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busybox/init/init.c
Eric Andersen a920871c3a Ignoring SIGCHLD causes a race leading to the occasional hang of init 
when init will wait() on itself in waitfor() when the child exits before
init is scheduled to run.  Letting init hang is very seriously bad.
 -Erik
2002-09-25 15:08:40 +00:00

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/* vi: set sw=4 ts=4: */
/*
* Mini init implementation for busybox
*
* Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
* Copyright (C) 1999-2002 by Erik Andersen <andersee@debian.org>
* 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 <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 <limits.h>
#include <sys/fcntl.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "busybox.h"
#ifdef CONFIG_SYSLOGD
# include <sys/syslog.h>
#endif
#if defined(__UCLIBC__) && !defined(__UCLIBC_HAS_MMU__)
#define fork vfork
#endif
#define INIT_BUFFS_SIZE 256
/* From <linux/vt.h> */
struct vt_stat {
unsigned short v_active; /* active vt */
unsigned short v_signal; /* signal to send */
unsigned short v_state; /* vt bitmask */
};
static const int VT_GETSTATE = 0x5603; /* get global vt state info */
/* From <linux/serial.h> */
struct serial_struct {
int type;
int line;
int port;
int irq;
int flags;
int xmit_fifo_size;
int custom_divisor;
int baud_base;
unsigned short close_delay;
char reserved_char[2];
int hub6;
unsigned short closing_wait; /* time to wait before closing */
unsigned short closing_wait2; /* no longer used... */
int reserved[4];
};
#if (__GNU_LIBRARY__ > 5) || defined(__dietlibc__)
#include <sys/reboot.h>
#define init_reboot(magic) reboot(magic)
#else
#define init_reboot(magic) reboot(0xfee1dead, 672274793, magic)
#endif
#ifndef _PATH_STDPATH
#define _PATH_STDPATH "/usr/bin:/bin:/usr/sbin:/sbin"
#endif
#if defined CONFIG_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
#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
#if __GNU_LIBRARY__ > 5
#include <sys/kdaemon.h>
#else
extern int bdflush(int func, long int data);
#endif
#define SHELL "/bin/sh" /* Default shell */
#define LOGIN_SHELL "-" SHELL /* Default login shell */
#define INITTAB "/etc/inittab" /* inittab file location */
#ifndef INIT_SCRIPT
#define INIT_SCRIPT "/etc/init.d/rcS" /* Default sysinit script. */
#endif
#define MAXENV 16 /* Number of env. vars */
/* Allowed init action types */
#define SYSINIT 0x001
#define RESPAWN 0x002
#define ASKFIRST 0x004
#define WAIT 0x008
#define ONCE 0x010
#define CTRLALTDEL 0x020
#define SHUTDOWN 0x040
#define RESTART 0x080
/* A mapping between "inittab" action name strings and action type codes. */
struct init_action_type {
const char *name;
int action;
};
static const struct init_action_type actions[] = {
{"sysinit", SYSINIT},
{"respawn", RESPAWN},
{"askfirst", ASKFIRST},
{"wait", WAIT},
{"once", ONCE},
{"ctrlaltdel", CTRLALTDEL},
{"shutdown", SHUTDOWN},
{"restart", RESTART},
{0, 0}
};
/* Set up a linked list of init_actions, to be read from inittab */
struct init_action {
pid_t pid;
char command[INIT_BUFFS_SIZE];
char terminal[INIT_BUFFS_SIZE];
struct init_action *next;
int action;
};
/* Static variables */
static struct init_action *init_action_list = NULL;
static int kernelVersion = 0;
static char termType[32] = "TERM=linux";
static char console[32] = _PATH_CONSOLE;
#ifndef CONFIG_SYSLOGD
static char *log = VC_5;
#endif
static sig_atomic_t got_cont = 0;
static const int LOG = 0x1;
static const int CONSOLE = 0x2;
#if defined CONFIG_FEATURE_EXTRA_QUIET
static const int MAYBE_CONSOLE = 0x0;
#else
#define MAYBE_CONSOLE CONSOLE
#endif
#ifndef RB_HALT_SYSTEM
static const int RB_HALT_SYSTEM = 0xcdef0123;
static const int RB_ENABLE_CAD = 0x89abcdef;
static const int RB_DISABLE_CAD = 0;
#define RB_POWER_OFF 0x4321fedc
static const int RB_AUTOBOOT = 0x01234567;
#endif
/* Function prototypes */
static void delete_init_action(struct init_action *a);
static int waitfor(struct init_action *a);
static void loop_forever(void)
{
while (1)
sleep(1);
}
/* Print a message to the specified device.
* Device may be bitwise-or'd from LOG | CONSOLE */
#ifdef DEBUG_INIT
static inline messageND(int device, char *fmt, ...)
{
}
#else
#define messageND message
#endif
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 CONFIG_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);
syslog_msg(LOG_USER, LOG_INFO, msg);
}
#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_fd = device_open(log, O_RDWR | O_NDELAY)) < 0) {
log_fd = -2;
fprintf(stderr, "Bummer, can't write to log on %s!\n", log);
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);
va_end(arguments);
}
}
}
/* Set terminal settings to reasonable defaults */
static void set_term(int fd)
{
struct termios tty;
tcgetattr(fd, &tty);
/* set control chars */
tty.c_cc[VINTR] = 3; /* C-c */
tty.c_cc[VQUIT] = 28; /* C-\ */
tty.c_cc[VERASE] = 127; /* C-? */
tty.c_cc[VKILL] = 21; /* C-u */
tty.c_cc[VEOF] = 4; /* C-d */
tty.c_cc[VSTART] = 17; /* C-q */
tty.c_cc[VSTOP] = 19; /* C-s */
tty.c_cc[VSUSP] = 26; /* C-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 |= CREAD | 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?
Units are kBytes to avoid overflow on 4GB machines */
static int check_free_memory(void)
{
struct sysinfo info;
unsigned int result, u, s = 10;
if (sysinfo(&info) != 0) {
perror_msg("Error checking free memory");
return -1;
}
/* Kernels 2.0.x and 2.2.x return info.mem_unit==0 with values in bytes.
* Kernels 2.4.0 return info.mem_unit in bytes. */
u = info.mem_unit;
if (u == 0)
u = 1;
while ((u & 1) == 0 && s > 0) {
u >>= 1;
s--;
}
result = (info.totalram >> s) + (info.totalswap >> s);
result = result * u;
if (result < 0)
result = INT_MAX;
return result;
}
static void console_init(void)
{
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) {
safe_strncpy(console, s, sizeof(console));
}
#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)
safe_strncpy(console, SC_0, sizeof(console));
else if (strcmp(s, "ttyb") == 0)
safe_strncpy(console, SC_1, sizeof(console));
}
#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, SC_FORMAT, sr.line);
} else if (ioctl(0, VT_GETSTATE, &vt) == 0) {
/* this is linux virtual tty */
snprintf(console, sizeof(console) - 1, VC_FORMAT, vt.v_active);
} else {
safe_strncpy(console, _PATH_CONSOLE, sizeof(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++;
safe_strncpy(console, _PATH_CONSOLE, sizeof(console));
continue;
}
/* Can't open selected console -- try vt1 */
if (!tried_vtprimary) {
tried_vtprimary++;
safe_strncpy(console, VC_1, sizeof(console));
continue;
}
break;
}
if (fd < 0) {
/* Perhaps we should panic here? */
safe_strncpy(console, "/dev/null", sizeof(console));
} else {
/* check for serial console */
if (ioctl(0, TIOCGSERIAL, &sr) == 0) {
/* Force the TERM setting to vt102 for serial console --
* if TERM is set to linux (the default) */
if (strcmp(termType, "TERM=linux") == 0)
safe_strncpy(termType, "TERM=vt102", sizeof(termType));
}
close(fd);
}
message(LOG, "console=%s\n", console);
}
static void fixup_argv(int argc, char **argv, char *new_argv0)
{
int len;
/* Fix up argv[0] to be certain we claim to be init */
len = strlen(argv[0]);
memset(argv[0], 0, len);
safe_strncpy(argv[0], new_argv0, len + 1);
/* Wipe argv[1]-argv[N] so they don't clutter the ps listing */
len = 1;
while (argc > len) {
memset(argv[len], 0, strlen(argv[len]));
len++;
}
}
/* 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(void)
{
struct stat statBuf;
if (check_free_memory() > 1000)
return;
#if !defined(__UCLIBC__) || defined(__UCLIBC_HAS_MMU__)
if (stat("/etc/fstab", &statBuf) == 0) {
/* swapon -a requires /proc typically */
system("/bin/mount -t proc proc /proc");
/* Try to turn on swap */
system("/sbin/swapon -a");
if (check_free_memory() < 1000)
goto goodnight;
} else
goto goodnight;
return;
#endif
goodnight:
message(CONSOLE, "\rSorry, your computer does not have enough memory.\n");
loop_forever();
}
static pid_t run(struct init_action *a)
{
struct stat sb;
int i, j, junk;
pid_t pid, pgrp, tmp_pid;
char *s, *tmpCmd, *cmd[INIT_BUFFS_SIZE], *cmdpath;
char buf[INIT_BUFFS_SIZE + 6]; /* INIT_BUFFS_SIZE+strlen("exec ")+1 */
sigset_t nmask, omask;
char *environment[MAXENV + 1] = {
termType,
"HOME=/",
"PATH=" _PATH_STDPATH,
"SHELL=" SHELL,
"USER=root",
NULL
};
static const char press_enter[] =
#ifdef CUSTOMIZED_BANNER
#include CUSTOMIZED_BANNER
#endif
"\nPlease press Enter to activate this console. ";
/* inherit environment to the child, merging our values -andy */
for (i = 0; environ[i]; i++) {
for (j = 0; environment[j]; j++) {
s = strchr(environment[j], '=');
if (!strncmp(environ[i], environment[j], s - environment[j]))
break;
}
if (!environment[j]) {
environment[j++] = environ[i];
environment[j] = NULL;
}
}
/* Block sigchild while forking. */
sigemptyset(&nmask);
sigaddset(&nmask, SIGCHLD);
sigprocmask(SIG_BLOCK, &nmask, &omask);
if ((pid = fork()) == 0) {
/* Clean up */
close(0);
close(1);
close(2);
sigprocmask(SIG_SETMASK, &omask, NULL);
/* Reset signal handlers that were set by the parent process */
signal(SIGUSR1, SIG_DFL);
signal(SIGUSR2, SIG_DFL);
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
signal(SIGHUP, SIG_DFL);
signal(SIGCONT, SIG_DFL);
signal(SIGSTOP, SIG_DFL);
signal(SIGTSTP, SIG_DFL);
/* Create a new session and make ourself the process
* group leader for non-interactive jobs */
if ((a->action & (RESPAWN)) == 0)
setsid();
/* Open the new terminal device */
if ((device_open(a->terminal, O_RDWR | O_NOCTTY)) < 0) {
if (stat(a->terminal, &sb) != 0) {
message(LOG | CONSOLE, "\rdevice '%s' does not exist.\n",
a->terminal);
_exit(1);
}
message(LOG | CONSOLE, "\rBummer, can't open %s\n", a->terminal);
_exit(1);
}
/* Non-interactive jobs should not get a controling tty */
if ((a->action & (RESPAWN)) == 0)
(void) ioctl(0, TIOCSCTTY, 0);
/* Make sure the terminal will act fairly normal for us */
set_term(0);
/* Setup stdout, stderr for the new process so
* they point to the supplied terminal */
dup(0);
dup(0);
/* For interactive jobs, create a new session
* and become the process group leader */
if ((a->action & (RESPAWN)))
setsid();
/* If the init Action requires us to wait, then force the
* supplied terminal to be the controlling tty. */
if (a->action & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN | RESTART)) {
/* Now fork off another process to just hang around */
if ((pid = fork()) < 0) {
message(LOG | CONSOLE, "Can't fork!\n");
_exit(1);
}
if (pid > 0) {
/* We are the parent -- wait till the child is done */
signal(SIGINT, SIG_IGN);
signal(SIGTSTP, SIG_IGN);
signal(SIGQUIT, SIG_IGN);
signal(SIGCHLD, SIG_DFL);
/* Wait for child to exit */
while ((tmp_pid = waitpid(pid, &junk, 0)) != pid);
/* See if stealing the controlling tty back is necessary */
pgrp = tcgetpgrp(0);
if (pgrp != getpid())
_exit(0);
/* Use a temporary process to steal the controlling tty. */
if ((pid = fork()) < 0) {
message(LOG | CONSOLE, "\rCan't fork!\n");
_exit(1);
}
if (pid == 0) {
setsid();
ioctl(0, TIOCSCTTY, 1);
_exit(0);
}
while ((tmp_pid = waitpid(pid, &junk, 0)) != pid) {
if (tmp_pid < 0 && errno == ECHILD)
break;
}
_exit(0);
}
/* Now fall though to actually execute things */
}
/* See if any special /bin/sh requiring characters are present */
if (strpbrk(a->command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
cmd[0] = SHELL;
cmd[1] = "-c";
strcat(strcpy(buf, "exec "), a->command);
cmd[2] = buf;
cmd[3] = NULL;
} else {
/* Convert command (char*) into cmd (char**, one word per string) */
strcpy(buf, a->command);
s = buf;
for (tmpCmd = buf, i = 0; (tmpCmd = strsep(&s, " \t")) != NULL;) {
if (*tmpCmd != '\0') {
cmd[i] = tmpCmd;
i++;
}
}
cmd[i] = NULL;
}
cmdpath = cmd[0];
/*
Interactive shells want to see a dash in argv[0]. This
typically is handled by login, argv will be setup this
way if a dash appears at the front of the command path
(like "-/bin/sh").
*/
if (*cmdpath == '-') {
/* skip over the dash */
++cmdpath;
/* find the last component in the command pathname */
s = get_last_path_component(cmdpath);
/* make a new argv[0] */
if ((cmd[0] = malloc(strlen(s) + 2)) == NULL) {
message(LOG | CONSOLE, "malloc failed");
cmd[0] = cmdpath;
} else {
cmd[0][0] = '-';
strcpy(cmd[0] + 1, s);
}
}
if (a->action & ASKFIRST) {
/*
* 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.
*/
messageND(LOG,
"Waiting for enter to start '%s' (pid %d, terminal %s)\n",
cmdpath, getpid(), a->terminal);
write(fileno(stdout), press_enter, sizeof(press_enter) - 1);
getc(stdin);
}
/* Log the process name and args */
messageND(LOG, "Starting pid %d, console %s: '%s'\n",
getpid(), a->terminal, cmdpath);
#if defined CONFIG_FEATURE_INIT_COREDUMPS
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(cmdpath, cmd, environment);
/* We're still here? Some error happened. */
message(LOG | CONSOLE, "\rBummer, could not run '%s': %s\n", cmdpath,
strerror(errno));
_exit(-1);
}
sigprocmask(SIG_SETMASK, &omask, NULL);
return pid;
}
static int waitfor(struct init_action *a)
{
int pid;
int status, wpid;
pid = run(a);
while (1) {
wpid = wait(&status);
if (wpid > 0 && wpid != pid) {
continue;
}
if (wpid == pid)
break;
}
return wpid;
}
/* Run all commands of a particular type */
static void run_actions(int action)
{
struct init_action *a, *tmp;
for (a = init_action_list; a; a = tmp) {
tmp = a->next;
if (a->action == action) {
if (a->
action & (SYSINIT | WAIT | CTRLALTDEL | SHUTDOWN | RESTART)) {
waitfor(a);
delete_init_action(a);
} else if (a->action & ONCE) {
run(a);
delete_init_action(a);
} else if (a->action & (RESPAWN | ASKFIRST)) {
/* Only run stuff with pid==0. If they have
* a pid, that means it is still running */
if (a->pid == 0) {
a->pid = run(a);
}
}
}
}
}
#ifndef DEBUG_INIT
static void shutdown_system(void)
{
sigset_t block_signals;
/* run everything to be run at "shutdown". This is done _prior_
* to killing everything, in case people wish to use scripts to
* shut things down gracefully... */
run_actions(SHUTDOWN);
/* first disable all our signals */
sigemptyset(&block_signals);
sigaddset(&block_signals, SIGHUP);
sigaddset(&block_signals, SIGCHLD);
sigaddset(&block_signals, SIGUSR1);
sigaddset(&block_signals, SIGUSR2);
sigaddset(&block_signals, SIGINT);
sigaddset(&block_signals, SIGTERM);
sigaddset(&block_signals, SIGCONT);
sigaddset(&block_signals, SIGSTOP);
sigaddset(&block_signals, SIGTSTP);
sigprocmask(SIG_BLOCK, &block_signals, NULL);
/* Allow Ctrl-Alt-Del to reboot system. */
init_reboot(RB_ENABLE_CAD);
message(CONSOLE | LOG, "\n\rThe system is going down NOW !!\n");
sync();
/* Send signals to every process _except_ pid 1 */
message(CONSOLE | LOG, "\rSending SIGTERM to all processes.\n");
kill(-1, SIGTERM);
sleep(1);
sync();
message(CONSOLE | LOG, "\rSending SIGKILL to all processes.\n");
kill(-1, SIGKILL);
sleep(1);
sync();
if (kernelVersion > 0 && kernelVersion <= KERNEL_VERSION(2, 2, 11)) {
/* bdflush, kupdate not needed for kernels >2.2.11 */
bdflush(1, 0);
sync();
}
}
static void exec_signal(int sig)
{
struct init_action *a, *tmp;
sigset_t unblock_signals;
for (a = init_action_list; a; a = tmp) {
tmp = a->next;
if (a->action & RESTART) {
shutdown_system();
/* unblock all signals, blocked in shutdown_system() */
sigemptyset(&unblock_signals);
sigaddset(&unblock_signals, SIGHUP);
sigaddset(&unblock_signals, SIGCHLD);
sigaddset(&unblock_signals, SIGUSR1);
sigaddset(&unblock_signals, SIGUSR2);
sigaddset(&unblock_signals, SIGINT);
sigaddset(&unblock_signals, SIGTERM);
sigaddset(&unblock_signals, SIGCONT);
sigaddset(&unblock_signals, SIGSTOP);
sigaddset(&unblock_signals, SIGTSTP);
sigprocmask(SIG_UNBLOCK, &unblock_signals, NULL);
message(CONSOLE | LOG, "\rTrying to re-exec %s\n", a->command);
execl(a->command, a->command, NULL);
message(CONSOLE | LOG, "\rexec of '%s' failed: %s\n",
a->command, strerror(errno));
sync();
sleep(2);
init_reboot(RB_HALT_SYSTEM);
loop_forever();
}
}
}
static void halt_signal(int sig)
{
shutdown_system();
message(CONSOLE | LOG,
#if #cpu(s390)
/* Seems the s390 console is Wierd(tm). */
"\rThe system is halted. You may reboot now.\n"
#else
"\rThe system is halted. Press Reset or turn off power\n"
#endif
);
sync();
/* allow time for last message to reach serial console */
sleep(2);
if (sig == SIGUSR2 && kernelVersion >= KERNEL_VERSION(2, 2, 0))
init_reboot(RB_POWER_OFF);
else
init_reboot(RB_HALT_SYSTEM);
loop_forever();
}
static void reboot_signal(int sig)
{
shutdown_system();
message(CONSOLE | LOG, "\rPlease stand by while rebooting the system.\n");
sync();
/* allow time for last message to reach serial console */
sleep(2);
init_reboot(RB_AUTOBOOT);
loop_forever();
}
static void ctrlaltdel_signal(int sig)
{
run_actions(CTRLALTDEL);
}
/* The SIGSTOP & SIGTSTP handler */
static void stop_handler(int sig)
{
int saved_errno = errno;
got_cont = 0;
while (!got_cont)
pause();
got_cont = 0;
errno = saved_errno;
}
/* The SIGCONT handler */
static void cont_handler(int sig)
{
got_cont = 1;
}
#endif /* ! DEBUG_INIT */
static void new_init_action(int action, char *command, char *cons)
{
struct init_action *new_action, *a;
if (*cons == '\0')
cons = console;
/* do not run entries if console device is not available */
if (access(cons, R_OK | W_OK))
return;
if (strcmp(cons, "/dev/null") == 0 && (action & ASKFIRST))
return;
new_action = calloc((size_t) (1), sizeof(struct init_action));
if (!new_action) {
message(LOG | CONSOLE, "\rMemory allocation failure\n");
loop_forever();
}
/* Append to the end of the list */
for (a = init_action_list; a && a->next; a = a->next);
if (a) {
a->next = new_action;
} else {
init_action_list = new_action;
}
strcpy(new_action->command, command);
new_action->action = action;
strcpy(new_action->terminal, cons);
new_action->pid = 0;
/* message(LOG|CONSOLE, "command='%s' action='%d' terminal='%s'\n",
new_action->command, new_action->action, new_action->terminal); */
}
static void delete_init_action(struct init_action *action)
{
struct init_action *a, *b = NULL;
for (a = init_action_list; a; b = a, a = a->next) {
if (a == action) {
if (b == NULL) {
init_action_list = a->next;
} else {
b->next = a->next;
}
free(a);
break;
}
}
}
/* NOTE that if CONFIG_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 CONFIG_FEATURE_USE_INITTAB
* _is_ defined, but /etc/inittab is missing, this
* results in the same set of default behaviors.
*/
static void parse_inittab(void)
{
#ifdef CONFIG_FEATURE_USE_INITTAB
FILE *file;
char buf[INIT_BUFFS_SIZE], lineAsRead[INIT_BUFFS_SIZE],
tmpConsole[INIT_BUFFS_SIZE];
char *id, *runlev, *action, *command, *eol;
const struct init_action_type *a = actions;
int foundIt;
file = fopen(INITTAB, "r");
if (file == NULL) {
/* No inittab file -- set up some default behavior */
#endif
/* Reboot on Ctrl-Alt-Del */
new_init_action(CTRLALTDEL, "/sbin/reboot", console);
/* Umount all filesystems on halt/reboot */
new_init_action(SHUTDOWN, "/bin/umount -a -r", console);
#if !defined(__UCLIBC__) || defined(__UCLIBC_HAS_MMU__)
/* Swapoff on halt/reboot */
new_init_action(SHUTDOWN, "/sbin/swapoff -a", console);
#endif
/* Prepare to restart init when a HUP is received */
new_init_action(RESTART, "/sbin/init", console);
/* Askfirst shell on tty1-4 */
new_init_action(ASKFIRST, LOGIN_SHELL, console);
new_init_action(ASKFIRST, LOGIN_SHELL, VC_2);
new_init_action(ASKFIRST, LOGIN_SHELL, VC_3);
new_init_action(ASKFIRST, LOGIN_SHELL, VC_4);
/* sysinit */
new_init_action(SYSINIT, INIT_SCRIPT, console);
return;
#ifdef CONFIG_FEATURE_USE_INITTAB
}
while (fgets(buf, INIT_BUFFS_SIZE, 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, "\rBad 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, "\rBad inittab entry: %s\n", lineAsRead);
continue;
} else {
*action = '\0';
++action;
}
/* Separate the action from the command */
command = strchr(action, ':');
if (command == NULL || *(command + 1) == '\0') {
message(LOG | CONSOLE, "\rBad inittab entry: %s\n", lineAsRead);
continue;
} else {
*command = '\0';
++command;
}
/* Ok, now process it */
a = actions;
while (a->name != 0) {
if (strcmp(a->name, action) == 0) {
if (*id != '\0') {
strcpy(tmpConsole, "/dev/");
strncat(tmpConsole, id, INIT_BUFFS_SIZE - 6);
id = tmpConsole;
}
new_init_action(a->action, command, id);
foundIt = TRUE;
}
a++;
}
if (foundIt == TRUE)
continue;
else {
/* Choke on an unknown action */
message(LOG | CONSOLE, "\rBad inittab entry: %s\n", lineAsRead);
}
}
fclose(file);
return;
#endif /* CONFIG_FEATURE_USE_INITTAB */
}
extern int init_main(int argc, char **argv)
{
struct init_action *a;
pid_t wpid;
int status;
if (argc > 1 && !strcmp(argv[1], "-q")) {
/* don't assume init's pid == 1 */
long *pid = find_pid_by_name("init");
if (!pid || *pid <= 0) {
pid = find_pid_by_name("linuxrc");
if (!pid || *pid <= 0)
error_msg_and_die("no process killed");
}
kill(*pid, SIGHUP);
exit(0);
}
#ifndef DEBUG_INIT
/* Expect to be invoked as init with PID=1 or be invoked as linuxrc */
if (getpid() != 1
#ifdef CONFIG_FEATURE_INITRD
&& strstr(applet_name, "linuxrc") == NULL
#endif
) {
show_usage();
}
/* Set up sig handlers -- be sure to
* clear all of these in run() */
signal(SIGHUP, exec_signal);
signal(SIGUSR1, halt_signal);
signal(SIGUSR2, halt_signal);
signal(SIGINT, ctrlaltdel_signal);
signal(SIGTERM, reboot_signal);
signal(SIGCONT, cont_handler);
signal(SIGSTOP, stop_handler);
signal(SIGTSTP, stop_handler);
/* 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);
if (device_open(console, O_RDWR | O_NOCTTY) == 0) {
set_term(0);
close(0);
}
chdir("/");
setsid();
/* Make sure PATH is set to something sane */
putenv("PATH=" _PATH_STDPATH);
/* Hello world */
message(MAYBE_CONSOLE | LOG, "\rinit started: %s\n", full_version);
/* 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 tty2-4 */
new_init_action(ASKFIRST, LOGIN_SHELL, VC_2);
new_init_action(ASKFIRST, LOGIN_SHELL, VC_3);
new_init_action(ASKFIRST, LOGIN_SHELL, VC_4);
/* Start a shell on tty1 */
new_init_action(RESPAWN, LOGIN_SHELL, console);
} else {
/* Not in single user mode -- see what inittab says */
/* NOTE that if CONFIG_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();
}
/* Make the command line just say "init" -- thats all, nothing else */
fixup_argv(argc, argv, "init");
/* Now run everything that needs to be run */
/* First run the sysinit command */
run_actions(SYSINIT);
/* Next run anything that wants to block */
run_actions(WAIT);
/* Next run anything to be run only once */
run_actions(ONCE);
/* If there is nothing else to do, stop */
if (init_action_list == NULL) {
message(LOG | CONSOLE,
"\rNo more tasks for init -- sleeping forever.\n");
loop_forever();
}
/* Now run the looping stuff for the rest of forever */
while (1) {
/* run the respawn stuff */
run_actions(RESPAWN);
/* run the askfirst stuff */
run_actions(ASKFIRST);
/* Don't consume all CPU time -- sleep a bit */
sleep(1);
/* Wait for a child process to exit */
wpid = wait(&status);
if (wpid > 0) {
/* Find out who died and clean up their corpse */
for (a = init_action_list; a; a = a->next) {
if (a->pid == wpid) {
/* Set the pid to 0 so that the process gets
* restarted by run_actions() */
a->pid = 0;
message(LOG, "Process '%s' (pid %d) exited. "
"Scheduling it for restart.\n", a->command, wpid);
}
}
}
}
}
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/
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