1 /* init.c - init program.
2 *
3 * Copyright 2012 Harvind Singh <harvindsingh1981@gmail.com>
4 * Copyright 2013 Kyungwan Han <asura321@gmail.com>
5 *
6 * No Standard
7
8 USE_INIT(NEWTOY(init, "", TOYFLAG_SBIN))
9
10 config INIT
11 bool "init"
12 default n
13 help
14 usage: init
15
16 System V style init.
17
18 First program to run (as PID 1) when the system comes up, reading
19 /etc/inittab to determine actions.
20 */
21
22 #include "toys.h"
23 #include <sys/reboot.h>
24
25 struct action_list_seed {
26 struct action_list_seed *next;
27 pid_t pid;
28 uint8_t action;
29 char *terminal_name;
30 char *command;
31 } *action_list_pointer = NULL;
32 int caught_signal;
33
34 //INITTAB action defination
35 #define SYSINIT 0x01
36 #define WAIT 0x02
37 #define ONCE 0x04
38 #define RESPAWN 0x08
39 #define ASKFIRST 0x10
40 #define CTRLALTDEL 0x20
41 #define SHUTDOWN 0x40
42 #define RESTART 0x80
43
initialize_console(void)44 static void initialize_console(void)
45 {
46 int fd;
47 char *p = getenv("CONSOLE");
48
49 if (!p) p = getenv("console");
50 if (!p) {
51 fd = open("/dev/null", O_RDWR);
52 if (fd >= 0) {
53 while (fd < 2) fd = dup(fd);
54 while (fd > 2) close(fd--);
55 }
56 } else {
57 fd = open(p, O_RDWR | O_NONBLOCK | O_NOCTTY);
58 if (fd < 0) printf("Unable to open console %s\n",p);
59 else {
60 dup2(fd,0);
61 dup2(fd,1);
62 dup2(fd,2);
63 }
64 }
65
66 if (!getenv("TERM")) putenv("TERM=linux");
67 }
68
reset_term(int fd)69 static void reset_term(int fd)
70 {
71 struct termios terminal;
72
73 tcgetattr(fd, &terminal);
74 terminal.c_cc[VINTR] = 3; //ctrl-c
75 terminal.c_cc[VQUIT] = 28; /*ctrl-\*/
76 terminal.c_cc[VERASE] = 127; //ctrl-?
77 terminal.c_cc[VKILL] = 21; //ctrl-u
78 terminal.c_cc[VEOF] = 4; //ctrl-d
79 terminal.c_cc[VSTART] = 17; //ctrl-q
80 terminal.c_cc[VSTOP] = 19; //ctrl-s
81 terminal.c_cc[VSUSP] = 26; //ctrl-z
82
83 terminal.c_line = 0;
84 terminal.c_cflag &= CRTSCTS|PARODD|PARENB|CSTOPB|CSIZE|CBAUDEX|CBAUD;
85 terminal.c_cflag |= CLOCAL|HUPCL|CREAD;
86
87 //enable start/stop input and output control + map CR to NL on input
88 terminal.c_iflag = IXON|IXOFF|ICRNL;
89
90 //Map NL to CR-NL on output
91 terminal.c_oflag = ONLCR|OPOST;
92 terminal.c_lflag = IEXTEN|ECHOKE|ECHOCTL|ECHOK|ECHOE|ECHO|ICANON|ISIG;
93 tcsetattr(fd, TCSANOW, &terminal);
94 }
95
add_new_action(uint8_t action,char * command,char * term)96 static void add_new_action(uint8_t action,char *command,char *term)
97 {
98 struct action_list_seed *x,**y;
99
100 y = &action_list_pointer;
101 x = *y;
102 while (x) {
103 if (!(strcmp(x->command, command)) && !(strcmp(x->terminal_name, term))) {
104 *y = x->next; //remove from the list
105 while(*y) y = &(*y)->next; //traverse through list till end
106 x->next = NULL;
107 break;
108 }
109 y = &(x)->next;
110 x = *y;
111 }
112
113 //create a new node
114 if (!x) {
115 x = xzalloc(sizeof(*x));
116 x->command = xstrdup(command);
117 x->terminal_name = xstrdup(term);
118 }
119 x->action = action;
120 *y = x;
121 }
122
inittab_parsing(void)123 static void inittab_parsing(void)
124 {
125 int i, fd, line_number = 0, token_count = 0;
126 char *p, *q, *extracted_token, *tty_name = NULL, *command = NULL, *tmp;
127 uint8_t action = 0;
128 char *act_name = "sysinit\0wait\0once\0respawn\0askfirst\0ctrlaltdel\0"
129 "shutdown\0restart\0";
130
131 fd = open("/etc/inittab", O_RDONLY);
132 if (fd < 0) {
133 error_msg("Unable to open /etc/inittab. Using Default inittab");
134 add_new_action(SYSINIT, "/etc/init.d/rcS", "");
135 add_new_action(RESPAWN, "/sbin/getty -n -l /bin/sh -L 115200 tty1 vt100", "");
136 } else {
137 while((q = p = get_line(fd))) { //read single line from /etc/inittab
138 char *x;
139
140 if ((x = strchr(p, '#'))) *x = '\0';
141 line_number++;
142 token_count = 0;
143 action = 0;
144 tty_name = command = NULL;
145
146 while ((extracted_token = strsep(&p,":"))) {
147 token_count++;
148 switch (token_count) {
149 case 1:
150 if (*extracted_token) {
151 if (!strncmp(extracted_token, "/dev/", 5))
152 tty_name = xmprintf("%s",extracted_token);
153 else tty_name = xmprintf("/dev/%s",extracted_token);
154 } else tty_name = xstrdup("");
155 break;
156 case 2:
157 break;
158 case 3:
159 for (tmp = act_name, i = 0; *tmp; i++, tmp += strlen(tmp) +1) {
160 if (!strcmp(tmp, extracted_token)) {
161 action = 1 << i;
162 break;
163 }
164 }
165 if (!*tmp) error_msg("Invalid action at line number %d ---- ignoring",line_number);
166 break;
167 case 4:
168 command = xstrdup(extracted_token);
169 break;
170 default:
171 error_msg("Bad inittab entry at line %d", line_number);
172 break;
173 }
174 } //while token
175
176 if (q) free(q);
177 if (token_count != 4) {
178 free(tty_name);
179 free(command);
180 continue;
181 }
182 if (action) add_new_action(action, command, tty_name);
183 free(tty_name);
184 free(command);
185 } //while line
186
187 close(fd);
188 }
189 }
190
reload_inittab(void)191 static void reload_inittab(void)
192 {
193 // Remove all inactive actions, then reload /etc/inittab
194 struct action_list_seed **y;
195 y = &action_list_pointer;
196 while (*y) {
197 if (!(*y)->pid) {
198 struct action_list_seed *x = *y;
199 free(x->terminal_name);
200 free(x->command);
201 *y = (*y)->next;
202 free(x);
203 continue;
204 }
205 y = &(*y)->next;
206 }
207 inittab_parsing();
208 }
209
run_command(char * command)210 static void run_command(char *command)
211 {
212 char *final_command[128];
213 int hyphen = (command[0]=='-');
214
215 command = command + hyphen;
216 if (!strpbrk(command, "?<>'\";[]{}\\|=()*&^$!`~")) {
217 char *next_command;
218 char *extracted_command;
219 int x = 0;
220
221 next_command = strncpy(toybuf, command - hyphen, sizeof(toybuf));
222 next_command[sizeof(toybuf) - 1] = toybuf[sizeof(toybuf) - 1 ] = '\0';
223 command = next_command + hyphen;
224 while ((extracted_command = strsep(&next_command," \t"))) {
225 if (*extracted_command) {
226 final_command[x] = extracted_command;
227 x++;
228 }
229 }
230 final_command[x] = NULL;
231 } else {
232 snprintf(toybuf, sizeof(toybuf), "exec %s", command);
233 command = "-/bin/sh"+1;
234 final_command[0] = ("-/bin/sh"+!hyphen);
235 final_command[1] = "-c";
236 final_command[2] = toybuf;
237 final_command[3] = NULL;
238 }
239 if (hyphen) ioctl(0, TIOCSCTTY, 0);
240 execvp(command, final_command);
241 error_msg("unable to run %s",command);
242 }
243
244 //runs all same type of actions
final_run(struct action_list_seed * x)245 static pid_t final_run(struct action_list_seed *x)
246 {
247 pid_t pid;
248 int fd;
249 sigset_t signal_set;
250
251 sigfillset(&signal_set);
252 sigprocmask(SIG_BLOCK, &signal_set, NULL);
253 if (x->action & ASKFIRST) pid = fork();
254 else pid = vfork();
255
256 if (pid > 0) {
257 //parent process or error
258 //unblock the signals
259 sigfillset(&signal_set);
260 sigprocmask(SIG_UNBLOCK, &signal_set, NULL);
261
262 return pid;
263 } else if (pid < 0) {
264 perror_msg("fork fail");
265 sleep(1);
266 return 0;
267 }
268
269 //new born child process
270 sigset_t signal_set_c;
271 sigfillset(&signal_set_c);
272 sigprocmask(SIG_UNBLOCK, &signal_set_c, NULL);
273 setsid(); //new session
274
275 if (x->terminal_name[0]) {
276 close(0);
277 fd = open(x->terminal_name, (O_RDWR|O_NONBLOCK),0600);
278 if (fd != 0) {
279 error_msg("Unable to open %s,%s\n", x->terminal_name, strerror(errno));
280 _exit(EXIT_FAILURE);
281 } else {
282 dup2(0, 1);
283 dup2(0, 2);
284 }
285 }
286 reset_term(0);
287 run_command(x->command);
288 _exit(-1);
289 }
290
mark_as_terminated_process(pid_t pid)291 static struct action_list_seed* mark_as_terminated_process(pid_t pid)
292 {
293 struct action_list_seed *x;
294
295 if (pid > 0) {
296 for (x = action_list_pointer; x; x = x->next) {
297 if (x->pid == pid) {
298 x->pid = 0;
299 return x;
300 }
301 }
302 }
303
304 return NULL;
305 }
306
waitforpid(pid_t pid)307 static void waitforpid(pid_t pid)
308 {
309 if (pid <= 0) return;
310
311 while (!kill(pid, 0)) mark_as_terminated_process(wait(NULL));
312 }
313
run_action_from_list(int action)314 static void run_action_from_list(int action)
315 {
316 pid_t pid;
317 struct action_list_seed *x = action_list_pointer;
318
319 for (; x; x = x->next) {
320 if (!(x->action & action)) continue;
321 if (x->action & (SHUTDOWN|ONCE|SYSINIT|CTRLALTDEL|WAIT)) {
322 pid = final_run(x);
323 if (!pid) return;
324 if (x->action & (SHUTDOWN|SYSINIT|CTRLALTDEL|WAIT)) waitforpid(pid);
325 }
326 if (x->action & (ASKFIRST|RESPAWN))
327 if (!(x->pid)) x->pid = final_run(x);
328 }
329 }
330
set_default(void)331 static void set_default(void)
332 {
333 sigset_t signal_set_c;
334
335 sigatexit(SIG_DFL);
336 sigfillset(&signal_set_c);
337 sigprocmask(SIG_UNBLOCK,&signal_set_c, NULL);
338
339 run_action_from_list(SHUTDOWN);
340 error_msg("The system is going down NOW!");
341 kill(-1, SIGTERM);
342 error_msg("Sent SIGTERM to all processes");
343 sync();
344 sleep(1);
345 kill(-1,SIGKILL);
346 sync();
347 }
348
halt_poweroff_reboot_handler(int sig_no)349 static void halt_poweroff_reboot_handler(int sig_no)
350 {
351 unsigned int reboot_magic_no = 0;
352 pid_t pid;
353
354 set_default();
355
356 switch (sig_no) {
357 case SIGUSR1:
358 error_msg("Requesting system halt");
359 reboot_magic_no=RB_HALT_SYSTEM;
360 break;
361 case SIGUSR2:
362 error_msg("Requesting system poweroff");
363 reboot_magic_no=RB_POWER_OFF;
364 break;
365 case SIGTERM:
366 error_msg("Requesting system reboot");
367 reboot_magic_no=RB_AUTOBOOT;
368 break;
369 default:
370 break;
371 }
372
373 sleep(1);
374 pid = vfork();
375
376 if (pid == 0) {
377 reboot(reboot_magic_no);
378 _exit(EXIT_SUCCESS);
379 }
380
381 while(1) sleep(1);
382 }
383
restart_init_handler(int sig_no)384 static void restart_init_handler(int sig_no)
385 {
386 struct action_list_seed *x;
387 pid_t pid;
388 int fd;
389
390 for (x = action_list_pointer; x; x = x->next) {
391 if (!(x->action & RESTART)) continue;
392
393 set_default();
394
395 if (x->terminal_name[0]) {
396 close(0);
397 fd = open(x->terminal_name, (O_RDWR|O_NONBLOCK),0600);
398
399 if (fd != 0) {
400 error_msg("Unable to open %s,%s\n", x->terminal_name, strerror(errno));
401 sleep(1);
402 pid = vfork();
403
404 if (pid == 0) {
405 reboot(RB_HALT_SYSTEM);
406 _exit(EXIT_SUCCESS);
407 }
408
409 while(1) sleep(1);
410 } else {
411 dup2(0, 1);
412 dup2(0, 2);
413 reset_term(0);
414 run_command(x->command);
415 }
416 }
417 }
418 }
419
catch_signal(int sig_no)420 static void catch_signal(int sig_no)
421 {
422 caught_signal = sig_no;
423 error_msg("signal seen: %d", sig_no);
424 }
425
pause_handler(int sig_no)426 static void pause_handler(int sig_no)
427 {
428 int signal_backup,errno_backup;
429 pid_t pid;
430
431 errno_backup = errno;
432 signal_backup = caught_signal;
433 xsignal(SIGCONT, catch_signal);
434
435 while(1) {
436 if (caught_signal == SIGCONT) break;
437 do pid = waitpid(-1,NULL,WNOHANG); while((pid==-1) && (errno=EINTR));
438 mark_as_terminated_process(pid);
439 sleep(1);
440 }
441
442 signal(SIGCONT, SIG_DFL);
443 errno = errno_backup;
444 caught_signal = signal_backup;
445 }
446
check_if_pending_signals(void)447 static int check_if_pending_signals(void)
448 {
449 int signal_caught = 0;
450
451 while(1) {
452 int sig = caught_signal;
453 if (!sig) return signal_caught;
454 caught_signal = 0;
455 signal_caught = 1;
456 if (sig == SIGINT) run_action_from_list(CTRLALTDEL);
457 else if (sig == SIGHUP) {
458 error_msg("reloading inittab");
459 reload_inittab();
460 }
461 }
462 }
463
init_main(void)464 void init_main(void)
465 {
466 struct sigaction sig_act;
467
468 if (getpid() != 1) error_exit("Already running");
469 printf("Started init\n");
470 initialize_console();
471 reset_term(0);
472
473 if (chdir("/")) perror_exit("Can't cd to /");
474 setsid();
475
476 putenv("HOME=/");
477 putenv("PATH=/sbin:/usr/sbin:/bin:/usr/bin");
478 putenv("SHELL=/bin/sh");
479 putenv("USER=root");
480
481 inittab_parsing();
482 xsignal(SIGUSR1, halt_poweroff_reboot_handler);//halt
483 xsignal(SIGUSR2, halt_poweroff_reboot_handler);//poweroff
484 xsignal(SIGTERM, halt_poweroff_reboot_handler);//reboot
485 xsignal(SIGQUIT, restart_init_handler);//restart init
486 memset(&sig_act, 0, sizeof(sig_act));
487 sigfillset(&sig_act.sa_mask);
488 sigdelset(&sig_act.sa_mask, SIGCONT);
489 sig_act.sa_handler = pause_handler;
490 sigaction(SIGTSTP, &sig_act, NULL);
491 memset(&sig_act, 0, sizeof(sig_act));
492 sig_act.sa_handler = catch_signal;
493 sigaction(SIGINT, &sig_act, NULL);
494 sigaction(SIGHUP, &sig_act, NULL);
495 run_action_from_list(SYSINIT);
496 check_if_pending_signals();
497 run_action_from_list(WAIT);
498 check_if_pending_signals();
499 run_action_from_list(ONCE);
500 while (1) {
501 int suspected_WNOHANG = check_if_pending_signals();
502
503 run_action_from_list(RESPAWN | ASKFIRST);
504 suspected_WNOHANG = suspected_WNOHANG|check_if_pending_signals();
505 sleep(1);//let cpu breath
506 suspected_WNOHANG = suspected_WNOHANG|check_if_pending_signals();
507 if (suspected_WNOHANG) suspected_WNOHANG=WNOHANG;
508
509 while(1) {
510 pid_t pid = waitpid(-1, NULL, suspected_WNOHANG);
511
512 if (pid <= 0) break;
513 mark_as_terminated_process(pid);
514 suspected_WNOHANG = WNOHANG;
515 }
516 }
517 }
518