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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
*
*/
#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 <paths.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>
#include <linux/serial.h> /* for serial_struct */
#include <sys/vt.h> /* for vt_stat */
#include <sys/ioctl.h>
#include <linux/version.h>
#ifdef BB_SYSLOGD
#include <sys/syslog.h>
#endif
#if ! defined BB_FEATURE_USE_PROCFS
#error Sorry, I depend on the /proc filesystem right now.
#endif
#ifndef KERNEL_VERSION
#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
#endif
#define VT_PRIMARY "/dev/tty1" /* Primary virtual console */
#define VT_SECONDARY "/dev/tty2" /* Virtual console */
#define VT_LOG "/dev/tty3" /* Virtual console */
#define SERIAL_CON0 "/dev/ttyS0" /* Primary serial console */
#define SERIAL_CON1 "/dev/ttyS1" /* Serial console */
#define GETTY "/sbin/getty" /* Default location of getty */
#define SHELL "/bin/sh" /* Default shell */
#ifndef BB_INIT_SCRIPT
#define BB_INIT_SCRIPT "/etc/init.d/rcS" /* Initscript. */
#endif
#define LOG 0x1
#define CONSOLE 0x2
static char *console = _PATH_CONSOLE;
static char *second_console = VT_SECONDARY;
static char *log = VT_LOG;
static int kernel_version = 0;
/* try to open up the specified device */
int device_open(char *device, int mode)
{
int m, f, fd = -1;
m = mode | O_NONBLOCK;
/* Retry up to 5 times */
for (f = 0; f < 5; f++)
if ((fd = open(device, m)) >= 0)
break;
if (fd < 0)
return fd;
/* Reset original flags. */
if (m != mode)
fcntl(fd, F_SETFL, mode);
return fd;
}
/* print a message to the specified device:
* device may be bitwise-or'd from LOG | CONSOLE */
void message(int device, char *fmt, ...)
{
int fd;
va_list arguments;
#ifdef BB_SYSLOGD
/* Log the message to syslogd */
if (device & LOG ) {
char msg[1024];
va_start(arguments, fmt);
vsnprintf(msg, sizeof(msg), fmt, arguments);
va_end(arguments);
syslog(LOG_DAEMON|LOG_NOTICE, 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 == NULL) {
/* don't even try to log, because there is no such console */
log_fd = -2;
/* log to main console instead */
device = CONSOLE;
}
else if ((log_fd = device_open(log, O_RDWR|O_NDELAY)) < 0) {
log_fd=-1;
fprintf(stderr, "Bummer, can't write to log on %s!\r\n", log);
fflush(stderr);
return;
}
}
if ( (device & LOG) && (log_fd >= 0) ) {
va_start(arguments, fmt);
vdprintf(log_fd, fmt, arguments);
va_end(arguments);
}
#endif
if (device & CONSOLE) {
/* Always send console messages to /dev/console so people will see them. */
if ((fd = device_open(_PATH_CONSOLE, O_WRONLY|O_NOCTTY|O_NDELAY)) >= 0) {
va_start(arguments, fmt);
vdprintf(fd, fmt, arguments);
va_end(arguments);
close(fd);
} else {
fprintf(stderr, "Bummer, can't print: ");
va_start(arguments, fmt);
vfprintf(stderr, fmt, arguments);
fflush(stderr);
va_end(arguments);
}
}
}
/* Set terminal settings to reasonable defaults */
void set_term( int fd)
{
struct termios tty;
static const char control_characters[] = {
'\003', '\034', '\177', '\025', '\004', '\0',
'\1', '\0', '\021', '\023', '\032', '\0', '\022',
'\017', '\027', '\026', '\0'
};
tcgetattr(fd, &tty);
/* set control chars */
memcpy(tty.c_cc, control_characters, sizeof(control_characters));
/* use line dicipline 0 */
tty.c_line = 0;
/* Make it be sane */
//tty.c_cflag &= CBAUD|CBAUDEX|CSIZE|CSTOPB|PARENB|PARODD;
//tty.c_cflag |= HUPCL|CLOCAL;
/* input modes */
tty.c_iflag = ICRNL|IXON|IXOFF;
/* output modes */
tty.c_oflag = OPOST|ONLCR;
/* local modes */
tty.c_lflag = ISIG|ICANON|ECHO|ECHOE|ECHOK|ECHOCTL|ECHOKE|IEXTEN;
tcsetattr(fd, TCSANOW, &tty);
}
/* How much memory does this machine have? */
static int mem_total()
{
char s[80];
char *p = "/proc/meminfo";
FILE *f;
const char pattern[] = "MemTotal:";
if ((f = fopen(p, "r")) < 0) {
message(LOG, "Error opening %s: %s\n", p, strerror( errno));
return -1;
}
while (NULL != fgets(s, 79, f)) {
p = strstr(s, pattern);
if (NULL != p) {
fclose(f);
return (atoi(p + strlen(pattern)));
}
}
return -1;
}
static void console_init()
{
int fd;
int tried_devcons = 0;
int tried_vtprimary = 0;
struct serial_struct sr;
char *s;
if ((s = getenv("CONSOLE")) != NULL) {
console = s;
}
#if #cpu(sparc)
/* sparc kernel supports console=tty[ab] parameter which is also
* passed to init, so catch it here */
else if ((s = getenv("console")) != NULL) {
/* remap tty[ab] to /dev/ttyS[01] */
if (strcmp( s, "ttya" )==0)
console = SERIAL_CON0;
else if (strcmp( s, "ttyb" )==0)
console = SERIAL_CON1;
}
#endif
else {
struct vt_stat vt;
static char the_console[13];
console = the_console;
/* 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( the_console, sizeof the_console, "/dev/ttyS%d", sr.line );
}
else if (ioctl(0, VT_GETSTATE, &vt) == 0) {
/* this is linux virtual tty */
snprintf( the_console, sizeof the_console, "/dev/tty%d", vt.v_active );
} else {
console = _PATH_CONSOLE;
tried_devcons++;
}
}
while ((fd = open(console, O_RDONLY | O_NONBLOCK)) < 0) {
/* Can't open selected console -- try /dev/console */
if (!tried_devcons) {
tried_devcons++;
console = _PATH_CONSOLE;
continue;
}
/* Can't open selected console -- try vt1 */
if (!tried_vtprimary) {
tried_vtprimary++;
console = VT_PRIMARY;
continue;
}
break;
}
if (fd < 0)
/* Perhaps we should panic here? */
console = "/dev/null";
else {
/* check for serial console and disable logging to tty3 & running a
* shell to tty2 */
if (ioctl(0,TIOCGSERIAL,&sr) == 0) {
message(LOG|CONSOLE, "serial console detected. Disabling 2nd virtual terminal.\r\n", console );
log = NULL;
second_console = NULL;
}
close(fd);
}
message(LOG, "console=%s\n", console );
}
static int waitfor(int pid)
{
int status, wpid;
message(LOG, "Waiting for process %d.\n", pid);
while ((wpid = wait(&status)) != pid) {
if (wpid > 0)
message(LOG, "pid %d exited, status=0x%x.\n", wpid, status);
}
return wpid;
}
static pid_t run(const char * const* command,
char *terminal, int get_enter)
{
int fd;
pid_t pid;
const char * const* cmd = command+1;
static const char press_enter[] =
"\nPlease press Enter to activate this console. ";
if ((pid = fork()) == 0) {
/* Clean up */
close(0);
close(1);
close(2);
setsid();
/* Reset signal handlers set for parent process */
signal(SIGUSR1, SIG_DFL);
signal(SIGUSR2, SIG_DFL);
signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
if ((fd = device_open(terminal, O_RDWR)) < 0) {
message(LOG, "Bummer, can't open %s\r\n", terminal);
exit(-1);
}
dup(fd);
dup(fd);
tcsetpgrp(0, getpgrp());
set_term(0);
if (get_enter==TRUE) {
/*
* Save memory by not exec-ing anything large (like a shell)
* before the user wants it. This is critical if swap is not
* enabled and the system has low memory. Generally this will
* be run on the second virtual console, and the first will
* be allowed to start a shell or whatever an init script
* specifies.
*/
char c;
message(LOG, "Waiting for enter to start '%s' (pid %d, console %s)\r\n",
*cmd, getpid(), terminal );
write(1, press_enter, sizeof(press_enter) - 1);
read(0, &c, 1);
}
/* Log the process name and args */
message(LOG|CONSOLE, "Starting pid %d, console %s: '", getpid(), terminal);
while ( *cmd) message(LOG|CONSOLE, "%s ", *cmd++);
message(LOG|CONSOLE, "'\r\n");
/* Now run it. The new program will take over this PID,
* so nothing further in init.c should be run. */
execvp(*command, (char**)command+1);
message(LOG, "Bummer, could not run '%s'\n", command);
exit(-1);
}
return pid;
}
/* Make sure there is enough memory to do something useful. *
* Calls swapon if needed so be sure /proc is mounted. */
static void check_memory()
{
struct stat statbuf;
const char* const swap_on_cmd[] =
{ "/bin/swapon", "swapon", "-a", 0};
if (mem_total() > 3500)
return;
if (stat("/etc/fstab", &statbuf) == 0) {
/* Try to turn on swap */
waitfor(run(swap_on_cmd, log, FALSE));
if (mem_total() < 3500)
goto goodnight;
} else
goto goodnight;
return;
goodnight:
message(CONSOLE, "Sorry, your computer does not have enough memory.\r\n");
while (1) sleep(1);
}
static void shutdown_system(void)
{
const char* const swap_off_cmd[] = { "swapoff", "swapoff", "-a", 0};
const char* const umount_cmd[] = { "umount", "umount", "-a", 0};
#ifndef DEBUG_INIT
/* Allow Ctrl-Alt-Del to reboot system. */
reboot(RB_ENABLE_CAD);
#endif
message(CONSOLE, "\r\nThe system is going down NOW !!\r\n");
sync();
/* Send signals to every process _except_ pid 1 */
message(CONSOLE, "Sending SIGHUP to all processes.\r\n");
#ifndef DEBUG_INIT
kill(-1, SIGHUP);
#endif
sleep(2);
sync();
message(CONSOLE, "Sending SIGKILL to all processes.\r\n");
#ifndef DEBUG_INIT
kill(-1, SIGKILL);
#endif
sleep(1);
message(CONSOLE, "Disabling swap.\r\n");
waitfor(run( swap_off_cmd, console, FALSE));
message(CONSOLE, "Unmounting filesystems.\r\n");
waitfor(run( umount_cmd, console, FALSE));
sync();
if (kernel_version > 0 && kernel_version <= 2 * 65536 + 2 * 256 + 11) {
/* bdflush, kupdate not needed for kernels >2.2.11 */
message(CONSOLE, "Flushing buffers.\r\n");
bdflush(1, 0);
sync();
}
}
static void halt_signal(int sig)
{
shutdown_system();
message(CONSOLE,
"The system is halted. Press CTRL-ALT-DEL or turn off power\r\n");
sync();
#ifndef DEBUG_INIT
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)
if (sig == SIGUSR2)
reboot(RB_POWER_OFF);
else
#endif
reboot(RB_HALT_SYSTEM);
#endif
exit(0);
}
static void reboot_signal(int sig)
{
shutdown_system();
message(CONSOLE, "Please stand by while rebooting the system.\r\n");
sync();
#ifndef DEBUG_INIT
reboot(RB_AUTOBOOT);
#endif
exit(0);
}
extern int init_main(int argc, char **argv)
{
int run_rc = FALSE;
int single = FALSE;
int wait_for_enter_tty1 = TRUE;
int wait_for_enter_tty2 = TRUE;
pid_t pid1 = 0;
pid_t pid2 = 0;
struct stat statbuf;
char which_vt1[30];
char which_vt2[30];
const char* const rc_script_command[] = { BB_INIT_SCRIPT, BB_INIT_SCRIPT, 0};
const char* const getty1_command[] = { GETTY, GETTY, "38400", which_vt1, 0};
const char* const getty2_command[] = { GETTY, GETTY, "38400", which_vt2, 0};
const char* const shell_command[] = { SHELL, "-" SHELL, 0};
const char* const* tty1_command = shell_command;
const char* const* tty2_command = shell_command;
#ifdef BB_INIT_CMD_IF_RC_SCRIPT_EXITS
const char* const rc_exit_command[] = { "BB_INIT_CMD_IF_RC_SCRIPT_EXITS",
"BB_INIT_CMD_IF_RC_SCRIPT_EXITS", 0 };
#endif
#ifdef DEBUG_INIT
char *hello_msg_format =
"init(%d) started: BusyBox v%s (%s) multi-call binary\r\n";
#else
char *hello_msg_format =
"init started: BusyBox v%s (%s) multi-call binary\r\n";
#endif
#ifndef DEBUG_INIT
/* Expect to be PID 1 iff we are run as init (not linuxrc) */
if (getpid() != 1 && strstr(argv[0], "init")!=NULL ) {
usage( "init\n\nInit is the parent of all processes.\n\n"
"This version of init is designed to be run only by the kernel\n");
}
#endif
/* Set up sig handlers -- be sure to
* clear all of these in run() */
signal(SIGUSR1, halt_signal);
signal(SIGUSR2, reboot_signal);
signal(SIGINT, reboot_signal);
signal(SIGTERM, reboot_signal);
/* Turn off rebooting via CTL-ALT-DEL -- we get a
* SIGINT on CAD so we can shut things down gracefully... */
#ifndef DEBUG_INIT
reboot(RB_DISABLE_CAD);
#endif
/* Figure out where the default console should be */
console_init();
/* Close whatever files are open, and reset the console. */
close(0);
close(1);
close(2);
set_term(0);
setsid();
/* Make sure PATH is set to something sane */
putenv(_PATH_STDPATH);
/* Hello world */
#ifndef DEBUG_INIT
message(CONSOLE|LOG, hello_msg_format, BB_VER, BB_BT);
#else
message(CONSOLE|LOG, hello_msg_format, getpid(), BB_VER, BB_BT);
#endif
/* Mount /proc */
if (mount ("proc", "/proc", "proc", 0, 0) == 0) {
message(CONSOLE|LOG, "Mounting /proc: done.\n");
kernel_version = get_kernel_revision();
} else
message(CONSOLE|LOG, "Mounting /proc: failed!\n");
/* 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"))) {
single = TRUE;
tty1_command = shell_command;
tty2_command = shell_command;
}
/* Make sure an init script exists before trying to run it */
if (single==FALSE && stat(BB_INIT_SCRIPT, &statbuf)==0) {
run_rc = TRUE;
wait_for_enter_tty1 = FALSE;
tty1_command = rc_script_command;
}
/* Make sure /sbin/getty exists before trying to run it */
if (stat(GETTY, &statbuf)==0) {
char* where;
/* First do tty2 */
wait_for_enter_tty2 = FALSE;
where = strrchr( second_console, '/');
if ( where != NULL) {
where++;
strncpy( which_vt2, where, sizeof(which_vt2));
}
tty2_command = getty2_command;
/* Check on hooking a getty onto tty1 */
if (run_rc == FALSE && single==FALSE) {
wait_for_enter_tty1 = FALSE;
where = strrchr( console, '/');
if ( where != NULL) {
where++;
strncpy( which_vt1, where, sizeof(which_vt1));
}
tty1_command = getty1_command;
}
}
/* Ok, now launch the tty1_command and tty2_command */
for (;;) {
pid_t wpid;
int status;
if (pid1 == 0 && tty1_command) {
pid1 = run(tty1_command, console, wait_for_enter_tty1);
}
#ifdef BB_FEATURE_INIT_SECOND_CONSOLE
if (pid2 == 0 && tty2_command && second_console) {
pid2 = run(tty2_command, second_console, wait_for_enter_tty2);
}
#endif
wpid = wait(&status);
if (wpid > 0 ) {
message(LOG, "pid %d exited, status=%x.\n", wpid, status);
}
/* Don't respawn init script if it exits */
if (wpid == pid1) {
if (run_rc == FALSE) {
pid1 = 0;
}
#ifdef BB_INIT_CMD_IF_RC_SCRIPT_EXITS
else {
pid1 = 0;
run_rc=FALSE;
wait_for_enter_tty1=TRUE;
tty1_command=rc_exit_command;
}
#endif
}
#ifdef BB_FEATURE_INIT_SECOND_CONSOLE
if (wpid == pid2) {
pid2 = 0;
}
#endif
sleep(1);
}
}
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