busybox/init.c

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1999-10-21 03:38:37 +05:30
/*
* 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 */
#include <sys/ioctl.h>
static const char init_usage[] = "Used internally by the system.";
static char console[16] = "";
static const char* default_console = "/dev/tty2";
static char* first_terminal = NULL;
static const char* second_terminal = "/dev/tty2";
static const char* log = "/dev/tty3";
static char* term_ptr = NULL;
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static void
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message(const char* terminal, const char * pattern, ...)
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{
int fd;
FILE * con = 0;
va_list arguments;
/*
* Open the console device each time a message is printed. If the user
* has switched consoles, the open will get the new console. If we kept
* the console open, we'd always print to the same one.
*/
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if ( !terminal
|| ((fd = open(terminal, O_WRONLY|O_NOCTTY)) < 0)
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|| ((con = fdopen(fd, "w")) == NULL) )
return;
va_start(arguments, pattern);
vfprintf(con, pattern, arguments);
va_end(arguments);
fclose(con);
}
static int
waitfor(int pid)
{
int status;
int wpid;
message(log, "Waiting for process %d.\n", pid);
while ( (wpid = wait(&status)) != pid ) {
if ( wpid > 0 ) {
message(
log
,"pid %d exited, status=%x.\n"
,wpid
,status);
}
}
return wpid;
}
static int
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run(const char* program, const char* const* arguments,
const char* terminal, int get_enter)
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{
static const char control_characters[] = {
'\003',
'\034',
'\177',
'\025',
'\004',
'\0',
'\1',
'\0',
'\021',
'\023',
'\032',
'\0',
'\022',
'\017',
'\027',
'\026',
'\0'
};
static char * environment[] = {
"HOME=/",
"PATH=/bin:/sbin:/usr/bin:/usr/sbin",
"SHELL=/bin/sh",
0,
"USER=root",
0
};
static const char press_enter[] =
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"\nPlease press Enter to activate this console. ";
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int pid;
environment[3]=term_ptr;
pid = fork();
if ( pid == 0 ) {
struct termios t;
const char * const * arg;
close(0);
close(1);
close(2);
setsid();
open(terminal, O_RDWR);
dup(0);
dup(0);
tcsetpgrp(0, getpgrp());
tcgetattr(0, &t);
memcpy(t.c_cc, control_characters, sizeof(control_characters));
t.c_line = 0;
t.c_iflag = ICRNL|IXON|IXOFF;
t.c_oflag = OPOST|ONLCR;
t.c_lflag = ISIG|ICANON|ECHO|ECHOE|ECHOK|ECHOCTL|ECHOKE|IEXTEN;
tcsetattr(0, TCSANOW, &t);
if ( get_enter ) {
/*
* 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
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* be allowed to start a shell or whatever an init script
* specifies.
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*/
char c;
write(1, press_enter, sizeof(press_enter) - 1);
read(0, &c, 1);
}
message(log, "Executing ");
arg = arguments;
while ( *arg != 0 )
message(log, "%s ", *arg++);
message(log, "\n");
execve(program, (char * *)arguments, (char * *)environment);
message(log, "%s: could not execute: %s.\r\n", program, strerror(errno));
exit(-1);
}
return pid;
}
static int
mem_total()
{
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char s[80];
char *p;
FILE *f;
const char pattern[]="MemTotal:";
f=fopen("/proc/meminfo","r");
while (NULL != fgets(s,79,f)) {
p=strstr(s, pattern);
if (NULL != p) {
fclose(f);
return(atoi(p+strlen(pattern)));
}
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}
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return -1;
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}
static void
set_free_pages()
{
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char s[80];
FILE *f;
f=fopen("/proc/sys/vm/freepages","r");
fgets(s,79,f);
if (atoi(s) < 32) {
fclose(f);
f=fopen("/proc/sys/vm/freepages","w");
fprintf(f,"30\t40\t50\n");
printf("\nIncreased /proc/sys/vm/freepages values to 30/40/50\n");
}
fclose(f);
}
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static void
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shutdown_system(void)
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{
static const char * const umount_args[] = {"/bin/umount", "-a", "-n", 0};
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static const char * const swapoff_args[] = {"/bin/swapoff", "-a", 0};
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message(console, "The system is going down NOW !!");
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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);
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waitfor(run("/bin/swapoff", swapoff_args, console, 0));
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waitfor(run("/bin/umount", umount_args, console, 0));
sync();
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if (get_kernel_revision() <= 2*65536+2*256+11) {
/* Removed bdflush call, kupdate in kernels >2.2.11 */
bdflush(1, 0);
sync();
}
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}
static void
halt_signal(int sig)
{
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shutdown_system();
message(console, "The system is halted. Press CTRL-ALT-DEL or turn off power\r\n");
reboot( RB_HALT_SYSTEM);
exit(0);
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}
static void
reboot_signal(int sig)
{
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shutdown_system();
message(console, "Please stand by while rebooting the system.\r\n");
reboot( RB_AUTOBOOT);
exit(0);
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}
static void
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configure_terminals( int serial_cons, int single_user_mode )
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{
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char *tty;
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struct serial_struct sr;
struct vt_stat vt;
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switch (serial_cons) {
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case -1:
/* 2.2 kernels:
* identify the real console backend and try to make use of it */
if (ioctl(0,TIOCGSERIAL,&sr) == 0) {
sprintf( console, "/dev/ttyS%d", sr.line );
serial_cons = sr.line+1;
}
else if (ioctl(0, VT_GETSTATE, &vt) == 0) {
sprintf( console, "/dev/tty%d", vt.v_active );
serial_cons = 0;
}
else {
/* unknown backend: fallback to /dev/console */
strcpy( console, "/dev/console" );
serial_cons = 0;
}
break;
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case 1:
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strcpy( console, "/dev/cua0" );
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break;
case 2:
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strcpy( console, "/dev/cua1" );
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break;
default:
tty = ttyname(0);
if (tty) {
strcpy( console, tty );
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if (!strncmp( tty, "/dev/cua", 8 ))
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serial_cons=1;
}
else
/* falls back to /dev/tty1 if an error occurs */
strcpy( console, default_console );
}
if (!first_terminal)
first_terminal = console;
#if defined (__sparc__)
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if (serial_cons > 0 && !strncmp(term_ptr,"TERM=linux",10))
term_ptr = "TERM=vt100";
#endif
if (serial_cons) {
/* disable other but the first terminal:
* VT is not initialized anymore on 2.2 kernel when booting from
* serial console, therefore modprobe is flooding the display with
* "can't locate module char-major-4" messages. */
log = 0;
second_terminal = 0;
}
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}
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extern int
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init_main(int argc, char * * argv)
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{
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const char * rc_arguments[100];
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const char * arguments[100];
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int run_rc = TRUE;
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int j;
int pid1 = 0;
int pid2 = 0;
struct stat statbuf;
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const char * tty_commands[3] = { "etc/init.d/rcS", "bin/sh"};
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int serial_console = 0;
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int retval;
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/*
* If I am started as /linuxrc instead of /sbin/init, I don't have the
* environment that init expects. I can't fix the signal behavior. Try
* to divorce from the controlling terminal with setsid(). This won't work
* if I am the process group leader.
*/
setsid();
signal(SIGUSR1, halt_signal);
signal(SIGUSR2, reboot_signal);
signal(SIGINT, reboot_signal);
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signal(SIGTERM, reboot_signal);
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reboot(RB_DISABLE_CAD);
message(log, "%s: started. ", argv[0]);
for ( j = 1; j < argc; j++ ) {
if ( strcmp(argv[j], "single") == 0 ) {
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run_rc = FALSE;
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tty_commands[0] = "bin/sh";
tty_commands[1] = 0;
}
}
for ( j = 0; __environ[j] != 0; j++ ) {
if ( strncmp(__environ[j], "tty", 3) == 0
&& __environ[j][3] >= '1'
&& __environ[j][3] <= '2'
&& __environ[j][4] == '=' ) {
const char * s = &__environ[j][5];
if ( *s == 0 || strcmp(s, "off") == 0 )
s = 0;
tty_commands[__environ[j][3] - '1'] = s;
}
/* Should catch the syntax of Sparc kernel console setting. */
/* The kernel does not recognize a serial console when getting*/
/* console=/dev/ttySX !! */
else if ( strcmp(__environ[j], "console=ttya") == 0 ) {
serial_console=1;
}
else if ( strcmp(__environ[j], "console=ttyb") == 0 ) {
serial_console=2;
}
/* standard console settings */
else if ( strncmp(__environ[j], "console=", 8) == 0 ) {
first_terminal=&(__environ[j][8]);
}
else if ( strncmp(__environ[j], "TERM=", 5) == 0) {
term_ptr=__environ[j];
}
}
printf("mounting /proc ...\n");
if (mount("/proc","/proc","proc",0,0)) {
perror("mounting /proc failed\n");
}
printf("\tdone.\n");
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if (get_kernel_revision() >= 2*65536+1*256+71) {
/* if >= 2.1.71 kernel, /dev/console is not a symlink anymore:
* use it as primary console */
serial_console=-1;
}
/* Make sure /etc/init.d/rc exists */
retval= stat(tty_commands[0],&statbuf);
if (retval)
run_rc = FALSE;
configure_terminals( serial_console, run_rc);
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set_free_pages();
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/* not enough memory to do anything useful*/
if (mem_total() < 2000) {
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retval= stat("/etc/fstab",&statbuf);
if (retval) {
printf("You do not have enough RAM, sorry.\n");
while (1) { sleep(1);}
} else {
/* Try to turn on swap */
static const char * const swapon_args[] = {"/bin/swapon", "-a", 0};
waitfor(run("/bin/swapon", swapon_args, console, 0));
if (mem_total() < 2000) {
printf("You do not have enough RAM, sorry.\n");
while (1) { sleep(1);}
}
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}
}
/*
* Don't modify **argv directly, it would show up in the "ps" display.
* I don't want "init" to look like "rc".
*/
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rc_arguments[0] = tty_commands[0];
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for ( j = 1; j < argc; j++ ) {
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rc_arguments[j] = argv[j];
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}
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rc_arguments[j] = 0;
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arguments[0] = "-sh";
arguments[1] = 0;
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/* Ok, now launch the rc script /etc/init.d/rcS and prepare to start up
* some VTs on tty1 and tty2 if somebody hits enter
*/
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for ( ; ; ) {
int wpid;
int status;
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if ( pid1 == 0 && tty_commands[0] ) {
if ( run_rc == TRUE ) {
pid1 = run(tty_commands[0], rc_arguments, first_terminal, 0);
} else {
pid2 = run(tty_commands[1], arguments, first_terminal, 1);
}
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}
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if ( pid2 == 0 && second_terminal && tty_commands[1] ) {
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pid2 = run(tty_commands[1], arguments, second_terminal, 1);
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}
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wpid = wait(&status);
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if ( wpid > 0 && wpid != pid1) {
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message(log, "pid %d exited, status=%x.\n", wpid, status);
}
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if ( wpid == pid2 ) {
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pid2 = 0;
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}
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}
}