busybox/init.c

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/*
* Mini init implementation for busybox
*
*
* Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
* Adjusted by so many folks, it's impossible to keep track.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
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#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <termios.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <sys/wait.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/reboot.h>
#include <sys/kdaemon.h>
#include <sys/sysmacros.h>
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#include <linux/serial.h> /* for serial_struct */
#include <sys/vt.h> /* for vt_stat */
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#include <sys/ioctl.h>
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#define DEBUG_INIT
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#define CONSOLE "/dev/console" /* Logical system console */
#define VT_PRIMARY "/dev/tty0" /* Virtual console master */
#define VT_SECONDARY "/dev/tty1" /* Virtual console master */
#define VT_LOG "/dev/tty2" /* Virtual console master */
#define SHELL "/bin/sh" /* Default shell */
#define INITSCRIPT "/etc/init.d/rcS" /* Initscript. */
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#define PATH_DEFAULT "PATH=/usr/local/sbin:/sbin:/bin:/usr/sbin:/usr/bin"
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static char *console = CONSOLE;
static char *second_terminal = "/dev/tty2";
static char *log = "/dev/tty3";
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/* try to open up the specified device */
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int device_open(char *device, int mode)
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{
int m, f, fd = -1;
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mode = m | O_NONBLOCK;
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/* Retry up to 5 times */
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for (f = 0; f < 5; f++)
if ((fd = open(device, m)) >= 0)
break;
if (fd < 0)
return fd;
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/* Set original flags. */
if (m != mode)
fcntl(fd, F_SETFL, mode);
return fd;
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}
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/* print a message to the specified device */
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void message(char *device, char *fmt, ...)
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{
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int fd;
va_list arguments;
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if ((fd = device_open(device, O_WRONLY | O_NOCTTY | O_NDELAY)) >= 0) {
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va_start(arguments, fmt);
vdprintf(fd, fmt, arguments);
va_end(arguments);
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close(fd);
} else
vprintf(fmt, arguments);
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}
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/* Set terminal settings to reasonable defaults */
void set_term()
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{
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int fd;
struct termios tty;
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if ((fd = device_open(console, O_RDWR | O_NOCTTY)) < 0) {
message(log, "can't open %s\n", console);
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return;
}
ioctl(fd, TCGETS, &tty);
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tty.c_cflag &= CBAUD | CBAUDEX | CSIZE | CSTOPB | PARENB | PARODD;
tty.c_cflag |= HUPCL | CLOCAL;
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tty.c_cc[VINTR] = 3;
tty.c_cc[VQUIT] = 28;
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tty.c_cc[VERASE] = 127;
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tty.c_cc[VKILL] = 24;
tty.c_cc[VEOF] = 4;
tty.c_cc[VTIME] = 0;
tty.c_cc[VMIN] = 1;
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tty.c_cc[VSTART] = 17;
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tty.c_cc[VSTOP] = 19;
tty.c_cc[VSUSP] = 26;
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/* Set pre and post processing */
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tty.c_iflag = IGNPAR | ICRNL | IXON | IXANY;
tty.c_oflag = OPOST | ONLCR;
tty.c_lflag = ISIG | ICANON | ECHO | ECHOCTL | ECHOPRT | ECHOKE;
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/* Now set the terminal line. */
ioctl(fd, TCSETS, &tty);
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close(fd);
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}
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static int mem_total()
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{
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char s[80];
char *p;
FILE *f;
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const char pattern[] = "MemTotal:";
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f = fopen("/proc/meminfo", "r");
while (NULL != fgets(s, 79, f)) {
p = strstr(s, pattern);
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if (NULL != p) {
fclose(f);
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return (atoi(p + strlen(pattern)));
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}
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}
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return -1;
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}
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static void set_free_pages()
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{
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char s[80];
FILE *f;
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f = fopen("/proc/sys/vm/freepages", "r");
fgets(s, 79, f);
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if (atoi(s) < 32) {
fclose(f);
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f = fopen("/proc/sys/vm/freepages", "w");
fprintf(f, "30\t40\t50\n");
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printf("\nIncreased /proc/sys/vm/freepages values to 30/40/50\n");
}
fclose(f);
}
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static void console_init()
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{
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int fd;
int tried_devcons = 0;
int tried_vtmaster = 0;
char *s;
if ((s = getenv("CONSOLE")) != NULL)
console = s;
else {
console = CONSOLE;
tried_devcons++;
}
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while ((fd = open(console, O_RDONLY | O_NONBLOCK)) < 0) {
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if (!tried_devcons) {
tried_devcons++;
console = CONSOLE;
continue;
}
if (!tried_vtmaster) {
tried_vtmaster++;
console = VT_PRIMARY;
continue;
}
break;
}
if (fd < 0)
console = "/dev/null";
else
close(fd);
}
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static int waitfor(int pid)
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{
int status, wpid;
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message(log, "Waiting for process %d.\n", pid);
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while ((wpid = wait(&status)) != pid) {
if (wpid > 0)
message(log, "pid %d exited, status=%x.\n", wpid, status);
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}
return wpid;
}
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static int run(const char *command, char *terminal, int get_enter)
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{
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int f, pid;
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char *args[16];
char buf[256];
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char *ptr;
static const char press_enter[] =
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"\nPlease press Enter to activate this console. ";
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/* Make a proper command from the command string */
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strcpy(buf, command);
ptr = buf;
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for (f = 1; f < 15; f++) {
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/* Skip white space */
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while (*ptr == ' ' || *ptr == '\t')
ptr++;
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args[f] = ptr;
/* May be trailing space.. */
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if (*ptr == 0)
break;
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/* Skip this `word' */
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while (*ptr && *ptr != ' ' && *ptr != '\t' && *ptr != '#')
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ptr++;
/* If end-of-line, break */
if (*ptr == '#' || *ptr == 0) {
f++;
*ptr = 0;
break;
}
/* End word with \0 and continue */
args[f] = NULL;
}
args[0] = args[1];
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if ((pid = fork()) == 0) {
/* Clean up */
close(0);
close(1);
close(2);
setsid();
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if ((f = device_open(terminal, O_RDWR | O_NOCTTY)) < 0) {
message(log, "open(%s) failed: %s\n", terminal, strerror(errno));
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return -1;
}
dup(f);
dup(f);
tcsetpgrp(0, getpgrp());
set_term();
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if (get_enter) {
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/*
* 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.
*/
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char c;
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write(1, press_enter, sizeof(press_enter) - 1);
read(0, &c, 1);
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message(console, "Got an enter\r\n");
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}
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/* Log the process name and args */
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message(console, "Executing ");
message(console, "'%s'\r\n", command);
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/* Now run it. This should take over the PID, so nothing
* further in init.c should be run by this PID. */
execvp(args[1], args + 1);
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message(console, "Hmm. Trying as a script.\r\n");
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/* If shell scripts are not executed, force the issue */
if (errno == ENOEXEC) {
char buf[256];
args[1] = SHELL;
args[2] = "-c";
strcpy(buf, "exec ");
strcat(buf, command);
args[3] = buf;
args[4] = NULL;
execvp(args[1], args + 1);
}
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message(console, "Could not execute '%s'\n", command);
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exit(-1);
}
return pid;
}
#ifndef DEBUG_INIT
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static void shutdown_system(void)
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{
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message(console, "The system is going down NOW !!\r\n");
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sync();
/* Allow Ctrl-Alt-Del to reboot system. */
reboot(RB_ENABLE_CAD);
/* Send signals to every process _except_ pid 1 */
message(console, "Sending SIGHUP to all processes.\r\n");
kill(-1, SIGHUP);
sleep(2);
sync();
message(console, "Sending SIGKILL to all processes.\r\n");
kill(-1, SIGKILL);
sleep(1);
waitfor(run("/bin/swapoff -a", console, 0));
waitfor(run("/bin/umount -a -n", console, 0));
sync();
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if (get_kernel_revision() <= 2 * 65536 + 2 * 256 + 11) {
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/* Removed bdflush call, kupdate in kernels >2.2.11 */
bdflush(1, 0);
sync();
}
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}
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static void halt_signal(int sig)
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{
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shutdown_system();
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message(console,
"The system is halted. Press CTRL-ALT-DEL or turn off power\r\n");
reboot(RB_POWER_OFF);
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exit(0);
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}
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static void reboot_signal(int sig)
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{
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shutdown_system();
message(console, "Please stand by while rebooting the system.\r\n");
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reboot(RB_AUTOBOOT);
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exit(0);
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}
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#endif
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extern int init_main(int argc, char **argv)
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{
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int run_rc = TRUE;
int pid1 = 0;
int pid2 = 0;
struct stat statbuf;
const char *init_commands = SHELL "-c exec " INITSCRIPT;
const char *shell_commands = SHELL;
const char *tty0_commands = init_commands;
const char *tty1_commands = shell_commands;
char *hello_msg_format =
"init started: BusyBox v%s (%s) multi-call binary\r\n";
const char *no_memory =
"Sorry, your computer does not have enough memory.\r\n";
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#ifndef DEBUG_INIT
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/* Set up sig handlers */
signal(SIGUSR1, halt_signal);
signal(SIGSEGV, halt_signal);
signal(SIGPWR, halt_signal);
signal(SIGALRM, halt_signal);
signal(SIGHUP, halt_signal);
signal(SIGUSR2, reboot_signal);
signal(SIGINT, reboot_signal);
signal(SIGTERM, reboot_signal);
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#endif
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/* Figure out where the default console should be */
console_init();
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/* Turn off rebooting via CTL-ALT-DEL -- we get a
* SIGINT on CAD so we can shut things down gracefully... */
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#ifndef DEBUG_INIT
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reboot(RB_DISABLE_CAD);
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#endif
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/* Close whatever files are open, and reset the console. */
close(0);
close(1);
close(2);
set_term();
setsid();
/* Make sure PATH is set to something sane */
if (getenv("PATH") == NULL)
putenv(PATH_DEFAULT);
/* Hello world */
message(log, hello_msg_format, BB_VER, BB_BT);
message(console, hello_msg_format, BB_VER, BB_BT);
/* Mount /proc */
if (mount("/proc", "/proc", "proc", 0, 0)) {
message(log, "Mounting /proc: failed!\n");
message(console, "Mounting /proc: failed!\r\n");
} else {
message(console, "Mounting /proc: done.\r\n");
}
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/* Make sure there is enough memory to do something useful */
set_free_pages();
if (mem_total() < 2000) {
int retval;
retval = stat("/etc/fstab", &statbuf);
if (retval) {
message(console, "%s", no_memory);
while (1) {
sleep(1);
}
} else {
/* Try to turn on swap */
waitfor(run("/bin/swapon -a", console, 0));
if (mem_total() < 2000) {
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message(console, "%s", no_memory);
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while (1) {
sleep(1);
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}
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}
}
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}
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/* 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"))) {
run_rc = FALSE;
tty0_commands = shell_commands;
tty1_commands = 0;
}
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/* Make sure an init script exists before trying to run it */
if (run_rc == TRUE && stat(INITSCRIPT, &statbuf)) {
tty0_commands = shell_commands;
tty1_commands = shell_commands;
}
/* Ok, now launch the rc script and/or prepare to
* start up some VTs if somebody hits enter...
*/
for (;;) {
int wpid;
int status;
if (pid1 == 0 && tty0_commands) {
pid1 = run(tty0_commands, console, 1);
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}
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if (pid2 == 0 && tty1_commands) {
pid2 = run(tty1_commands, second_terminal, 1);
}
wpid = wait(&status);
if (wpid > 0 && wpid != pid1) {
message(log, "pid %d exited, status=%x.\n", wpid, status);
}
/* Don't respawn an init script if it exits */
if (run_rc == FALSE && wpid == pid1) {
pid1 = 0;
}
if (wpid == pid2) {
pid2 = 0;
}
sleep(1);
}
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}