import less(1)

[unleashed/tickless.git] / usr / src / lib / libc / port / gen / getutx.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */


/*
 * Routines to read and write the /etc/utmpx file. Also contains
 * binary compatibility routines to support the old utmp interfaces
 * on systems with MAXPID <= SHRT_MAX.
 */

#include "lint.h"
#include <sys/types.h>
#include <stdio.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <utmpx.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <ctype.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <pthread.h>
#include <limits.h>
#include <signal.h>
#include <spawn.h>

#define IDLEN           4       /* length of id field in utmp */
#define SC_WILDC        0xff    /* wild char for utmp ids */
#define MAXFILE         79      /* Maximum pathname length for "utmpx" file */

#define MAXVAL          255             /* max value for an id `character' */
#define IPIPE           "/var/run/initpipe"     /* FIFO to send pids to init */
#define UPIPE           "/var/run/utmppipe"     /* FIFO to send pids to utmpd */

#define VAR_UTMPX_FILE  "/var/adm/utmpx" /* for sanity check only */


/*
 * format of message sent to init
 */

typedef struct  pidrec {
        int     pd_type;        /* command type */
        pid_t   pd_pid;         /* pid */
} pidrec_t;

/*
 * pd_type's
 */
#define ADDPID 1        /* add a pid to "godchild" list */
#define REMPID 2        /* remove a pid to "godchild" list */

static void     utmpx_frec2api(const struct futmpx *, struct utmpx *);
static void     utmpx_api2frec(const struct utmpx *, struct futmpx *);

static void     unlockutx(void);
static void     sendpid(int, pid_t);
static void     sendupid(int, pid_t);
static int      idcmp(const char *, const char *);
static int      allocid(char *, unsigned char *);
static int      lockutx(void);

static struct utmpx *invoke_utmp_update(const struct utmpx *);
static struct futmpx *getoneutx(off_t *);
static void     putoneutx(const struct utmpx *, off_t);
static int      big_pids_in_use(void);

/*
 * prototypes for utmp compatibility routines (in getut.c)
 */
extern struct utmp *_compat_getutent(void);
extern struct utmp *_compat_getutid(const struct utmp *);
extern struct utmp *_compat_getutline(const struct utmp *);
extern struct utmp *_compat_pututline(const struct utmp *);
extern void _compat_setutent(void);
extern void _compat_endutent(void);
extern void _compat_updwtmp(const char *, struct utmp *);
extern struct utmp *_compat_makeut(struct utmp *);

static int fd = -1;     /* File descriptor for the utmpx file. */
static int ut_got_maxpid = 0;   /* Flag set when sysconf(_SC_MAXPID) called */
static pid_t ut_maxpid = 0;     /* Value of MAXPID from sysconf */
static int tempfd = -1;  /* To store fd between lockutx() and unlockutx() */

static  FILE    *fp = NULL;     /* Buffered file descriptior for utmpx file */
static int changed_name = 0;    /* Flag set when not using utmpx file */
static char utmpxfile[MAXFILE+1] = UTMPX_FILE;  /* Name of the current */
char _compat_utmpfile[MAXFILE+1];
static int compat_utmpflag = 0; /* old compat mode flag */

static struct futmpx fubuf;     /* Copy of last entry read in. */
static struct utmpx ubuf;       /* Last entry returned to client */

static struct utmp utmpcompat;  /* Buffer for returning utmp-format data */
/*
 * In the 64-bit world, the utmpx data structure grows because of
 * the ut_time field (a struct timeval) grows in the middle of it.
 */
static void
utmpx_frec2api(const struct futmpx *src, struct utmpx *dst)
{
        if (src == NULL)
                return;

        (void) strncpy(dst->ut_user, src->ut_user, sizeof (dst->ut_user));
        (void) strncpy(dst->ut_line, src->ut_line, sizeof (dst->ut_line));
        (void) memcpy(dst->ut_id, src->ut_id, sizeof (dst->ut_id));
        dst->ut_pid = src->ut_pid;
        dst->ut_type = src->ut_type;
        dst->ut_exit.e_termination = src->ut_exit.e_termination;
        dst->ut_exit.e_exit = src->ut_exit.e_exit;
        dst->ut_tv.tv_sec = (time_t)src->ut_tv.tv_sec;
        dst->ut_tv.tv_usec = (suseconds_t)src->ut_tv.tv_usec;
        dst->ut_session = src->ut_session;
        bzero(dst->pad, sizeof (dst->pad));
        dst->ut_syslen = src->ut_syslen;
        (void) memcpy(dst->ut_host, src->ut_host, sizeof (dst->ut_host));
}

static void
utmpx_api2frec(const struct utmpx *src, struct futmpx *dst)
{
        if (src == NULL)
                return;

        (void) strncpy(dst->ut_user, src->ut_user, sizeof (dst->ut_user));
        (void) strncpy(dst->ut_line, src->ut_line, sizeof (dst->ut_line));
        (void) memcpy(dst->ut_id, src->ut_id, sizeof (dst->ut_id));
        dst->ut_pid = src->ut_pid;
        dst->ut_type = src->ut_type;
        dst->ut_exit.e_termination = src->ut_exit.e_termination;
        dst->ut_exit.e_exit = src->ut_exit.e_exit;
        dst->ut_tv.tv_sec = (time32_t)src->ut_tv.tv_sec;
        dst->ut_tv.tv_usec = (int32_t)src->ut_tv.tv_usec;
        dst->ut_session = src->ut_session;
        bzero(dst->pad, sizeof (dst->pad));
        dst->ut_syslen = src->ut_syslen;
        (void) memcpy(dst->ut_host, src->ut_host, sizeof (dst->ut_host));
}

/*
 * "getutxent_frec" gets the raw version of the next entry in the utmpx file.
 */
static struct futmpx *
getutxent_frec(void)
{
        /*
         * If the "utmpx" file is not open, attempt to open it for
         * reading.  If there is no file, attempt to create one.  If
         * both attempts fail, return NULL.  If the file exists, but
         * isn't readable and writeable, do not attempt to create.
         */
        if (fd < 0) {

                if ((fd = open(utmpxfile, O_RDWR|O_CREAT, 0644)) < 0) {

                        /*
                         * If the open failed for permissions, try opening
                         * it only for reading.  All "pututxline()" later
                         * will fail the writes.
                         */

                        if ((fd = open(utmpxfile, O_RDONLY)) < 0)
                                return (NULL);

                        if ((fp = fopen(utmpxfile, "rF")) == NULL) {
                                (void) close(fd);
                                fd = -1;
                                return (NULL);
                        }

                } else {
                        /*
                         * Get the stream pointer
                         */
                        if ((fp = fopen(utmpxfile, "r+F")) == NULL) {
                                (void) close(fd);
                                fd = -1;
                                return (NULL);
                        }
                }
        }

        /*
         * Try to read in the next entry from the utmpx file.
         */
        if (fread(&fubuf, sizeof (fubuf), 1, fp) != 1) {
                /*
                 * Make sure fubuf is zeroed.
                 */
                bzero(&fubuf, sizeof (fubuf));
                return (NULL);
        }

        return (&fubuf);
}

/*
 * "big_pids_in_use" determines whether large pid numbers are in use
 * or not.  If MAXPID won't fit in a signed short, the utmp.ut_pid
 * field will overflow.
 *
 * Returns 0 if small pids are in use, 1 otherwise
 */
static int
big_pids_in_use(void)
{
        if (!ut_got_maxpid) {
                ut_got_maxpid++;
                ut_maxpid = sysconf(_SC_MAXPID);
        }
        return (ut_maxpid > SHRT_MAX ? 1 : 0);
}

/*
 * "getutxent" gets the next entry in the utmpx file.
 */
struct utmpx *
getutxent(void)
{
        struct futmpx *futxp;

        futxp = getutxent_frec();
        utmpx_frec2api(&fubuf, &ubuf);
        if (futxp == NULL)
                return (NULL);
        return (&ubuf);
}
/*
 * "getutent" gets the next entry in the utmp file.
 */
struct utmp *
getutent(void)
{
        struct utmpx *utmpx;

        if (compat_utmpflag)
                return (_compat_getutent());

        /* fail if we can't represent maxpid properly */
        if (big_pids_in_use()) {
                errno = EOVERFLOW;
                return (NULL);
        }

        if ((utmpx = getutxent()) == NULL)
                return (NULL);

        getutmp(utmpx, &utmpcompat);
        return (&utmpcompat);
}

/*
 * "getutxid" finds the specified entry in the utmpx file.  If
 * it can't find it, it returns NULL.
 */
struct utmpx *
getutxid(const struct utmpx *entry)
{
        short type;

        /*
         * From XPG5: "The getutxid() or getutxline() may cache data.
         * For this reason, to use getutxline() to search for multiple
         * occurrences, it is necessary to zero out the static data after
         * each success, or getutxline() could just return a pointer to
         * the same utmpx structure over and over again."
         */
        utmpx_api2frec(&ubuf, &fubuf);

        /*
         * Start looking for entry. Look in our current buffer before
         * reading in new entries.
         */
        do {
                /*
                 * If there is no entry in "fubuf", skip to the read.
                 */
                if (fubuf.ut_type != EMPTY) {
                        switch (entry->ut_type) {

                        /*
                         * Do not look for an entry if the user sent
                         * us an EMPTY entry.
                         */
                        case EMPTY:
                                return (NULL);

                        /*
                         * For RUN_LVL, BOOT_TIME, OLD_TIME, and NEW_TIME
                         * entries, only the types have to match.  If they do,
                         * return the address of internal buffer.
                         */
                        case RUN_LVL:
                        case BOOT_TIME:
                        case DOWN_TIME:
                        case OLD_TIME:
                        case NEW_TIME:
                                if (entry->ut_type == fubuf.ut_type) {
                                        utmpx_frec2api(&fubuf, &ubuf);
                                        return (&ubuf);
                                }
                                break;

                        /*
                         * For INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS,
                         * and DEAD_PROCESS the type of the entry in "fubuf",
                         * must be one of the above and id's must match.
                         */
                        case INIT_PROCESS:
                        case LOGIN_PROCESS:
                        case USER_PROCESS:
                        case DEAD_PROCESS:
                                if (((type = fubuf.ut_type) == INIT_PROCESS ||
                                    type == LOGIN_PROCESS ||
                                    type == USER_PROCESS ||
                                    type == DEAD_PROCESS) &&
                                    (fubuf.ut_id[0] == entry->ut_id[0]) &&
                                    (fubuf.ut_id[1] == entry->ut_id[1]) &&
                                    (fubuf.ut_id[2] == entry->ut_id[2]) &&
                                    (fubuf.ut_id[3] == entry->ut_id[3])) {
                                        utmpx_frec2api(&fubuf, &ubuf);
                                        return (&ubuf);
                                }
                                break;

                        /*
                         * Do not search for illegal types of entry.
                         */
                        default:
                                return (NULL);
                        }
                }
        } while (getutxent_frec() != NULL);

        /*
         * Return NULL since the proper entry wasn't found.
         */
        utmpx_frec2api(&fubuf, &ubuf);
        return (NULL);
}

/*
 * "getutid" finds the specified entry in the utmp file.  If
 * it can't find it, it returns NULL.
 */
struct utmp *
getutid(const struct utmp *entry)
{
        struct utmpx utmpx;
        struct utmpx *utmpx2;

        if (compat_utmpflag)
                return (_compat_getutid(entry));

        /* fail if we can't represent maxpid properly */
        if (big_pids_in_use()) {
                errno = EOVERFLOW;
                return (NULL);
        }
        getutmpx(entry, &utmpx);
        if ((utmpx2 = getutxid(&utmpx)) == NULL)
                return (NULL);
        getutmp(utmpx2, &utmpcompat);
        return (&utmpcompat);
}

/*
 * "getutxline" searches the "utmpx" file for a LOGIN_PROCESS or
 * USER_PROCESS with the same "line" as the specified "entry".
 */
struct utmpx *
getutxline(const struct utmpx *entry)
{
        /*
         * From XPG5: "The getutxid() or getutxline() may cache data.
         * For this reason, to use getutxline() to search for multiple
         * occurrences, it is necessary to zero out the static data after
         * each success, or getutxline() could just return a pointer to
         * the same utmpx structure over and over again."
         */
        utmpx_api2frec(&ubuf, &fubuf);

        do {
                /*
                 * If the current entry is the one we are interested in,
                 * return a pointer to it.
                 */
                if (fubuf.ut_type != EMPTY &&
                    (fubuf.ut_type == LOGIN_PROCESS ||
                    fubuf.ut_type == USER_PROCESS) &&
                    strncmp(&entry->ut_line[0], &fubuf.ut_line[0],
                    sizeof (fubuf.ut_line)) == 0) {
                        utmpx_frec2api(&fubuf, &ubuf);
                        return (&ubuf);
                }
        } while (getutxent_frec() != NULL);

        /*
         * Since entry wasn't found, return NULL.
         */
        utmpx_frec2api(&fubuf, &ubuf);
        return (NULL);
}

/*
 * "getutline" searches the "utmp" file for a LOGIN_PROCESS or
 * USER_PROCESS with the same "line" as the specified "entry".
 */
struct utmp *
getutline(const struct utmp *entry)
{
        struct utmpx utmpx;
        struct utmpx *utmpx2;

        if (compat_utmpflag)
                return (_compat_getutline(entry));

        /* fail if we can't represent maxpid properly */
        if (big_pids_in_use()) {
                errno = EOVERFLOW;
                return (NULL);
        }
        /* call getutxline */
        getutmpx(entry, &utmpx);
        if ((utmpx2 = getutxline(&utmpx)) == NULL)
                return (NULL);
        getutmp(utmpx2, &utmpcompat);
        return (&utmpcompat);
}

/*
 * invoke_utmp_update
 *
 * Invokes the utmp_update program which has the privilege to write
 * to the /etc/utmp file.
 */

#define UTMP_UPDATE     "/usr/lib/utmp_update"
#define STRSZ   64      /* Size of char buffer for argument strings */

static struct utmpx *
invoke_utmp_update(const struct utmpx *entryx)
{
        extern char **_environ;

        posix_spawnattr_t attr;
        int status;
        int cancel_state;
        pid_t child;
        pid_t w;
        int i;
        char user[STRSZ], id[STRSZ], line[STRSZ], pid[STRSZ], type[STRSZ],
            term[STRSZ], exit[STRSZ], time[STRSZ], time_usec[STRSZ],
            session_id[STRSZ], syslen[32];
        char pad[sizeof (entryx->pad) * 2 + 1];
        char host[sizeof (entryx->ut_host) + 1];
        struct utmpx *curx = NULL;
        char bin2hex[] = "0123456789ABCDEF";
        unsigned char *cp;
        char *argvec[15];
        int error;

        /*
         * Convert the utmp struct to strings for command line arguments.
         */
        (void) strncpy(user, entryx->ut_user, sizeof (entryx->ut_user));
        user[sizeof (entryx->ut_user)] = '\0';
        (void) strncpy(id, entryx->ut_id, sizeof (entryx->ut_id));
        id[sizeof (entryx->ut_id)] = '\0';
        (void) strncpy(line, entryx->ut_line, sizeof (entryx->ut_line));
        line[sizeof (entryx->ut_line)] = '\0';
        (void) sprintf(pid, "%d", (int)entryx->ut_pid);
        (void) sprintf(type, "%d", entryx->ut_type);
        (void) sprintf(term, "%d", entryx->ut_exit.e_termination);
        (void) sprintf(exit, "%d", entryx->ut_exit.e_exit);
        (void) sprintf(time, "%ld", entryx->ut_tv.tv_sec);
        (void) sprintf(time_usec, "%ld", entryx->ut_tv.tv_usec);
        (void) sprintf(session_id, "%d", entryx->ut_session);

        cp = (unsigned char *)entryx->pad;
        for (i = 0; i < sizeof (entryx->pad); ++i) {
                pad[i << 1] = bin2hex[(cp[i] >> 4) & 0xF];
                pad[(i << 1) + 1] = bin2hex[cp[i] & 0xF];
        }
        pad[sizeof (pad) - 1] = '\0';

        (void) sprintf(syslen, "%d", entryx->ut_syslen);
        (void) strlcpy(host, entryx->ut_host, sizeof (host));

        argvec[0] = UTMP_UPDATE;
        argvec[1] = user;
        argvec[2] = id;
        argvec[3] = line;
        argvec[4] = pid;
        argvec[5] = type;
        argvec[6] = term;
        argvec[7] = exit;
        argvec[8] = time;
        argvec[9] = time_usec;
        argvec[10] = session_id;
        argvec[11] = pad;
        argvec[12] = syslen;
        argvec[13] = host;
        argvec[14] = NULL;

        /*
         * No SIGCHLD, please, and let no one else reap our child.
         */
        error = posix_spawnattr_init(&attr);
        if (error) {
                errno = error;
                goto out;
        }
        error = posix_spawnattr_setflags(&attr,
            POSIX_SPAWN_NOSIGCHLD_NP | POSIX_SPAWN_WAITPID_NP);
        if (error) {
                (void) posix_spawnattr_destroy(&attr);
                errno = error;
                goto out;
        }
        error = posix_spawn(&child, UTMP_UPDATE, NULL, &attr, argvec, _environ);
        (void) posix_spawnattr_destroy(&attr);
        if (error) {
                errno = error;
                goto out;
        }

        (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancel_state);
        do {
                w = waitpid(child, &status, 0);
        } while (w == -1 && errno == EINTR);
        (void) pthread_setcancelstate(cancel_state, NULL);

        /*
         * We can get ECHILD if the process is ignoring SIGCLD.
         */
        if (!(w == -1 && errno == ECHILD) &&
            (w == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0)) {
                /*
                 * The child encountered an error,
                 */
                goto out;
        }

        /*
         * Normal termination.  Return a pointer to the entry we just made.
         */
        setutxent();    /* Reset file pointer */

        while ((curx = getutxent()) != NULL) {
                if (curx->ut_type != EMPTY &&
                    (curx->ut_type == LOGIN_PROCESS ||
                    curx->ut_type == USER_PROCESS ||
                    curx->ut_type == DEAD_PROCESS) &&
                    strncmp(&entryx->ut_line[0], &curx->ut_line[0],
                    sizeof (curx->ut_line)) == 0)
                        break;
        }

out:
        return (curx);
}

/*
 * "pututxline" writes the structure sent into the utmpx file.
 * If there is already an entry with the same id, then it is
 * overwritten, otherwise a new entry is made at the end of the
 * utmpx file.
 */

struct utmpx *
pututxline(const struct utmpx *entry)
{
        struct utmpx *answer;
        int lock = 0;
        struct utmpx tmpxbuf;
        struct futmpx ftmpxbuf;

        /*
         * Copy the user supplied entry into our temporary buffer to
         * avoid the possibility that the user is actually passing us
         * the address of "ubuf".
         */
        if (entry == NULL)
                return (NULL);

        (void) memcpy(&tmpxbuf, entry, sizeof (tmpxbuf));
        utmpx_api2frec(entry, &ftmpxbuf);

        if (fd < 0) {
                (void) getutxent_frec();
                if (fd < 0)
                        return (NULL);
        }

        /*
         * If we are not the superuser than we can't write to /etc/utmp,
         * so invoke update_utmp(8) to write the entry for us.
         */
        if (changed_name == 0 && geteuid() != 0)
                return (invoke_utmp_update(entry));

        /*
         * Find the proper entry in the utmpx file.  Start at the current
         * location.  If it isn't found from here to the end of the
         * file, then reset to the beginning of the file and try again.
         * If it still isn't found, then write a new entry at the end of
         * the file.  (Making sure the location is an integral number of
         * utmp structures into the file incase the file is scribbled.)
         */

        if (getutxid(&tmpxbuf) == NULL) {

                setutxent();

                /*
                 * Lock the the entire file from here onwards.
                 */
                if (getutxid(&tmpxbuf) == NULL) {
                        lock++;
                        if (lockf(fd, F_LOCK, 0) < 0)
                                return (NULL);
                        (void) fseek(fp, 0, SEEK_END);
                } else
                        (void) fseek(fp, -(long)sizeof (struct futmpx),
                            SEEK_CUR);
        } else
                (void) fseek(fp, -(long)sizeof (struct futmpx), SEEK_CUR);

        /*
         * Write out the user supplied structure.  If the write fails,
         * then the user probably doesn't have permission to write the
         * utmpx file.
         */
        if (fwrite(&ftmpxbuf, sizeof (ftmpxbuf), 1, fp) != 1) {
                answer = NULL;
        } else {
                /*
                 * Save the new user structure into ubuf and fubuf so that
                 * it will be up to date in the future.
                 */
                (void) fflush(fp);
                (void) memcpy(&fubuf, &ftmpxbuf, sizeof (fubuf));
                utmpx_frec2api(&fubuf, &ubuf);
                answer = &ubuf;
        }

        if (lock)
                (void) lockf(fd, F_ULOCK, 0);

        if (answer != NULL && (tmpxbuf.ut_type == USER_PROCESS ||
            tmpxbuf.ut_type == DEAD_PROCESS))
                sendupid(tmpxbuf.ut_type == USER_PROCESS ? ADDPID : REMPID,
                    (pid_t)tmpxbuf.ut_pid);
        return (answer);
}
/*
 * "pututline" is a wrapper that calls pututxline after converting
 * the utmp record to a utmpx record.
 */
struct utmp *
pututline(const struct utmp *entry)
{
        struct utmpx utmpx;
        struct utmpx *utmpx2;

        if (compat_utmpflag)
                return (_compat_pututline(entry));

        getutmpx(entry, &utmpx);
        if ((utmpx2 = pututxline(&utmpx)) == NULL)
                return (NULL);
        getutmp(utmpx2, &utmpcompat);
        return (&utmpcompat);
}

/*
 * "setutxent" just resets the utmpx file back to the beginning.
 */
void
setutxent(void)
{
        if (fd != -1)
                (void) lseek(fd, 0L, SEEK_SET);

        if (fp != NULL)
                (void) fseek(fp, 0L, SEEK_SET);

        /*
         * Zero the stored copy of the last entry read, since we are
         * resetting to the beginning of the file.
         */
        bzero(&ubuf, sizeof (ubuf));
        bzero(&fubuf, sizeof (fubuf));
}

/*
 * "setutent" is a wrapper that calls setutxent
 */
void
setutent(void)
{
        if (compat_utmpflag) {
                _compat_setutent();
                return;
        }

        setutxent();
}

/*
 * "endutxent" closes the utmpx file.
 */
void
endutxent(void)
{
        if (fd != -1)
                (void) close(fd);
        fd = -1;

        if (fp != NULL)
                (void) fclose(fp);
        fp = NULL;

        bzero(&ubuf, sizeof (ubuf));
        bzero(&fubuf, sizeof (fubuf));
}

/*
 * "endutent" is a wrapper that calls endutxent
 * and clears the utmp compatibility buffer.
 */
void
endutent(void)
{
        if (compat_utmpflag) {
                _compat_endutent();
                return;
        }

        endutxent();
        bzero(&utmpcompat, sizeof (utmpcompat));
}

/*
 * "utmpxname" allows the user to read a file other than the
 * normal "utmpx" file.
 */
int
utmpxname(const char *newfile)
{
        size_t len;

        /*
         * Determine if the new filename will fit.  If not, return 0.
         */
        if ((len = strlen(newfile)) > MAXFILE-1)
                return (0);

        /*
         * The name of the utmpx file has to end with 'x'
         */
        if (newfile[len-1] != 'x')
                return (0);

        /*
         * Otherwise copy in the new file name.
         */
        else
                (void) strcpy(&utmpxfile[0], newfile);
        /*
         * Make sure everything is reset to the beginning state.
         */
        endutxent();

        /*
         * If the file is being changed to /etc/utmpx or /var/adm/utmpx then
         * we clear the flag so pututxline invokes utmp_update.  Otherwise
         * we set the flag indicating that they changed to another name.
         */
        if (strcmp(utmpxfile, UTMPX_FILE) == 0 ||
            strcmp(utmpxfile, VAR_UTMPX_FILE) == 0)
                changed_name = 0;
        else
                changed_name = 1;

        return (1);
}

/*
 * "utmpname" allows the user to read a file other than the
 * normal "utmp" file. If the file specified is "/var/adm/utmp"
 * or "/var/adm/wtmp", it is translated to the corresponding "utmpx"
 * format name, and all "utmp" operations become wrapped calls
 * to the equivalent "utmpx" routines, with data conversions
 * as appropriate.  In the event the application wishes to read
 * an actual "old" utmp file (named something other than /var/adm/utmp),
 * calling this function with that name enables backward compatibility
 * mode, where we actually call the old utmp routines to operate on
 * the old file.
 */
int
utmpname(const char *newfile)
{
        char name[MAXFILE+1];

        if (strlen(newfile) > MAXFILE)
                return (0);

        if (strcmp(newfile, "/var/adm/utmp") == 0 ||
            strcmp(newfile, "/var/adm/wtmp") == 0) {
                (void) strcpy(name, newfile);
                (void) strcat(name, "x");
                compat_utmpflag = 0;    /* turn off old compat mode */
                return (utmpxname(name));
        } else {
                (void) strcpy(_compat_utmpfile, newfile);
                compat_utmpflag = 1;
                return (1);
        }
}

/*
 * Add the record to wtmpx.
 */
void
updwtmpx(const char *filex, struct utmpx *utx)
{
        struct futmpx futx;
        int wfdx;

        if ((wfdx = open(filex, O_WRONLY | O_APPEND)) < 0)
                return;

        (void) lseek(wfdx, 0, SEEK_END);

        utmpx_api2frec(utx, &futx);
        (void) write(wfdx, &futx, sizeof (futx));

done:
        (void) close(wfdx);
}

/*
 * Add record to wtmp (actually wtmpx). If not updating /var/adm/wtmp,
 * use the old utmp compatibility routine to write a utmp-format
 * record to the file specified.
 */
void
updwtmp(const char *file, struct utmp *ut)
{
        struct utmpx utmpx;
        char xfile[MAXFILE + 1];

        if (strcmp(file, "/var/adm/wtmp") == 0) {
                (void) strlcpy(xfile, file, sizeof (xfile) - 1);
                (void) strcat(xfile, "x");
                getutmpx(ut, &utmpx);
                updwtmpx((const char *)&xfile, &utmpx);
        } else
                _compat_updwtmp(file, ut);
}

/*
 * modutx - modify a utmpx entry.  Also notify init about new pids or
 *      old pids that it no longer needs to care about
 *
 *      args:   utp- point to utmpx structure to be created
 */
struct utmpx *
modutx(const struct utmpx *utp)
{
        int i;
        struct utmpx utmp;              /* holding area */
        struct utmpx *ucp = &utmp;      /* and a pointer to it */
        struct utmpx *up;               /* "current" utmpx entry */
        struct futmpx *fup;             /* being examined */

        for (i = 0; i < IDLEN; ++i) {
                if ((unsigned char)utp->ut_id[i] == SC_WILDC)
                        return (NULL);
        }

        /*
         * copy the supplied utmpx structure someplace safe
         */
        (void) memcpy(&utmp, utp, sizeof (utmp));
        setutxent();
        while (fup = getutxent_frec()) {
                if (idcmp(ucp->ut_id, fup->ut_id))
                        continue;

                /*
                 * only get here if ids are the same, i.e. found right entry
                 */
                if (ucp->ut_pid != fup->ut_pid) {
                        sendpid(REMPID, (pid_t)fup->ut_pid);
                        sendpid(ADDPID, (pid_t)ucp->ut_pid);
                }
                break;
        }
        up = pututxline(ucp);
        if (ucp->ut_type == DEAD_PROCESS)
                sendpid(REMPID, (pid_t)ucp->ut_pid);
        if (up)
                updwtmpx(WTMPX_FILE, up);
        endutxent();
        return (up);
}

/*
 * modut - modify a utmp entry.  Also notify init about new pids or
 *      old pids that it no longer needs to care about
 *
 *      args:   utmp - point to utmp structure to be created
 */
struct utmp *
modut(struct utmp *utp)
{
        struct utmpx utmpx;
        struct utmpx *utmpx2;

        getutmpx(utp, &utmpx);
        if ((utmpx2 = modutx(&utmpx)) == NULL)
                return (NULL);

        getutmp(utmpx2, utp);
        return (utp);
}

/*
 * idcmp - compare two id strings, return  0 if same, non-zero if not *
 *      args:   s1 - first id string
 *              s2 - second id string
 */
static int
idcmp(const char *s1, const char *s2)
{
        int i;

        for (i = 0; i < IDLEN; ++i)
                if ((unsigned char) *s1 != SC_WILDC && (*s1++ != *s2++))
                        return (-1);
        return (0);
}


/*
 * allocid - allocate an unused id for utmp, either by recycling a
 *      DEAD_PROCESS entry or creating a new one.  This routine only
 *      gets called if a wild card character was specified.
 *
 *      args:   srcid - pattern for new id
 *              saveid - last id matching pattern for a non-dead process
 */
static int
allocid(char *srcid, unsigned char *saveid)
{
        int i;          /* scratch variable */
        int changed;            /* flag to indicate that a new id has */
                                /* been generated */
        char copyid[IDLEN];     /* work area */

        (void) memcpy(copyid, srcid, IDLEN);
        changed = 0;
        for (i = 0; i < IDLEN; ++i) {

                /*
                 * if this character isn't wild, it'll be part of the
                 * generated id
                 */
                if ((unsigned char) copyid[i] != SC_WILDC)
                        continue;

                /*
                 * it's a wild character, retrieve the character from the
                 * saved id
                 */
                copyid[i] = saveid[i];

                /*
                 * if we haven't changed anything yet, try to find a new char
                 * to use
                 */
                if (!changed && (saveid[i] < MAXVAL)) {

                /*
                 * Note: this algorithm is taking the "last matched" id
                 * and trying to make a 1 character change to it to create
                 * a new one.  Rather than special-case the first time
                 * (when no perturbation is really necessary), just don't
                 * allocate the first valid id.
                 */

                        while (++saveid[i] < MAXVAL) {
                                /*
                                 * make sure new char is alphanumeric
                                 */
                                if (isalnum(saveid[i])) {
                                        copyid[i] = saveid[i];
                                        changed = 1;
                                        break;
                                }
                        }

                        if (!changed) {
                                /*
                                 * Then 'reset' the current count at
                                 * this position to it's lowest valid
                                 * value, and propagate the carry to
                                 * the next wild-card slot
                                 *
                                 * See 1113208.
                                 */
                                saveid[i] = 0;
                                while (!isalnum(saveid[i]))
                                saveid[i]++;
                                copyid[i] = ++saveid[i];
                        }
                }
        }
        /*
         * changed is true if we were successful in allocating an id
         */
        if (changed) {
                (void) memcpy(srcid, copyid, IDLEN);
                return (0);
        } else {
                return (-1);
        }
}


/*
 * lockutx - lock utmpx file
 */
static int
lockutx(void)
{
        int lockfd;

        if ((lockfd = open(UTMPX_FILE, O_RDWR|O_CREAT, 0644)) < 0)
                return (-1);

        if (lockf(lockfd, F_LOCK, 0) < 0) {
                (void) close(lockfd);
                return (-1);
        }

        tempfd = fd;
        fd = lockfd;

        return (0);

}



/*
 * unlockutx - unlock utmpx file
 */
static void
unlockutx(void)
{
        (void) lockf(fd, F_ULOCK, 0);
        (void) close(fd);
        fd = tempfd;
}


/*
 * sendpid - send message to init to add or remove a pid from the
 *      "godchild" list
 *
 *      args:   cmd - ADDPID or REMPID
 *              pid - pid of "godchild"
 */
static void
sendpid(int cmd, pid_t pid)
{
        int pfd;                /* file desc. for init pipe */
        pidrec_t prec;          /* place for message to be built */

        /*
         * if for some reason init didn't open initpipe, open it read/write
         * here to avoid sending SIGPIPE to the calling process
         */
        pfd = open(IPIPE, O_RDWR);
        if (pfd < 0)
                return;
        prec.pd_pid = pid;
        prec.pd_type = cmd;
        (void) write(pfd, &prec, sizeof (pidrec_t));
        (void) close(pfd);
}

/*
 * makeutx - create a utmpx entry, recycling an id if a wild card is
 *      specified.  Also notify init about the new pid
 *
 *      args:   utmpx - point to utmpx structure to be created
 */

struct utmpx *
makeutx(const struct utmpx *utmp)
{
        struct utmpx *utp;
        struct futmpx *ut;              /* "current" utmpx being examined */
        unsigned char saveid[IDLEN];    /* the last id we matched that was */
                                        /* NOT a dead proc */
        int falphanum = 0x30;           /* first alpha num char */
        off_t offset;

        /*
         * Are any wild card char's present in the idlen string?
         */
        if (memchr(utmp->ut_id, SC_WILDC, IDLEN) != NULL) {
                /*
                 * try to lock the utmpx file, only needed if
                 * we're doing wildcard matching
                 */
                if (lockutx())
                        return (NULL);

                /*
                 * used in allocid
                 */
                (void) memset(saveid, falphanum, IDLEN);

                while (ut = getoneutx(&offset))
                        if (idcmp(utmp->ut_id, ut->ut_id)) {
                                continue;
                        } else {
                                /*
                                 * Found a match. We are done if this is
                                 * a free slot. Else record this id. We
                                 * will need it to generate the next new id.
                                 */
                                if (ut->ut_type == DEAD_PROCESS)
                                        break;
                                else
                                        (void) memcpy(saveid, ut->ut_id,
                                            IDLEN);
                        }

                if (ut) {

                        /*
                         * Unused entry, reuse it. We know the offset. So
                         * just go to that offset  utmpx and write it out.
                         */
                        (void) memcpy((caddr_t)utmp->ut_id, ut->ut_id, IDLEN);

                        putoneutx(utmp, offset);
                        updwtmpx(WTMPX_FILE, (struct utmpx *)utmp);
                        unlockutx();
                        sendpid(ADDPID, (pid_t)utmp->ut_pid);
                        return ((struct utmpx *)utmp);
                } else {
                        /*
                         * nothing available, allocate an id and
                         * write it out at the end.
                         */

                        if (allocid((char *)utmp->ut_id, saveid)) {
                                unlockutx();
                                return (NULL);
                        } else {
                                /*
                                 * Seek to end and write out the entry
                                 * and also update the utmpx file.
                                 */
                                (void) lseek(fd, 0L, SEEK_END);
                                offset = lseek(fd, 0L, SEEK_CUR);

                                putoneutx(utmp, offset);
                                updwtmpx(WTMPX_FILE, (struct utmpx *)utmp);
                                unlockutx();
                                sendpid(ADDPID, (pid_t)utmp->ut_pid);
                                return ((struct utmpx *)utmp);
                        }
                }
        } else {
                utp = pututxline(utmp);
                if (utp)
                        updwtmpx(WTMPX_FILE, utp);
                endutxent();
                sendpid(ADDPID, (pid_t)utmp->ut_pid);
                return (utp);
        }
}

/*
 * makeut - create a utmp entry, recycling an id if a wild card is
 *      specified.  Also notify init about the new pid
 *
 *      args:   utmp - point to utmp structure to be created
 */
struct utmp *
makeut(struct utmp *utmp)
{
        struct utmpx utmpx;
        struct utmpx *utmpx2;

        if (compat_utmpflag)
                return (_compat_makeut(utmp));

        getutmpx(utmp, &utmpx);
        if ((utmpx2 = makeutx(&utmpx)) == NULL)
                return (NULL);

        getutmp(utmpx2, utmp);
        return (utmp);
}


#define UTMPNBUF        200     /* Approx 8k (FS Block) size */
static struct futmpx    *utmpbuf = NULL;

/*
 * Buffered read routine to get one entry from utmpx file
 */
static struct futmpx *
getoneutx(off_t *off)
{
        static  size_t idx = 0; /* Current index in the utmpbuf */
        static  size_t nidx = 0;        /* Max entries in this utmpbuf */
        static  int nbuf = 0;   /* number of utmpbufs read from disk */
        ssize_t nbytes, bufsz = sizeof (struct futmpx) * UTMPNBUF;

        if (utmpbuf == NULL)
                if ((utmpbuf = malloc(bufsz)) == NULL) {
                        perror("malloc");
                        return (NULL);
                }

        if (idx == nidx) {
                /*
                 *      We have read all entries in the utmpbuf. Read
                 *      the buffer from the disk.
                 */
                if ((nbytes = read(fd, utmpbuf, bufsz)) < bufsz) {
                        /*
                         *      Partial read only. keep count of the
                         *      number of valid entries in the buffer
                         */
                        nidx = nbytes / sizeof (struct futmpx);
                } else {
                        /*
                         *      We read in the full UTMPNBUF entries
                         *      Great !
                         */
                        nidx = UTMPNBUF;
                }
                nbuf++;         /* Number of buf we have read in. */
                idx = 0;        /* reset index within utmpbuf */
        }

        /*
         *      Current offset of this buffer in the file
         */
        *off = (((nbuf - 1) * UTMPNBUF) + idx) * sizeof (struct futmpx);

        if (idx < nidx) {
                /*
                 *      We still have at least one valid buffer in
                 *      utmpbuf to be passed to the caller.
                 */
                return (&utmpbuf[idx++]);
        }

        /*
         *      Reached EOF. Return NULL. Offset is set correctly
         *      to append at the end of the file
         */

        return (NULL);
}

static void
putoneutx(const struct utmpx *utpx, off_t off)
{
        struct  futmpx futx;

        utmpx_api2frec(utpx, &futx);
        (void) lseek(fd, off, SEEK_SET);        /* seek in the utmpx file */
        (void) write(fd, &futx, sizeof (futx));
}

/*
 * sendupid - send message to utmpd to add or remove a pid from the
 *      list of procs to watch
 *
 *      args:   cmd - ADDPID or REMPID
 *              pid - process ID of process to watch
 */
static void
sendupid(int cmd, pid_t pid)
{
        int pfd;                /* file desc. for utmp pipe */
        pidrec_t prec;          /* place for message to be built */

        /*
         * if for some reason utmp didn't open utmppipe, open it read/write
         * here to avoid sending SIGPIPE to the calling process
         */

        pfd = open(UPIPE, O_RDWR | O_NONBLOCK | O_NDELAY);
        if (pfd < 0)
                return;
        prec.pd_pid = pid;
        prec.pd_type = cmd;
        (void) write(pfd, &prec, sizeof (pidrec_t));
        (void) close(pfd);
}

/*
 * getutmpx - convert a utmp record into a utmpx record
 */
void
getutmpx(const struct utmp *ut, struct utmpx *utx)
{
        (void) memcpy(utx->ut_user, ut->ut_user, sizeof (ut->ut_user));
        (void) bzero(&utx->ut_user[sizeof (ut->ut_user)],
            sizeof (utx->ut_user) - sizeof (ut->ut_user));
        (void) memcpy(utx->ut_line, ut->ut_line, sizeof (ut->ut_line));
        (void) bzero(&utx->ut_line[sizeof (ut->ut_line)],
            sizeof (utx->ut_line) - sizeof (ut->ut_line));
        (void) memcpy(utx->ut_id, ut->ut_id, sizeof (ut->ut_id));
        utx->ut_pid = ut->ut_pid;
        utx->ut_type = ut->ut_type;
        utx->ut_exit = ut->ut_exit;
        utx->ut_tv.tv_sec = ut->ut_time;
        utx->ut_tv.tv_usec = 0;
        utx->ut_session = 0;
        bzero(utx->pad, sizeof (utx->pad));
        bzero(utx->ut_host, sizeof (utx->ut_host));
        utx->ut_syslen = 0;
}

/*
 * getutmp - convert a utmpx record into a utmp record
 */
void
getutmp(const struct utmpx *utx, struct utmp *ut)
{
        (void) memcpy(ut->ut_user, utx->ut_user, sizeof (ut->ut_user));
        (void) memcpy(ut->ut_line, utx->ut_line, sizeof (ut->ut_line));
        (void) memcpy(ut->ut_id, utx->ut_id, sizeof (utx->ut_id));
        ut->ut_pid = utx->ut_pid;
        ut->ut_type = utx->ut_type;
        ut->ut_exit = utx->ut_exit;
        ut->ut_time = utx->ut_tv.tv_sec;
}