aboutsummaryrefslogtreecommitdiff
path: root/init/init.c
blob: 35f2255b5a48b50f71f5a7c864db5aa7b1f7c7e1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
/* vi: set sw=4 ts=4: */
/*
 * Mini init implementation for busybox
 *
 *
 * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
 * Adjusted by so many folks, it's impossible to keep track.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/* Turn this on to disable all the dangerous 
   rebooting stuff when debugging.
#define DEBUG_INIT
*/

#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <paths.h>
#include <signal.h>
#include <stdarg.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <asm/types.h>
#include <linux/serial.h>		/* for serial_struct */
#include <linux/version.h>
#include <linux/reboot.h>
#include <linux/unistd.h>
#include <linux/vt.h>				/* for vt_stat */
#include <sys/fcntl.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/wait.h>
#ifdef BB_SYSLOGD
# include <sys/syslog.h>
#endif


#ifndef RB_HALT_SYSTEM
#define RB_HALT_SYSTEM  0xcdef0123
#define RB_ENABLE_CAD   0x89abcdef
#define RB_DISABLE_CAD  0
#define RB_POWER_OFF    0x4321fedc
#define RB_AUTOBOOT     0x01234567
#if defined(__GLIBC__)
#include <sys/reboot.h>
  #define init_reboot(magic) reboot(magic)
#else
  #define init_reboot(magic) reboot(0xfee1dead, 672274793, magic)
#endif
#endif

#ifndef _PATH_STDPATH
#define _PATH_STDPATH	"/usr/bin:/bin:/usr/sbin:/sbin"
#endif


#if defined BB_FEATURE_INIT_COREDUMPS
/*
 * When a file named CORE_ENABLE_FLAG_FILE exists, setrlimit is called 
 * before processes are spawned to set core file size as unlimited.
 * This is for debugging only.  Don't use this is production, unless
 * you want core dumps lying about....
 */
#define CORE_ENABLE_FLAG_FILE "/.init_enable_core"
#include <sys/resource.h>
#include <sys/time.h>
#endif

#ifndef KERNEL_VERSION
#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
#endif

#if defined(__GLIBC__)
#include <sys/kdaemon.h>
#else
static _syscall2(int, bdflush, int, func, int, data);
#endif							/* __GLIBC__ */


#define VT_PRIMARY   "/dev/tty1"     /* Primary virtual console */
#define VT_SECONDARY "/dev/tty2"     /* Virtual console */
#define VT_LOG       "/dev/tty3"     /* Virtual console */
#define SERIAL_CON0  "/dev/ttyS0"    /* Primary serial console */
#define SERIAL_CON1  "/dev/ttyS1"    /* Serial console */
#define SHELL        "/bin/sh"	     /* Default shell */
#define INITTAB      "/etc/inittab"  /* inittab file location */
#ifndef INIT_SCRIPT
#define INIT_SCRIPT  "/etc/init.d/rcS"   /* Default sysinit script. */
#endif

#define LOG     0x1
#define CONSOLE 0x2

/* Allowed init action types */
typedef enum {
	SYSINIT = 1,
	RESPAWN,
	ASKFIRST,
	WAIT,
	ONCE,
	CTRLALTDEL
} initActionEnum;

/* A mapping between "inittab" action name strings and action type codes. */
typedef struct initActionType {
	const char *name;
	initActionEnum action;
} initActionType;

static const struct initActionType actions[] = {
	{"sysinit", SYSINIT},
	{"respawn", RESPAWN},
	{"askfirst", ASKFIRST},
	{"wait", WAIT},
	{"once", ONCE},
	{"ctrlaltdel", CTRLALTDEL},
	{0}
};

/* Set up a linked list of initActions, to be read from inittab */
typedef struct initActionTag initAction;
struct initActionTag {
	pid_t pid;
	char process[256];
	char console[256];
	initAction *nextPtr;
	initActionEnum action;
};
initAction *initActionList = NULL;


static char *secondConsole = VT_SECONDARY;
static char *log           = VT_LOG;
static int  kernelVersion  = 0;
static char termType[32]   = "TERM=linux";
static char console[32]    = _PATH_CONSOLE;

static void delete_initAction(initAction * action);


/* Print a message to the specified device.
 * Device may be bitwise-or'd from LOG | CONSOLE */
static void message(int device, char *fmt, ...)
		   __attribute__ ((format (printf, 2, 3)));
static void message(int device, char *fmt, ...)
{
	va_list arguments;
	int fd;

#ifdef BB_SYSLOGD

	/* Log the message to syslogd */
	if (device & LOG) {
		char msg[1024];

		va_start(arguments, fmt);
		vsnprintf(msg, sizeof(msg), fmt, arguments);
		va_end(arguments);
		openlog("init", 0, LOG_USER);
		syslog(LOG_USER|LOG_INFO, msg);
		closelog();
	}
#else
	static int log_fd = -1;

	/* Take full control of the log tty, and never close it.
	 * It's mine, all mine!  Muhahahaha! */
	if (log_fd < 0) {
		if (log == NULL) {
			/* don't even try to log, because there is no such console */
			log_fd = -2;
			/* log to main console instead */
			device = CONSOLE;
		} else if ((log_fd = device_open(log, O_RDWR|O_NDELAY)) < 0) {
			log_fd = -2;
			fprintf(stderr, "Bummer, can't write to log on %s!\r\n", log);
			fflush(stderr);
			log = NULL;
			device = CONSOLE;
		}
	}
	if ((device & LOG) && (log_fd >= 0)) {
		va_start(arguments, fmt);
		vdprintf(log_fd, fmt, arguments);
		va_end(arguments);
	}
#endif

	if (device & CONSOLE) {
		/* Always send console messages to /dev/console so people will see them. */
		if (
			(fd =
			 device_open(_PATH_CONSOLE,
						 O_WRONLY | O_NOCTTY | O_NDELAY)) >= 0) {
			va_start(arguments, fmt);
			vdprintf(fd, fmt, arguments);
			va_end(arguments);
			close(fd);
		} else {
			fprintf(stderr, "Bummer, can't print: ");
			va_start(arguments, fmt);
			vfprintf(stderr, fmt, arguments);
			fflush(stderr);
			va_end(arguments);
		}
	}
}

#define CTRLCHAR(ch)	((ch)-0x40)

/* Set terminal settings to reasonable defaults */
void set_term(int fd)
{
	struct termios tty;

	tcgetattr(fd, &tty);

	/* set control chars */
	tty.c_cc[VINTR]  = CTRLCHAR('C');	/* Ctrl-C */
	tty.c_cc[VQUIT]  = CTRLCHAR('\\');	/* Ctrl-\ */
	tty.c_cc[VERASE] = CTRLCHAR('?');	/* Ctrl-? */
	tty.c_cc[VKILL]  = CTRLCHAR('U');	/* Ctrl-U */
	tty.c_cc[VEOF]   = CTRLCHAR('D');	/* Ctrl-D */
	tty.c_cc[VSTART] = CTRLCHAR('Q');	/* Ctrl-Q */
	tty.c_cc[VSTOP]  = CTRLCHAR('S');	/* Ctrl-S */
	tty.c_cc[VSUSP]  = CTRLCHAR('Z');	/* Ctrl-Z */

	/* use line dicipline 0 */
	tty.c_line = 0;

	/* Make it be sane */
	tty.c_cflag &= CBAUD|CBAUDEX|CSIZE|CSTOPB|PARENB|PARODD;
	tty.c_cflag |= HUPCL|CLOCAL;

	/* input modes */
	tty.c_iflag = ICRNL | IXON | IXOFF;

	/* output modes */
	tty.c_oflag = OPOST | ONLCR;

	/* local modes */
	tty.c_lflag =
		ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN;

	tcsetattr(fd, TCSANOW, &tty);
}

/* How much memory does this machine have? */
static int check_free_memory()
{
	struct sysinfo info;

	/* Pre initialize mem_unit in case this kernel is something prior to
	 * the linux 2.4 kernel (which will actually fill in mem_unit... */
	sysinfo(&info);
	if (sysinfo(&info) != 0) {
		printf("Error checking free memory: %s\n", strerror(errno));
		return -1;
	}
	if (info.mem_unit==0) {
		/* Looks like we have a kernel prior to Linux 2.4.x */
		info.mem_unit=1024;
		info.totalram/=info.mem_unit;
		info.totalswap/=info.mem_unit;
	} else {
		/* Bah. Linux 2.4.x completely changed sysinfo. This can in theory
		overflow a 32 bit unsigned long, but who puts more then 4GiB ram+swap
		on an embedded system? */
		info.mem_unit/=1024;
		info.totalram*=info.mem_unit;
		info.totalswap*=info.mem_unit;
	}

	return(info.totalram+info.totalswap);
}

static void console_init()
{
	int fd;
	int tried_devcons = 0;
	int tried_vtprimary = 0;
	struct vt_stat vt;
	struct serial_struct sr;
	char *s;

	if ((s = getenv("TERM")) != NULL) {
		snprintf(termType, sizeof(termType) - 1, "TERM=%s", s);
	}

	if ((s = getenv("CONSOLE")) != NULL) {
		snprintf(console, sizeof(console) - 1, "%s", s);
	}
#if #cpu(sparc)
	/* sparc kernel supports console=tty[ab] parameter which is also 
	 * passed to init, so catch it here */
	else if ((s = getenv("console")) != NULL) {
		/* remap tty[ab] to /dev/ttyS[01] */
		if (strcmp(s, "ttya") == 0)
			snprintf(console, sizeof(console) - 1, "%s", SERIAL_CON0);
		else if (strcmp(s, "ttyb") == 0)
			snprintf(console, sizeof(console) - 1, "%s", SERIAL_CON1);
	}
#endif
	else {
		/* 2.2 kernels: identify the real console backend and try to use it */
		if (ioctl(0, TIOCGSERIAL, &sr) == 0) {
			/* this is a serial console */
			snprintf(console, sizeof(console) - 1, "/dev/ttyS%d", sr.line);
		} else if (ioctl(0, VT_GETSTATE, &vt) == 0) {
			/* this is linux virtual tty */
			snprintf(console, sizeof(console) - 1, "/dev/tty%d",
					 vt.v_active);
		} else {
			snprintf(console, sizeof(console) - 1, "%s", _PATH_CONSOLE);
			tried_devcons++;
		}
	}

	while ((fd = open(console, O_RDONLY | O_NONBLOCK)) < 0) {
		/* Can't open selected console -- try /dev/console */
		if (!tried_devcons) {
			tried_devcons++;
			snprintf(console, sizeof(console) - 1, "%s", _PATH_CONSOLE);
			continue;
		}
		/* Can't open selected console -- try vt1 */
		if (!tried_vtprimary) {
			tried_vtprimary++;
			snprintf(console, sizeof(console) - 1, "%s", VT_PRIMARY);
			continue;
		}
		break;
	}
	if (fd < 0) {
		/* Perhaps we should panic here? */
		snprintf(console, sizeof(console) - 1, "/dev/null");
	} else {
		/* check for serial console and disable logging to tty3 & running a
		   * shell to tty2 */
		if (ioctl(0, TIOCGSERIAL, &sr) == 0) {
			log = NULL;
			secondConsole = NULL;
			/* Force the TERM setting to vt102 for serial console --
			 * iff TERM is set to linux (the default) */
			if (strcmp( termType, "TERM=linux" ) == 0)
				snprintf(termType, sizeof(termType) - 1, "TERM=vt102");
			message(LOG | CONSOLE,
					"serial console detected.  Disabling virtual terminals.\r\n");
		}
		close(fd);
	}
	message(LOG, "console=%s\n", console);
}

static pid_t run(char *command, char *terminal, int get_enter)
{
	int i, fd;
	pid_t pid;
	char *tmpCmd;
	char *cmd[255];
	char buf[255];
	static const char press_enter[] =

		"\nPlease press Enter to activate this console. ";
	char *environment[] = {
		"HOME=/",
		"PATH=/usr/bin:/bin:/usr/sbin:/sbin",
		"SHELL=/bin/sh",
		termType,
		"USER=root",
		0
	};


	if ((pid = fork()) == 0) {
		/* Clean up */
		close(0);
		close(1);
		close(2);
		setsid();

		/* Reset signal handlers set for parent process */
		signal(SIGUSR1, SIG_DFL);
		signal(SIGUSR2, SIG_DFL);
		signal(SIGINT, SIG_DFL);
		signal(SIGTERM, SIG_DFL);
		signal(SIGHUP, SIG_DFL);

		if ((fd = device_open(terminal, O_RDWR)) < 0) {
			message(LOG | CONSOLE, "Bummer, can't open %s\r\n", terminal);
			exit(1);
		}
		dup2(fd, 0);
		dup2(fd, 1);
		dup2(fd, 2);
		ioctl(0, TIOCSCTTY, 0);
		tcsetpgrp(0, getpgrp());
		set_term(0);

		if (get_enter == TRUE) {
			/*
			 * Save memory by not exec-ing anything large (like a shell)
			 * before the user wants it. This is critical if swap is not
			 * enabled and the system has low memory. Generally this will
			 * be run on the second virtual console, and the first will
			 * be allowed to start a shell or whatever an init script 
			 * specifies.
			 */
			char c;
#ifdef DEBUG_INIT
			pid_t shell_pgid = getpid();
			message(LOG, "Waiting for enter to start '%s' (pid %d, console %s)\r\n",
					command, shell_pgid, terminal);
#endif
			write(fileno(stdout), press_enter, sizeof(press_enter) - 1);
			read(fileno(stdin), &c, 1);
		}

#ifdef DEBUG_INIT
		/* Log the process name and args */
		message(LOG, "Starting pid %d, console %s: '%s'\r\n",
				shell_pgid, terminal, command);
#endif

		/* See if any special /bin/sh requiring characters are present */
		if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
			cmd[0] = SHELL;
			cmd[1] = "-c";
			strcpy(buf, "exec ");
			strncat(buf, command, sizeof(buf) - strlen(buf) - 1);
			cmd[2] = buf;
			cmd[3] = NULL;
		} else {
			/* Convert command (char*) into cmd (char**, one word per string) */
			for (tmpCmd = command, i = 0;
				 (tmpCmd = strsep(&command, " \t")) != NULL;) {
				if (*tmpCmd != '\0') {
					cmd[i] = tmpCmd;
					tmpCmd++;
					i++;
				}
			}
			cmd[i] = NULL;
		}

#if defined BB_FEATURE_INIT_COREDUMPS
		{
			struct stat sb;
			if (stat (CORE_ENABLE_FLAG_FILE, &sb) == 0) {
				struct rlimit limit;
				limit.rlim_cur = RLIM_INFINITY;
				limit.rlim_max = RLIM_INFINITY;
				setrlimit(RLIMIT_CORE, &limit);
			}
		}
#endif

		/* Now run it.  The new program will take over this PID, 
		 * so nothing further in init.c should be run. */
		execve(cmd[0], cmd, environment);

		/* We're still here?  Some error happened. */
		message(LOG | CONSOLE, "Bummer, could not run '%s': %s\n", cmd[0],
				strerror(errno));
		exit(-1);
	}
	return pid;
}

static int waitfor(char *command, char *terminal, int get_enter)
{
	int status, wpid;
	int pid = run(command, terminal, get_enter);

	while (1) {
		wpid = wait(&status);
		if (wpid > 0 && wpid != pid) {
			continue;
		}
		if (wpid == pid)
			break;
	}
	return wpid;
}

/* Make sure there is enough memory to do something useful. *
 * Calls "swapon -a" if needed so be sure /etc/fstab is present... */
static void check_memory()
{
	struct stat statBuf;

	if (check_free_memory() > 1000)
		return;

	if (stat("/etc/fstab", &statBuf) == 0) {
		/* swapon -a requires /proc typically */
		waitfor("mount proc /proc -t proc", console, FALSE);
		/* Try to turn on swap */
		waitfor("swapon -a", console, FALSE);
		if (check_free_memory() < 1000)
			goto goodnight;
	} else
		goto goodnight;
	return;

  goodnight:
	message(CONSOLE,
			"Sorry, your computer does not have enough memory.\r\n");
	while (1)
		sleep(1);
}

/* Run all commands to be run right before halt/reboot */
static void run_lastAction(void)
{
	initAction *a;
	for (a = initActionList; a; a = a->nextPtr) {
		if (a->action == CTRLALTDEL) {
			waitfor(a->process, a->console, FALSE);
			delete_initAction(a);
		}
	}
}


#ifndef DEBUG_INIT
static void shutdown_system(void)
{

	/* first disable our SIGHUP signal */
	signal(SIGHUP, SIG_DFL);

	/* Allow Ctrl-Alt-Del to reboot system. */
	init_reboot(RB_ENABLE_CAD);

	message(CONSOLE|LOG, "\r\nThe system is going down NOW !!\r\n");
	sync();

	/* Send signals to every process _except_ pid 1 */
	message(CONSOLE|LOG, "Sending SIGTERM to all processes.\r\n");
	kill(-1, SIGTERM);
	sleep(1);
	sync();

	message(CONSOLE|LOG, "Sending SIGKILL to all processes.\r\n");
	kill(-1, SIGKILL);
	sleep(1);

	/* run everything to be run at "ctrlaltdel" */
	run_lastAction();

	sync();
	if (kernelVersion > 0 && kernelVersion <= 2 * 65536 + 2 * 256 + 11) {
		/* bdflush, kupdate not needed for kernels >2.2.11 */
		bdflush(1, 0);
		sync();
	}
}

static void halt_signal(int sig)
{
	shutdown_system();
	message(CONSOLE|LOG,
			"The system is halted. Press %s or turn off power\r\n",
			(secondConsole == NULL)	/* serial console */
			? "Reset" : "CTRL-ALT-DEL");
	sync();

	/* allow time for last message to reach serial console */
	sleep(2);

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)
	if (sig == SIGUSR2)
		init_reboot(RB_POWER_OFF);
	else
#endif
		init_reboot(RB_HALT_SYSTEM);
	exit(0);
}

static void reboot_signal(int sig)
{
	shutdown_system();
	message(CONSOLE|LOG, "Please stand by while rebooting the system.\r\n");
	sync();

	/* allow time for last message to reach serial console */
	sleep(2);

	init_reboot(RB_AUTOBOOT);
	exit(0);
}

#if defined BB_FEATURE_INIT_CHROOT

#if ! defined BB_FEATURE_USE_PROCFS
#error Sorry, I depend on the /proc filesystem right now.
#endif

static void check_chroot(int sig)
{
	char *argv_init[2] = { "init", NULL, };
	char *envp_init[3] = { "HOME=/", "TERM=linux", NULL, };
	char rootpath[256], *tc;
	int fd;

	if ((fd = open("/proc/sys/kernel/init-chroot", O_RDONLY)) == -1) {
		message(CONSOLE,
				"SIGHUP recived, but could not open proc file\r\n");
		sleep(2);
		return;
	}
	if (read(fd, rootpath, sizeof(rootpath)) == -1) {
		message(CONSOLE,
				"SIGHUP recived, but could not read proc file\r\n");
		sleep(2);
		return;
	}
	close(fd);

	if (rootpath[0] == '\0') {
		message(CONSOLE,
				"SIGHUP recived, but new root is not valid: %s\r\n",
				rootpath);
		sleep(2);
		return;
	}

	tc = strrchr(rootpath, '\n');
	*tc = '\0';

	/* Ok, making it this far means we commit */
	message(CONSOLE, "Please stand by, changing root to `%s'.\r\n",
			rootpath);

	/* kill all other programs first */
	message(CONSOLE, "Sending SIGTERM to all processes.\r\n");
	kill(-1, SIGTERM);
	sleep(2);
	sync();

	message(CONSOLE, "Sending SIGKILL to all processes.\r\n");
	kill(-1, SIGKILL);
	sleep(2);
	sync();

	/* ok, we don't need /proc anymore. we also assume that the signaling
	 * process left the rest of the filesystems alone for us */
	umount("/proc");

	/* Ok, now we chroot. Hopefully we only have two things mounted, the
	 * new chroot'd mount point, and the old "/" mount. s,
	 * we go ahead and unmount the old "/". This should trigger the kernel
	 * to set things up the Right Way(tm). */

	if (!chroot(rootpath))
		umount("/dev/root");

	/* If the chroot fails, we are already too far to turn back, so we
	 * continue and hope that executing init below will revive the system */

	/* close all of our descriptors and open new ones */
	close(0);
	close(1);
	close(2);
	open("/dev/console", O_RDWR, 0);
	dup(0);
	dup(0);

	message(CONSOLE, "Executing real init...\r\n");
	/* execute init in the (hopefully) new root */
	execve("/sbin/init", argv_init, envp_init);

	message(CONSOLE,
			"ERROR: Could not exec new init. Press %s to reboot.\r\n",
			(secondConsole == NULL)	/* serial console */
			? "Reset" : "CTRL-ALT-DEL");
	return;
}
#endif							/* BB_FEATURE_INIT_CHROOT */

#endif							/* ! DEBUG_INIT */

void new_initAction(initActionEnum action, char *process, char *cons)
{
	initAction *newAction;

	if (*cons == '\0')
		cons = console;

	/* If BusyBox detects that a serial console is in use, 
	 * then entries not refering to the console or null devices will _not_ be run.
	 * The exception to this rule is the null device.
	 */
	if (secondConsole == NULL && strcmp(cons, console)
		&& strcmp(cons, "/dev/null"))
		return;

	newAction = calloc((size_t) (1), sizeof(initAction));
	if (!newAction) {
		message(LOG | CONSOLE, "Memory allocation failure\n");
		while (1)
			sleep(1);
	}
	newAction->nextPtr = initActionList;
	initActionList = newAction;
	strncpy(newAction->process, process, 255);
	newAction->action = action;
	strncpy(newAction->console, cons, 255);
	newAction->pid = 0;
//    message(LOG|CONSOLE, "process='%s' action='%d' console='%s'\n",
//      newAction->process, newAction->action, newAction->console);
}

static void delete_initAction(initAction * action)
{
	initAction *a, *b = NULL;

	for (a = initActionList; a; b = a, a = a->nextPtr) {
		if (a == action) {
			if (b == NULL) {
				initActionList = a->nextPtr;
			} else {
				b->nextPtr = a->nextPtr;
			}
			free(a);
			break;
		}
	}
}

/* NOTE that if BB_FEATURE_USE_INITTAB is NOT defined,
 * then parse_inittab() simply adds in some default
 * actions(i.e runs INIT_SCRIPT and then starts a pair 
 * of "askfirst" shells).  If BB_FEATURE_USE_INITTAB 
 * _is_ defined, but /etc/inittab is missing, this 
 * results in the same set of default behaviors.
 * */
void parse_inittab(void)
{
#ifdef BB_FEATURE_USE_INITTAB
	FILE *file;
	char buf[256], lineAsRead[256], tmpConsole[256];
	char *id, *runlev, *action, *process, *eol;
	const struct initActionType *a = actions;
	int foundIt;


	file = fopen(INITTAB, "r");
	if (file == NULL) {
		/* No inittab file -- set up some default behavior */
#endif
		/* Swapoff on halt/reboot */
		new_initAction(CTRLALTDEL, "/sbin/swapoff -a > /dev/null 2>&1", console);
		/* Umount all filesystems on halt/reboot */
		new_initAction(CTRLALTDEL, "/bin/umount -a -r > /dev/null 2>&1", console);
		/* Askfirst shell on tty1 */
		new_initAction(ASKFIRST, SHELL, console);
		/* Askfirst shell on tty2 */
		if (secondConsole != NULL)
			new_initAction(ASKFIRST, SHELL, secondConsole);
		/* sysinit */
		new_initAction(SYSINIT, INIT_SCRIPT, console);

		return;
#ifdef BB_FEATURE_USE_INITTAB
	}

	while (fgets(buf, 255, file) != NULL) {
		foundIt = FALSE;
		/* Skip leading spaces */
		for (id = buf; *id == ' ' || *id == '\t'; id++);

		/* Skip the line if it's a comment */
		if (*id == '#' || *id == '\n')
			continue;

		/* Trim the trailing \n */
		eol = strrchr(id, '\n');
		if (eol != NULL)
			*eol = '\0';

		/* Keep a copy around for posterity's sake (and error msgs) */
		strcpy(lineAsRead, buf);

		/* Separate the ID field from the runlevels */
		runlev = strchr(id, ':');
		if (runlev == NULL || *(runlev + 1) == '\0') {
			message(LOG | CONSOLE, "Bad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*runlev = '\0';
			++runlev;
		}

		/* Separate the runlevels from the action */
		action = strchr(runlev, ':');
		if (action == NULL || *(action + 1) == '\0') {
			message(LOG | CONSOLE, "Bad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*action = '\0';
			++action;
		}

		/* Separate the action from the process */
		process = strchr(action, ':');
		if (process == NULL || *(process + 1) == '\0') {
			message(LOG | CONSOLE, "Bad inittab entry: %s\n", lineAsRead);
			continue;
		} else {
			*process = '\0';
			++process;
		}

		/* Ok, now process it */
		a = actions;
		while (a->name != 0) {
			if (strcmp(a->name, action) == 0) {
				if (*id != '\0') {
					struct stat statBuf;

					strcpy(tmpConsole, "/dev/");
					strncat(tmpConsole, id, 200);
					if (stat(tmpConsole, &statBuf) != 0) {
						message(LOG | CONSOLE,
								"device '%s' does not exist.  Did you read the directions?\n",
								tmpConsole);
						break;
					}
					id = tmpConsole;
				}
				new_initAction(a->action, process, id);
				foundIt = TRUE;
			}
			a++;
		}
		if (foundIt == TRUE)
			continue;
		else {
			/* Choke on an unknown action */
			message(LOG | CONSOLE, "Bad inittab entry: %s\n", lineAsRead);
		}
	}
	return;
#endif /* BB_FEATURE_USE_INITTAB */
}



extern int init_main(int argc, char **argv)
{
	initAction *a;
	pid_t wpid;
	int status;

#ifndef DEBUG_INIT
	/* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
	if (getpid() != 1
#ifdef BB_FEATURE_LINUXRC
			&& strstr(argv[0], "linuxrc") == NULL
#endif
	                  )
	{
			usage("init\n\nInit is the parent of all processes.\n\n"
				  "This version of init is designed to be run only "
				  "by the kernel.\n");
	}
	/* Set up sig handlers  -- be sure to
	 * clear all of these in run() */
	signal(SIGUSR1, halt_signal);
	signal(SIGUSR2, halt_signal);
	signal(SIGINT, reboot_signal);
	signal(SIGTERM, reboot_signal);
#if defined BB_FEATURE_INIT_CHROOT
	signal(SIGHUP, check_chroot);
#endif

	/* Turn off rebooting via CTL-ALT-DEL -- we get a 
	 * SIGINT on CAD so we can shut things down gracefully... */
	init_reboot(RB_DISABLE_CAD);
#endif

	/* Figure out what kernel this is running */
	kernelVersion = get_kernel_revision();

	/* Figure out where the default console should be */
	console_init();

	/* Close whatever files are open, and reset the console. */
	close(0);
	close(1);
	close(2);
	set_term(0);
	chdir("/");
	setsid();

	/* Make sure PATH is set to something sane */
	putenv(_PATH_STDPATH);

	/* Hello world */
#ifndef DEBUG_INIT
	message(
#if ! defined BB_FEATURE_EXTRA_QUIET
			CONSOLE|
#endif
			LOG,
			"init started:  BusyBox v%s (%s) multi-call binary\r\n",
			BB_VER, BB_BT);
#else
	message(
#if ! defined BB_FEATURE_EXTRA_QUIET
			CONSOLE|
#endif
			LOG,
			"init(%d) started:  BusyBox v%s (%s) multi-call binary\r\n",
			getpid(), BB_VER, BB_BT);
#endif


	/* Make sure there is enough memory to do something useful. */
	check_memory();

	/* Check if we are supposed to be in single user mode */
	if (argc > 1 && (!strcmp(argv[1], "single") ||
					 !strcmp(argv[1], "-s") || !strcmp(argv[1], "1"))) {
		/* Ask first then start a shell on tty2 */
		if (secondConsole != NULL)
			new_initAction(ASKFIRST, SHELL, secondConsole);
		/* Start a shell on tty1 */
		new_initAction(RESPAWN, SHELL, console);
	} else {
		/* Not in single user mode -- see what inittab says */

		/* NOTE that if BB_FEATURE_USE_INITTAB is NOT defined,
		 * then parse_inittab() simply adds in some default
		 * actions(i.e runs INIT_SCRIPT and then starts a pair 
		 * of "askfirst" shells */
		parse_inittab();
	}

	/* Fix up argv[0] to be certain we claim to be init */
	strncpy(argv[0], "init", strlen(argv[0])+1);
	if (argc > 1)
		strncpy(argv[1], "\0", strlen(argv[1])+1);

	/* Now run everything that needs to be run */

	/* First run the sysinit command */
	for (a = initActionList; a; a = a->nextPtr) {
		if (a->action == SYSINIT) {
			waitfor(a->process, a->console, FALSE);
			/* Now remove the "sysinit" entry from the list */
			delete_initAction(a);
		}
	}
	/* Next run anything that wants to block */
	for (a = initActionList; a; a = a->nextPtr) {
		if (a->action == WAIT) {
			waitfor(a->process, a->console, FALSE);
			/* Now remove the "wait" entry from the list */
			delete_initAction(a);
		}
	}
	/* Next run anything to be run only once */
	for (a = initActionList; a; a = a->nextPtr) {
		if (a->action == ONCE) {
			run(a->process, a->console, FALSE);
			/* Now remove the "once" entry from the list */
			delete_initAction(a);
		}
	}
	/* If there is nothing else to do, stop */
	if (initActionList == NULL) {
		message(LOG | CONSOLE,
				"No more tasks for init -- sleeping forever.\n");
		while (1)
			sleep(1);
	}

	/* Now run the looping stuff for the rest of forever */
	while (1) {
		for (a = initActionList; a; a = a->nextPtr) {
			/* Only run stuff with pid==0.  If they have
			 * a pid, that means they are still running */
			if (a->pid == 0) {
				switch (a->action) {
				case RESPAWN:
					/* run the respawn stuff */
					a->pid = run(a->process, a->console, FALSE);
					break;
				case ASKFIRST:
					/* run the askfirst stuff */
					a->pid = run(a->process, a->console, TRUE);
					break;
					/* silence the compiler's incessant whining */
				default:
					break;
				}
			}
		}
		/* Wait for a child process to exit */
		wpid = wait(&status);
		if (wpid > 0) {
			/* Find out who died and clean up their corpse */
			for (a = initActionList; a; a = a->nextPtr) {
				if (a->pid == wpid) {
					a->pid = 0;
					message(LOG,
							"Process '%s' (pid %d) exited.  Scheduling it for restart.\n",
							a->process, wpid);
				}
			}
		}
		sleep(1);
	}
}

/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/