2 * linux/drivers/char/vt_ioctl.c
4 * Copyright (C) 1992 obz under the linux copyright
6 * Dynamic diacritical handling - aeb@cwi.nl - Dec 1993
7 * Dynamic keymap and string allocation - aeb@cwi.nl - May 1994
8 * Restrict VT switching via ioctl() - grif@cs.ucr.edu - Dec 1995
9 * Some code moved for less code duplication - Andi Kleen - Mar 1997
10 * Check put/get_user, cleanups - acme@conectiva.com.br - Jun 2001
13 #include <linux/config.h>
14 #include <linux/types.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
17 #include <linux/tty.h>
18 #include <linux/timer.h>
19 #include <linux/kernel.h>
22 #include <linux/string.h>
23 #include <linux/slab.h>
24 #include <linux/major.h>
26 #include <linux/console.h>
29 #include <asm/uaccess.h>
31 #include <linux/kbd_kern.h>
32 #include <linux/vt_kern.h>
33 #include <linux/kbd_diacr.h>
34 #include <linux/selection.h>
37 extern struct tty_driver *console_driver;
39 #define VT_IS_IN_USE(i) (console_driver->ttys[i] && console_driver->ttys[i]->count)
40 #define VT_BUSY(i) (VT_IS_IN_USE(i) || i == fg_console || i == sel_cons)
43 * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
44 * experimentation and study of X386 SYSV handling.
46 * One point of difference: SYSV vt's are /dev/vtX, which X >= 0, and
47 * /dev/console is a separate ttyp. Under Linux, /dev/tty0 is /dev/console,
48 * and the vc start at /dev/ttyX, X >= 1. We maintain that here, so we will
49 * always treat our set of vt as numbered 1..MAX_NR_CONSOLES (corresponding to
50 * ttys 0..MAX_NR_CONSOLES-1). Explicitly naming VT 0 is illegal, but using
51 * /dev/tty0 (fg_console) as a target is legal, since an implicit aliasing
52 * to the current console is done by the main ioctl code.
55 struct vt_struct *vt_cons[MAX_NR_CONSOLES];
57 /* Keyboard type: Default is KB_101, but can be set by machine
60 unsigned char keyboard_type = KB_101;
63 #include <linux/syscalls.h>
67 * these are the valid i/o ports we're allowed to change. they map all the
72 #define GPNUM (GPLAST - GPFIRST + 1)
74 #define i (tmp.kb_index)
75 #define s (tmp.kb_table)
76 #define v (tmp.kb_value)
78 do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm, struct kbd_struct *kbd)
81 ushort *key_map, val, ov;
83 if (copy_from_user(&tmp, user_kbe, sizeof(struct kbentry)))
88 key_map = key_maps[s];
91 if (kbd->kbdmode != VC_UNICODE && KTYP(val) >= NR_TYPES)
94 val = (i ? K_HOLE : K_NOSUCHMAP);
95 return put_user(val, &user_kbe->kb_value);
99 if (!i && v == K_NOSUCHMAP) {
100 /* disallocate map */
101 key_map = key_maps[s];
104 if (key_map[0] == U(K_ALLOCATED)) {
112 if (KTYP(v) < NR_TYPES) {
113 if (KVAL(v) > max_vals[KTYP(v)])
116 if (kbd->kbdmode != VC_UNICODE)
119 /* ++Geert: non-PC keyboards may generate keycode zero */
120 #if !defined(__mc68000__) && !defined(__powerpc__)
121 /* assignment to entry 0 only tests validity of args */
126 if (!(key_map = key_maps[s])) {
129 if (keymap_count >= MAX_NR_OF_USER_KEYMAPS &&
130 !capable(CAP_SYS_RESOURCE))
133 key_map = (ushort *) kmalloc(sizeof(plain_map),
137 key_maps[s] = key_map;
138 key_map[0] = U(K_ALLOCATED);
139 for (j = 1; j < NR_KEYS; j++)
140 key_map[j] = U(K_HOLE);
145 break; /* nothing to do */
149 if (((ov == K_SAK) || (v == K_SAK)) && !capable(CAP_SYS_ADMIN))
152 if (!s && (KTYP(ov) == KT_SHIFT || KTYP(v) == KT_SHIFT))
153 compute_shiftstate();
163 do_kbkeycode_ioctl(int cmd, struct kbkeycode __user *user_kbkc, int perm)
165 struct kbkeycode tmp;
168 if (copy_from_user(&tmp, user_kbkc, sizeof(struct kbkeycode)))
172 kc = getkeycode(tmp.scancode);
174 kc = put_user(kc, &user_kbkc->keycode);
179 kc = setkeycode(tmp.scancode, tmp.keycode);
186 do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
188 struct kbsentry *kbs;
194 char *first_free, *fj, *fnw;
198 kbs = kmalloc(sizeof(*kbs), GFP_KERNEL);
204 /* we mostly copy too much here (512bytes), but who cares ;) */
205 if (copy_from_user(kbs, user_kdgkb, sizeof(struct kbsentry))) {
209 kbs->kb_string[sizeof(kbs->kb_string)-1] = '\0';
214 sz = sizeof(kbs->kb_string) - 1; /* sz should have been
216 up = user_kdgkb->kb_string;
219 for ( ; *p && sz; p++, sz--)
220 if (put_user(*p, up++)) {
224 if (put_user('\0', up)) {
229 return ((p && *p) ? -EOVERFLOW : 0);
237 first_free = funcbufptr + (funcbufsize - funcbufleft);
238 for (j = i+1; j < MAX_NR_FUNC && !func_table[j]; j++)
245 delta = (q ? -strlen(q) : 1) + strlen(kbs->kb_string);
246 if (delta <= funcbufleft) { /* it fits in current buf */
247 if (j < MAX_NR_FUNC) {
248 memmove(fj + delta, fj, first_free - fj);
249 for (k = j; k < MAX_NR_FUNC; k++)
251 func_table[k] += delta;
255 funcbufleft -= delta;
256 } else { /* allocate a larger buffer */
258 while (sz < funcbufsize - funcbufleft + delta)
260 fnw = (char *) kmalloc(sz, GFP_KERNEL);
269 memmove(fnw, funcbufptr, fj - funcbufptr);
270 for (k = 0; k < j; k++)
272 func_table[k] = fnw + (func_table[k] - funcbufptr);
274 if (first_free > fj) {
275 memmove(fnw + (fj - funcbufptr) + delta, fj, first_free - fj);
276 for (k = j; k < MAX_NR_FUNC; k++)
278 func_table[k] = fnw + (func_table[k] - funcbufptr) + delta;
280 if (funcbufptr != func_buf)
283 funcbufleft = funcbufleft - delta + sz - funcbufsize;
286 strcpy(func_table[i], kbs->kb_string);
296 do_fontx_ioctl(int cmd, struct consolefontdesc __user *user_cfd, int perm, struct console_font_op *op)
298 struct consolefontdesc cfdarg;
301 if (copy_from_user(&cfdarg, user_cfd, sizeof(struct consolefontdesc)))
308 op->op = KD_FONT_OP_SET;
309 op->flags = KD_FONT_FLAG_OLD;
311 op->height = cfdarg.charheight;
312 op->charcount = cfdarg.charcount;
313 op->data = cfdarg.chardata;
314 return con_font_op(fg_console, op);
316 op->op = KD_FONT_OP_GET;
317 op->flags = KD_FONT_FLAG_OLD;
319 op->height = cfdarg.charheight;
320 op->charcount = cfdarg.charcount;
321 op->data = cfdarg.chardata;
322 i = con_font_op(fg_console, op);
325 cfdarg.charheight = op->height;
326 cfdarg.charcount = op->charcount;
327 if (copy_to_user(user_cfd, &cfdarg, sizeof(struct consolefontdesc)))
336 do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud, int perm, unsigned int console)
338 struct unimapdesc tmp;
341 if (copy_from_user(&tmp, user_ud, sizeof tmp))
344 i = verify_area(VERIFY_WRITE, tmp.entries,
345 tmp.entry_ct*sizeof(struct unipair));
352 return con_set_unimap(console, tmp.entry_ct, tmp.entries);
354 if (!perm && fg_console != console)
356 return con_get_unimap(console, tmp.entry_ct, &(user_ud->entry_ct), tmp.entries);
362 * We handle the console-specific ioctl's here. We allow the
363 * capability to modify any console, not just the fg_console.
365 int vt_ioctl(struct tty_struct *tty, struct file * file,
366 unsigned int cmd, unsigned long arg)
368 struct vt_struct *vt = (struct vt_struct *)tty->driver_data;
369 struct vc_data *vc = vc_cons[vt->vc_num].d;
370 struct console_font_op op; /* used in multiple places here */
371 struct kbd_struct * kbd;
372 unsigned int console;
374 void __user *up = (void __user *)arg;
377 console = vt->vc_num;
379 if (!vc_cons_allocated(console)) /* impossible? */
383 * To have permissions to do most of the vt ioctls, we either have
384 * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
387 if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
390 kbd = kbd_table + console;
404 unsigned int ticks, count;
407 * Generate the tone for the appropriate number of ticks.
408 * If the time is zero, turn off sound ourselves.
410 ticks = HZ * ((arg >> 16) & 0xffff) / 1000;
411 count = ticks ? (arg & 0xffff) : 0;
413 count = 1193182 / count;
414 kd_mksound(count, ticks);
422 ucval = keyboard_type;
426 * These cannot be implemented on any machine that implements
427 * ioperm() in user level (such as Alpha PCs) or not at all.
429 * XXX: you should never use these, just call ioperm directly..
435 * KDADDIO and KDDELIO may be able to add ports beyond what
436 * we reject here, but to be safe...
438 if (arg < GPFIRST || arg > GPLAST)
440 return sys_ioperm(arg, 1, (cmd == KDADDIO)) ? -ENXIO : 0;
444 return sys_ioperm(GPFIRST, GPNUM,
445 (cmd == KDENABIO)) ? -ENXIO : 0;
448 /* Linux m68k/i386 interface for setting the keyboard delay/repeat rate */
452 struct kbd_repeat kbrep;
455 if (!capable(CAP_SYS_TTY_CONFIG))
458 if (copy_from_user(&kbrep, up, sizeof(struct kbd_repeat)))
460 err = kbd_rate(&kbrep);
463 if (copy_to_user(up, &kbrep, sizeof(struct kbd_repeat)))
470 * currently, setting the mode from KD_TEXT to KD_GRAPHICS
471 * doesn't do a whole lot. i'm not sure if it should do any
472 * restoration of modes or what...
474 * XXX It should at least call into the driver, fbdev's definitely
475 * need to restore their engine state. --BenH
490 if (vt_cons[console]->vc_mode == (unsigned char) arg)
492 vt_cons[console]->vc_mode = (unsigned char) arg;
493 if (console != fg_console)
496 * explicitly blank/unblank the screen if switching modes
498 acquire_console_sem();
500 do_unblank_screen(1);
503 release_console_sem();
507 ucval = vt_cons[console]->vc_mode;
513 * these work like a combination of mmap and KDENABIO.
514 * this could be easily finished.
523 kbd->kbdmode = VC_RAW;
526 kbd->kbdmode = VC_MEDIUMRAW;
529 kbd->kbdmode = VC_XLATE;
530 compute_shiftstate();
533 kbd->kbdmode = VC_UNICODE;
534 compute_shiftstate();
539 if (tty->ldisc.flush_buffer)
540 tty->ldisc.flush_buffer(tty);
544 ucval = ((kbd->kbdmode == VC_RAW) ? K_RAW :
545 (kbd->kbdmode == VC_MEDIUMRAW) ? K_MEDIUMRAW :
546 (kbd->kbdmode == VC_UNICODE) ? K_UNICODE :
550 /* this could be folded into KDSKBMODE, but for compatibility
551 reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
555 clr_vc_kbd_mode(kbd, VC_META);
558 set_vc_kbd_mode(kbd, VC_META);
566 ucval = (vc_kbd_mode(kbd, VC_META) ? K_ESCPREFIX : K_METABIT);
568 return put_user(ucval, (int __user *)arg);
572 if(!capable(CAP_SYS_TTY_CONFIG))
574 return do_kbkeycode_ioctl(cmd, up, perm);
578 return do_kdsk_ioctl(cmd, up, perm, kbd);
582 return do_kdgkb_ioctl(cmd, up, perm);
586 struct kbdiacrs __user *a = up;
588 if (put_user(accent_table_size, &a->kb_cnt))
590 if (copy_to_user(a->kbdiacr, accent_table, accent_table_size*sizeof(struct kbdiacr)))
597 struct kbdiacrs __user *a = up;
602 if (get_user(ct,&a->kb_cnt))
606 accent_table_size = ct;
607 if (copy_from_user(accent_table, a->kbdiacr, ct*sizeof(struct kbdiacr)))
612 /* the ioctls below read/set the flags usually shown in the leds */
613 /* don't use them - they will go away without warning */
615 ucval = kbd->ledflagstate | (kbd->default_ledflagstate << 4);
623 kbd->ledflagstate = (arg & 7);
624 kbd->default_ledflagstate = ((arg >> 4) & 7);
628 /* the ioctls below only set the lights, not the functions */
629 /* for those, see KDGKBLED and KDSKBLED above */
631 ucval = getledstate();
633 return put_user(ucval, (char __user *)arg);
638 setledstate(kbd, arg);
642 * A process can indicate its willingness to accept signals
643 * generated by pressing an appropriate key combination.
644 * Thus, one can have a daemon that e.g. spawns a new console
645 * upon a keypress and then changes to it.
646 * See also the kbrequest field of inittab(5).
650 extern int spawnpid, spawnsig;
651 if (!perm || !capable(CAP_KILL))
653 if (arg < 1 || arg > _NSIG || arg == SIGKILL)
655 spawnpid = current->pid;
666 if (copy_from_user(&tmp, up, sizeof(struct vt_mode)))
668 if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS)
670 acquire_console_sem();
671 vt_cons[console]->vt_mode = tmp;
672 /* the frsig is ignored, so we set it to 0 */
673 vt_cons[console]->vt_mode.frsig = 0;
674 vt_cons[console]->vt_pid = current->pid;
675 /* no switch is required -- saw@shade.msu.ru */
676 vt_cons[console]->vt_newvt = -1;
677 release_console_sem();
686 acquire_console_sem();
687 memcpy(&tmp, &vt_cons[console]->vt_mode, sizeof(struct vt_mode));
688 release_console_sem();
690 rc = copy_to_user(up, &tmp, sizeof(struct vt_mode));
691 return rc ? -EFAULT : 0;
695 * Returns global vt state. Note that VT 0 is always open, since
696 * it's an alias for the current VT, and people can't use it here.
697 * We cannot return state for more than 16 VTs, since v_state is short.
701 struct vt_stat __user *vtstat = up;
702 unsigned short state, mask;
704 if (put_user(fg_console + 1, &vtstat->v_active))
706 state = 1; /* /dev/tty0 is always open */
707 for (i = 0, mask = 2; i < MAX_NR_CONSOLES && mask; ++i, mask <<= 1)
710 return put_user(state, &vtstat->v_state);
714 * Returns the first available (non-opened) console.
717 for (i = 0; i < MAX_NR_CONSOLES; ++i)
718 if (! VT_IS_IN_USE(i))
720 ucval = i < MAX_NR_CONSOLES ? (i+1) : -1;
724 * ioctl(fd, VT_ACTIVATE, num) will cause us to switch to vt # num,
725 * with num >= 1 (switches to vt 0, our console, are not allowed, just
726 * to preserve sanity).
731 if (arg == 0 || arg > MAX_NR_CONSOLES)
734 acquire_console_sem();
735 i = vc_allocate(arg);
736 release_console_sem();
743 * wait until the specified VT has been activated
748 if (arg == 0 || arg > MAX_NR_CONSOLES)
750 return vt_waitactive(arg-1);
753 * If a vt is under process control, the kernel will not switch to it
754 * immediately, but postpone the operation until the process calls this
755 * ioctl, allowing the switch to complete.
757 * According to the X sources this is the behavior:
758 * 0: pending switch-from not OK
759 * 1: pending switch-from OK
760 * 2: completed switch-to OK
765 if (vt_cons[console]->vt_mode.mode != VT_PROCESS)
769 * Switching-from response
771 if (vt_cons[console]->vt_newvt >= 0)
775 * Switch disallowed, so forget we were trying
778 vt_cons[console]->vt_newvt = -1;
783 * The current vt has been released, so
784 * complete the switch.
787 acquire_console_sem();
788 newvt = vt_cons[console]->vt_newvt;
789 vt_cons[console]->vt_newvt = -1;
790 i = vc_allocate(newvt);
792 release_console_sem();
796 * When we actually do the console switch,
797 * make sure we are atomic with respect to
798 * other console switches..
800 complete_change_console(newvt);
801 release_console_sem();
806 * Switched-to response
811 * If it's just an ACK, ignore it
813 if (arg != VT_ACKACQ)
820 * Disallocate memory associated to VT (but leave VT1)
823 if (arg > MAX_NR_CONSOLES)
826 /* disallocate all unused consoles, but leave 0 */
827 acquire_console_sem();
828 for (i=1; i<MAX_NR_CONSOLES; i++)
831 release_console_sem();
833 /* disallocate a single console, if possible */
837 if (arg) { /* leave 0 */
838 acquire_console_sem();
840 release_console_sem();
847 struct vt_sizes __user *vtsizes = up;
851 if (get_user(ll, &vtsizes->v_rows) ||
852 get_user(cc, &vtsizes->v_cols))
854 for (i = 0; i < MAX_NR_CONSOLES; i++) {
855 acquire_console_sem();
856 vc_resize(i, cc, ll);
857 release_console_sem();
864 struct vt_consize __user *vtconsize = up;
865 ushort ll,cc,vlin,clin,vcol,ccol;
868 if (verify_area(VERIFY_READ, vtconsize,
869 sizeof(struct vt_consize)))
871 __get_user(ll, &vtconsize->v_rows);
872 __get_user(cc, &vtconsize->v_cols);
873 __get_user(vlin, &vtconsize->v_vlin);
874 __get_user(clin, &vtconsize->v_clin);
875 __get_user(vcol, &vtconsize->v_vcol);
876 __get_user(ccol, &vtconsize->v_ccol);
877 vlin = vlin ? vlin : vc->vc_scan_lines;
881 return -EINVAL; /* Parameters don't add up */
896 for (i = 0; i < MAX_NR_CONSOLES; i++) {
899 acquire_console_sem();
901 vc_cons[i].d->vc_scan_lines = vlin;
903 vc_cons[i].d->vc_font.height = clin;
904 vc_resize(i, cc, ll);
905 release_console_sem();
913 op.op = KD_FONT_OP_SET;
914 op.flags = KD_FONT_FLAG_OLD | KD_FONT_FLAG_DONT_RECALC; /* Compatibility */
919 return con_font_op(fg_console, &op);
923 op.op = KD_FONT_OP_GET;
924 op.flags = KD_FONT_FLAG_OLD;
929 return con_font_op(fg_console, &op);
935 return con_set_cmap(up);
938 return con_get_cmap(up);
942 return do_fontx_ioctl(cmd, up, perm, &op);
949 #ifdef BROKEN_GRAPHICS_PROGRAMS
950 /* With BROKEN_GRAPHICS_PROGRAMS defined, the default
951 font is not saved. */
955 op.op = KD_FONT_OP_SET_DEFAULT;
957 i = con_font_op(fg_console, &op);
959 con_set_default_unimap(fg_console);
966 if (copy_from_user(&op, up, sizeof(op)))
968 if (!perm && op.op != KD_FONT_OP_GET)
970 i = con_font_op(console, &op);
972 if (copy_to_user(up, &op, sizeof(op)))
980 return con_set_trans_old(up);
983 return con_get_trans_old(up);
988 return con_set_trans_new(up);
991 return con_get_trans_new(up);
994 { struct unimapinit ui;
997 i = copy_from_user(&ui, up, sizeof(struct unimapinit));
998 if (i) return -EFAULT;
999 con_clear_unimap(console, &ui);
1005 return do_unimap_ioctl(cmd, up, perm, console);
1008 if (!capable(CAP_SYS_TTY_CONFIG))
1012 case VT_UNLOCKSWITCH:
1013 if (!capable(CAP_SYS_TTY_CONFIG))
1018 return -ENOIOCTLCMD;
1023 * Sometimes we want to wait until a particular VT has been activated. We
1024 * do it in a very simple manner. Everybody waits on a single queue and
1025 * get woken up at once. Those that are satisfied go on with their business,
1026 * while those not ready go back to sleep. Seems overkill to add a wait
1027 * to each vt just for this - usually this does nothing!
1029 static DECLARE_WAIT_QUEUE_HEAD(vt_activate_queue);
1032 * Sleeps until a vt is activated, or the task is interrupted. Returns
1033 * 0 if activation, -EINTR if interrupted.
1035 int vt_waitactive(int vt)
1038 DECLARE_WAITQUEUE(wait, current);
1040 add_wait_queue(&vt_activate_queue, &wait);
1042 set_current_state(TASK_INTERRUPTIBLE);
1044 if (vt == fg_console)
1047 if (signal_pending(current))
1051 remove_wait_queue(&vt_activate_queue, &wait);
1052 current->state = TASK_RUNNING;
1056 #define vt_wake_waitactive() wake_up(&vt_activate_queue)
1058 void reset_vc(unsigned int new_console)
1060 vt_cons[new_console]->vc_mode = KD_TEXT;
1061 kbd_table[new_console].kbdmode = VC_XLATE;
1062 vt_cons[new_console]->vt_mode.mode = VT_AUTO;
1063 vt_cons[new_console]->vt_mode.waitv = 0;
1064 vt_cons[new_console]->vt_mode.relsig = 0;
1065 vt_cons[new_console]->vt_mode.acqsig = 0;
1066 vt_cons[new_console]->vt_mode.frsig = 0;
1067 vt_cons[new_console]->vt_pid = -1;
1068 vt_cons[new_console]->vt_newvt = -1;
1069 if (!in_interrupt()) /* Via keyboard.c:SAK() - akpm */
1070 reset_palette(new_console) ;
1074 * Performs the back end of a vt switch
1076 void complete_change_console(unsigned int new_console)
1078 unsigned char old_vc_mode;
1080 last_console = fg_console;
1083 * If we're switching, we could be going from KD_GRAPHICS to
1084 * KD_TEXT mode or vice versa, which means we need to blank or
1085 * unblank the screen later.
1087 old_vc_mode = vt_cons[fg_console]->vc_mode;
1088 switch_screen(new_console);
1091 * This can't appear below a successful kill_proc(). If it did,
1092 * then the *blank_screen operation could occur while X, having
1093 * received acqsig, is waking up on another processor. This
1094 * condition can lead to overlapping accesses to the VGA range
1095 * and the framebuffer (causing system lockups).
1097 * To account for this we duplicate this code below only if the
1098 * controlling process is gone and we've called reset_vc.
1100 if (old_vc_mode != vt_cons[new_console]->vc_mode)
1102 if (vt_cons[new_console]->vc_mode == KD_TEXT)
1103 do_unblank_screen(1);
1109 * If this new console is under process control, send it a signal
1110 * telling it that it has acquired. Also check if it has died and
1111 * clean up (similar to logic employed in change_console())
1113 if (vt_cons[new_console]->vt_mode.mode == VT_PROCESS)
1116 * Send the signal as privileged - kill_proc() will
1117 * tell us if the process has gone or something else
1120 if (kill_proc(vt_cons[new_console]->vt_pid,
1121 vt_cons[new_console]->vt_mode.acqsig,
1125 * The controlling process has died, so we revert back to
1126 * normal operation. In this case, we'll also change back
1127 * to KD_TEXT mode. I'm not sure if this is strictly correct
1128 * but it saves the agony when the X server dies and the screen
1129 * remains blanked due to KD_GRAPHICS! It would be nice to do
1130 * this outside of VT_PROCESS but there is no single process
1131 * to account for and tracking tty count may be undesirable.
1133 reset_vc(new_console);
1135 if (old_vc_mode != vt_cons[new_console]->vc_mode)
1137 if (vt_cons[new_console]->vc_mode == KD_TEXT)
1138 do_unblank_screen(1);
1146 * Wake anyone waiting for their VT to activate
1148 vt_wake_waitactive();
1153 * Performs the front-end of a vt switch
1155 void change_console(unsigned int new_console)
1157 if ((new_console == fg_console) || (vt_dont_switch))
1159 if (!vc_cons_allocated(new_console))
1163 * If this vt is in process mode, then we need to handshake with
1164 * that process before switching. Essentially, we store where that
1165 * vt wants to switch to and wait for it to tell us when it's done
1166 * (via VT_RELDISP ioctl).
1168 * We also check to see if the controlling process still exists.
1169 * If it doesn't, we reset this vt to auto mode and continue.
1170 * This is a cheap way to track process control. The worst thing
1171 * that can happen is: we send a signal to a process, it dies, and
1172 * the switch gets "lost" waiting for a response; hopefully, the
1173 * user will try again, we'll detect the process is gone (unless
1174 * the user waits just the right amount of time :-) and revert the
1175 * vt to auto control.
1177 if (vt_cons[fg_console]->vt_mode.mode == VT_PROCESS)
1180 * Send the signal as privileged - kill_proc() will
1181 * tell us if the process has gone or something else
1184 if (kill_proc(vt_cons[fg_console]->vt_pid,
1185 vt_cons[fg_console]->vt_mode.relsig,
1189 * It worked. Mark the vt to switch to and
1190 * return. The process needs to send us a
1191 * VT_RELDISP ioctl to complete the switch.
1193 vt_cons[fg_console]->vt_newvt = new_console;
1198 * The controlling process has died, so we revert back to
1199 * normal operation. In this case, we'll also change back
1200 * to KD_TEXT mode. I'm not sure if this is strictly correct
1201 * but it saves the agony when the X server dies and the screen
1202 * remains blanked due to KD_GRAPHICS! It would be nice to do
1203 * this outside of VT_PROCESS but there is no single process
1204 * to account for and tracking tty count may be undesirable.
1206 reset_vc(fg_console);
1209 * Fall through to normal (VT_AUTO) handling of the switch...
1214 * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
1216 if (vt_cons[fg_console]->vc_mode == KD_GRAPHICS)
1219 complete_change_console(new_console);