lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* vi: set sw=4 ts=4: */ |
| 2 | /* |
| 3 | * Mini init implementation for busybox |
| 4 | * |
| 5 | * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>. |
| 6 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> |
| 7 | * Adjusted by so many folks, it's impossible to keep track. |
| 8 | * |
| 9 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
| 10 | */ |
| 11 | |
| 12 | //applet:IF_INIT(APPLET(init, BB_DIR_SBIN, BB_SUID_DROP)) |
| 13 | //applet:IF_FEATURE_INITRD(APPLET_ODDNAME(linuxrc, init, BB_DIR_ROOT, BB_SUID_DROP, linuxrc)) |
| 14 | |
| 15 | //kbuild:lib-$(CONFIG_INIT) += init.o |
| 16 | |
| 17 | //config:config INIT |
| 18 | //config: bool "init" |
| 19 | //config: default y |
| 20 | //config: select FEATURE_SYSLOG |
| 21 | //config: help |
| 22 | //config: init is the first program run when the system boots. |
| 23 | //config: |
| 24 | //config:config FEATURE_USE_INITTAB |
| 25 | //config: bool "Support reading an inittab file" |
| 26 | //config: default y |
| 27 | //config: depends on INIT |
| 28 | //config: help |
| 29 | //config: Allow init to read an inittab file when the system boot. |
| 30 | //config: |
| 31 | //config:config FEATURE_KILL_REMOVED |
| 32 | //config: bool "Support killing processes that have been removed from inittab" |
| 33 | //config: default n |
| 34 | //config: depends on FEATURE_USE_INITTAB |
| 35 | //config: help |
| 36 | //config: When respawn entries are removed from inittab and a SIGHUP is |
| 37 | //config: sent to init, this option will make init kill the processes |
| 38 | //config: that have been removed. |
| 39 | //config: |
| 40 | //config:config FEATURE_KILL_DELAY |
| 41 | //config: int "How long to wait between TERM and KILL (0 - send TERM only)" if FEATURE_KILL_REMOVED |
| 42 | //config: range 0 1024 |
| 43 | //config: default 0 |
| 44 | //config: depends on FEATURE_KILL_REMOVED |
| 45 | //config: help |
| 46 | //config: With nonzero setting, init sends TERM, forks, child waits N |
| 47 | //config: seconds, sends KILL and exits. Setting it too high is unwise |
| 48 | //config: (child will hang around for too long and could actually kill |
| 49 | //config: the wrong process!) |
| 50 | //config: |
| 51 | //config:config FEATURE_INIT_SCTTY |
| 52 | //config: bool "Run commands with leading dash with controlling tty" |
| 53 | //config: default y |
| 54 | //config: depends on INIT |
| 55 | //config: help |
| 56 | //config: If this option is enabled, init will try to give a controlling |
| 57 | //config: tty to any command which has leading hyphen (often it's "-/bin/sh"). |
| 58 | //config: More precisely, init will do "ioctl(STDIN_FILENO, TIOCSCTTY, 0)". |
| 59 | //config: If device attached to STDIN_FILENO can be a ctty but is not yet |
| 60 | //config: a ctty for other session, it will become this process' ctty. |
| 61 | //config: This is not the traditional init behavour, but is often what you want |
| 62 | //config: in an embedded system where the console is only accessed during |
| 63 | //config: development or for maintenance. |
| 64 | //config: NB: using cttyhack applet may work better. |
| 65 | //config: |
| 66 | //config:config FEATURE_INIT_SYSLOG |
| 67 | //config: bool "Enable init to write to syslog" |
| 68 | //config: default y |
| 69 | //config: depends on INIT |
| 70 | //config: |
| 71 | //config:config FEATURE_EXTRA_QUIET |
| 72 | //config: bool "Be _extra_ quiet on boot" |
| 73 | //config: default y |
| 74 | //config: depends on INIT |
| 75 | //config: help |
| 76 | //config: Prevent init from logging some messages to the console during boot. |
| 77 | //config: |
| 78 | //config:config FEATURE_INIT_COREDUMPS |
| 79 | //config: bool "Support dumping core for child processes (debugging only)" |
| 80 | //config: default y |
| 81 | //config: depends on INIT |
| 82 | //config: help |
| 83 | //config: If this option is enabled and the file /.init_enable_core |
| 84 | //config: exists, then init will call setrlimit() to allow unlimited |
| 85 | //config: core file sizes. If this option is disabled, processes |
| 86 | //config: will not generate any core files. |
| 87 | //config: |
| 88 | //config:config FEATURE_INITRD |
| 89 | //config: bool "Support running init from within an initrd (not initramfs)" |
| 90 | //config: default y |
| 91 | //config: depends on INIT |
| 92 | //config: help |
| 93 | //config: Legacy support for running init under the old-style initrd. Allows |
| 94 | //config: the name linuxrc to act as init, and it doesn't assume init is PID 1. |
| 95 | //config: |
| 96 | //config: This does not apply to initramfs, which runs /init as PID 1 and |
| 97 | //config: requires no special support. |
| 98 | //config: |
| 99 | //config:config INIT_TERMINAL_TYPE |
| 100 | //config: string "Initial terminal type" |
| 101 | //config: default "linux" |
| 102 | //config: depends on INIT |
| 103 | //config: help |
| 104 | //config: This is the initial value set by init for the TERM environment |
| 105 | //config: variable. This variable is used by programs which make use of |
| 106 | //config: extended terminal capabilities. |
| 107 | //config: |
| 108 | //config: Note that on Linux, init attempts to detect serial terminal and |
| 109 | //config: sets TERM to "vt102" if one is found. |
| 110 | //config: |
| 111 | //config:config FEATURE_ETC_RC |
| 112 | //config: bool "Run /etc/rc before loading /etc/inittab" |
| 113 | //config: default n |
| 114 | //config: depends on INIT |
| 115 | //config: help |
| 116 | //config: Legacy in case inittab lives in an unmounted filesystem. |
| 117 | |
| 118 | #define DEBUG_SEGV_HANDLER 0 |
| 119 | |
| 120 | #include "libbb.h" |
| 121 | #include <syslog.h> |
| 122 | #include <paths.h> |
| 123 | #include <sys/resource.h> |
| 124 | #ifdef __linux__ |
| 125 | # include <linux/vt.h> |
| 126 | # include <sys/sysinfo.h> |
| 127 | #endif |
| 128 | #include "reboot.h" /* reboot() constants */ |
| 129 | |
| 130 | #if DEBUG_SEGV_HANDLER |
| 131 | # undef _GNU_SOURCE |
| 132 | # define _GNU_SOURCE 1 |
| 133 | # undef __USE_GNU |
| 134 | # define __USE_GNU 1 |
| 135 | # include <execinfo.h> |
| 136 | # include <sys/ucontext.h> |
| 137 | #endif |
| 138 | |
| 139 | /* Used only for sanitizing purposes in set_sane_term() below. On systems where |
| 140 | * the baud rate is stored in a separate field, we can safely disable them. */ |
| 141 | #ifndef CBAUD |
| 142 | # define CBAUD 0 |
| 143 | # define CBAUDEX 0 |
| 144 | #endif |
| 145 | |
| 146 | /* Was a CONFIG_xxx option. A lot of people were building |
| 147 | * not fully functional init by switching it on! */ |
| 148 | #define DEBUG_INIT 0 |
| 149 | |
| 150 | #define COMMAND_SIZE 256 |
| 151 | #define CONSOLE_NAME_SIZE 32 |
| 152 | |
| 153 | /* Default sysinit script. */ |
| 154 | #ifndef INIT_SCRIPT |
| 155 | #define INIT_SCRIPT "/etc/rc" |
| 156 | #endif |
| 157 | |
| 158 | /* Each type of actions can appear many times. They will be |
| 159 | * handled in order. RESTART is an exception, only 1st is used. |
| 160 | */ |
| 161 | /* Start these actions first and wait for completion */ |
| 162 | #define SYSINIT 0x01 |
| 163 | /* Start these after SYSINIT and wait for completion */ |
| 164 | #define WAIT 0x02 |
| 165 | /* Start these after WAIT and *dont* wait for completion */ |
| 166 | #define ONCE 0x04 |
| 167 | /* |
| 168 | * NB: while SYSINIT/WAIT/ONCE are being processed, |
| 169 | * SIGHUP ("reread /etc/inittab") will be processed only after |
| 170 | * each group of actions. If new inittab adds, say, a SYSINIT action, |
| 171 | * it will not be run, since init is already "past SYSINIT stage". |
| 172 | */ |
| 173 | /* Start these after ONCE are started, restart on exit */ |
| 174 | #define RESPAWN 0x08 |
| 175 | /* Like RESPAWN, but wait for <Enter> to be pressed on tty */ |
| 176 | #define ASKFIRST 0x10 |
| 177 | /* |
| 178 | * Start these on SIGINT, and wait for completion. |
| 179 | * Then go back to respawning RESPAWN and ASKFIRST actions. |
| 180 | * NB: kernel sends SIGINT to us if Ctrl-Alt-Del was pressed. |
| 181 | */ |
| 182 | #define CTRLALTDEL 0x20 |
| 183 | /* |
| 184 | * Start these before killing all processes in preparation for |
| 185 | * running RESTART actions or doing low-level halt/reboot/poweroff |
| 186 | * (initiated by SIGUSR1/SIGTERM/SIGUSR2). |
| 187 | * Wait for completion before proceeding. |
| 188 | */ |
| 189 | #define SHUTDOWN 0x40 |
| 190 | /* |
| 191 | * exec() on SIGQUIT. SHUTDOWN actions are started and waited for, |
| 192 | * then all processes are killed, then init exec's 1st RESTART action, |
| 193 | * replacing itself by it. If no RESTART action specified, |
| 194 | * SIGQUIT has no effect. |
| 195 | */ |
| 196 | #define RESTART 0x80 |
| 197 | |
| 198 | |
| 199 | /* A linked list of init_actions, to be read from inittab */ |
| 200 | struct init_action { |
| 201 | struct init_action *next; |
| 202 | pid_t pid; |
| 203 | uint8_t action_type; |
| 204 | char terminal[CONSOLE_NAME_SIZE]; |
| 205 | char command[COMMAND_SIZE]; |
| 206 | }; |
| 207 | |
| 208 | static struct init_action *init_action_list = NULL; |
| 209 | |
| 210 | static const char *log_console = VC_5; |
| 211 | |
| 212 | enum { |
| 213 | L_LOG = 0x1, |
| 214 | L_CONSOLE = 0x2, |
| 215 | }; |
| 216 | |
| 217 | /* Print a message to the specified device. |
| 218 | * "where" may be bitwise-or'd from L_LOG | L_CONSOLE |
| 219 | * NB: careful, we can be called after vfork! |
| 220 | */ |
| 221 | #define dbg_message(...) do { if (DEBUG_INIT) message(__VA_ARGS__); } while (0) |
| 222 | static void message(int where, const char *fmt, ...) |
| 223 | __attribute__ ((format(printf, 2, 3))); |
| 224 | static void message(int where, const char *fmt, ...) |
| 225 | { |
| 226 | va_list arguments; |
| 227 | unsigned l; |
| 228 | char msg[128]; |
| 229 | |
| 230 | msg[0] = '\r'; |
| 231 | va_start(arguments, fmt); |
| 232 | l = 1 + vsnprintf(msg + 1, sizeof(msg) - 2, fmt, arguments); |
| 233 | if (l > sizeof(msg) - 1) |
| 234 | l = sizeof(msg) - 1; |
| 235 | va_end(arguments); |
| 236 | |
| 237 | #if ENABLE_FEATURE_INIT_SYSLOG |
| 238 | msg[l] = '\0'; |
| 239 | if (where & L_LOG) { |
| 240 | /* Log the message to syslogd */ |
| 241 | openlog(applet_name, 0, LOG_DAEMON); |
| 242 | /* don't print "\r" */ |
| 243 | syslog(LOG_INFO, "%s", msg + 1); |
| 244 | closelog(); |
| 245 | } |
| 246 | msg[l++] = '\n'; |
| 247 | msg[l] = '\0'; |
| 248 | #else |
| 249 | { |
| 250 | static int log_fd = -1; |
| 251 | |
| 252 | msg[l++] = '\n'; |
| 253 | msg[l] = '\0'; |
| 254 | /* Take full control of the log tty, and never close it. |
| 255 | * It's mine, all mine! Muhahahaha! */ |
| 256 | if (log_fd < 0) { |
| 257 | if (!log_console) { |
| 258 | log_fd = STDERR_FILENO; |
| 259 | } else { |
| 260 | log_fd = device_open(log_console, O_WRONLY | O_NONBLOCK | O_NOCTTY); |
| 261 | if (log_fd < 0) { |
| 262 | bb_error_msg("can't log to %s", log_console); |
| 263 | where = L_CONSOLE; |
| 264 | } else { |
| 265 | close_on_exec_on(log_fd); |
| 266 | } |
| 267 | } |
| 268 | } |
| 269 | if (where & L_LOG) { |
| 270 | full_write(log_fd, msg, l); |
| 271 | if (log_fd == STDERR_FILENO) |
| 272 | return; /* don't print dup messages */ |
| 273 | } |
| 274 | } |
| 275 | #endif |
| 276 | |
| 277 | if (where & L_CONSOLE) { |
| 278 | /* Send console messages to console so people will see them. */ |
| 279 | full_write(STDERR_FILENO, msg, l); |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | static void console_init(void) |
| 284 | { |
| 285 | #ifdef VT_OPENQRY |
| 286 | int vtno; |
| 287 | #endif |
| 288 | char *s; |
| 289 | |
| 290 | s = getenv("CONSOLE"); |
| 291 | if (!s) |
| 292 | s = getenv("console"); |
| 293 | if (s) { |
| 294 | int fd = open(s, O_RDWR | O_NONBLOCK | O_NOCTTY); |
| 295 | if (fd >= 0) { |
| 296 | dup2(fd, STDIN_FILENO); |
| 297 | dup2(fd, STDOUT_FILENO); |
| 298 | xmove_fd(fd, STDERR_FILENO); |
| 299 | } |
| 300 | dbg_message(L_LOG, "console='%s'", s); |
| 301 | } else { |
| 302 | /* Make sure fd 0,1,2 are not closed |
| 303 | * (so that they won't be used by future opens) */ |
| 304 | bb_sanitize_stdio(); |
| 305 | // Users report problems |
| 306 | // /* Make sure init can't be blocked by writing to stderr */ |
| 307 | // fcntl(STDERR_FILENO, F_SETFL, fcntl(STDERR_FILENO, F_GETFL) | O_NONBLOCK); |
| 308 | } |
| 309 | |
| 310 | s = getenv("TERM"); |
| 311 | #ifdef VT_OPENQRY |
| 312 | if (ioctl(STDIN_FILENO, VT_OPENQRY, &vtno) != 0) { |
| 313 | /* Not a linux terminal, probably serial console. |
| 314 | * Force the TERM setting to vt102 |
| 315 | * if TERM is set to linux (the default) */ |
| 316 | if (!s || strcmp(s, "linux") == 0) |
| 317 | putenv((char*)"TERM=vt102"); |
| 318 | if (!ENABLE_FEATURE_INIT_SYSLOG) |
| 319 | log_console = NULL; |
| 320 | } else |
| 321 | #endif |
| 322 | if (!s) |
| 323 | putenv((char*)"TERM=" CONFIG_INIT_TERMINAL_TYPE); |
| 324 | } |
| 325 | |
| 326 | /* Set terminal settings to reasonable defaults. |
| 327 | * NB: careful, we can be called after vfork! */ |
| 328 | static void set_sane_term(void) |
| 329 | { |
| 330 | struct termios tty; |
| 331 | |
| 332 | tcgetattr(STDIN_FILENO, &tty); |
| 333 | |
| 334 | /* set control chars */ |
| 335 | tty.c_cc[VINTR] = 3; /* C-c */ |
| 336 | tty.c_cc[VQUIT] = 28; /* C-\ */ |
| 337 | tty.c_cc[VERASE] = 127; /* C-? */ |
| 338 | tty.c_cc[VKILL] = 21; /* C-u */ |
| 339 | tty.c_cc[VEOF] = 4; /* C-d */ |
| 340 | tty.c_cc[VSTART] = 17; /* C-q */ |
| 341 | tty.c_cc[VSTOP] = 19; /* C-s */ |
| 342 | tty.c_cc[VSUSP] = 26; /* C-z */ |
| 343 | |
| 344 | #ifdef __linux__ |
| 345 | /* use line discipline 0 */ |
| 346 | tty.c_line = 0; |
| 347 | #endif |
| 348 | |
| 349 | /* Make it be sane */ |
| 350 | #ifndef CRTSCTS |
| 351 | # define CRTSCTS 0 |
| 352 | #endif |
| 353 | /* added CRTSCTS to fix Debian bug 528560 */ |
| 354 | tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD | CRTSCTS; |
| 355 | tty.c_cflag |= CREAD | HUPCL | CLOCAL; |
| 356 | |
| 357 | /* input modes */ |
| 358 | tty.c_iflag = ICRNL | IXON | IXOFF; |
xf.li | 7ccf837 | 2024-03-07 00:08:02 -0800 | [diff] [blame] | 359 | tty.c_iflag &= ~(IXON | IXOFF); |
lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 360 | /* output modes */ |
| 361 | tty.c_oflag = OPOST | ONLCR; |
| 362 | |
| 363 | /* local modes */ |
| 364 | tty.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE | IEXTEN; |
| 365 | |
| 366 | tcsetattr_stdin_TCSANOW(&tty); |
| 367 | } |
| 368 | |
| 369 | /* Open the new terminal device. |
| 370 | * NB: careful, we can be called after vfork! */ |
| 371 | static int open_stdio_to_tty(const char* tty_name) |
| 372 | { |
| 373 | /* empty tty_name means "use init's tty", else... */ |
| 374 | if (tty_name[0]) { |
| 375 | int fd; |
| 376 | |
| 377 | close(STDIN_FILENO); |
| 378 | /* fd can be only < 0 or 0: */ |
| 379 | fd = device_open(tty_name, O_RDWR); |
| 380 | if (fd) { |
| 381 | message(L_LOG | L_CONSOLE, "can't open %s: %s", |
| 382 | tty_name, strerror(errno)); |
| 383 | return 0; /* failure */ |
| 384 | } |
| 385 | dup2(STDIN_FILENO, STDOUT_FILENO); |
| 386 | dup2(STDIN_FILENO, STDERR_FILENO); |
| 387 | } |
| 388 | set_sane_term(); |
| 389 | return 1; /* success */ |
| 390 | } |
| 391 | |
| 392 | static void reset_sighandlers_and_unblock_sigs(void) |
| 393 | { |
| 394 | bb_signals(0 |
| 395 | + (1 << SIGUSR1) |
| 396 | + (1 << SIGUSR2) |
| 397 | + (1 << SIGTERM) |
| 398 | + (1 << SIGQUIT) |
| 399 | + (1 << SIGINT) |
| 400 | + (1 << SIGHUP) |
| 401 | + (1 << SIGTSTP) |
| 402 | + (1 << SIGSTOP) |
| 403 | , SIG_DFL); |
| 404 | sigprocmask_allsigs(SIG_UNBLOCK); |
| 405 | } |
| 406 | |
| 407 | /* Wrapper around exec: |
| 408 | * Takes string (max COMMAND_SIZE chars). |
| 409 | * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'. |
| 410 | * Otherwise splits words on whitespace, deals with leading dash, |
| 411 | * and uses plain exec(). |
| 412 | * NB: careful, we can be called after vfork! |
| 413 | */ |
| 414 | static void init_exec(const char *command) |
| 415 | { |
| 416 | char *cmd[COMMAND_SIZE / 2]; |
| 417 | char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */ |
| 418 | int dash = (command[0] == '-' /* maybe? && command[1] == '/' */); |
| 419 | |
| 420 | command += dash; |
| 421 | |
| 422 | /* See if any special /bin/sh requiring characters are present */ |
| 423 | if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) { |
| 424 | sprintf(buf, "exec %s", command); /* excluding "-" */ |
| 425 | /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */ |
| 426 | cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash); |
| 427 | cmd[1] = (char*)"-c"; |
| 428 | cmd[2] = buf; |
| 429 | cmd[3] = NULL; |
| 430 | command = LIBBB_DEFAULT_LOGIN_SHELL + 1; |
| 431 | } else { |
| 432 | /* Convert command (char*) into cmd (char**, one word per string) */ |
| 433 | char *word, *next; |
| 434 | int i = 0; |
| 435 | next = strcpy(buf, command - dash); /* command including "-" */ |
| 436 | command = next + dash; |
| 437 | while ((word = strsep(&next, " \t")) != NULL) { |
| 438 | if (*word != '\0') { /* not two spaces/tabs together? */ |
| 439 | cmd[i] = word; |
| 440 | i++; |
| 441 | } |
| 442 | } |
| 443 | cmd[i] = NULL; |
| 444 | } |
| 445 | /* If we saw leading "-", it is interactive shell. |
| 446 | * Try harder to give it a controlling tty. |
| 447 | */ |
| 448 | if (ENABLE_FEATURE_INIT_SCTTY && dash) { |
| 449 | /* _Attempt_ to make stdin a controlling tty. */ |
| 450 | ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/); |
| 451 | } |
| 452 | /* Here command never contains the dash, cmd[0] might */ |
| 453 | BB_EXECVP(command, cmd); |
| 454 | message(L_LOG | L_CONSOLE, "can't run '%s': %s", command, strerror(errno)); |
| 455 | /* returns if execvp fails */ |
| 456 | } |
| 457 | |
| 458 | /* Used only by run_actions */ |
| 459 | static pid_t run(const struct init_action *a) |
| 460 | { |
| 461 | pid_t pid; |
| 462 | |
| 463 | /* Careful: don't be affected by a signal in vforked child */ |
| 464 | sigprocmask_allsigs(SIG_BLOCK); |
| 465 | if (BB_MMU && (a->action_type & ASKFIRST)) |
| 466 | pid = fork(); |
| 467 | else |
| 468 | pid = vfork(); |
| 469 | if (pid < 0) |
| 470 | message(L_LOG | L_CONSOLE, "can't fork"); |
| 471 | if (pid) { |
| 472 | sigprocmask_allsigs(SIG_UNBLOCK); |
| 473 | return pid; /* Parent or error */ |
| 474 | } |
| 475 | |
| 476 | /* Child */ |
| 477 | |
| 478 | /* Reset signal handlers that were set by the parent process */ |
| 479 | reset_sighandlers_and_unblock_sigs(); |
| 480 | |
| 481 | /* Create a new session and make ourself the process group leader */ |
| 482 | setsid(); |
| 483 | |
| 484 | /* Open the new terminal device */ |
| 485 | if (!open_stdio_to_tty(a->terminal)) |
| 486 | _exit(EXIT_FAILURE); |
| 487 | |
| 488 | /* NB: on NOMMU we can't wait for input in child, so |
| 489 | * "askfirst" will work the same as "respawn". */ |
| 490 | if (BB_MMU && (a->action_type & ASKFIRST)) { |
| 491 | static const char press_enter[] ALIGN1 = |
| 492 | #ifdef CUSTOMIZED_BANNER |
| 493 | #include CUSTOMIZED_BANNER |
| 494 | #endif |
| 495 | "\nPlease press Enter to activate this console. "; |
| 496 | char c; |
| 497 | /* |
| 498 | * Save memory by not exec-ing anything large (like a shell) |
| 499 | * before the user wants it. This is critical if swap is not |
| 500 | * enabled and the system has low memory. Generally this will |
| 501 | * be run on the second virtual console, and the first will |
| 502 | * be allowed to start a shell or whatever an init script |
| 503 | * specifies. |
| 504 | */ |
| 505 | dbg_message(L_LOG, "waiting for enter to start '%s'" |
| 506 | "(pid %d, tty '%s')\n", |
| 507 | a->command, getpid(), a->terminal); |
| 508 | full_write(STDOUT_FILENO, press_enter, sizeof(press_enter) - 1); |
| 509 | while (safe_read(STDIN_FILENO, &c, 1) == 1 && c != '\n') |
| 510 | continue; |
| 511 | } |
| 512 | |
| 513 | /* |
| 514 | * When a file named /.init_enable_core exists, setrlimit is called |
| 515 | * before processes are spawned to set core file size as unlimited. |
| 516 | * This is for debugging only. Don't use this is production, unless |
| 517 | * you want core dumps lying about.... |
| 518 | */ |
| 519 | if (ENABLE_FEATURE_INIT_COREDUMPS) { |
| 520 | if (access("/.init_enable_core", F_OK) == 0) { |
| 521 | struct rlimit limit; |
| 522 | limit.rlim_cur = RLIM_INFINITY; |
| 523 | limit.rlim_max = RLIM_INFINITY; |
| 524 | setrlimit(RLIMIT_CORE, &limit); |
| 525 | } |
| 526 | } |
| 527 | |
| 528 | /* Log the process name and args */ |
| 529 | message(L_LOG, "starting pid %d, tty '%s': '%s'", |
| 530 | getpid(), a->terminal, a->command); |
| 531 | |
| 532 | /* Now run it. The new program will take over this PID, |
| 533 | * so nothing further in init.c should be run. */ |
| 534 | init_exec(a->command); |
| 535 | /* We're still here? Some error happened. */ |
| 536 | _exit(-1); |
| 537 | } |
| 538 | |
| 539 | static struct init_action *mark_terminated(pid_t pid) |
| 540 | { |
| 541 | struct init_action *a; |
| 542 | |
| 543 | if (pid > 0) { |
| 544 | update_utmp(pid, DEAD_PROCESS, |
| 545 | /*tty_name:*/ NULL, |
| 546 | /*username:*/ NULL, |
| 547 | /*hostname:*/ NULL |
| 548 | ); |
| 549 | for (a = init_action_list; a; a = a->next) { |
| 550 | if (a->pid == pid) { |
| 551 | a->pid = 0; |
| 552 | return a; |
| 553 | } |
| 554 | } |
| 555 | } |
| 556 | return NULL; |
| 557 | } |
| 558 | |
| 559 | static void waitfor(pid_t pid) |
| 560 | { |
| 561 | /* waitfor(run(x)): protect against failed fork inside run() */ |
| 562 | if (pid <= 0) |
| 563 | return; |
| 564 | |
| 565 | /* Wait for any child (prevent zombies from exiting orphaned processes) |
| 566 | * but exit the loop only when specified one has exited. */ |
| 567 | while (1) { |
| 568 | pid_t wpid = wait(NULL); |
| 569 | mark_terminated(wpid); |
| 570 | /* Unsafe. SIGTSTP handler might have wait'ed it already */ |
| 571 | /*if (wpid == pid) break;*/ |
| 572 | /* More reliable: */ |
| 573 | if (kill(pid, 0)) |
| 574 | break; |
| 575 | } |
| 576 | } |
| 577 | |
| 578 | /* Run all commands of a particular type */ |
| 579 | static void run_actions(int action_type) |
| 580 | { |
| 581 | struct init_action *a; |
| 582 | |
| 583 | for (a = init_action_list; a; a = a->next) { |
| 584 | if (!(a->action_type & action_type)) |
| 585 | continue; |
| 586 | |
| 587 | if (a->action_type & (SYSINIT | WAIT | ONCE | CTRLALTDEL | SHUTDOWN)) { |
| 588 | pid_t pid = run(a); |
| 589 | if (a->action_type & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN)) |
| 590 | waitfor(pid); |
| 591 | } |
| 592 | if (a->action_type & (RESPAWN | ASKFIRST)) { |
| 593 | /* Only run stuff with pid == 0. If pid != 0, |
| 594 | * it is already running |
| 595 | */ |
| 596 | if (a->pid == 0) |
| 597 | a->pid = run(a); |
| 598 | } |
| 599 | } |
| 600 | } |
| 601 | |
| 602 | static void new_init_action(uint8_t action_type, const char *command, const char *cons) |
| 603 | { |
| 604 | struct init_action *a, **nextp; |
| 605 | |
| 606 | /* Scenario: |
| 607 | * old inittab: |
| 608 | * ::shutdown:umount -a -r |
| 609 | * ::shutdown:swapoff -a |
| 610 | * new inittab: |
| 611 | * ::shutdown:swapoff -a |
| 612 | * ::shutdown:umount -a -r |
| 613 | * On reload, we must ensure entries end up in correct order. |
| 614 | * To achieve that, if we find a matching entry, we move it |
| 615 | * to the end. |
| 616 | */ |
| 617 | nextp = &init_action_list; |
| 618 | while ((a = *nextp) != NULL) { |
| 619 | /* Don't enter action if it's already in the list. |
| 620 | * This prevents losing running RESPAWNs. |
| 621 | */ |
| 622 | if (strcmp(a->command, command) == 0 |
| 623 | && strcmp(a->terminal, cons) == 0 |
| 624 | ) { |
| 625 | /* Remove from list */ |
| 626 | *nextp = a->next; |
| 627 | /* Find the end of the list */ |
| 628 | while (*nextp != NULL) |
| 629 | nextp = &(*nextp)->next; |
| 630 | a->next = NULL; |
| 631 | goto append; |
| 632 | } |
| 633 | nextp = &a->next; |
| 634 | } |
| 635 | |
| 636 | a = xzalloc(sizeof(*a)); |
| 637 | |
| 638 | /* Append to the end of the list */ |
| 639 | append: |
| 640 | *nextp = a; |
| 641 | a->action_type = action_type; |
| 642 | safe_strncpy(a->command, command, sizeof(a->command)); |
| 643 | safe_strncpy(a->terminal, cons, sizeof(a->terminal)); |
| 644 | dbg_message(L_LOG | L_CONSOLE, "command='%s' action=%d tty='%s'\n", |
| 645 | a->command, a->action_type, a->terminal); |
| 646 | } |
| 647 | |
| 648 | /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined, |
| 649 | * then parse_inittab() simply adds in some default |
| 650 | * actions(i.e., runs INIT_SCRIPT and then starts a pair |
| 651 | * of "askfirst" shells). If CONFIG_FEATURE_USE_INITTAB |
| 652 | * _is_ defined, but /etc/inittab is missing, this |
| 653 | * results in the same set of default behaviors. |
| 654 | */ |
| 655 | static void parse_inittab(void) |
| 656 | { |
| 657 | #if ENABLE_FEATURE_USE_INITTAB |
| 658 | char *token[4]; |
| 659 | #if ENABLE_INSTALL_TO_RECOVERY |
| 660 | parser_t *parser = config_open2("/recovery/etc/inittab", fopen_for_read); |
| 661 | #else |
| 662 | parser_t *parser = config_open2("/etc/inittab", fopen_for_read); |
| 663 | #endif |
| 664 | if (parser == NULL) |
| 665 | #endif |
| 666 | { |
| 667 | /* No inittab file - set up some default behavior */ |
| 668 | /* Reboot on Ctrl-Alt-Del */ |
| 669 | new_init_action(CTRLALTDEL, "reboot", ""); |
| 670 | /* Umount all filesystems on halt/reboot */ |
| 671 | new_init_action(SHUTDOWN, "umount -a -r", ""); |
| 672 | /* Swapoff on halt/reboot */ |
| 673 | if (ENABLE_SWAPONOFF) |
| 674 | new_init_action(SHUTDOWN, "swapoff -a", ""); |
| 675 | /* Prepare to restart init when a QUIT is received */ |
| 676 | new_init_action(RESTART, "init", ""); |
| 677 | /* Askfirst shell on tty1-4 */ |
| 678 | new_init_action(ASKFIRST, bb_default_login_shell, ""); |
| 679 | //TODO: VC_1 instead of ""? "" is console -> ctty problems -> angry users |
| 680 | new_init_action(ASKFIRST, bb_default_login_shell, VC_2); |
| 681 | new_init_action(ASKFIRST, bb_default_login_shell, VC_3); |
| 682 | new_init_action(ASKFIRST, bb_default_login_shell, VC_4); |
| 683 | /* sysinit */ |
| 684 | new_init_action(SYSINIT, INIT_SCRIPT, ""); |
| 685 | return; |
| 686 | } |
| 687 | |
| 688 | #if ENABLE_FEATURE_USE_INITTAB |
| 689 | /* optional_tty:ignored_runlevel:action:command |
| 690 | * Delims are not to be collapsed and need exactly 4 tokens |
| 691 | */ |
| 692 | while (config_read(parser, token, 4, 0, "#:", |
| 693 | PARSE_NORMAL & ~(PARSE_TRIM | PARSE_COLLAPSE))) { |
| 694 | /* order must correspond to SYSINIT..RESTART constants */ |
| 695 | static const char actions[] ALIGN1 = |
| 696 | "sysinit\0""wait\0""once\0""respawn\0""askfirst\0" |
| 697 | "ctrlaltdel\0""shutdown\0""restart\0"; |
| 698 | int action; |
| 699 | char *tty = token[0]; |
| 700 | |
| 701 | if (!token[3]) /* less than 4 tokens */ |
| 702 | goto bad_entry; |
| 703 | action = index_in_strings(actions, token[2]); |
| 704 | if (action < 0 || !token[3][0]) /* token[3]: command */ |
| 705 | goto bad_entry; |
| 706 | /* turn .*TTY -> /dev/TTY */ |
| 707 | if (tty[0]) { |
| 708 | tty = concat_path_file("/dev/", skip_dev_pfx(tty)); |
| 709 | } |
| 710 | new_init_action(1 << action, token[3], tty); |
| 711 | if (tty[0]) |
| 712 | free(tty); |
| 713 | continue; |
| 714 | bad_entry: |
| 715 | message(L_LOG | L_CONSOLE, "Bad inittab entry at line %d", |
| 716 | parser->lineno); |
| 717 | } |
| 718 | config_close(parser); |
| 719 | #endif |
| 720 | } |
| 721 | |
| 722 | static void pause_and_low_level_reboot(unsigned magic) NORETURN; |
| 723 | static void pause_and_low_level_reboot(unsigned magic) |
| 724 | { |
| 725 | pid_t pid; |
| 726 | |
| 727 | /* Allow time for last message to reach serial console, etc */ |
| 728 | sleep(1); |
| 729 | |
| 730 | /* We have to fork here, since the kernel calls do_exit(EXIT_SUCCESS) |
| 731 | * in linux/kernel/sys.c, which can cause the machine to panic when |
| 732 | * the init process exits... */ |
| 733 | pid = vfork(); |
| 734 | if (pid == 0) { /* child */ |
| 735 | reboot(magic); |
| 736 | _exit(EXIT_SUCCESS); |
| 737 | } |
| 738 | while (1) |
| 739 | sleep(1); |
| 740 | } |
| 741 | |
| 742 | static void run_shutdown_and_kill_processes(void) |
| 743 | { |
| 744 | /* Run everything to be run at "shutdown". This is done _prior_ |
| 745 | * to killing everything, in case people wish to use scripts to |
| 746 | * shut things down gracefully... */ |
| 747 | run_actions(SHUTDOWN); |
| 748 | |
| 749 | message(L_CONSOLE | L_LOG, "The system is going down NOW!"); |
| 750 | |
| 751 | /* Send signals to every process _except_ pid 1 */ |
| 752 | kill(-1, SIGTERM); |
| 753 | message(L_CONSOLE | L_LOG, "Sent SIG%s to all processes", "TERM"); |
| 754 | sync(); |
| 755 | sleep(1); |
| 756 | |
| 757 | kill(-1, SIGKILL); |
| 758 | message(L_CONSOLE, "Sent SIG%s to all processes", "KILL"); |
| 759 | sync(); |
| 760 | /*sleep(1); - callers take care about making a pause */ |
| 761 | } |
| 762 | |
| 763 | /* Signal handling by init: |
| 764 | * |
| 765 | * For process with PID==1, on entry kernel sets all signals to SIG_DFL |
| 766 | * and unmasks all signals. However, for process with PID==1, |
| 767 | * default action (SIG_DFL) on any signal is to ignore it, |
| 768 | * even for special signals SIGKILL and SIGCONT. |
| 769 | * Also, any signal can be caught or blocked. |
| 770 | * (but SIGSTOP is still handled specially, at least in 2.6.20) |
| 771 | * |
| 772 | * We install two kinds of handlers, "immediate" and "delayed". |
| 773 | * |
| 774 | * Immediate handlers execute at any time, even while, say, sysinit |
| 775 | * is running. |
| 776 | * |
| 777 | * Delayed handlers just set a flag variable. The variable is checked |
| 778 | * in the main loop and acted upon. |
| 779 | * |
| 780 | * halt/poweroff/reboot and restart have immediate handlers. |
| 781 | * They only traverse linked list of struct action's, never modify it, |
| 782 | * this should be safe to do even in signal handler. Also they |
| 783 | * never return. |
| 784 | * |
| 785 | * SIGSTOP and SIGTSTP have immediate handlers. They just wait |
| 786 | * for SIGCONT to happen. |
| 787 | * |
| 788 | * SIGHUP has a delayed handler, because modifying linked list |
| 789 | * of struct action's from a signal handler while it is manipulated |
| 790 | * by the program may be disastrous. |
| 791 | * |
| 792 | * Ctrl-Alt-Del has a delayed handler. Not a must, but allowing |
| 793 | * it to happen even somewhere inside "sysinit" would be a bit awkward. |
| 794 | * |
| 795 | * There is a tiny probability that SIGHUP and Ctrl-Alt-Del will collide |
| 796 | * and only one will be remembered and acted upon. |
| 797 | */ |
| 798 | |
| 799 | /* The SIGUSR[12]/SIGTERM handler */ |
| 800 | static void halt_reboot_pwoff(int sig) NORETURN; |
| 801 | static void halt_reboot_pwoff(int sig) |
| 802 | { |
| 803 | const char *m; |
| 804 | unsigned rb; |
| 805 | |
| 806 | /* We may call run() and it unmasks signals, |
| 807 | * including the one masked inside this signal handler. |
| 808 | * Testcase which would start multiple reboot scripts: |
| 809 | * while true; do reboot; done |
| 810 | * Preventing it: |
| 811 | */ |
| 812 | reset_sighandlers_and_unblock_sigs(); |
| 813 | |
| 814 | run_shutdown_and_kill_processes(); |
| 815 | |
| 816 | m = "halt"; |
| 817 | rb = RB_HALT_SYSTEM; |
| 818 | if (sig == SIGTERM) { |
| 819 | m = "reboot"; |
| 820 | rb = RB_AUTOBOOT; |
| 821 | } else if (sig == SIGUSR2) { |
| 822 | m = "poweroff"; |
| 823 | rb = RB_POWER_OFF; |
| 824 | } |
| 825 | message(L_CONSOLE, "Requesting system %s", m); |
| 826 | pause_and_low_level_reboot(rb); |
| 827 | /* not reached */ |
| 828 | } |
| 829 | |
| 830 | /* Handler for QUIT - exec "restart" action, |
| 831 | * else (no such action defined) do nothing */ |
| 832 | static void restart_handler(int sig UNUSED_PARAM) |
| 833 | { |
| 834 | struct init_action *a; |
| 835 | |
| 836 | for (a = init_action_list; a; a = a->next) { |
| 837 | if (!(a->action_type & RESTART)) |
| 838 | continue; |
| 839 | |
| 840 | /* Starting from here, we won't return. |
| 841 | * Thus don't need to worry about preserving errno |
| 842 | * and such. |
| 843 | */ |
| 844 | |
| 845 | reset_sighandlers_and_unblock_sigs(); |
| 846 | |
| 847 | run_shutdown_and_kill_processes(); |
| 848 | |
| 849 | #ifdef RB_ENABLE_CAD |
| 850 | /* Allow Ctrl-Alt-Del to reboot the system. |
| 851 | * This is how kernel sets it up for init, we follow suit. |
| 852 | */ |
| 853 | reboot(RB_ENABLE_CAD); /* misnomer */ |
| 854 | #endif |
| 855 | |
| 856 | if (open_stdio_to_tty(a->terminal)) { |
| 857 | dbg_message(L_CONSOLE, "Trying to re-exec %s", a->command); |
| 858 | /* Theoretically should be safe. |
| 859 | * But in practice, kernel bugs may leave |
| 860 | * unkillable processes, and wait() may block forever. |
| 861 | * Oh well. Hoping "new" init won't be too surprised |
| 862 | * by having children it didn't create. |
| 863 | */ |
| 864 | //while (wait(NULL) > 0) |
| 865 | // continue; |
| 866 | init_exec(a->command); |
| 867 | } |
| 868 | /* Open or exec failed */ |
| 869 | pause_and_low_level_reboot(RB_HALT_SYSTEM); |
| 870 | /* not reached */ |
| 871 | } |
| 872 | } |
| 873 | |
| 874 | /* The SIGSTOP/SIGTSTP handler |
| 875 | * NB: inside it, all signals except SIGCONT are masked |
| 876 | * via appropriate setup in sigaction(). |
| 877 | */ |
| 878 | static void stop_handler(int sig UNUSED_PARAM) |
| 879 | { |
| 880 | smallint saved_bb_got_signal; |
| 881 | int saved_errno; |
| 882 | |
| 883 | saved_bb_got_signal = bb_got_signal; |
| 884 | saved_errno = errno; |
| 885 | signal(SIGCONT, record_signo); |
| 886 | |
| 887 | while (1) { |
| 888 | pid_t wpid; |
| 889 | |
| 890 | if (bb_got_signal == SIGCONT) |
| 891 | break; |
| 892 | /* NB: this can accidentally wait() for a process |
| 893 | * which we waitfor() elsewhere! waitfor() must have |
| 894 | * code which is resilient against this. |
| 895 | */ |
| 896 | wpid = wait_any_nohang(NULL); |
| 897 | mark_terminated(wpid); |
| 898 | sleep(1); |
| 899 | } |
| 900 | |
| 901 | signal(SIGCONT, SIG_DFL); |
| 902 | errno = saved_errno; |
| 903 | bb_got_signal = saved_bb_got_signal; |
| 904 | } |
| 905 | |
| 906 | #if ENABLE_FEATURE_USE_INITTAB |
| 907 | static void reload_inittab(void) |
| 908 | { |
| 909 | struct init_action *a, **nextp; |
| 910 | |
| 911 | message(L_LOG, "reloading /etc/inittab"); |
| 912 | |
| 913 | /* Disable old entries */ |
| 914 | for (a = init_action_list; a; a = a->next) |
| 915 | a->action_type = 0; |
| 916 | |
| 917 | /* Append new entries, or modify existing entries |
| 918 | * (incl. setting a->action_type) if cmd and device name |
| 919 | * match new ones. End result: only entries with |
| 920 | * a->action_type == 0 are stale. |
| 921 | */ |
| 922 | parse_inittab(); |
| 923 | |
| 924 | #if ENABLE_FEATURE_KILL_REMOVED |
| 925 | /* Kill stale entries */ |
| 926 | /* Be nice and send SIGTERM first */ |
| 927 | for (a = init_action_list; a; a = a->next) |
| 928 | if (a->action_type == 0 && a->pid != 0) |
| 929 | kill(a->pid, SIGTERM); |
| 930 | if (CONFIG_FEATURE_KILL_DELAY) { |
| 931 | /* NB: parent will wait in NOMMU case */ |
| 932 | if ((BB_MMU ? fork() : vfork()) == 0) { /* child */ |
| 933 | sleep(CONFIG_FEATURE_KILL_DELAY); |
| 934 | for (a = init_action_list; a; a = a->next) |
| 935 | if (a->action_type == 0 && a->pid != 0) |
| 936 | kill(a->pid, SIGKILL); |
| 937 | _exit(EXIT_SUCCESS); |
| 938 | } |
| 939 | } |
| 940 | #endif |
| 941 | |
| 942 | /* Remove stale entries and SYSINIT entries. |
| 943 | * We never rerun SYSINIT entries anyway, |
| 944 | * removing them too saves a few bytes */ |
| 945 | nextp = &init_action_list; |
| 946 | while ((a = *nextp) != NULL) { |
| 947 | if ((a->action_type & ~SYSINIT) == 0) { |
| 948 | *nextp = a->next; |
| 949 | free(a); |
| 950 | } else { |
| 951 | nextp = &a->next; |
| 952 | } |
| 953 | } |
| 954 | |
| 955 | /* Not needed: */ |
| 956 | /* run_actions(RESPAWN | ASKFIRST); */ |
| 957 | /* - we return to main loop, which does this automagically */ |
| 958 | } |
| 959 | #endif |
| 960 | |
| 961 | static int check_delayed_sigs(void) |
| 962 | { |
| 963 | int sigs_seen = 0; |
| 964 | |
| 965 | while (1) { |
| 966 | smallint sig = bb_got_signal; |
| 967 | |
| 968 | if (!sig) |
| 969 | return sigs_seen; |
| 970 | bb_got_signal = 0; |
| 971 | sigs_seen = 1; |
| 972 | #if ENABLE_FEATURE_USE_INITTAB |
| 973 | if (sig == SIGHUP) |
| 974 | reload_inittab(); |
| 975 | #endif |
| 976 | if (sig == SIGINT) |
| 977 | run_actions(CTRLALTDEL); |
| 978 | } |
| 979 | } |
| 980 | |
| 981 | #if DEBUG_SEGV_HANDLER |
| 982 | static |
| 983 | void handle_sigsegv(int sig, siginfo_t *info, void *ucontext) |
| 984 | { |
| 985 | long ip; |
| 986 | ucontext_t *uc; |
| 987 | |
| 988 | uc = ucontext; |
| 989 | ip = uc->uc_mcontext.gregs[REG_EIP]; |
| 990 | fdprintf(2, "signal:%d address:0x%lx ip:0x%lx\n", |
| 991 | sig, |
| 992 | /* this is void*, but using %p would print "(null)" |
| 993 | * even for ptrs which are not exactly 0, but, say, 0x123: |
| 994 | */ |
| 995 | (long)info->si_addr, |
| 996 | ip); |
| 997 | { |
| 998 | /* glibc extension */ |
| 999 | void *array[50]; |
| 1000 | int size; |
| 1001 | size = backtrace(array, 50); |
| 1002 | backtrace_symbols_fd(array, size, 2); |
| 1003 | } |
| 1004 | for (;;) sleep(9999); |
| 1005 | } |
| 1006 | #endif |
| 1007 | |
| 1008 | int init_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 1009 | int init_main(int argc UNUSED_PARAM, char **argv) |
| 1010 | { |
| 1011 | if (argv[1] && strcmp(argv[1], "-q") == 0) { |
| 1012 | return kill(1, SIGHUP); |
| 1013 | } |
| 1014 | |
| 1015 | #if DEBUG_SEGV_HANDLER |
| 1016 | { |
| 1017 | struct sigaction sa; |
| 1018 | memset(&sa, 0, sizeof(sa)); |
| 1019 | sa.sa_sigaction = handle_sigsegv; |
| 1020 | sa.sa_flags = SA_SIGINFO; |
| 1021 | sigaction(SIGSEGV, &sa, NULL); |
| 1022 | sigaction(SIGILL, &sa, NULL); |
| 1023 | sigaction(SIGFPE, &sa, NULL); |
| 1024 | sigaction(SIGBUS, &sa, NULL); |
| 1025 | } |
| 1026 | #endif |
| 1027 | |
| 1028 | if (!DEBUG_INIT) { |
| 1029 | /* Expect to be invoked as init with PID=1 or be invoked as linuxrc */ |
| 1030 | if (getpid() != 1 |
| 1031 | && (!ENABLE_FEATURE_INITRD || applet_name[0] != 'l') /* not linuxrc? */ |
| 1032 | ) { |
| 1033 | bb_error_msg_and_die("must be run as PID 1"); |
| 1034 | } |
| 1035 | #ifdef RB_DISABLE_CAD |
| 1036 | /* Turn off rebooting via CTL-ALT-DEL - we get a |
| 1037 | * SIGINT on CAD so we can shut things down gracefully... */ |
| 1038 | reboot(RB_DISABLE_CAD); /* misnomer */ |
| 1039 | #endif |
| 1040 | } |
| 1041 | |
| 1042 | /* If, say, xmalloc would ever die, we don't want to oops kernel |
| 1043 | * by exiting. |
| 1044 | * NB: we set die_sleep *after* PID 1 check and bb_show_usage. |
| 1045 | * Otherwise, for example, "init u" ("please rexec yourself" |
| 1046 | * command for sysvinit) will show help text (which isn't too bad), |
| 1047 | * *and sleep forever* (which is bad!) |
| 1048 | */ |
| 1049 | die_sleep = 30 * 24*60*60; |
| 1050 | |
| 1051 | /* Figure out where the default console should be */ |
| 1052 | console_init(); |
| 1053 | set_sane_term(); |
| 1054 | xchdir("/"); |
| 1055 | setsid(); |
| 1056 | |
| 1057 | /* Make sure environs is set to something sane */ |
| 1058 | putenv((char *) "HOME=/"); |
| 1059 | putenv((char *) bb_PATH_root_path); |
| 1060 | putenv((char *) "SHELL=/bin/sh"); |
| 1061 | putenv((char *) "USER=root"); /* needed? why? */ |
| 1062 | |
| 1063 | if (argv[1]) |
| 1064 | xsetenv("RUNLEVEL", argv[1]); |
| 1065 | |
| 1066 | #if !ENABLE_FEATURE_EXTRA_QUIET |
| 1067 | /* Hello world */ |
| 1068 | message(L_CONSOLE | L_LOG, "init started: %s", bb_banner); |
| 1069 | #endif |
| 1070 | |
| 1071 | #if ENABLE_FEATURE_ETC_RC |
| 1072 | { |
| 1073 | pid_t pid; |
| 1074 | pid = vfork(); |
| 1075 | if (pid == 0) { /* child */ |
| 1076 | close(0); |
| 1077 | execl("/bin/sh", "sh", "/etc/rc", NULL); |
| 1078 | _exit(0); |
| 1079 | } |
| 1080 | waitfor(pid); |
| 1081 | } |
| 1082 | #endif |
| 1083 | |
| 1084 | /* struct sysinfo is linux-specific */ |
| 1085 | #ifdef __linux__ |
| 1086 | /* Make sure there is enough memory to do something useful. */ |
| 1087 | if (ENABLE_SWAPONOFF) { |
| 1088 | struct sysinfo info; |
| 1089 | |
| 1090 | if (sysinfo(&info) == 0 |
| 1091 | && (info.mem_unit ? info.mem_unit : 1) * (long long)info.totalram < 1024*1024 |
| 1092 | ) { |
| 1093 | message(L_CONSOLE, "Low memory, forcing swapon"); |
| 1094 | /* swapon -a requires /proc typically */ |
| 1095 | new_init_action(SYSINIT, "mount -t proc proc /proc", ""); |
| 1096 | /* Try to turn on swap */ |
| 1097 | new_init_action(SYSINIT, "swapon -a", ""); |
| 1098 | run_actions(SYSINIT); /* wait and removing */ |
| 1099 | } |
| 1100 | } |
| 1101 | #endif |
| 1102 | |
| 1103 | /* Check if we are supposed to be in single user mode */ |
| 1104 | if (argv[1] |
| 1105 | && (strcmp(argv[1], "single") == 0 || strcmp(argv[1], "-s") == 0 || LONE_CHAR(argv[1], '1')) |
| 1106 | ) { |
| 1107 | /* ??? shouldn't we set RUNLEVEL="b" here? */ |
| 1108 | /* Start a shell on console */ |
| 1109 | new_init_action(RESPAWN, bb_default_login_shell, ""); |
| 1110 | } else { |
| 1111 | /* Not in single user mode - see what inittab says */ |
| 1112 | |
| 1113 | /* NOTE that if CONFIG_FEATURE_USE_INITTAB is NOT defined, |
| 1114 | * then parse_inittab() simply adds in some default |
| 1115 | * actions(i.e., INIT_SCRIPT and a pair |
| 1116 | * of "askfirst" shells */ |
| 1117 | parse_inittab(); |
| 1118 | } |
| 1119 | |
| 1120 | #if ENABLE_SELINUX |
| 1121 | if (getenv("SELINUX_INIT") == NULL) { |
| 1122 | int enforce = 0; |
| 1123 | |
| 1124 | putenv((char*)"SELINUX_INIT=YES"); |
| 1125 | if (selinux_init_load_policy(&enforce) == 0) { |
| 1126 | BB_EXECVP(argv[0], argv); |
| 1127 | } else if (enforce > 0) { |
| 1128 | /* SELinux in enforcing mode but load_policy failed */ |
| 1129 | message(L_CONSOLE, "can't load SELinux Policy. " |
| 1130 | "Machine is in enforcing mode. Halting now."); |
| 1131 | return EXIT_FAILURE; |
| 1132 | } |
| 1133 | } |
| 1134 | #endif |
| 1135 | |
| 1136 | /* Make the command line just say "init" - thats all, nothing else */ |
| 1137 | strncpy(argv[0], "init", strlen(argv[0])); |
| 1138 | /* Wipe argv[1]-argv[N] so they don't clutter the ps listing */ |
| 1139 | while (*++argv) |
| 1140 | memset(*argv, 0, strlen(*argv)); |
| 1141 | |
| 1142 | /* Set up signal handlers */ |
| 1143 | if (!DEBUG_INIT) { |
| 1144 | struct sigaction sa; |
| 1145 | |
| 1146 | bb_signals(0 |
| 1147 | + (1 << SIGUSR1) /* halt */ |
| 1148 | + (1 << SIGTERM) /* reboot */ |
| 1149 | + (1 << SIGUSR2) /* poweroff */ |
| 1150 | , halt_reboot_pwoff); |
| 1151 | signal(SIGQUIT, restart_handler); /* re-exec another init */ |
| 1152 | |
| 1153 | /* Stop handler must allow only SIGCONT inside itself */ |
| 1154 | memset(&sa, 0, sizeof(sa)); |
| 1155 | sigfillset(&sa.sa_mask); |
| 1156 | sigdelset(&sa.sa_mask, SIGCONT); |
| 1157 | sa.sa_handler = stop_handler; |
| 1158 | /* NB: sa_flags doesn't have SA_RESTART. |
| 1159 | * It must be able to interrupt wait(). |
| 1160 | */ |
| 1161 | sigaction_set(SIGTSTP, &sa); /* pause */ |
| 1162 | /* Does not work as intended, at least in 2.6.20. |
| 1163 | * SIGSTOP is simply ignored by init: |
| 1164 | */ |
| 1165 | sigaction_set(SIGSTOP, &sa); /* pause */ |
| 1166 | |
| 1167 | /* SIGINT (Ctrl-Alt-Del) must interrupt wait(), |
| 1168 | * setting handler without SA_RESTART flag. |
| 1169 | */ |
| 1170 | bb_signals_recursive_norestart((1 << SIGINT), record_signo); |
| 1171 | } |
| 1172 | |
| 1173 | /* Set up "reread /etc/inittab" handler. |
| 1174 | * Handler is set up without SA_RESTART, it will interrupt syscalls. |
| 1175 | */ |
| 1176 | if (!DEBUG_INIT && ENABLE_FEATURE_USE_INITTAB) |
| 1177 | bb_signals_recursive_norestart((1 << SIGHUP), record_signo); |
| 1178 | |
| 1179 | /* Now run everything that needs to be run */ |
| 1180 | /* First run the sysinit command */ |
| 1181 | run_actions(SYSINIT); |
| 1182 | check_delayed_sigs(); |
| 1183 | /* Next run anything that wants to block */ |
| 1184 | run_actions(WAIT); |
| 1185 | check_delayed_sigs(); |
| 1186 | /* Next run anything to be run only once */ |
| 1187 | run_actions(ONCE); |
| 1188 | |
| 1189 | /* Now run the looping stuff for the rest of forever. |
| 1190 | */ |
| 1191 | while (1) { |
| 1192 | int maybe_WNOHANG; |
| 1193 | |
| 1194 | maybe_WNOHANG = check_delayed_sigs(); |
| 1195 | |
| 1196 | /* (Re)run the respawn/askfirst stuff */ |
| 1197 | run_actions(RESPAWN | ASKFIRST); |
| 1198 | maybe_WNOHANG |= check_delayed_sigs(); |
| 1199 | |
| 1200 | /* Don't consume all CPU time - sleep a bit */ |
| 1201 | sleep(1); |
| 1202 | maybe_WNOHANG |= check_delayed_sigs(); |
| 1203 | |
| 1204 | /* Wait for any child process(es) to exit. |
| 1205 | * |
| 1206 | * If check_delayed_sigs above reported that a signal |
| 1207 | * was caught, wait will be nonblocking. This ensures |
| 1208 | * that if SIGHUP has reloaded inittab, respawn and askfirst |
| 1209 | * actions will not be delayed until next child death. |
| 1210 | */ |
| 1211 | if (maybe_WNOHANG) |
| 1212 | maybe_WNOHANG = WNOHANG; |
| 1213 | while (1) { |
| 1214 | pid_t wpid; |
| 1215 | struct init_action *a; |
| 1216 | |
| 1217 | /* If signals happen _in_ the wait, they interrupt it, |
| 1218 | * bb_signals_recursive_norestart set them up that way |
| 1219 | */ |
| 1220 | wpid = waitpid(-1, NULL, maybe_WNOHANG); |
| 1221 | if (wpid <= 0) |
| 1222 | break; |
| 1223 | |
| 1224 | a = mark_terminated(wpid); |
| 1225 | if (a) { |
| 1226 | message(L_LOG, "process '%s' (pid %d) exited. " |
| 1227 | "Scheduling for restart.", |
| 1228 | a->command, wpid); |
| 1229 | } |
| 1230 | /* See if anyone else is waiting to be reaped */ |
| 1231 | maybe_WNOHANG = WNOHANG; |
| 1232 | } |
| 1233 | } /* while (1) */ |
| 1234 | } |
| 1235 | |
| 1236 | //usage:#define linuxrc_trivial_usage NOUSAGE_STR |
| 1237 | //usage:#define linuxrc_full_usage "" |
| 1238 | |
| 1239 | //usage:#define init_trivial_usage |
| 1240 | //usage: "" |
| 1241 | //usage:#define init_full_usage "\n\n" |
| 1242 | //usage: "Init is the parent of all processes" |
| 1243 | //usage: |
| 1244 | //usage:#define init_notes_usage |
| 1245 | //usage: "This version of init is designed to be run only by the kernel.\n" |
| 1246 | //usage: "\n" |
| 1247 | //usage: "BusyBox init doesn't support multiple runlevels. The runlevels field of\n" |
| 1248 | //usage: "the /etc/inittab file is completely ignored by BusyBox init. If you want\n" |
| 1249 | //usage: "runlevels, use sysvinit.\n" |
| 1250 | //usage: "\n" |
| 1251 | //usage: "BusyBox init works just fine without an inittab. If no inittab is found,\n" |
| 1252 | //usage: "it has the following default behavior:\n" |
| 1253 | //usage: "\n" |
| 1254 | //usage: " ::sysinit:/etc/init.d/rcS\n" |
| 1255 | //usage: " ::askfirst:/bin/sh\n" |
| 1256 | //usage: " ::ctrlaltdel:/sbin/reboot\n" |
| 1257 | //usage: " ::shutdown:/sbin/swapoff -a\n" |
| 1258 | //usage: " ::shutdown:/bin/umount -a -r\n" |
| 1259 | //usage: " ::restart:/sbin/init\n" |
| 1260 | //usage: "\n" |
| 1261 | //usage: "if it detects that /dev/console is _not_ a serial console, it will also run:\n" |
| 1262 | //usage: "\n" |
| 1263 | //usage: " tty2::askfirst:/bin/sh\n" |
| 1264 | //usage: " tty3::askfirst:/bin/sh\n" |
| 1265 | //usage: " tty4::askfirst:/bin/sh\n" |
| 1266 | //usage: "\n" |
| 1267 | //usage: "If you choose to use an /etc/inittab file, the inittab entry format is as follows:\n" |
| 1268 | //usage: "\n" |
| 1269 | //usage: " <id>:<runlevels>:<action>:<process>\n" |
| 1270 | //usage: "\n" |
| 1271 | //usage: " <id>:\n" |
| 1272 | //usage: "\n" |
| 1273 | //usage: " WARNING: This field has a non-traditional meaning for BusyBox init!\n" |
| 1274 | //usage: " The id field is used by BusyBox init to specify the controlling tty for\n" |
| 1275 | //usage: " the specified process to run on. The contents of this field are\n" |
| 1276 | //usage: " appended to \"/dev/\" and used as-is. There is no need for this field to\n" |
| 1277 | //usage: " be unique, although if it isn't you may have strange results. If this\n" |
| 1278 | //usage: " field is left blank, the controlling tty is set to the console. Also\n" |
| 1279 | //usage: " note that if BusyBox detects that a serial console is in use, then only\n" |
| 1280 | //usage: " entries whose controlling tty is either the serial console or /dev/null\n" |
| 1281 | //usage: " will be run. BusyBox init does nothing with utmp. We don't need no\n" |
| 1282 | //usage: " stinkin' utmp.\n" |
| 1283 | //usage: "\n" |
| 1284 | //usage: " <runlevels>:\n" |
| 1285 | //usage: "\n" |
| 1286 | //usage: " The runlevels field is completely ignored.\n" |
| 1287 | //usage: "\n" |
| 1288 | //usage: " <action>:\n" |
| 1289 | //usage: "\n" |
| 1290 | //usage: " Valid actions include: sysinit, respawn, askfirst, wait,\n" |
| 1291 | //usage: " once, restart, ctrlaltdel, and shutdown.\n" |
| 1292 | //usage: "\n" |
| 1293 | //usage: " The available actions can be classified into two groups: actions\n" |
| 1294 | //usage: " that are run only once, and actions that are re-run when the specified\n" |
| 1295 | //usage: " process exits.\n" |
| 1296 | //usage: "\n" |
| 1297 | //usage: " Run only-once actions:\n" |
| 1298 | //usage: "\n" |
| 1299 | //usage: " 'sysinit' is the first item run on boot. init waits until all\n" |
| 1300 | //usage: " sysinit actions are completed before continuing. Following the\n" |
| 1301 | //usage: " completion of all sysinit actions, all 'wait' actions are run.\n" |
| 1302 | //usage: " 'wait' actions, like 'sysinit' actions, cause init to wait until\n" |
| 1303 | //usage: " the specified task completes. 'once' actions are asynchronous,\n" |
| 1304 | //usage: " therefore, init does not wait for them to complete. 'restart' is\n" |
| 1305 | //usage: " the action taken to restart the init process. By default this should\n" |
| 1306 | //usage: " simply run /sbin/init, but can be a script which runs pivot_root or it\n" |
| 1307 | //usage: " can do all sorts of other interesting things. The 'ctrlaltdel' init\n" |
| 1308 | //usage: " actions are run when the system detects that someone on the system\n" |
| 1309 | //usage: " console has pressed the CTRL-ALT-DEL key combination. Typically one\n" |
| 1310 | //usage: " wants to run 'reboot' at this point to cause the system to reboot.\n" |
| 1311 | //usage: " Finally the 'shutdown' action specifies the actions to taken when\n" |
| 1312 | //usage: " init is told to reboot. Unmounting filesystems and disabling swap\n" |
| 1313 | //usage: " is a very good here.\n" |
| 1314 | //usage: "\n" |
| 1315 | //usage: " Run repeatedly actions:\n" |
| 1316 | //usage: "\n" |
| 1317 | //usage: " 'respawn' actions are run after the 'once' actions. When a process\n" |
| 1318 | //usage: " started with a 'respawn' action exits, init automatically restarts\n" |
| 1319 | //usage: " it. Unlike sysvinit, BusyBox init does not stop processes from\n" |
| 1320 | //usage: " respawning out of control. The 'askfirst' actions acts just like\n" |
| 1321 | //usage: " respawn, except that before running the specified process it\n" |
| 1322 | //usage: " displays the line \"Please press Enter to activate this console.\"\n" |
| 1323 | //usage: " and then waits for the user to press enter before starting the\n" |
| 1324 | //usage: " specified process.\n" |
| 1325 | //usage: "\n" |
| 1326 | //usage: " Unrecognized actions (like initdefault) will cause init to emit an\n" |
| 1327 | //usage: " error message, and then go along with its business. All actions are\n" |
| 1328 | //usage: " run in the order they appear in /etc/inittab.\n" |
| 1329 | //usage: "\n" |
| 1330 | //usage: " <process>:\n" |
| 1331 | //usage: "\n" |
| 1332 | //usage: " Specifies the process to be executed and its command line.\n" |
| 1333 | //usage: "\n" |
| 1334 | //usage: "Example /etc/inittab file:\n" |
| 1335 | //usage: "\n" |
| 1336 | //usage: " # This is run first except when booting in single-user mode\n" |
| 1337 | //usage: " #\n" |
| 1338 | //usage: " ::sysinit:/etc/init.d/rcS\n" |
| 1339 | //usage: " \n" |
| 1340 | //usage: " # /bin/sh invocations on selected ttys\n" |
| 1341 | //usage: " #\n" |
| 1342 | //usage: " # Start an \"askfirst\" shell on the console (whatever that may be)\n" |
| 1343 | //usage: " ::askfirst:-/bin/sh\n" |
| 1344 | //usage: " # Start an \"askfirst\" shell on /dev/tty2-4\n" |
| 1345 | //usage: " tty2::askfirst:-/bin/sh\n" |
| 1346 | //usage: " tty3::askfirst:-/bin/sh\n" |
| 1347 | //usage: " tty4::askfirst:-/bin/sh\n" |
| 1348 | //usage: " \n" |
| 1349 | //usage: " # /sbin/getty invocations for selected ttys\n" |
| 1350 | //usage: " #\n" |
| 1351 | //usage: " tty4::respawn:/sbin/getty 38400 tty4\n" |
| 1352 | //usage: " tty5::respawn:/sbin/getty 38400 tty5\n" |
| 1353 | //usage: " \n" |
| 1354 | //usage: " \n" |
| 1355 | //usage: " # Example of how to put a getty on a serial line (for a terminal)\n" |
| 1356 | //usage: " #\n" |
| 1357 | //usage: " #::respawn:/sbin/getty -L ttyS0 9600 vt100\n" |
| 1358 | //usage: " #::respawn:/sbin/getty -L ttyS1 9600 vt100\n" |
| 1359 | //usage: " #\n" |
| 1360 | //usage: " # Example how to put a getty on a modem line\n" |
| 1361 | //usage: " #::respawn:/sbin/getty 57600 ttyS2\n" |
| 1362 | //usage: " \n" |
| 1363 | //usage: " # Stuff to do when restarting the init process\n" |
| 1364 | //usage: " ::restart:/sbin/init\n" |
| 1365 | //usage: " \n" |
| 1366 | //usage: " # Stuff to do before rebooting\n" |
| 1367 | //usage: " ::ctrlaltdel:/sbin/reboot\n" |
| 1368 | //usage: " ::shutdown:/bin/umount -a -r\n" |
| 1369 | //usage: " ::shutdown:/sbin/swapoff -a\n" |