vt.c

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/*
 *  linux/drivers/char/vt.c
 *
 *  Copyright (C) 1992 obz under the linux copyright
 *
 *  Dynamic diacritical handling - aeb@cwi.nl - Dec 1993
 *  Dynamic keymap and string allocation - aeb@cwi.nl - May 1994
 *  Restrict VT switching via ioctl() - grif@cs.ucr.edu - Dec 1995
 *  Some code moved for less code duplication - Andi Kleen - Mar 1997
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/timer.h>
#include <linux/kernel.h>
#include <linux/kd.h>
#include <linux/vt.h>
#include <linux/string.h>
#include <linux/malloc.h>
#include <linux/major.h>
#include <linux/fs.h>

#include <asm/io.h>
#include <asm/uaccess.h>

#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/kbd_diacr.h>
#include <linux/selection.h>

#ifdef CONFIG_FB_COMPAT_XPMAC
#include <asm/vc_ioctl.h>
#endif /* CONFIG_FB_COMPAT_XPMAC */

char vt_dont_switch = 0;
extern struct tty_driver console_driver;

#define VT_IS_IN_USE(i) (console_driver.table[i] && console_driver.table[i]->count)
#define VT_BUSY(i)      (VT_IS_IN_USE(i) || i == fg_console || i == sel_cons)

/*
 * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
 * experimentation and study of X386 SYSV handling.
 *
 * One point of difference: SYSV vt's are /dev/vtX, which X >= 0, and
 * /dev/console is a separate ttyp. Under Linux, /dev/tty0 is /dev/console,
 * and the vc start at /dev/ttyX, X >= 1. We maintain that here, so we will
 * always treat our set of vt as numbered 1..MAX_NR_CONSOLES (corresponding to
 * ttys 0..MAX_NR_CONSOLES-1). Explicitly naming VT 0 is illegal, but using
 * /dev/tty0 (fg_console) as a target is legal, since an implicit aliasing
 * to the current console is done by the main ioctl code.
 */

struct vt_struct *vt_cons[MAX_NR_CONSOLES];

/* Keyboard type: Default is KB_101, but can be set by machine
 * specific code.
 */
unsigned char keyboard_type = KB_101;

#ifndef __alpha__
asmlinkage int sys_ioperm(unsigned long from, unsigned long num, int on);
#endif

unsigned int video_font_height;
unsigned int default_font_height;
unsigned int video_scan_lines;

/*
 * these are the valid i/o ports we're allowed to change. they map all the
 * video ports
 */
#define GPFIRST 0x3b4
#define GPLAST 0x3df
#define GPNUM (GPLAST - GPFIRST + 1)

/*
 * Generates sound of some frequency for some number of clock ticks
 *
 * If freq is 0, will turn off sound, else will turn it on for that time.
 * If msec is 0, will return immediately, else will sleep for msec time, then
 * turn sound off.
 *
 * We also return immediately, which is what was implied within the X
 * comments - KDMKTONE doesn't put the process to sleep.
 */

#if defined(__i386__) || defined(__alpha__) || defined(__powerpc__) \
    || (defined(__mips__) && !defined(CONFIG_SGI))

static void
kd_nosound(unsigned long ignored)
{
        /* disable counter 2 */
        outb(inb_p(0x61)&0xFC, 0x61);
        return;
}

void
_kd_mksound(unsigned int hz, unsigned int ticks)
{
        static struct timer_list sound_timer = { NULL, NULL, 0, 0,
                                                 kd_nosound };

        unsigned int count = 0;

        if (hz > 20 && hz < 32767)
                count = 1193180 / hz;
        
        cli();
        del_timer(&sound_timer);
        if (count) {
                /* enable counter 2 */
                outb_p(inb_p(0x61)|3, 0x61);
                /* set command for counter 2, 2 byte write */
                outb_p(0xB6, 0x43);
                /* select desired HZ */
                outb_p(count & 0xff, 0x42);
                outb((count >> 8) & 0xff, 0x42);

                if (ticks) {
                        sound_timer.expires = jiffies+ticks;
                        add_timer(&sound_timer);
                }
        } else
                kd_nosound(0);
        sti();
        return;
}

#else

void
_kd_mksound(unsigned int hz, unsigned int ticks)
{
}

#endif

void (*kd_mksound)(unsigned int hz, unsigned int ticks) = _kd_mksound;


#define i (tmp.kb_index)
#define s (tmp.kb_table)
#define v (tmp.kb_value)
static inline int
do_kdsk_ioctl(int cmd, struct kbentry *user_kbe, int perm, struct kbd_struct *kbd)
{
        struct kbentry tmp;
        ushort *key_map, val, ov;

        if (copy_from_user(&tmp, user_kbe, sizeof(struct kbentry)))
                return -EFAULT;
        if (i >= NR_KEYS || s >= MAX_NR_KEYMAPS)
                return -EINVAL; 

        switch (cmd) {
        case KDGKBENT:
                key_map = key_maps[s];
                if (key_map) {
                    val = U(key_map[i]);
                    if (kbd->kbdmode != VC_UNICODE && KTYP(val) >= NR_TYPES)
                        val = K_HOLE;
                } else
                    val = (i ? K_HOLE : K_NOSUCHMAP);
                return put_user(val, &user_kbe->kb_value);
        case KDSKBENT:
                if (!perm)
                        return -EPERM;
                if (!i && v == K_NOSUCHMAP) {
                        /* disallocate map */
                        key_map = key_maps[s];
                        if (s && key_map) {
                            key_maps[s] = 0;
                            if (key_map[0] == U(K_ALLOCATED)) {
                                        kfree_s(key_map, sizeof(plain_map));
                                        keymap_count--;
                            }
                        }
                        break;
                }

                if (KTYP(v) < NR_TYPES) {
                    if (KVAL(v) > max_vals[KTYP(v)])
                                return -EINVAL;
                } else
                    if (kbd->kbdmode != VC_UNICODE)
                                return -EINVAL;

                /* ++Geert: non-PC keyboards may generate keycode zero */
#if !defined(__mc68000__) && !defined(__powerpc__)
                /* assignment to entry 0 only tests validity of args */
                if (!i)
                        break;
#endif

                if (!(key_map = key_maps[s])) {
                        int j;

                        if (keymap_count >= MAX_NR_OF_USER_KEYMAPS && 
                            !capable(CAP_SYS_RESOURCE))
                                return -EPERM;

                        key_map = (ushort *) kmalloc(sizeof(plain_map),
                                                     GFP_KERNEL);
                        if (!key_map)
                                return -ENOMEM;
                        key_maps[s] = key_map;
                        key_map[0] = U(K_ALLOCATED);
                        for (j = 1; j < NR_KEYS; j++)
                                key_map[j] = U(K_HOLE);
                        keymap_count++;
                }
                ov = U(key_map[i]);
                if (v == ov)
                        break;  /* nothing to do */
                /*
                 * Attention Key.
                 */
                if (((ov == K_SAK) || (v == K_SAK)) && !capable(CAP_SYS_ADMIN))
                        return -EPERM;
                key_map[i] = U(v);
                if (!s && (KTYP(ov) == KT_SHIFT || KTYP(v) == KT_SHIFT))
                        compute_shiftstate();
                break;
        }
        return 0;
}
#undef i
#undef s
#undef v

static inline int 
do_kbkeycode_ioctl(int cmd, struct kbkeycode *user_kbkc, int perm)
{
        struct kbkeycode tmp;
        int kc = 0;

        if (copy_from_user(&tmp, user_kbkc, sizeof(struct kbkeycode)))
                return -EFAULT;
        switch (cmd) {
        case KDGETKEYCODE:
                kc = getkeycode(tmp.scancode);
                if (kc >= 0)
                        kc = put_user(kc, &user_kbkc->keycode);
                break;
        case KDSETKEYCODE:
                if (!perm)
                        return -EPERM;
                kc = setkeycode(tmp.scancode, tmp.keycode);
                break;
        }
        return kc;
}

static inline int
do_kdgkb_ioctl(int cmd, struct kbsentry *user_kdgkb, int perm)
{
        struct kbsentry tmp;
        char *p;
        u_char *q;
        int sz;
        int delta;
        char *first_free, *fj, *fnw;
        int i, j, k;

        /* we mostly copy too much here (512bytes), but who cares ;) */
        if (copy_from_user(&tmp, user_kdgkb, sizeof(struct kbsentry)))
                return -EFAULT;
        tmp.kb_string[sizeof(tmp.kb_string)-1] = '\0';
        if (tmp.kb_func >= MAX_NR_FUNC)
                return -EINVAL;
        i = tmp.kb_func;

        switch (cmd) {
        case KDGKBSENT:
                sz = sizeof(tmp.kb_string) - 1; /* sz should have been
                                                  a struct member */
                q = user_kdgkb->kb_string;
                p = func_table[i];
                if(p)
                        for ( ; *p && sz; p++, sz--)
                                put_user(*p, q++);
                put_user('\0', q);
                return ((p && *p) ? -EOVERFLOW : 0);
        case KDSKBSENT:
                if (!perm)
                        return -EPERM;

                q = func_table[i];
                first_free = funcbufptr + (funcbufsize - funcbufleft);
                for (j = i+1; j < MAX_NR_FUNC && !func_table[j]; j++) 
                        ;
                if (j < MAX_NR_FUNC)
                        fj = func_table[j];
                else
                        fj = first_free;

                delta = (q ? -strlen(q) : 1) + strlen(tmp.kb_string);
                if (delta <= funcbufleft) {     /* it fits in current buf */
                    if (j < MAX_NR_FUNC) {
                        memmove(fj + delta, fj, first_free - fj);
                        for (k = j; k < MAX_NR_FUNC; k++)
                            if (func_table[k])
                                func_table[k] += delta;
                    }
                    if (!q)
                      func_table[i] = fj;
                    funcbufleft -= delta;
                } else {                        /* allocate a larger buffer */
                    sz = 256;
                    while (sz < funcbufsize - funcbufleft + delta)
                      sz <<= 1;
                    fnw = (char *) kmalloc(sz, GFP_KERNEL);
                    if(!fnw)
                      return -ENOMEM;

                    if (!q)
                      func_table[i] = fj;
                    if (fj > funcbufptr)
                        memmove(fnw, funcbufptr, fj - funcbufptr);
                    for (k = 0; k < j; k++)
                      if (func_table[k])
                        func_table[k] = fnw + (func_table[k] - funcbufptr);

                    if (first_free > fj) {
                        memmove(fnw + (fj - funcbufptr) + delta, fj, first_free - fj);
                        for (k = j; k < MAX_NR_FUNC; k++)
                          if (func_table[k])
                            func_table[k] = fnw + (func_table[k] - funcbufptr) + delta;
                    }
                    if (funcbufptr != func_buf)
                      kfree_s(funcbufptr, funcbufsize);
                    funcbufptr = fnw;
                    funcbufleft = funcbufleft - delta + sz - funcbufsize;
                    funcbufsize = sz;
                }
                strcpy(func_table[i], tmp.kb_string);
                break;
        }
        return 0;
}

static inline int 
do_fontx_ioctl(int cmd, struct consolefontdesc *user_cfd, int perm)
{
        struct consolefontdesc cfdarg;
        struct console_font_op op;
        int i;

        if (copy_from_user(&cfdarg, user_cfd, sizeof(struct consolefontdesc))) 
                return -EFAULT;
        
        switch (cmd) {
        case PIO_FONTX:
                if (!perm)
                        return -EPERM;
                op.op = KD_FONT_OP_SET;
                op.flags = KD_FONT_FLAG_OLD;
                op.width = 8;
                op.height = cfdarg.charheight;
                op.charcount = cfdarg.charcount;
                op.data = cfdarg.chardata;
                return con_font_op(fg_console, &op);
        case GIO_FONTX: {
                op.op = KD_FONT_OP_GET;
                op.flags = KD_FONT_FLAG_OLD;
                op.width = 8;
                op.height = cfdarg.charheight;
                op.charcount = cfdarg.charcount;
                op.data = cfdarg.chardata;
                i = con_font_op(fg_console, &op);
                if (i)
                        return i;
                cfdarg.charheight = op.height;
                cfdarg.charcount = op.charcount;
                if (copy_to_user(user_cfd, &cfdarg, sizeof(struct consolefontdesc)))
                        return -EFAULT;
                return 0;
                }
        }
        return -EINVAL;
}

static inline int 
do_unimap_ioctl(int cmd, struct unimapdesc *user_ud,int perm)
{
        struct unimapdesc tmp;
        int i = 0; 

        if (copy_from_user(&tmp, user_ud, sizeof tmp))
                return -EFAULT;
        if (tmp.entries) {
                /* tmp.entry_ct is an unsigned short */
                i = verify_area(VERIFY_WRITE, tmp.entries,
                                (size_t)tmp.entry_ct * sizeof(struct unipair));
                if (i) return i;
        }
        switch (cmd) {
        case PIO_UNIMAP:
                if (!perm)
                        return -EPERM;
                return con_set_unimap(fg_console, tmp.entry_ct, tmp.entries);
        case GIO_UNIMAP:
                return con_get_unimap(fg_console, tmp.entry_ct, &(user_ud->entry_ct), tmp.entries);
        }
        return 0;
}

/*
 * We handle the console-specific ioctl's here.  We allow the
 * capability to modify any console, not just the fg_console. 
 */
int vt_ioctl(struct tty_struct *tty, struct file * file,
             unsigned int cmd, unsigned long arg)
{
        int i, perm;
        unsigned int console;
        unsigned char ucval;
        struct kbd_struct * kbd;
        struct vt_struct *vt = (struct vt_struct *)tty->driver_data;

        console = vt->vc_num;

        if (!vc_cons_allocated(console))        /* impossible? */
                return -ENOIOCTLCMD;

        /*
         * To have permissions to do most of the vt ioctls, we either have
         * to be the owner of the tty, or super-user.
         */
        perm = 0;
        if (current->tty == tty || suser())
                perm = 1;
 
        kbd = kbd_table + console;
        switch (cmd) {
        case KIOCSOUND:
                if (!perm)
                        return -EPERM;
                if (arg)
                        arg = 1193180 / arg;
                kd_mksound(arg, 0);
                return 0;

        case KDMKTONE:
                if (!perm)
                        return -EPERM;
        {
                unsigned int ticks, count;
                
                /*
                 * Generate the tone for the appropriate number of ticks.
                 * If the time is zero, turn off sound ourselves.
                 */
                ticks = HZ * ((arg >> 16) & 0xffff) / 1000;
                count = ticks ? (arg & 0xffff) : 0;
                if (count)
                        count = 1193180 / count;
                kd_mksound(count, ticks);
                return 0;
        }

        case KDGKBTYPE:
                /*
                 * this is naive.
                 */
                ucval = keyboard_type;
                goto setchar;

#ifndef __alpha__
                /*
                 * These cannot be implemented on any machine that implements
                 * ioperm() in user level (such as Alpha PCs).
                 */
        case KDADDIO:
        case KDDELIO:
                /*
                 * KDADDIO and KDDELIO may be able to add ports beyond what
                 * we reject here, but to be safe...
                 */
                if (arg < GPFIRST || arg > GPLAST)
                        return -EINVAL;
                return sys_ioperm(arg, 1, (cmd == KDADDIO)) ? -ENXIO : 0;

        case KDENABIO:
        case KDDISABIO:
                return sys_ioperm(GPFIRST, GPNUM,
                                  (cmd == KDENABIO)) ? -ENXIO : 0;
#endif

        case KDSETMODE:
                /*
                 * currently, setting the mode from KD_TEXT to KD_GRAPHICS
                 * doesn't do a whole lot. i'm not sure if it should do any
                 * restoration of modes or what...
                 */
                if (!perm)
                        return -EPERM;
                switch (arg) {
                case KD_GRAPHICS:
                        break;
                case KD_TEXT0:
                case KD_TEXT1:
                        arg = KD_TEXT;
                case KD_TEXT:
                        break;
                default:
                        return -EINVAL;
                }
                if (vt_cons[console]->vc_mode == (unsigned char) arg)
                        return 0;
                vt_cons[console]->vc_mode = (unsigned char) arg;
                if (console != fg_console)
                        return 0;
                /*
                 * explicitly blank/unblank the screen if switching modes
                 */
                if (arg == KD_TEXT)
                        unblank_screen();
                else
                        do_blank_screen(1);
                return 0;

        case KDGETMODE:
                ucval = vt_cons[console]->vc_mode;
                goto setint;

        case KDMAPDISP:
        case KDUNMAPDISP:
                /*
                 * these work like a combination of mmap and KDENABIO.
                 * this could be easily finished.
                 */
                return -EINVAL;

        case KDSKBMODE:
                if (!perm)
                        return -EPERM;
                switch(arg) {
                  case K_RAW:
                        kbd->kbdmode = VC_RAW;
                        break;
                  case K_MEDIUMRAW:
                        kbd->kbdmode = VC_MEDIUMRAW;
                        break;
                  case K_XLATE:
                        kbd->kbdmode = VC_XLATE;
                        compute_shiftstate();
                        break;
                  case K_UNICODE:
                        kbd->kbdmode = VC_UNICODE;
                        compute_shiftstate();
                        break;
                  default:
                        return -EINVAL;
                }
                if (tty->ldisc.flush_buffer)
                        tty->ldisc.flush_buffer(tty);
                return 0;

        case KDGKBMODE:
                ucval = ((kbd->kbdmode == VC_RAW) ? K_RAW :
                                 (kbd->kbdmode == VC_MEDIUMRAW) ? K_MEDIUMRAW :
                                 (kbd->kbdmode == VC_UNICODE) ? K_UNICODE :
                                 K_XLATE);
                goto setint;

        /* this could be folded into KDSKBMODE, but for compatibility
           reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
        case KDSKBMETA:
                switch(arg) {
                  case K_METABIT:
                        clr_vc_kbd_mode(kbd, VC_META);
                        break;
                  case K_ESCPREFIX:
                        set_vc_kbd_mode(kbd, VC_META);
                        break;
                  default:
                        return -EINVAL;
                }
                return 0;

        case KDGKBMETA:
                ucval = (vc_kbd_mode(kbd, VC_META) ? K_ESCPREFIX : K_METABIT);
        setint:
                return put_user(ucval, (int *)arg); 

        case KDGETKEYCODE:
        case KDSETKEYCODE:
                if(!suser())
                        perm=0;
                return do_kbkeycode_ioctl(cmd, (struct kbkeycode *)arg, perm);

        case KDGKBENT:
        case KDSKBENT:
                return do_kdsk_ioctl(cmd, (struct kbentry *)arg, perm, kbd);

        case KDGKBSENT:
        case KDSKBSENT:
                return do_kdgkb_ioctl(cmd, (struct kbsentry *)arg, perm);

        case KDGKBDIACR:
        {
                struct kbdiacrs *a = (struct kbdiacrs *)arg;

                if (put_user(accent_table_size, &a->kb_cnt))
                        return -EFAULT;
                if (copy_to_user(a->kbdiacr, accent_table, accent_table_size*sizeof(struct kbdiacr)))
                        return -EFAULT;
                return 0;
        }

        case KDSKBDIACR:
        {
                struct kbdiacrs *a = (struct kbdiacrs *)arg;
                unsigned int ct;

                if (!perm)
                        return -EPERM;
                if (get_user(ct,&a->kb_cnt))
                        return -EFAULT;
                if (ct >= MAX_DIACR)
                        return -EINVAL;
                accent_table_size = ct;
                if (copy_from_user(accent_table, a->kbdiacr, ct*sizeof(struct kbdiacr)))
                        return -EFAULT;
                return 0;
        }

        /* the ioctls below read/set the flags usually shown in the leds */
        /* don't use them - they will go away without warning */
        case KDGKBLED:
                ucval = kbd->ledflagstate | (kbd->default_ledflagstate << 4);
                goto setchar;

        case KDSKBLED:
                if (!perm)
                        return -EPERM;
                if (arg & ~0x77)
                        return -EINVAL;
                kbd->ledflagstate = (arg & 7);
                kbd->default_ledflagstate = ((arg >> 4) & 7);
                set_leds();
                return 0;

        /* the ioctls below only set the lights, not the functions */
        /* for those, see KDGKBLED and KDSKBLED above */
        case KDGETLED:
                ucval = getledstate();
        setchar:
                return put_user(ucval, (char*)arg);

        case KDSETLED:
                if (!perm)
                  return -EPERM;
                setledstate(kbd, arg);
                return 0;

        /*
         * A process can indicate its willingness to accept signals
         * generated by pressing an appropriate key combination.
         * Thus, one can have a daemon that e.g. spawns a new console
         * upon a keypress and then changes to it.
         * Probably init should be changed to do this (and have a
         * field ks (`keyboard signal') in inittab describing the
         * desired action), so that the number of background daemons
         * does not increase.
         */
        case KDSIGACCEPT:
        {
                extern int spawnpid, spawnsig;
                if (!perm)
                  return -EPERM;
                if (arg < 1 || arg > _NSIG || arg == SIGKILL)
                  return -EINVAL;
                spawnpid = current->pid;
                spawnsig = arg;
                return 0;
        }

        case VT_SETMODE:
        {
                struct vt_mode tmp;

                if (!perm)
                        return -EPERM;
                if (copy_from_user(&tmp, (void*)arg, sizeof(struct vt_mode)))
                        return -EFAULT;
                if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS)
                        return -EINVAL;
                vt_cons[console]->vt_mode = tmp;
                /* the frsig is ignored, so we set it to 0 */
                vt_cons[console]->vt_mode.frsig = 0;
                vt_cons[console]->vt_pid = current->pid;
                /* no switch is required -- saw@shade.msu.ru */
                vt_cons[console]->vt_newvt = -1; 
                return 0;
        }

        case VT_GETMODE:
                return copy_to_user((void*)arg, &(vt_cons[console]->vt_mode), 
                                                        sizeof(struct vt_mode)) ? -EFAULT : 0; 

        /*
         * Returns global vt state. Note that VT 0 is always open, since
         * it's an alias for the current VT, and people can't use it here.
         * We cannot return state for more than 16 VTs, since v_state is short.
         */
        case VT_GETSTATE:
        {
                struct vt_stat *vtstat = (struct vt_stat *)arg;
                unsigned short state, mask;

                i = verify_area(VERIFY_WRITE,(void *)vtstat, sizeof(struct vt_stat));
                if (i)
                        return i;
                put_user(fg_console + 1, &vtstat->v_active);
                state = 1;      /* /dev/tty0 is always open */
                for (i = 0, mask = 2; i < MAX_NR_CONSOLES && mask; ++i, mask <<= 1)
                        if (VT_IS_IN_USE(i))
                                state |= mask;
                return put_user(state, &vtstat->v_state);
        }

        /*
         * Returns the first available (non-opened) console.
         */
        case VT_OPENQRY:
                for (i = 0; i < MAX_NR_CONSOLES; ++i)
                        if (! VT_IS_IN_USE(i))
                                break;
                ucval = i < MAX_NR_CONSOLES ? (i+1) : -1;
                goto setint;             

        /*
         * ioctl(fd, VT_ACTIVATE, num) will cause us to switch to vt # num,
         * with num >= 1 (switches to vt 0, our console, are not allowed, just
         * to preserve sanity).
         */
        case VT_ACTIVATE:
                if (!perm)
                        return -EPERM;
                if (arg == 0 || arg > MAX_NR_CONSOLES)
                        return -ENXIO;
                arg--;
                i = vc_allocate(arg);
                if (i)
                        return i;
                set_console(arg);
                return 0;

        /*
         * wait until the specified VT has been activated
         */
        case VT_WAITACTIVE:
                if (!perm)
                        return -EPERM;
                if (arg == 0 || arg > MAX_NR_CONSOLES)
                        return -ENXIO;
                return vt_waitactive(arg-1);

        /*
         * If a vt is under process control, the kernel will not switch to it
         * immediately, but postpone the operation until the process calls this
         * ioctl, allowing the switch to complete.
         *
         * According to the X sources this is the behavior:
         *      0:      pending switch-from not OK
         *      1:      pending switch-from OK
         *      2:      completed switch-to OK
         */
        case VT_RELDISP:
                if (!perm)
                        return -EPERM;
                if (vt_cons[console]->vt_mode.mode != VT_PROCESS)
                        return -EINVAL;

                /*
                 * Switching-from response
                 */
                if (vt_cons[console]->vt_newvt >= 0)
                {
                        if (arg == 0)
                                /*
                                 * Switch disallowed, so forget we were trying
                                 * to do it.
                                 */
                                vt_cons[console]->vt_newvt = -1;

                        else
                        {
                                /*
                                 * The current vt has been released, so
                                 * complete the switch.
                                 */
                                int newvt = vt_cons[console]->vt_newvt;
                                vt_cons[console]->vt_newvt = -1;
                                i = vc_allocate(newvt);
                                if (i)
                                        return i;
                                /*
                                 * When we actually do the console switch,
                                 * make sure we are atomic with respect to
                                 * other console switches..
                                 */
                                start_bh_atomic();
                                complete_change_console(newvt);
                                end_bh_atomic();
                        }
                }

                /*
                 * Switched-to response
                 */
                else
                {
                        /*
                         * If it's just an ACK, ignore it
                         */
                        if (arg != VT_ACKACQ)
                                return -EINVAL;
                }

                return 0;

         /*
          * Disallocate memory associated to VT (but leave VT1)
          */
         case VT_DISALLOCATE:
                if (arg > MAX_NR_CONSOLES)
                        return -ENXIO;
                if (arg == 0) {
                    /* disallocate all unused consoles, but leave 0 */
                    for (i=1; i<MAX_NR_CONSOLES; i++)
                      if (! VT_BUSY(i))
                        vc_disallocate(i);
                } else {
                    /* disallocate a single console, if possible */
                    arg--;
                    if (VT_BUSY(arg))
                      return -EBUSY;
                    if (arg)                          /* leave 0 */
                      vc_disallocate(arg);
                }
                return 0;

        case VT_RESIZE:
        {
                struct vt_sizes *vtsizes = (struct vt_sizes *) arg;
                ushort ll,cc;
                if (!perm)
                        return -EPERM;
                i = verify_area(VERIFY_READ, (void *)vtsizes, sizeof(struct vt_sizes));
                if (i)
                        return i;
                get_user(ll, &vtsizes->v_rows);
                get_user(cc, &vtsizes->v_cols);
                return vc_resize_all(ll, cc);
        }

        case VT_RESIZEX:
        {
                struct vt_consize *vtconsize = (struct vt_consize *) arg;
                ushort ll,cc,vlin,clin,vcol,ccol;
                if (!perm)
                        return -EPERM;
                i = verify_area(VERIFY_READ, (void *)vtconsize, sizeof(struct vt_consize));
                if (i)
                        return i;
                get_user(ll, &vtconsize->v_rows);
                get_user(cc, &vtconsize->v_cols);
                get_user(vlin, &vtconsize->v_vlin);
                get_user(clin, &vtconsize->v_clin);
                get_user(vcol, &vtconsize->v_vcol);
                get_user(ccol, &vtconsize->v_ccol);
                vlin = vlin ? vlin : video_scan_lines;
                if ( clin )
                  {
                    if ( ll )
                      {
                        if ( ll != vlin/clin )
                          return -EINVAL; /* Parameters don't add up */
                      }
                    else 
                      ll = vlin/clin;
                  }
                if ( vcol && ccol )
                  {
                    if ( cc )
                      {
                        if ( cc != vcol/ccol )
                          return -EINVAL;
                      }
                    else
                      cc = vcol/ccol;
                  }

                if ( clin > 32 )
                  return -EINVAL;
                    
                if ( vlin )
                  video_scan_lines = vlin;
                if ( clin )
                  video_font_height = clin;
                
                return vc_resize_all(ll, cc);
        }

        case PIO_FONT: {
                struct console_font_op op;
                if (!perm)
                        return -EPERM;
                op.op = KD_FONT_OP_SET;
                op.flags = KD_FONT_FLAG_OLD | KD_FONT_FLAG_DONT_RECALC; /* Compatibility */
                op.width = 8;
                op.height = 0;
                op.charcount = 256;
                op.data = (char *) arg;
                return con_font_op(fg_console, &op);
        }

        case GIO_FONT: {
                struct console_font_op op;
                op.op = KD_FONT_OP_GET;
                op.flags = KD_FONT_FLAG_OLD;
                op.width = 8;
                op.height = 32;
                op.charcount = 256;
                op.data = (char *) arg;
                return con_font_op(fg_console, &op);
        }

        case PIO_CMAP:
                if (!perm)
                        return -EPERM;
                return con_set_cmap((char *)arg);

        case GIO_CMAP:
                return con_get_cmap((char *)arg);

        case PIO_FONTX:
        case GIO_FONTX:
                return do_fontx_ioctl(cmd, (struct consolefontdesc *)arg, perm);

        case PIO_FONTRESET:
        {
                if (!perm)
                        return -EPERM;

#ifdef BROKEN_GRAPHICS_PROGRAMS
                /* With BROKEN_GRAPHICS_PROGRAMS defined, the default
                   font is not saved. */
                return -ENOSYS;
#else
                {
                struct console_font_op op;
                op.op = KD_FONT_OP_SET_DEFAULT;
                op.data = NULL;
                i = con_font_op(fg_console, &op);
                if (i) return i;
                con_set_default_unimap(fg_console);
                return 0;
                }
#endif
        }

        case KDFONTOP: {
                struct console_font_op op;
                if (copy_from_user(&op, (void *) arg, sizeof(op)))
                        return -EFAULT;
                if (!perm && op.op != KD_FONT_OP_GET)
                        return -EPERM;
                i = con_font_op(console, &op);
                if (i) return i;
                if (copy_to_user((void *) arg, &op, sizeof(op)))
                        return -EFAULT;
                return 0;
        }

        case PIO_SCRNMAP:
                if (!perm)
                        return -EPERM;
                return con_set_trans_old((unsigned char *)arg);

        case GIO_SCRNMAP:
                return con_get_trans_old((unsigned char *)arg);

        case PIO_UNISCRNMAP:
                if (!perm)
                        return -EPERM;
                return con_set_trans_new((unsigned short *)arg);

        case GIO_UNISCRNMAP:
                return con_get_trans_new((unsigned short *)arg);

        case PIO_UNIMAPCLR:
              { struct unimapinit ui;
                if (!perm)
                        return -EPERM;
                i = copy_from_user(&ui, (void *)arg, sizeof(struct unimapinit));
                if (i) return -EFAULT;
                con_clear_unimap(fg_console, &ui);
                return 0;
              }

        case PIO_UNIMAP:
        case GIO_UNIMAP:
                return do_unimap_ioctl(cmd, (struct unimapdesc *)arg, perm);

        case VT_LOCKSWITCH:
                if (!suser())
                   return -EPERM;
                vt_dont_switch = 1;
                return 0;
        case VT_UNLOCKSWITCH:
                if (!suser())
                   return -EPERM;
                vt_dont_switch = 0;
                return 0;
#ifdef CONFIG_FB_COMPAT_XPMAC
        case VC_GETMODE:
                {
                        struct vc_mode mode;

                        i = verify_area(VERIFY_WRITE, (void *) arg,
                                        sizeof(struct vc_mode));
                        if (i == 0)
                                i = console_getmode(&mode);
                        if (i)
                                return i;
                        if (copy_to_user((void *) arg, &mode, sizeof(mode)))
                                return -EFAULT;
                        return 0;
                }
        case VC_SETMODE:
        case VC_INQMODE:
                {
                        struct vc_mode mode;

                        if (!perm)
                                return -EPERM;
                        i = verify_area(VERIFY_READ, (void *) arg,
                                        sizeof(struct vc_mode));
                        if (i)
                                return i;
                        if (copy_from_user(&mode, (void *) arg, sizeof(mode)))
                                return -EFAULT;
                        return console_setmode(&mode, cmd == VC_SETMODE);
                }
        case VC_SETCMAP:
                {
                        unsigned char cmap[3][256], *p;
                        int n_entries, cmap_size, i, j;

                        if (!perm)
                                return -EPERM;
                        if (arg == (unsigned long) VC_POWERMODE_INQUIRY
                            || arg <= VESA_POWERDOWN) {
                                /* compatibility hack: VC_POWERMODE
                                   was changed from 0x766a to 0x766c */
                                return console_powermode((int) arg);
                        }
                        i = verify_area(VERIFY_READ, (void *) arg,
                                        sizeof(int));
                        if (i)
                                return i;
                        if (get_user(cmap_size, (int *) arg))
                                return -EFAULT;
                        if (cmap_size % 3)
                                return -EINVAL;
                        n_entries = cmap_size / 3;
                        if ((unsigned) n_entries > 256)
                                return -EINVAL;
                        p = (unsigned char *) (arg + sizeof(int));
                        for (j = 0; j < n_entries; ++j)
                                for (i = 0; i < 3; ++i)
                                        if (get_user(cmap[i][j], p++))
                                                return -EFAULT;
                        return console_setcmap(n_entries, cmap[0],
                                               cmap[1], cmap[2]);
                }
        case VC_GETCMAP:
                /* not implemented yet */
                return -ENOIOCTLCMD;
        case VC_POWERMODE:
                if (!perm)
                        return -EPERM;
                return console_powermode((int) arg);
#endif /* CONFIG_FB_COMPAT_XPMAC */
        default:
                return -ENOIOCTLCMD;
        }
}

/*
 * 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, -EINTR if interrupted.
 */
int vt_waitactive(int vt)
{
        int retval;
        struct wait_queue wait = { current, NULL };

        add_wait_queue(&vt_activate_queue, &wait);
        for (;;) {
                current->state = TASK_INTERRUPTIBLE;
                retval = 0;
                if (vt == fg_console)
                        break;
                retval = -EINTR;
                if (signal_pending(current))
                        break;
                schedule();
        }
        remove_wait_queue(&vt_activate_queue, &wait);
        current->state = TASK_RUNNING;
        return retval;
}

#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;

        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;
        switch_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)
                        unblank_screen();
                else
                        do_blank_screen(1);
        }

        /*
         * 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);
}

---