EXCLUSIVE, &tty->flags);
                        return 0;
                case TIOCNXCL:
                        clear_bit(TTY_EXCLUSIVE, &tty->flags);
                        return 0;
                case TIOCNOTTY:
                        if (current->tty != tty)
                                return -ENOTTY;
                        if (current->leader)
                                disassociate_ctty(0);
                        current->tty = NULL;
                        return 0;
                case TIOCSCTTY:
                        if (current->leader &&
                            (current->session == tty->session))
                                return 0;
                        /*
                         * The process must be a session leader and
                         * not have a controlling tty already.
                         */
                        if (!current->leader || current->tty)
                                return -EPERM;
                        if (tty->session > 0) {
                                /*
                                 * This tty is already the controlling
                                 * tty for another session group!
                                 */
                                if ((arg == 1) && suser()) {
                                        /*
                                         * Steal it away
                                         */
                                        struct task_struct *p;
 
                                        for_each_task(p)
                                                if (p->tty == tty)
                                                        p->tty = NULL;
                                } else
                                        return -EPERM;
                        }
                        current->tty = tty;
                        current->tty_old_pgrp = 0;
                        tty->session = current->session;
                        tty->pgrp = current->pgrp;
                        return 0;
                case TIOCGPGRP:
                        /*
                         * (tty == real_tty) is a cheap way of
                         * testing if the tty is NOT a master pty.
                         */
                        if (tty == real_tty && current->tty != real_tty)
                                return -ENOTTY;
                        retval = verify_area(VERIFY_WRITE, (void *) arg,
                                             sizeof (pid_t));
                        if (retval)
                                return retval;
                        put_user(real_tty->pgrp, (pid_t *) arg);
                        return 0;
                case TIOCSPGRP:
                        retval = tty_check_change(real_tty);
                        if (retval == -EIO)
                                return -ENOTTY;
                        if (retval)
                                return retval;
                        if (!current->tty ||
                            (current->tty != real_tty) ||
                            (real_tty->session != current->session))
                                return -ENOTTY;
                        pgrp = get_user((pid_t *) arg);
                        if (pgrp < 0)
                                return -EINVAL;
                        if (session_of_pgrp(pgrp) != current->session)
                                return -EPERM;
                        real_tty->pgrp = pgrp;
                        return 0;
                case TIOCGETD:
                        retval = verify_area(VERIFY_WRITE, (void *) arg,
                                             sizeof (int));
                        if (retval)
                                return retval;
                        put_user(tty->ldisc.num, (int *) arg);
                        return 0;
                case TIOCSETD:
                        retval = tty_check_change(tty);
                        if (retval)
                                return retval;
                        retval = verify_area(VERIFY_READ, (void *) arg,
                                             sizeof (int));
                        if (retval)
                                return retval;
                        arg = get_user((int *) arg);
                        return tty_set_ldisc(tty, arg);
#ifdef CONFIG_CONSOLE
                case TIOCLINUX:
                        if (tty->driver.type != TTY_DRIVER_TYPE_CONSOLE)
                                return -EINVAL;
                        if (current->tty != tty && !suser())
                                return -EPERM;
                        retval = verify_area(VERIFY_READ, (void *) arg, 1);
                        if (retval)
                                return retval;
                        switch (retval = get_user((char *)arg))
                        {
                                case 0:
                                case 8:
                                case 9:
                                        printk("TIOCLINUX (0/8/9) ioctl is gone - use /dev/vcs\n");
                                        return -EINVAL;
#if 0
                                case 1:
                                        printk("Deprecated TIOCLINUX (1) ioctl\n");
                                        return do_get_ps_info(arg);
#endif
                                case 2:
                                        return set_selection(arg, tty, 1);
                                case 3:
                                        return paste_selection(tty);
                                case 4:
                                        do_unblank_screen();
                                        return 0;
                                case 5:
                                        return sel_loadlut(arg);
                                case 6:
                        /*
                         * Make it possible to react to Shift+Mousebutton.
                         * Note that 'shift_state' is an undocumented
                         * kernel-internal variable; programs not closely
                         * related to the kernel should not use this.
                         */
                                        retval = verify_area(VERIFY_WRITE, (void *) arg, 1);
                                        if (retval)
                                                return retval;
                                        put_user(shift_state,(char *) arg);
                                        return 0;
                                case 7:
                                        retval = verify_area(VERIFY_WRITE, (void *) arg, 1);
                                        if (retval)
                                                return retval;
                                        put_user(mouse_reporting(),(char *) arg);
                                        return 0;
                                case 10:
                                        set_vesa_blanking(arg);
                                        return 0;
                                case 11:        /* set kmsg redirect */
                                        if (!suser())
                                                return -EPERM;
                                        retval = verify_area(VERIFY_READ,
                                                (void *) arg+1, 1);
                                        if (retval)
                                                return retval;
                                        kmsg_redirect = get_user((char *)arg+1);
                                        return 0;
                                case 12:        /* get fg_console */
                                        return fg_console;
                                default:
                                        return -EINVAL;
                        }
#endif /*CONFIG_CONSOLE*/
 
                case TIOCTTYGSTRUCT:
                        retval = verify_area(VERIFY_WRITE, (void *) arg,
                                                sizeof(struct tty_struct));
                        if (retval)
                                return retval;
                        memcpy_tofs((struct tty_struct *) arg,
                                    tty, sizeof(struct tty_struct));
                        return 0;
                default:
                        if (tty->driver.ioctl) {
                                retval = (tty->driver.ioctl)(tty, file,
                                                             cmd, arg);
                                if (retval != -ENOIOCTLCMD)
                                        return retval;
                        }
                        if (tty->ldisc.ioctl) {
                                retval = (tty->ldisc.ioctl)(tty, file,
                                                            cmd, arg);
                                if (retval != -ENOIOCTLCMD)
                                        return retval;
                        }
                        return -EINVAL;
                }
}
 
 
/*
 * This implements the "Secure Attention Key" ---  the idea is to
 * prevent trojan horses by killing all processes associated with this
 * tty when the user hits the "Secure Attention Key".  Required for
 * super-paranoid applications --- see the Orange Book for more details.
 *
 * This code could be nicer; ideally it should send a HUP, wait a few
 * seconds, then send a INT, and then a KILL signal.  But you then
 * have to coordinate with the init process, since all processes associated
 * with the current tty must be dead before the new getty is allowed
 * to spawn.
 */
void do_SAK( struct tty_struct *tty)
{
#ifdef TTY_SOFT_SAK
        tty_hangup(tty);
#else
        struct task_struct **p;
        int session;
        int             i;
        struct file     *filp;
 
        if (!tty)
                return;
        session  = tty->session;
        if (tty->ldisc.flush_buffer)
                tty->ldisc.flush_buffer(tty);
        if (tty->driver.flush_buffer)
                tty->driver.flush_buffer(tty);
        for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
                if (!(*p))
                        continue;
                if (((*p)->tty == tty) ||
                    ((session > 0) && ((*p)->session == session)))
                        send_sig(SIGKILL, *p, 1);
                else if ((*p)->files) {
                        for (i=0; i < NR_OPEN; i++) {
                                filp = (*p)->files->fd[i];
                                if (filp && (filp->f_op == &tty_fops) &&
                                    (filp->private_data == tty)) {
                                        send_sig(SIGKILL, *p, 1);
                                        break;
                                }
                        }
                }
        }
#endif
}
 
/*
 * This routine is called out of the software interrupt to flush data
 * from the flip buffer to the line discipline.
 */
static void flush_to_ldisc(void *private_)
{
        struct tty_struct *tty = (struct tty_struct *) private_;
        unsigned char   *cp;
        char            *fp;
        int             count;
 
        if (tty->flip.buf_num) {
                cp = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
                fp = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
                tty->flip.buf_num = 0;
 
                cli();
                tty->flip.char_buf_ptr = tty->flip.char_buf;
                tty->flip.flag_buf_ptr = tty->flip.flag_buf;
        } else {
                cp = tty->flip.char_buf;
                fp = tty->flip.flag_buf;
                tty->flip.buf_num = 1;
 
                cli();
                tty->flip.char_buf_ptr = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
                tty->flip.flag_buf_ptr = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
        }
        count = tty->flip.count;
        tty->flip.count = 0;
        sti();
 
#if 0
        if (count > tty->max_flip_cnt)
                tty->max_flip_cnt = count;
#endif
        tty->ldisc.receive_buf(tty, cp, fp, count);
}
 
/*
 * This subroutine initializes a tty structure.
 */
static void initialize_tty_struct(struct tty_struct *tty)
{
        memset(tty, 0, sizeof(struct tty_struct));
        tty->magic = TTY_MAGIC;
        tty->ldisc = ldiscs[N_TTY];
        tty->pgrp = -1;
        tty->flip.char_buf_ptr = tty->flip.char_buf;
        tty->flip.flag_buf_ptr = tty->flip.flag_buf;
        tty->flip.tqueue.routine = flush_to_ldisc;
        tty->flip.tqueue.data = tty;
}
 
/*
 * The default put_char routine if the driver did not define one.
 */
void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
{
        tty->driver.write(tty, 0, &ch, 1);
}
 
/*
 * Called by a tty driver to register itself.
 */
int tty_register_driver(struct tty_driver *driver)
{
        int error;
 
        if (driver->flags & TTY_DRIVER_INSTALLED)
                return 0;
 
        error = register_chrdev(driver->major, driver->name, &tty_fops);
        if (error < 0)
                return error;
 
        else if(driver->major == 0)
                driver->major = error;
 
        if (!driver->put_char)
                driver->put_char = tty_default_put_char;
 
        driver->prev = 0;
        driver->next = tty_drivers;
        if (tty_drivers) tty_drivers->prev = driver;
        tty_drivers = driver;
        return error;
}
 
/*
 * Called by a tty driver to unregister itself.
 */
int tty_unregister_driver(struct tty_driver *driver)
{
        int     retval;
        struct tty_driver *p;
        int     i, found = 0;
        const char *othername = NULL;
        struct termios *tp;
 
        if (*driver->refcount)
                return -EBUSY;
 
        for (p = tty_drivers; p; p = p->next) {
                if (p == driver)
                        found++;
                else if (p->major == driver->major)
                        othername = p->name;
        }
 
        if (!found)
                return -ENOENT;
 
        if (othername == NULL) {
                retval = unregister_chrdev(driver->major, driver->name);
                if (retval)
                        return retval;
        } else
                register_chrdev(driver->major, othername, &tty_fops);
 
        if (driver->prev)
                driver->prev->next = driver->next;
        else
                tty_drivers = driver->next;
 
        if (driver->next)
                driver->next->prev = driver->prev;
 
        for (i = 0; i < driver->num; i++) {
                tp = driver->termios[i];
                if (tp != NULL) {
                        kfree_s(tp, sizeof(struct termios));
                        driver->termios[i] = NULL;
                }
                tp = driver->termios_locked[i];
                if (tp != NULL) {
                        kfree_s(tp, sizeof(struct termios));
                        driver->termios_locked[i] = NULL;
                }
        }
        return 0;
}
 
 
/*
 * Initialize the console device. This is called *early*, so
 * we can't necessarily depend on lots of kernel help here.
 * Just do some early initializations, and do the complex setup
 * later.
 */
long console_init(long kmem_start, long kmem_end)
{
        /* Setup the default TTY line discipline. */
        memset(ldiscs, 0, sizeof(ldiscs));
        (void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);
 
        /*
         * Set up the standard termios.  Individual tty drivers may
         * deviate from this; this is used as a template.
         */
        memset(&tty_std_termios, 0, sizeof(struct termios));
        memcpy(tty_std_termios.c_cc, INIT_C_CC, NCCS);
        tty_std_termios.c_iflag = ICRNL | IXON;
        tty_std_termios.c_oflag = OPOST | ONLCR;
        tty_std_termios.c_cflag = B38400 | CS8 | CREAD | HUPCL;
        tty_std_termios.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
                ECHOCTL | ECHOKE | IEXTEN;
 
#ifdef CONFIG_CONSOLE
        /*
         * set up the console device so that later boot sequences can
         * inform about problems etc..
         */
        return con_init(kmem_start);
#else /* !CONFIG_CONSOLE */
        return kmem_start;
#endif /* !CONFIG_CONSOLE */
}
 
static struct tty_driver dev_tty_driver, dev_console_driver;
 
/*
 * Ok, now we can initialize the rest of the tty devices and can count
 * on memory allocations, interrupts etc..
 */
int tty_init(void)
{
        if (sizeof(struct tty_struct) > PAGE_SIZE)
                panic("size of tty structure > PAGE_SIZE!");
 
        /*
         * dev_tty_driver and dev_console_driver are actually magic
         * devices which get redirected at open time.  Nevertheless,
         * we register them so that register_chrdev is called
         * appropriately.
         */
        memset(&dev_tty_driver, 0, sizeof(struct tty_driver));
        dev_tty_driver.magic = TTY_DRIVER_MAGIC;
        dev_tty_driver.name = "tty";
        dev_tty_driver.name_base = 0;
        dev_tty_driver.major = TTY_MAJOR;
        dev_tty_driver.minor_start = 0;
        dev_tty_driver.num = 1;
 
        if (tty_register_driver(&dev_tty_driver))
                panic("Couldn't register /dev/tty driver\n");
 
        dev_console_driver = dev_tty_driver;
        dev_console_driver.name = "console";
        dev_console_driver.major = TTYAUX_MAJOR;
 
        if (tty_register_driver(&dev_console_driver))
                panic("Couldn't register /dev/console driver\n");
 
#ifdef CONFIG_FRAMEBUFFER
        fbmem_init();
#endif
 
#ifdef CONFIG_KEYBOARD
        kbd_init();
#endif
#ifdef CONFIG_COLDFIRE_SERIAL
        mcfrs_init();
#endif
#ifdef CONFIG_SERIAL
        rs_init();
#endif
 
#ifdef CONFIG_68328_SERIAL
        rs68328_init();
#endif
 
#ifdef CONFIG_68332_SERIAL
        rs68332_init();
#endif
#ifdef CONFIG_SCC
        scc_init();
#endif
#ifdef CONFIG_CYCLADES
        cy_init();
#endif
#ifdef CONFIG_STALLION
        stl_init();
#endif
#ifdef CONFIG_ISTALLION
        stli_init();
#endif
#ifdef CONFIG_DIGI
        pcxe_init();
#endif
#ifdef CONFIG_RISCOM8
        riscom8_init();
#endif
#ifdef CONFIG_SPECIALIX
        specialix_init();
#endif
        pty_init();
#ifdef CONFIG_CONSOLE
        vcs_init();
#endif
#ifdef CONFIG_68328_DIGI
        mc68328digi_init();
#endif
        return 0;
}
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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [drivers/] [char/] [tty_io.c] - Blame information for rev 1765

Line No.	Rev	Author	Line
1	1626	jcastillo	`/*`
2			`* linux/drivers/char/tty_io.c`
3			`*`
4			`* Copyright (C) 1991, 1992 Linus Torvalds`
5			`*/`
6
7			`/*`
8			`* 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles`
9			`* or rs-channels. It also implements echoing, cooked mode etc.`
10			`*`
11			`* Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.`
12			`*`
13			`* Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the`
14			`* tty_struct and tty_queue structures. Previously there was an array`
15			`* of 256 tty_struct's which was statically allocated, and the`
16			`* tty_queue structures were allocated at boot time. Both are now`
17			`* dynamically allocated only when the tty is open.`
18			`*`
19			`* Also restructured routines so that there is more of a separation`
20			`* between the high-level tty routines (tty_io.c and tty_ioctl.c) and`
21			`* the low-level tty routines (serial.c, pty.c, console.c). This`
22			`* makes for cleaner and more compact code. -TYT, 9/17/92`
23			`*`
24			`* Modified by Fred N. van Kempen, 01/29/93, to add line disciplines`
25			`* which can be dynamically activated and de-activated by the line`
26			`* discipline handling modules (like SLIP).`
27			`*`
28			`* NOTE: pay no attention to the line discipline code (yet); its`
29			`* interface is still subject to change in this version...`
30			`* -- TYT, 1/31/92`
31			`*`
32			`* Added functionality to the OPOST tty handling. No delays, but all`
33			`* other bits should be there.`
34			`* -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.`
35			`*`
36			`* Rewrote canonical mode and added more termios flags.`
37			`* -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94`
38			`*`
39			`* Reorganized FASYNC support so mouse code can share it.`
40			`* -- ctm@ardi.com, 9Sep95`