Imported from util-linux-2.11x tarball.

[thirdparty/util-linux.git] / login-utils / simpleinit.c

/* simpleinit.c - poe@daimi.aau.dk */
/* Version 2.0.2 */

/* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
 * - added Native Language Support
 * 2001-01-25 Richard Gooch <rgooch@atnf.csiro.au>
 * - fixed bug with failed services so they may be later "reclaimed"
 * 2001-02-02 Richard Gooch <rgooch@atnf.csiro.au>
 * - fixed race when reading from pipe and reaping children
 * 2001-02-18 sam@quux.dropbear.id.au
 * - fixed bug in <get_path>: multiple INIT_PATH components did not work
 * 2001-02-21 Richard Gooch <rgooch@atnf.csiro.au>
 * - block signals in handlers, so that longjmp() doesn't kill context
 * 2001-02-25 Richard Gooch <rgooch@atnf.csiro.au>
 * - make default INIT_PATH the boot_prog (if it is a directory) - YECCH
 */

#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <ctype.h>
#include <fcntl.h>
#include <string.h>
#include <signal.h>
#include <pwd.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <dirent.h>
#include <termios.h>
#include <utmp.h>
#include <setjmp.h>
#include <sched.h>
#ifdef SHADOW_PWD
#  include <shadow.h>
#endif
#include "my_crypt.h"
#include "pathnames.h"
#include "linux_reboot.h"
#include "xstrncpy.h"
#include "nls.h"
#include "simpleinit.h"

#define CMDSIZ     150  /* max size of a line in inittab */
#define NUMCMD     30   /* max number of lines in inittab */
#define NUMTOK     20   /* max number of tokens in inittab command */
#define PATH_SIZE  (CMDSIZ+CMDSIZ+1)

#define MAX_RESPAWN_RATE  5  /*  number of respawns per 100 seconds  */

#define TZFILE "/etc/TZ"
char tzone[CMDSIZ];
/* #define DEBUGGING */

/* Define this if you want init to ignore the termcap field in inittab for
   console ttys. */
/* #define SPECIAL_CONSOLE_TERM */

#define ever (;;)

struct initline {
        pid_t           pid;
        char            tty[10];
        char            termcap[30];
        char            *toks[NUMTOK];
        char            line[CMDSIZ];
        struct timeval  last_start;
        signed long     rate;
};

struct initline inittab[NUMCMD];
int numcmd;
int stopped = 0;        /* are we stopped */
static char boot_prog[PATH_SIZE] = _PATH_RC;
static char script_prefix[PATH_SIZE] = "\0";
static char final_prog[PATH_SIZE] = "\0";
static char init_path[PATH_SIZE] = "\0";
static int caught_sigint = 0;
static int no_reboot = 0;
static pid_t rc_child = -1;
static const char *initctl_name = "/dev/initctl";
static int initctl_fd = -1;
static volatile int do_longjmp = 0;
static sigjmp_buf jmp_env;


static void do_single (void);
static int do_rc_tty (const char *path);
static int process_path (const char *path, int (*func) (const char *path),
                         int ignore_dangling_symlink);
static int preload_file (const char *path);
static int run_file (const char *path);
static void spawn (int i), read_inittab (void);
static void sighup_handler (int sig);
static void sigtstp_handler (int sig);
static void sigint_handler (int sig);
static void sigchild_handler (int sig);
static void sigquit_handler (int sig);
static void sigterm_handler (int sig);
#ifdef SET_TZ
static void set_tz (void);
#endif
static void write_wtmp (void);
static pid_t mywait (int *status);
static int run_command (const char *file, const char *name, pid_t pid);


static void err (char *s)
{
        int fd;
        
        if((fd = open("/dev/console", O_WRONLY)) < 0) return;

        write(fd, "init: ", 6); 
        write(fd, s, strlen(s));
        close(fd);
}

static void enter_single (void)
{
    pid_t pid;
    int i;

    err(_("Booting to single user mode.\n"));
    if((pid = fork()) == 0) {
        /* the child */
        execl(_PATH_BSHELL, _PATH_BSHELL, NULL);
        err(_("exec of single user shell failed\n"));
    } else if(pid > 0) {
        while (waitpid (pid, &i, 0) != pid)  /*  Nothing  */;
    } else if(pid < 0) {
        err(_("fork of single user shell failed\n"));
    }
    unlink(_PATH_SINGLE);
}

int main(int argc, char *argv[])
{
        int                     vec, i;
        int                     want_single = 0;
        pid_t                   pid;
        struct sigaction        sa;


#ifdef SET_TZ
        set_tz();
#endif
        sigfillset (&sa.sa_mask);  /*  longjmp and nested signals don't mix  */
        sa.sa_flags = SA_ONESHOT;
        sa.sa_handler = sigint_handler;
        sigaction (SIGINT, &sa, NULL);
        sa.sa_flags = 0;
        sa.sa_handler = sigtstp_handler;
        sigaction (SIGTSTP, &sa, NULL);
        sa.sa_handler = sigterm_handler;
        sigaction (SIGTERM, &sa, NULL);
        sa.sa_handler = sigchild_handler;
        sigaction (SIGCHLD, &sa, NULL);
        sa.sa_handler = sigquit_handler;
        sigaction (SIGQUIT, &sa, NULL);

        setlocale(LC_ALL, "");
        bindtextdomain(PACKAGE, LOCALEDIR);
        textdomain(PACKAGE);

        my_reboot (LINUX_REBOOT_CMD_CAD_OFF);
        /*  Find script to run. Command-line overrides config file overrides
            built-in default  */
        for (i = 0; i < NUMCMD; i++) inittab[i].pid = -1;
        read_inittab ();
        for (i = 1; i < argc; i++) {
                if (strcmp (argv[i], "single") == 0)
                        want_single = 1;
                else if (strcmp (argv[i], "-noreboot") == 0)
                        no_reboot = 1;
                else if (strlen(script_prefix) + strlen(argv[i]) < PATH_SIZE) {
                        char path[PATH_SIZE];

                        strcpy (path, script_prefix);
                        strcat (path, argv[i]);
                        if (access (path, R_OK | X_OK) == 0)
                                strcpy (boot_prog, path);
                }
        }
        if (init_path[0] == '\0')
        {
            struct stat statbuf;

            if ( (stat (boot_prog, &statbuf) == 0) && S_ISDIR (statbuf.st_mode) )
            {
                strcpy (init_path, boot_prog);
                i = strlen (init_path);
                if (init_path[i - 1] == '/') init_path[i - 1] = '\0';
            }
        }

        if ( ( initctl_fd = open (initctl_name, O_RDWR, 0) ) < 0 ) {
                mkfifo (initctl_name, S_IRUSR | S_IWUSR);
                if ( ( initctl_fd = open (initctl_name, O_RDWR, 0) ) < 0 )
                        err ( _("error opening fifo\n") );
        }

        if ( want_single || (access (_PATH_SINGLE, R_OK) == 0) ) do_single ();

        /*If we get a SIGTSTP before multi-user mode, do nothing*/
        while (stopped)
                pause();

        if ( do_rc_tty (boot_prog) ) do_single ();

        while (stopped)  /*  Also if /etc/rc fails & we get SIGTSTP  */
                pause();

        write_wtmp();   /* write boottime record */
#ifdef DEBUGGING
        for(i = 0; i < numcmd; i++) {
                char **p;
                p = inittab[i].toks;
                printf("toks= %s %s %s %s\n",p[0], p[1], p[2], p[3]);
                printf("tty= %s\n", inittab[i].tty);
                printf("termcap= %s\n", inittab[i].termcap);
        }
        exit(0);
#endif
        signal (SIGHUP, sighup_handler);  /* Better semantics with signal(2) */

        for (i = 0; i < getdtablesize (); i++)
                if (i != initctl_fd) close (i);

        for(i = 0; i < numcmd; i++)
                spawn(i);

        if (final_prog[0] != '\0') {
                switch ( fork () )
                {
                  case 0:   /*  Child   */
                    execl (final_prog, final_prog, "start", NULL);
                    err ( _("error running finalprog\n") );
                    _exit (1);
                    break;
                  case -1:  /*  Error   */
                    err ( _("error forking finalprog\n") );
                    break;
                  default:  /*  Parent  */
                    break;
                }
        }

        for ever {
                pid = mywait (&vec);
                if (pid < 1) continue;

                /* clear utmp entry, and append to wtmp if possible */
                {
                    struct utmp *ut;
                    int ut_fd, lf;

                    utmpname(_PATH_UTMP);
                    setutent();
                    while((ut = getutent())) {
                        if(ut->ut_pid == pid) {
                            time(&ut->ut_time);
                            memset(&ut->ut_user, 0, UT_NAMESIZE);
                            memset(&ut->ut_host, 0, sizeof(ut->ut_host));
                            ut->ut_type = DEAD_PROCESS;
                            ut->ut_pid = 0;
                            ut->ut_addr = 0;
                            /*endutent();*/
                            pututline(ut);

                            if ((lf = open(_PATH_WTMPLOCK, O_CREAT|O_WRONLY, 0660)) >= 0) {
                                flock(lf, LOCK_EX|LOCK_NB);
                                if((ut_fd = open(_PATH_WTMP, O_APPEND|O_WRONLY)) >= 0) {
                                    write(ut_fd, ut, sizeof(struct utmp));
                                    close(ut_fd);
                                }
                                flock(lf, LOCK_UN|LOCK_NB);
                                close(lf);
                            }
                            break;
                        }
                    }
                    endutent();
                }

                for(i = 0; i < numcmd; i++) {
                        if(pid == inittab[i].pid || inittab[i].pid < 0) {
                                if (stopped)
                                        inittab[i].pid = -1;
                                else
                                        spawn(i);
                                if (pid == inittab[i].pid)
                                        break;
                        }
                }
        }
}       

#define MAXTRIES 3 /* number of tries allowed when giving the password */

/*
 * return true if singleuser mode is allowed.
 * If /etc/securesingle exists ask for root password, otherwise always OK.
 */
static int check_single_ok (void)
{
    char *pass, *rootpass = NULL;
    struct passwd *pwd;
    int i;

    if (access (_PATH_SECURE, R_OK) != 0) return 1;
    if ( ( pwd = getpwnam ("root") ) || ( pwd = getpwuid (0) ) )
        rootpass = pwd->pw_passwd;
    else
        return 1; /* a bad /etc/passwd should not lock out */

    for (i = 0; i < MAXTRIES; i++)
    {
        pass = getpass (_ ("Password: ") );
        if (pass == NULL) continue;
                
        if ( !strcmp (crypt (pass, rootpass), rootpass) ) return 1;

        puts (_ ("\nWrong password.\n") );
    }
    return 0;
}

static void do_single (void)
{
    char path[PATH_SIZE];

    if (caught_sigint) return;
    strcpy (path, script_prefix);
    strcat (path, "single");
    if (access (path, R_OK | X_OK) == 0)
        if (do_rc_tty (path) == 0) return;
    if ( check_single_ok () ) enter_single ();
}   /*  End Function do_single  */

/*
 * run boot script(s). The environment is passed to the script(s), so the RC
 * environment variable can be used to decide what to do.
 * RC may be set from LILO.
 * [RETURNS] 0 on success (exit status convention), otherwise error.
 */
static int do_rc_tty (const char *path)
{
    int status;
    pid_t pid;
    sigset_t ss;

    if (caught_sigint) return 0;
    process_path (path, preload_file, 0);
    /*  Launch off a subprocess to start a new session (required for frobbing
        the TTY) and capture control-C  */
    switch ( rc_child = fork () )
    {
      case 0:   /*  Child  */
        for (status = 1; status < NSIG; status++) signal (status, SIG_DFL);
        sigfillset (&ss);
        sigprocmask (SIG_UNBLOCK, &ss, NULL);
        sigdelset (&ss, SIGINT);
        sigdelset (&ss, SIGQUIT);
        setsid ();
        ioctl (0, TIOCSCTTY, 0);  /*  I want my control-C  */
        sigsuspend (&ss);  /*  Should never return, should just be killed  */
        break;             /*  No-one else is controlled by this TTY now   */
      case -1:  /*  Error  */
        return (1);
        /*break;*/
      default:  /*  Parent  */
        break;
    }
    /*  Parent  */
    process_path (path, run_file, 0);
    while (1)
    {
        if ( ( pid = mywait (&status) ) == rc_child )
            return (WTERMSIG (status) == SIGINT) ? 0 : 1;
        if (pid < 0) break;
    }
    kill (rc_child, SIGKILL);
    while (waitpid (rc_child, NULL, 0) != rc_child)  /*  Nothing  */;
    return 0;
}   /*  End Function do_rc_tty  */

static int process_path (const char *path, int (*func) (const char *path),
                         int ignore_dangling_symlink)
{
    struct stat statbuf;
    DIR *dp;
    struct dirent *de;

    if (lstat (path, &statbuf) != 0)
    {
        err (_ ("lstat of path failed\n") );
        return 1;
    }
    if ( S_ISLNK (statbuf.st_mode) )
    {
        if (stat (path, &statbuf) != 0)
        {
            if ( (errno == ENOENT) && ignore_dangling_symlink ) return 0;
            err (_ ("stat of path failed\n") );
            return 1;
        }
    }
    if ( !( statbuf.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH) ) ) return 0;
    if ( !S_ISDIR (statbuf.st_mode) ) return (*func) (path);
    if ( ( dp = opendir (path) ) == NULL )
    {
        err (_ ("open of directory failed\n") );
        return 1;
    }
    while ( ( de = readdir (dp) ) != NULL )
    {
        int retval;
        char newpath[PATH_SIZE];

        if (de->d_name[0] == '.') continue;
        retval = sprintf (newpath, "%s/%s", path, de->d_name);
        if (newpath[retval - 1] == '~') continue;  /*  Common mistake  */
        if ( ( retval = process_path (newpath, func, 1) ) ) return retval;
    }
    closedir (dp);
    return 0;
}   /*  End Function process_path  */

static int preload_file (const char *path)
{
    int fd;
    char ch;

    if ( ( fd = open (path, O_RDONLY, 0) ) < 0) return 0;
    while (read (fd, &ch, 1) == 1) lseek (fd, 1024, SEEK_CUR);
    close (fd);
    return 0;
}   /*  End Function preload_file  */

static int run_file (const char *path)
{
    const char *ptr;

    if ( ( ptr = strrchr ( (char *) path, '/' ) ) == NULL ) ptr = path;
    else ++ptr;
    return (run_command (path, ptr, 0) == SIG_FAILED) ? 1 : 0;
}   /*  End Function run_file  */

static void spawn (int i)
{
        pid_t pid;
        int j;
        signed long ds_taken;
        struct timeval ct;

        if (inittab[i].toks[0] == NULL) return;

        /*  Check if respawning too fast  */
        gettimeofday (&ct, NULL);
        ds_taken = ct.tv_sec - inittab[i].last_start.tv_sec;

        /* On the first iteration last_start==0 and ds_taken
           may be very large. Avoid overflow. -- Denis Vlasenko */
        if (ds_taken > 10000)
                ds_taken = 10000;

        ds_taken *= 10;
        ds_taken += (ct.tv_usec - inittab[i].last_start.tv_usec) / 100000;
        if (ds_taken < 1)
                ds_taken = 1;
        inittab[i].rate = (9 * inittab[i].rate + 1000 / ds_taken) / 10;
        if (inittab[i].rate > MAX_RESPAWN_RATE) {
                char txt[256];

                inittab[i].toks[0] = NULL;
                inittab[i].pid = -1;
                inittab[i].rate = 0;
                sprintf (txt,"respawning: \"%s\" too fast: quenching entry\n",
                         inittab[i].tty);
                err (_(txt));
                return;
        }

        if((pid = fork()) < 0) {
                inittab[i].pid = -1;
                err(_("fork failed\n"));
                return;
        }
        if(pid) {
                /* this is the parent */
                inittab[i].pid = pid;
                inittab[i].last_start = ct;
                sched_yield ();
                return;
        } else {
                /* this is the child */
                char term[40];
#ifdef SET_TZ
                char tz[CMDSIZ];
#endif
                char *env[3];
                
                setsid();
                for(j = 0; j < getdtablesize(); j++)
                        (void) close(j);

                (void) sprintf(term, "TERM=%s", inittab[i].termcap);
                env[0] = term;
                env[1] = (char *)0;
#ifdef SET_TZ
                (void) sprintf(tz, "TZ=%s", tzone);
                env[1] = tz;
#endif
                env[2] = (char *)0;

                execve(inittab[i].toks[0], inittab[i].toks, env);
                err(_("exec failed\n"));
                sleep(5);
                _exit(1);
        }
}

static void read_inittab (void)
{
        FILE *f;
        char buf[CMDSIZ];
        int i,j,k;
        int has_prog = 0;
        char *ptr, *getty;
        char prog[PATH_SIZE];
#ifdef SPECIAL_CONSOLE_TERM
        char tty[50];
        struct stat stb;
#endif
        char *termenv;
        
        termenv = getenv("TERM");       /* set by kernel */
        /* termenv = "vt100"; */
                        
        if(!(f = fopen(_PATH_INITTAB, "r"))) {
                err(_("cannot open inittab\n"));
                return;
        }

        prog[0] = '\0';
        i = 0;
        while(!feof(f) && i < NUMCMD - 2) {
                if(fgets(buf, CMDSIZ - 1, f) == 0) break;
                buf[CMDSIZ-1] = 0;

                for(k = 0; k < CMDSIZ && buf[k]; k++) {
                        if ((buf[k] == '#') || (buf[k] == '\n')) { 
                                buf[k] = 0; break; 
                        }
                }

                if(buf[0] == 0 || buf[0] == '\n') continue;
                ptr = strchr (buf, '=');
                if (ptr) {
                        ptr++;
                        if ( !strncmp (buf, "bootprog", 8) ) {
                                while ( isspace (*ptr) ) ++ptr;
                                strcpy (prog, ptr);
                                has_prog = 1;
                                continue;
                        }
                        if ( !strncmp (buf, "fileprefix", 10) ) {
                                while ( isspace (*ptr) ) ++ptr;
                                strcpy (script_prefix, ptr);
                                continue;
                        }
                        if ( !strncmp (buf, "PATH", 4) ) {
                                while ( isspace (*ptr) ) ++ptr;
                                setenv ("PATH", ptr, 1);
                                continue;
                        }
                        if ( !strncmp (buf, "INIT_PATH", 9) ) {
                                while ( isspace (*ptr) ) ++ptr;
                                strcpy (init_path, ptr);
                                continue;
                        }
                        if ( !strncmp (buf, "finalprog", 8) ) {
                                while ( isspace (*ptr) ) ++ptr;
                                strcpy (final_prog, ptr);
                                continue;
                        }
                }
                        

                (void) strcpy(inittab[i].line, buf);

                (void) strtok(inittab[i].line, ":");
                xstrncpy(inittab[i].tty, inittab[i].line, 10);
                xstrncpy(inittab[i].termcap, strtok((char *)0, ":"), 30);

                getty = strtok((char *)0, ":");
                (void) strtok(getty, " \t\n");
                inittab[i].toks[0] = getty;
                j = 1;
                while((ptr = strtok((char *)0, " \t\n")))
                        inittab[i].toks[j++] = ptr;
                inittab[i].toks[j] = (char *)0;

#ifdef SPECIAL_CONSOLE_TERM
                /* special-case termcap for the console ttys */
                (void) sprintf(tty, "/dev/%s", inittab[i].tty);
                if(!termenv || stat(tty, &stb) < 0) {
                        err(_("no TERM or cannot stat tty\n"));
                } else {
                        /* is it a console tty? */
                        if(major(stb.st_rdev) == 4 && minor(stb.st_rdev) < 64)
                                xstrncpy(inittab[i].termcap, termenv, 30);
                }
#endif

                i++;
        }
        fclose(f);
        numcmd = i;
        if (has_prog) {
                int len;
                char path[PATH_SIZE];

                strcpy (path, script_prefix);
                strcat (path, prog);
                len = strlen (path);
                if (path[len - 1] == '/') path[len - 1] = '\0';
                if (access (path, R_OK | X_OK) == 0)
                        strcpy (boot_prog, path);
        }
}   /*  End Function read_inittab  */

static void sighup_handler (int sig)
{
        int i,j;
        int oldnum;
        struct initline savetab[NUMCMD];
        int had_already;

        signal (SIGHUP, SIG_IGN);
        memcpy(savetab, inittab, NUMCMD * sizeof(struct initline));
        oldnum = numcmd;                
        read_inittab ();
        
        for(i = 0; i < numcmd; i++) {
                had_already = 0;
                for(j = 0; j < oldnum; j++) {
                        if(!strcmp(savetab[j].tty, inittab[i].tty)) {
                                had_already = 1;
                                if((inittab[i].pid = savetab[j].pid) < 0)
                                        spawn(i);
                        }
                }
                if (!had_already) spawn (i);
        }
        signal (SIGHUP, sighup_handler);
}   /*  End Function sighup_handler  */

static void sigtstp_handler (int sig)
{
    stopped = ~stopped;
    if (!stopped) sighup_handler (sig);
}   /*  End Function sigtstp_handler  */

static void sigterm_handler (int sig)
{
    int i;

    for (i = 0; i < numcmd; i++)
        if (inittab[i].pid > 0) kill (inittab[i].pid, SIGTERM);
}   /*  End Function sigterm_handler  */

static void sigint_handler (int sig)
{
    pid_t pid;

    caught_sigint = 1;
    kill (rc_child, SIGKILL);
    if (no_reboot) _exit (1) /*kill (0, SIGKILL)*/;
    sync ();
    sync ();
    pid = fork ();
    if (pid > 0) return;  /*  Parent                     */
    if (pid == 0)         /*  Child: reboot properly...  */
        execl (_PATH_REBOOT, _PATH_REBOOT, (char *) 0);

    /* fork or exec failed, try the hard way... */
    my_reboot (LINUX_REBOOT_CMD_RESTART);
}   /*  End Function sigint_handler  */

static void sigchild_handler (int sig)
{
    if (!do_longjmp) return;
    siglongjmp (jmp_env, 1);
}

static void sigquit_handler (int sig)
{
    execl (_PATH_REBOOT, _PATH_REBOOT, NULL); /*  It knows pid=1 must sleep  */
}

#ifdef SET_TZ
static void set_tz (void)
{
        FILE *f;
        int len;

        if((f=fopen(TZFILE, "r")) == (FILE *)NULL) return;
        fgets(tzone, CMDSIZ-2, f);
        fclose(f);
        if((len=strlen(tzone)) < 2) return;
        tzone[len-1] = 0; /* get rid of the '\n' */
        setenv("TZ", tzone, 0);
}
#endif

static void write_wtmp (void)
{
    int fd, lf;
    struct utmp ut;
    
    memset((char *)&ut, 0, sizeof(ut));
    strcpy(ut.ut_line, "~");
    memset(ut.ut_name, 0, sizeof(ut.ut_name));
    time(&ut.ut_time);
    ut.ut_type = BOOT_TIME;

    if ((lf = open(_PATH_WTMPLOCK, O_CREAT|O_WRONLY, 0660)) >= 0) {
        flock(lf, LOCK_EX|LOCK_NB); /* make sure init won't hang */
        if((fd = open(_PATH_WTMP, O_WRONLY|O_APPEND)) >= 0) {
            write(fd, (char *)&ut, sizeof(ut));
            close(fd);
        }
        flock(lf, LOCK_UN|LOCK_NB);
        close(lf);
    }
}   /*  End Function write_wtmp  */


struct needer_struct
{
    struct needer_struct *next;
    pid_t pid;
};

struct service_struct
{
    struct service_struct *prev, *next;    /*  Script services chain         */
    struct needer_struct *needers;         /*  Needers waiting for service   */
    struct script_struct *attempting_providers;
    int failed;                /*  TRUE if attempting provider failed badly  */
    char name[1];
};

struct script_struct
{
    pid_t pid;
    struct script_struct *prev, *next;              /*  For the list         */
    struct service_struct *first_service, *last_service; /*First is true name*/
    struct script_struct *next_attempting_provider; /*  Provider chain       */
};

struct list_head
{
    struct script_struct *first, *last;
    unsigned int num_entries;
};


static struct list_head available_list = {NULL, NULL, 0};
static struct list_head starting_list = {NULL, NULL, 0};
static struct service_struct *unavailable_services = NULL;  /*  For needers  */
static int num_needers = 0;


static int process_pidstat (pid_t pid, int status);
static void process_command (const struct command_struct *command);
static struct service_struct *find_service_in_list (const char *name,
                                                    struct service_struct *sv);
static struct script_struct *find_script_byname
    (const char *name,struct list_head *head, struct service_struct **service);
static struct script_struct *find_script_bypid (pid_t pid,
                                                struct list_head *head);
static void insert_entry (struct list_head *head, struct script_struct *entry);
static void remove_entry (struct list_head *head, struct script_struct *entry);
static void signal_needers (struct service_struct *service, int sig);
static void handle_nonworking (struct script_struct *script);
static int force_progress (void);
static void show_scripts (FILE *fp, const struct script_struct *script,
                          const char *type);
static const char *get_path (const char *file);


static pid_t mywait (int *status)
/*  [RETURNS] The pid for a process to be reaped, 0 if no process is to be
    reaped, and less than 0 if the boot scripts appear to have finished.
*/
{
    pid_t pid;
    sigset_t ss;
    long buffer[COMMAND_SIZE / sizeof (long)];
    struct command_struct *command = (struct command_struct *) buffer;

    if (initctl_fd < 0) return wait (status);
    /*  Some magic to avoid races which can result in lost signals   */
    command->command = -1;
    if ( sigsetjmp (jmp_env, 1) )
    {   /*  Jump from signal handler  */
        do_longjmp = 0;
        process_command (command);
        return 0;
    }
    sigemptyset (&ss);  /*  Block SIGCHLD so wait status cannot be lost  */
    sigaddset (&ss, SIGCHLD);
    sigprocmask (SIG_BLOCK, &ss, NULL);
    if ( ( pid = waitpid (-1, status, WNOHANG) ) > 0 )
    {
        sigprocmask (SIG_UNBLOCK, &ss, NULL);
        return process_pidstat (pid, *status);
    }
    do_longjmp = 1;  /*  After this, SIGCHLD will cause a jump backwards  */
    sigprocmask (SIG_UNBLOCK, &ss, NULL);
    read (initctl_fd, buffer, COMMAND_SIZE);
    do_longjmp = 0;
    process_command (command);
    return 0;
}   /*  End Function mywait  */

static pid_t process_pidstat (pid_t pid, int status)
/*  [RETURNS] The pid for a process to be reaped, 0 if no process is to be
    reaped, and less than 0 if the boot scripts appear to have finished.
*/
{
    int failed;
    struct script_struct *script;
    struct service_struct *service;

    if ( ( script = find_script_bypid (pid, &starting_list) ) == NULL )
        return pid;
    remove_entry (&starting_list, script);
    if ( WIFEXITED (status) && (WEXITSTATUS (status) == 0) )
    {
        struct script_struct *provider;

        /*  Notify needers and other providers  */
        for (service = script->first_service; service != NULL;
             service = service->next)
        {
            signal_needers (service, SIG_PRESENT);
            for (provider = service->attempting_providers; provider != NULL;
                 provider = provider->next_attempting_provider)
                kill (provider->pid, SIG_PRESENT);
            service->attempting_providers = NULL;
        }
        insert_entry (&available_list, script);
        return force_progress ();
    }
    failed = ( WIFEXITED (status) && (WEXITSTATUS (status) == 2) ) ? 0 : 1;
    for (service = script->first_service; service != NULL;
         service = service->next)
        service->failed = failed;
    handle_nonworking (script);
    return force_progress ();
}   /*  End Function process_pidstat  */

static void process_command (const struct command_struct *command)
{
    int ival;
    struct script_struct *script;
    struct service_struct *service;

    switch (command->command)
    {
      case COMMAND_TEST:
        kill (command->pid,
              (find_script_byname (command->name, &available_list,
                                   NULL) == NULL) ?
              SIG_NOT_PRESENT : SIG_PRESENT);
        break;
      case COMMAND_NEED:
        ival = run_command (command->name, command->name, command->pid);
        if (ival == 0)
        {
            ++num_needers;
            force_progress ();
        }
        else kill (command->pid, ival);
        break;
      case COMMAND_ROLLBACK:
        if (command->name[0] == '\0') script = NULL;
        else
        {
            if ( ( script = find_script_byname (command->name, &available_list,
                                                NULL) ) == NULL )
            {
                kill (command->pid, SIG_NOT_PRESENT);
                break;
            }
        }
        while (script != available_list.first)
        {
            pid_t pid;
            struct script_struct *victim = available_list.first;
            char txt[256];

            if ( ( pid = fork () ) == 0 )   /*  Child   */
            {
                for (ival = 1; ival < NSIG; ival++) signal (ival, SIG_DFL);
                open ("/dev/console", O_RDONLY, 0);
                open ("/dev/console", O_RDWR, 0);
                dup2 (1, 2);
                execlp (get_path (victim->first_service->name),
                        victim->first_service->name, "stop", NULL);
                sprintf (txt, _("error stopping service: \"%s\""),
                         victim->first_service->name);
                err (txt);
                _exit (SIG_NOT_STOPPED);
            }
            else if (pid == -1) break;      /*  Error   */
            else                            /*  Parent  */
            {
                while (waitpid (pid, &ival, 0) != pid) /*  Nothing  */;
                if ( WIFEXITED (ival) && (WEXITSTATUS (ival) == 0) )
                {
                    sprintf (txt, "Stopped service: %s\n",
                             victim->first_service->name);
                    remove_entry (&available_list, victim);
                    free (victim);
                    err (txt);
                }
                else break;
            }
        }
        kill (command->pid,
              (script ==available_list.first) ? SIG_STOPPED : SIG_NOT_STOPPED);
        break;
      case COMMAND_DUMP_LIST:
        if (fork () == 0) /* Do it in a child process so pid=1 doesn't block */
        {
            FILE *fp;

            if ( ( fp = fopen (command->name, "w") ) == NULL ) _exit (1);
            show_scripts (fp, available_list.first, "AVAILABLE");
            show_scripts (fp, starting_list.first, "STARTING");
            fputs ("UNAVAILABLE SERVICES:\n", fp);
            for (service = unavailable_services; service != NULL;
                 service = service->next)
                fprintf (fp, "%s (%s)\n", service->name,
                         service->failed ? "FAILED" : "not configured");
            fclose (fp);
            _exit (0);
        }
        break;
      case COMMAND_PROVIDE:
        /*  Sanity check  */
        if ( ( script = find_script_bypid (command->ppid, &starting_list) )
             == NULL )
        {
            kill (command->pid, SIG_NOT_CHILD);
            break;
        }
        if (find_script_byname (command->name, &available_list, NULL) != NULL)
        {
            kill (command->pid, SIG_PRESENT);
            break;
        }
        if (find_script_byname (command->name, &starting_list, &service)
            != NULL)
        {   /*  Someone else is trying to provide  */
            script->next_attempting_provider = service->attempting_providers;
            service->attempting_providers = script;
            break;
        }
        if ( ( service = find_service_in_list (command->name,
                                               unavailable_services) )
             == NULL )
        {   /*  We're the first to try and provide: create it  */
            if ( ( service =
                   calloc (1, strlen (command->name) + sizeof *service) )
                 == NULL )
            {
                kill (command->pid, SIG_NOT_CHILD);
                break;
            }
            strcpy (service->name, command->name);
        }
        else
        {   /*  Orphaned service: unhook and grab it  */
            if (service->prev == NULL) unavailable_services = service->next;
            else service->prev->next = service->next;
            if (service->next != NULL) service->next->prev = service->prev;
            service->next = NULL;
        }
        service->prev = script->last_service;
        script->last_service->next = service;
        script->last_service = service;
        kill (command->pid, SIG_NOT_PRESENT);
        break;
      case -1:
      default:
        break;
    }
}   /*  End Function process_command  */

static int run_command (const char *file, const char *name, pid_t pid)
{
    struct script_struct *script;
    struct needer_struct *needer = NULL;
    struct service_struct *service;

    if (find_script_byname (name, &available_list, NULL) != NULL)
        return SIG_PRESENT;
    if (pid != 0)
    {
        needer = calloc (1, sizeof *needer);
        if (needer == NULL) return SIG_FAILED;
        needer->pid = pid;
    }
    script = find_script_byname (name, &starting_list, &service);
    if (script == NULL)
        service = find_service_in_list (name, unavailable_services);
    if (service == NULL)
    {
        int i;
        char txt[1024];

        if ( ( script = calloc (1, sizeof *script) ) == NULL )
        {
            if (needer != NULL) free (needer);
            return SIG_FAILED;
        }
        service = calloc (1, strlen (name) + sizeof *service);
        if (service == NULL)
        {
            free (script);
            return SIG_FAILED;
        }
        strcpy (service->name, name);
        switch ( script->pid = fork () )
        {
          case 0:   /*  Child   */
            for (i = 1; i < NSIG; i++) signal (i, SIG_DFL);
            execlp (get_path (file), service->name, "start", NULL);
            sprintf (txt, "error running programme: \"%s\"\n", service->name);
            err ( _(txt) );
            _exit (SIG_FAILED);
            break;
          case -1:  /*  Error   */
            service->next = unavailable_services;
            if (unavailable_services != NULL)
                unavailable_services->prev = service;
            unavailable_services = service;
            free (script);
            if (needer != NULL) free (needer);
            return SIG_FAILED;
            /*break;*/
          default:  /*  Parent  */
            script->first_service = service;
            script->last_service = service;
            insert_entry (&starting_list, script);
            sched_yield ();
            break;
        }
    }
    if (needer == NULL) return 0;
    needer->next = service->needers;
    service->needers = needer;
    return 0;
}   /*  End Function run_command  */

static struct service_struct *find_service_in_list (const char *name,
                                                    struct service_struct *sv)
{
    for (; sv != NULL; sv = sv->next)
        if (strcmp (sv->name, name) == 0) return (sv);
    return NULL;
}   /*  End Function find_service_in_list  */

static struct script_struct *find_script_byname (const char *name,
                                                 struct list_head *head,
                                                 struct service_struct **service)
{
    struct script_struct *script;

    for (script = head->first; script != NULL; script = script->next)
    {
        struct service_struct *sv;

        if ( ( sv = find_service_in_list (name, script->first_service) )
             != NULL )
        {
            if (service != NULL) *service = sv;
            return (script);
        }
    }
    if (service != NULL) *service = NULL;
    return NULL;
}   /*  End Function find_script_byname  */

static struct script_struct *find_script_bypid (pid_t pid,
                                                struct list_head *head)
{
    struct script_struct *script;

    for (script = head->first; script != NULL; script = script->next)
        if (script->pid == pid) return (script);
    return NULL;
}   /*  End Function find_script_bypid  */

static void insert_entry (struct list_head *head, struct script_struct *entry)
{
    if (entry == NULL) return;
    entry->prev = NULL;
    entry->next = head->first;
    if (head->first != NULL) head->first->prev = entry;
    head->first = entry;
    if (head->last == NULL) head->last = entry;
    ++head->num_entries;
}   /*  End Function insert_entry  */

static void remove_entry (struct list_head *head, struct script_struct *entry)
{
    if (entry->prev == NULL) head->first = entry->next;
    else entry->prev->next = entry->next;
    if (entry->next == NULL) head->last = entry->prev;
    else entry->next->prev = entry->prev;
    --head->num_entries;
}   /*  End Function remove_entry  */

static void signal_needers (struct service_struct *service, int sig)
{
    struct needer_struct *needer, *next_needer;

    for (needer = service->needers; needer != NULL; needer = next_needer)
    {
        kill (needer->pid, sig);
        next_needer = needer->next;
        free (needer);
        --num_needers;
    }
    service->needers = NULL;
}   /*  End Function signal_needers  */

static void handle_nonworking (struct script_struct *script)
{
    struct service_struct *service, *next;

    for (service = script->first_service; service != NULL; service = next)
    {
        struct script_struct *provider = service->attempting_providers;

        next = service->next;
        if (provider == NULL)
        {
            service->prev = NULL;
            service->next = unavailable_services;
            if (unavailable_services != NULL)
                unavailable_services->prev = service;
            unavailable_services = service;
            continue;
        }
        service->attempting_providers = provider->next_attempting_provider;
        provider->last_service->next = service;
        service->prev = provider->last_service;
        provider->last_service = service;
        service->next = NULL;
        kill (provider->pid, SIG_NOT_PRESENT);
    }
    free (script);
}   /*  End Function handle_nonworking  */

static int force_progress (void)
/*  [RETURNS] 0 if boot scripts are still running, else -1.
*/
{
    struct service_struct *service;

    if (starting_list.num_entries > num_needers) return 0;
    /*  No progress can be made: signal needers  */
    for (service = unavailable_services; service != NULL;
         service = service->next)
        signal_needers (service,
                        service->failed ? SIG_FAILED : SIG_NOT_PRESENT);
    return (starting_list.num_entries < 1) ? -1 : 0;
}   /*  End Function force_progress  */

static void show_scripts (FILE *fp, const struct script_struct *script,
                          const char *type)
{
    fprintf (fp, "%s SERVICES:\n", type);
    for (; script != NULL; script = script->next)
    {
        struct service_struct *service = script->first_service;

        fputs (service->name, fp);
        for (service = service->next; service != NULL; service = service->next)
            fprintf (fp, "  (%s)", service->name);
        putc ('\n', fp);
    }
}   /*  End Function show_scripts  */

static const char *get_path (const char *file)
{
    char *p1, *p2;
    static char path[PATH_SIZE];

    if (file[0] == '/') return file;
    if (init_path[0] == '\0') return file;
    for (p1 = init_path; *p1 != '\0'; p1 = p2)
    {
        if ( ( p2 = strchr (p1, ':') ) == NULL )
            p2 = p1 + strlen (p1);
        strncpy (path, p1, p2 - p1);
        path[p2 - p1] = '/';
        strcpy (path + (p2 - p1) + 1, file);
        if (*p2 == ':') ++p2;
        if (access (path, X_OK) == 0) return path;
    }
    return file;
}   /*  End Function get_path  */