busybox/init/init.c

/*
 * 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 <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>

#define DEBUG_INIT

#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. */
#define PATH_DEFAULT    "PATH=/usr/local/sbin:/sbin:/bin:/usr/sbin:/usr/bin"

static int maxproclen=0;
static char* argv0;

static char* console = CONSOLE;
static char* second_terminal = "/dev/tty2";
static char* log = "/dev/tty3";



/* try to open up the specified device */
int device_open(char* device, int mode)
{
    int m, f, fd = -1;
    
    mode = m | 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;
    /* Set original flags. */
    if (m != mode)
	fcntl(fd, F_SETFL, mode);
    return fd;
}

/* print a message to the specified device */
void message(char* device, char *fmt, ...)
{
    int fd;
    va_list arguments;
    if ((fd = device_open(device, O_WRONLY|O_NOCTTY|O_NDELAY)) >= 0) {
	va_start(arguments, fmt);
	vdprintf(fd, fmt, arguments);
	va_end(arguments);
    }
    close( fd);
}

/* Set terminal settings to reasonable defaults */
void set_term()
{
    int fd;
    struct termios tty;

    if ((fd = device_open(console, O_RDWR|O_NOCTTY)) < 0) {
	message(log, "can't open %s", console);
	return;
    }
    ioctl(fd, TCGETS, &tty);
    tty.c_cflag &= CBAUD|CBAUDEX|CSIZE|CSTOPB|PARENB|PARODD;
    tty.c_cflag |= HUPCL|CLOCAL;

    tty.c_cc[VINTR]  = 3;
    tty.c_cc[VQUIT]  = 28;
    tty.c_cc[VERASE] = 127;
    tty.c_cc[VKILL]  = 24;
    tty.c_cc[VEOF]   = 4;
    tty.c_cc[VTIME]  = 0;
    tty.c_cc[VMIN]   = 1;
    tty.c_cc[VSTART] = 17;
    tty.c_cc[VSTOP]  = 19;
    tty.c_cc[VSUSP]  = 26;

    /* Set pre and post processing */
    tty.c_iflag = IGNPAR|ICRNL|IXON|IXANY;
    tty.c_oflag = OPOST|ONLCR;
    tty.c_lflag = ISIG|ICANON|ECHO|ECHOCTL|ECHOPRT|ECHOKE;

    /* Now set the terminal line. */
    ioctl(fd, TCSETS, &tty);
    close( fd);
}

static int
mem_total()
{
    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)));
	}
    }
    return -1;
}

static void
set_free_pages()
{
    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);
}


static void
console_init()
{
    int fd;
    int tried_devcons = 0;
    int tried_vtmaster = 0;
    char *s;

    if ((s = getenv("CONSOLE")) != NULL)
	console = s;
    else {
	console = CONSOLE;
	tried_devcons++;
    }
    while ((fd = open(console, O_RDONLY|O_NONBLOCK)) < 0) {
	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);
}

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=%x.\n", wpid, status);
    }
    return wpid;
}

static int
run(const char* command, char* terminal, int get_enter)
{
    int	f, pid;
    char *args[16];
    char buf[256];
    char* ptr;
    static const char press_enter[] = 
	"\nPlease press Enter to activate this console. ";

	
    /* Make a proper command from the command string */ 
    strcpy(buf, command);
    ptr = buf;
    for(f = 1; f < 15; f++) {
	/* Skip white space */
	while(*ptr == ' ' || *ptr == '\t') ptr++;
	args[f] = ptr;
	/* May be trailing space.. */
	if (*ptr == 0) break;
	/* Skip this `word' */
	while(*ptr && *ptr != ' ' && *ptr != '\t' && *ptr != '#')
	    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];
	

    if ((pid = fork()) == 0) {
	/* Clean up */
	close(0);
	close(1);
	close(2);
	setsid();

	if ((f = device_open(terminal, O_RDWR|O_NOCTTY)) < 0) {
	    message( log, "open(%s) failed: %s", terminal, strerror(errno));
	    return -1;
	}
	dup(f);
	dup(f);
	tcsetpgrp(0, getpgrp());
	set_term();

	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
	     * be allowed to start a shell or whatever an init script 
	     * specifies.
	     */
	    char	c;
	    write(1, press_enter, sizeof(press_enter) - 1);
	    read(0, &c, 1);
	}

	/* Log the process name and args */
	message(log, "Executing '%s'\n", command);

	/* 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);

	/* 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);
	}
	message(log, "Could not execute '%s'\n", command, strerror(errno));
	exit(-1);
    }
    return pid;
}

#ifndef DEBUG_INIT
static void
shutdown_system(void)
{

    message(console, "The system is going down NOW !!");
    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();
    if (get_kernel_revision() <= 2*65536+2*256+11) {
	/* Removed  bdflush call, kupdate in kernels >2.2.11 */
	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");
    reboot( RB_POWER_OFF);
    exit(0);
}

static void
reboot_signal(int sig)
{
    shutdown_system();
    message(console, "Please stand by while rebooting the system.\r\n");
    reboot( RB_AUTOBOOT);
    exit(0);
}
#endif

int setproctitle(char *fmt, ...)
{
    va_list ap;
    int len;
    char buf[256];

    buf[0] = 0;
    va_start(ap, fmt);
    len = vsprintf(buf, fmt, ap);
    va_end(ap);
    memset(argv0, 0, maxproclen + 1);
    strncpy(argv0, buf, maxproclen);
    return len;
}

extern int
init_main(int argc, char * * argv)
{
	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;
	const char* no_memory = 
	    "Sorry, your computer does not have enough memory.\n";

	/* For later use */
	argv0 = argv[0];
	maxproclen = strlen(argv[0]);
	setproctitle("init [boot]");


#ifndef DEBUG_INIT
	/* 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);
#endif
	/* Figure out where the default console should be */
	console_init();

	/* 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

	/* 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(console, "%s started:  BusyBox v%s (%s) multi-call binary", 
		argv[0], BB_VER, BB_BT);
	message(log, "%s started:  BusyBox v%s (%s) multi-call binary", 
		argv[0], BB_VER, BB_BT);


	/* Mount /proc */
	message(console, "Mounting /proc: \n");
	if (mount("/proc","/proc","proc",0,0)) {
	    message(log, "%s: could not mount /proc!\n", argv[0]);
	    message(console, "failed!\n");
	}
	message(console, "done.\n");


	/* 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) { 
		    message(console, "%s", no_memory);
		    while (1) { sleep(1);}
		}
	    }
	}

	/* Check if we are supposed to be in single user mode */
	if (!strcmp(argv[1], "single") || !strcmp(argv[1], "-s") || !strcmp(argv[1], "1")) {
		run_rc = FALSE;
		tty0_commands = shell_commands;
		tty1_commands = 0;
		setproctitle("init [S]");
	} else { 
	    setproctitle("init [1]");
	}

	/* 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);
		}
		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);
		}
		if ( wpid == pid2 ) {
			pid2 = 0;
		}
		sleep(1);
	}
}