sendmail/aux/vacation.c

	vacation.c revision d5e7c3fca16e5d67fa1a124aced8a4c587b01e1a
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 *  Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T
 *    All Rights Reserved
 */

/*
 *  Vacation
 *  Copyright (c) 1983  Eric P. Allman
 *  Berkeley, California
 *
 *  Copyright (c) 1983 Regents of the University of California.
 *  All rights reserved.  The Berkeley software License Agreement
 *  specifies the terms and conditions for redistribution.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#ifndef lint
static char SccsId[] = "%W% %E% SMI";
#endif /* not lint */

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <unistd.h>
#include <sysexits.h>
#include <pwd.h>
#include <ndbm.h>
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#include <strings.h>
#include <errno.h>

/*
 *  VACATION -- return a message to the sender when on vacation.
 *
 *  This program could be invoked as a message receiver
 *  when someone is on vacation.  It returns a message
 *  specified by the user to whoever sent the mail, taking
 *  care not to return a message too often to prevent
 *  "I am on vacation" loops.
 *
 *  For best operation, this program should run setuid to
 *  root or uucp or someone else that sendmail will believe
 *  a -f flag from.  Otherwise, the user must be careful
 *  to include a header on his .vacation.msg file.
 *
 *  Positional Parameters:
 *      the user to collect the vacation message from.
 *
 *  Flag Parameters:
 *      -I  initialize the database.
 *      -d  turn on debugging.
 *      -tT set the timeout to T.  messages arriving more
 *          often than T will be ignored to avoid loops.
 *
 *  Side Effects:
 *      A message is sent back to the sender.
 *
 *  Author:
 *      Eric Allman
 *      UCB/INGRES
 */

#define MAXLINE 256 /* max size of a line */

#define ONEWEEK (60L*60L*24L*7L)
#define MsgFile "/.vacation.msg"
#define FilterFile "/.vacation.filter"
#define DbFileBase "/.vacation"
#define _PATH_TMP   "/tmp/vacation.XXXXXX"

typedef int bool;

#define FALSE   0
#define TRUE    1

static time_t   Timeout = ONEWEEK;  /* timeout between notices per user */
static DBM  *db;
static bool Debug = FALSE;
static bool AnswerAll = FALSE;  /* default: answer if in To:/Cc: only */
static char *Subject = NULL;    /* subject in message header */
static char *EncodedSubject = NULL; /* subject in message header */
static char Charset[MAXLINE];   /* for use in reply message */
static char *AliasList[MAXLINE];    /* list of aliases to allow */
static int  AliasCount = 0;
static char *myname;        /* name of person "on vacation" */
static char *homedir;       /* home directory of said person */

extern time_t   convtime(char *, char);
extern bool decode_rfc2047(char *, char *, char *);

static bool ask(char *);
static bool junkmail(char *);
static bool filter_ok(char *, char *);
static bool knows(char *);
static bool sameword(char *, char *);
static char *getfrom(char **);
static char *newstr(char *);
static void AutoInstall();
static void initialize(char *);
static void sendmessage(char *, char *, char *);
static void setknows(char *);

void    usrerr(const char *, ...);

int
main(argc, argv)
    int argc;
    char **argv;
{
    char *from;
    char *p, *at, *c;
    struct passwd *pw;
    char *shortfrom;
    char buf[MAXLINE];
    char *message_file = MsgFile;
    char *db_file_base = DbFileBase;
    char *filter_file = FilterFile;
    char *sender;
    bool sender_oob = FALSE;
    bool initialize_only = FALSE;

    /* process arguments */
    while (--argc > 0 && (p = *++argv) != NULL && *p == '-')
    {
        switch (*++p)
        {
            case 'a':   /* add this to list of acceptable aliases */
            AliasList[AliasCount++] = argv[1];
            if (argc > 0) {
                argc--; argv++;
            }
            break;

            case 'd':   /* debug */
            Debug = TRUE;
            break;

            case 'e':   /* alternate filter file */
            filter_file = argv[1];
            if (argc > 0) {
                argc--; argv++;
            }
            break;

            case 'f':   /* alternate database file name base */
            db_file_base = argv[1];
            if (argc > 0) {
                argc--; argv++;
            }
            break;

            case 'I':   /* initialize */
            initialize_only = TRUE;
            break;

            case 'j':   /* answer all mail, even if not in To/Cc */
            AnswerAll = TRUE;
            break;

            case 'm':   /* alternate message file */
            message_file = argv[1];
            if (argc > 0) {
                argc--; argv++;
            }
            break;

            case 's':   /* sender: use this instead of getfrom() */
            sender = argv[1];
            sender_oob = TRUE;
            if (argc > 0) {
                argc--; argv++;
            }
            break;

            case 't':   /* set timeout */
            Timeout = convtime(++p, 'w');
            break;

            default:
            usrerr("Unknown flag -%s", p);
            exit(EX_USAGE);
        }
    }

    if (initialize_only)
    {
        initialize(db_file_base);
        exit(EX_OK);
    }

    /* verify recipient argument */
    if (argc == 0)
        AutoInstall();

    if (argc != 1)
    {
        usrerr("Usage: vacation username (or) vacation -I");
        exit(EX_USAGE);
    }

    myname = p;
    Charset[0] = '\0';

    /* find user's home directory */
    pw = getpwnam(myname);
    if (pw == NULL)
    {
        usrerr("user %s look up failed, name services outage ?",
            myname);
        exit(EX_TEMPFAIL);
    }
    homedir = newstr(pw->pw_dir);

    (void) snprintf(buf, sizeof (buf), "%s%s%s", homedir,
            (db_file_base[0] == '/') ? "" : "/", db_file_base);
    if (!(db = dbm_open(buf, O_RDWR, 0))) {
        usrerr("%s: %s\n", buf, strerror(errno));
        exit(EX_DATAERR);
    }

    if (sender_oob)
    {
        at = strchr(sender, '@');
        if (at != NULL)
            for (c = at + 1; *c; c++)
                *c = (char)tolower((char)*c);
        from = sender;
        shortfrom = sender;
    }
    else
        /* read message from standard input (just from line) */
        from = getfrom(&shortfrom);

    /* check if junk mail or this person is already informed */
    if (!junkmail(shortfrom) && filter_ok(shortfrom, filter_file) &&
        !knows(shortfrom))
    {
        /* mark this person as knowing */
        setknows(shortfrom);

        /* send the message back */
        (void) strlcpy(buf, homedir, sizeof (buf));
        if (message_file[0] != '/')
            (void) strlcat(buf, "/", sizeof (buf));
        (void) strlcat(buf, message_file, sizeof (buf));
        if (Debug)
            printf("Sending %s to %s\n", buf, from);
        else
        {
            sendmessage(buf, from, myname);
            /*NOTREACHED*/
        }
    }
    return (EX_OK);
}

/*
 *  GETFROM -- read message from standard input and return sender
 *
 *  Parameters:
 *      none.
 *
 *  Returns:
 *      pointer to the sender address.
 *
 *  Side Effects:
 *      Reads first line from standard input.
 */

static char *
getfrom(shortp)
char **shortp;
{
    static char line[MAXLINE];
    char *p, *start, *at, *bang, *c;
    char saveat;

    /* read the from line */
    if (fgets(line, sizeof (line), stdin) == NULL ||
        strncmp(line, "From ", 5) != NULL)
    {
        usrerr("No initial From line");
        exit(EX_PROTOCOL);
    }

    /* find the end of the sender address and terminate it */
    start = &line[5];
    p = strchr(start, ' ');
    if (p == NULL)
    {
        usrerr("Funny From line '%s'", line);
        exit(EX_PROTOCOL);
    }
    *p = '\0';

    /*
     * Strip all but the rightmost UUCP host
     * to prevent loops due to forwarding.
     * Start searching leftward from the leftmost '@'.
     *  a!b!c!d yields a short name of c!d
     *  a!b!c!d@e yields a short name of c!d@e
     *  e@a!b!c yields the same short name
     */
#ifdef VDEBUG
printf("start='%s'\n", start);
#endif /* VDEBUG */
    *shortp = start;            /* assume whole addr */
    if ((at = strchr(start, '@')) == NULL)  /* leftmost '@' */
        at = p;             /* if none, use end of addr */
    saveat = *at;
    *at = '\0';
    if ((bang = strrchr(start, '!')) != NULL) { /* rightmost '!' */
        char *bang2;
        *bang = '\0';
        /* 2nd rightmost '!' */
        if ((bang2 = strrchr(start, '!')) != NULL)
            *shortp = bang2 + 1;        /* move past ! */
        *bang = '!';
    }
    *at = saveat;
#ifdef VDEBUG
printf("place='%s'\n", *shortp);
#endif /* VDEBUG */
    for (c = at + 1; *c; c++)
        *c = (char)tolower((char)*c);

    /* return the sender address */
    return (start);
}

/*
 *  JUNKMAIL -- read the header and tell us if this is junk/bulk mail.
 *
 *  Parameters:
 *      from -- the Return-Path of the sender.  We assume that
 *          anything from "*-REQUEST@*" is bulk mail.
 *
 *  Returns:
 *      TRUE -- if this is junk or bulk mail (that is, if the
 *          sender shouldn't receive a response).
 *      FALSE -- if the sender deserves a response.
 *
 *  Side Effects:
 *      May read the header from standard input.  When this
 *      returns the position on stdin is undefined.
 */

static bool
junkmail(from)
    char *from;
{
    register char *p;
    char buf[MAXLINE+1];
    bool inside, onlist;

    /* test for inhuman sender */
    p = strrchr(from, '@');
    if (p != NULL)
    {
        *p = '\0';
        if (sameword(&p[-8],  "-REQUEST") ||
            sameword(&p[-10], "Postmaster") ||
            sameword(&p[-13], "MAILER-DAEMON"))
        {
            *p = '@';
            return (TRUE);
        }
        *p = '@';
    }

#define Delims " \n\t:,:;()<>@!"

    /* read the header looking for "interesting" lines */
    inside = FALSE;
    onlist = FALSE;
    while (fgets(buf, MAXLINE, stdin) != NULL && buf[0] != '\n')
    {
        if (buf[0] != ' ' && buf[0] != '\t' && strchr(buf, ':') == NULL)
            return (FALSE);         /* no header found */

        p = strtok(buf, Delims);
        if (p == NULL)
            continue;

        if (sameword(p, "To") || sameword(p, "Cc"))
        {
            inside = TRUE;
            p = strtok((char *)NULL, Delims);
            if (p == NULL)
                continue;

        } else              /* continuation line? */
            if (inside)
            inside =  (buf[0] == ' ' || buf[0] == '\t');

        if (inside) {
            int i;

            do {
            if (sameword(p, myname))
                onlist = TRUE;      /* I am on the list */

            for (i = 0; i < AliasCount; i++)
                if (sameword(p, AliasList[i]))
                onlist = TRUE;      /* alias on list */

            } while (p = strtok((char *)NULL, Delims));
            continue;
        }

        if (sameword(p, "Precedence"))
        {
            /* find the value of this field */
            p = strtok((char *)NULL, Delims);
            if (p == NULL)
                continue;

            /* see if it is "junk" or "bulk" */
            p[4] = '\0';
            if (sameword(p, "junk") || sameword(p, "bulk"))
                return (TRUE);
        }

        if (sameword(p, "Subject"))
        {
            char *decoded_subject;

            Subject = newstr(buf+9);
            if (p = strrchr(Subject, '\n'))
                *p = '\0';
            EncodedSubject = newstr(Subject);
            decoded_subject = newstr(Subject);
            if (decode_rfc2047(Subject, decoded_subject, Charset))
                Subject = decoded_subject;
            else
                Charset[0] = '\0';
            if (Debug)
                printf("Subject=%s\n", Subject);
        }
    }
    if (AnswerAll)
        return (FALSE);
    else
        return (!onlist);
}

/*
 *  FILTER_OK -- see if the Return-Path is in the filter file.
 *       Note that a non-existent filter file means everything
 *       is OK, but an empty file means nothing is OK.
 *
 *  Parameters:
 *      from -- the Return-Path of the sender.
 *
 *  Returns:
 *      TRUE -- if this is in the filter file
 *          (sender should receive a response).
 *      FALSE -- if the sender does not deserve a response.
 */

static bool
filter_ok(from, filter_file)
    char *from;
    char *filter_file;
{
    char file[MAXLINE];
    char line[MAXLINE];
    char *match_start;
    size_t line_len, from_len;
    bool result = FALSE;
    bool negated = FALSE;
    FILE *f;

    from_len = strlen(from);
    (void) strlcpy(file, homedir, sizeof (file));
    if (filter_file[0] != '/')
        (void) strlcat(file, "/", sizeof (file));
    (void) strlcat(file, filter_file, sizeof (file));
    f = fopen(file, "r");
    if (f == NULL) {
        /*
         * If the file does not exist, then there is no filter to
         * apply, so we simply return TRUE.
         */
        if (Debug)
            (void) printf("%s does not exist, filter ok.\n",
                file);
        return (TRUE);
    }
    while (fgets(line, MAXLINE, f)) {
        line_len = strlen(line);
        /* zero out trailing newline */
        if (line[line_len - 1] == '\n')
            line[--line_len] = '\0';
        /* skip blank lines */
        if (line_len == 0)
            continue;
        /* skip comment lines */
        if (line[0] == '#')
            continue;
        if (line[0] == '!') {
            negated = TRUE;
            match_start = &line[1];
            line_len--;
        } else {
            negated = FALSE;
            match_start = &line[0];
        }
        if (strchr(line, '@') != NULL) {
            /* @ => full address */
            if (strcasecmp(match_start, from) == 0) {
                result = TRUE;
                if (Debug)
                    (void) printf("filter match on %s\n",
                        line);
                break;
            }
        } else {
            /* no @ => domain */
            if (from_len <= line_len)
                continue;
            /*
             * Make sure the last part of from is the domain line
             * and that the character immediately preceding is an
             * '@' or a '.', otherwise we could get false positives
             * from e.g. twinsun.com for sun.com .
             */
            if (strncasecmp(&from[from_len - line_len],
                match_start, line_len) == 0 &&
                (from[from_len - line_len -1] == '@' ||
                from[from_len - line_len -1] == '.')) {
                result = TRUE;
                if (Debug)
                    (void) printf("filter match on %s\n",
                        line);
                break;
            }
        }
    }
    (void) fclose(f);
    if (Debug && !result)
        (void) printf("no filter match\n");
    return (!negated && result);
}

/*
 *  KNOWS -- predicate telling if user has already been informed.
 *
 *  Parameters:
 *      user -- the user who sent this message.
 *
 *  Returns:
 *      TRUE if 'user' has already been informed that the
 *          recipient is on vacation.
 *      FALSE otherwise.
 *
 *  Side Effects:
 *      none.
 */

static bool
knows(user)
    char *user;
{
    datum key, data;
    time_t now, then;

    (void) time(&now);
    key.dptr = user;
    key.dsize = strlen(user) + 1;
    data = dbm_fetch(db, key);
    if (data.dptr == NULL)
        return (FALSE);

    bcopy(data.dptr, (char *)&then, sizeof (then));
    if (then + Timeout < now)
        return (FALSE);
    if (Debug)
        printf("User %s already knows\n", user);
    return (TRUE);
}

/*
 *  SETKNOWS -- set that this user knows about the vacation.
 *
 *  Parameters:
 *      user -- the user who should be marked.
 *
 *  Returns:
 *      none.
 *
 *  Side Effects:
 *      The dbm file is updated as appropriate.
 */

static void
setknows(user)
    char *user;
{
    datum key, data;
    time_t now;

    key.dptr = user;
    key.dsize = strlen(user) + 1;
    (void) time(&now);
    data.dptr = (char *)&now;
    data.dsize = sizeof (now);
    dbm_store(db, key, data, DBM_REPLACE);
}

static bool
any8bitchars(line)
    char *line;
{
    char *c;

    for (c = line; *c; c++)
        if (*c & 0x80)
            return (TRUE);
    return (FALSE);
}

/*
 *  SENDMESSAGE -- send a message to a particular user.
 *
 *  Parameters:
 *      msgf -- filename containing the message.
 *      user -- user who should receive it.
 *
 *  Returns:
 *      none.
 *
 *  Side Effects:
 *      sends mail to 'user' using /usr/lib/sendmail.
 */

static void
sendmessage(msgf, user, myname)
    char *msgf;
    char *user;
    char *myname;
{
    FILE *f, *fpipe, *tmpf;
    char line[MAXLINE];
    char *p, *tmpf_name;
    int i, pipefd[2], tmpfd;
    bool seen8bitchars = FALSE;
    bool in_header = TRUE;

    /* find the message to send */
    f = fopen(msgf, "r");
    if (f == NULL)
    {
        f = fopen("/etc/mail/vacation.def", "r");
        if (f == NULL)
            usrerr("No message to send");
            exit(EX_OSFILE);
    }

    if (pipe(pipefd) < 0) {
        usrerr("pipe() failed");
        exit(EX_OSERR);
    }
    i = fork();
    if (i < 0) {
        usrerr("fork() failed");
        exit(EX_OSERR);
    }
    if (i == 0) {
        dup2(pipefd[0], 0);
        close(pipefd[0]);
        close(pipefd[1]);
        fclose(f);
        execl("/usr/lib/sendmail", "sendmail", "-eq", "-f", myname,
            "--", user, NULL);
        usrerr("can't exec /usr/lib/sendmail");
        exit(EX_OSERR);
    }
    close(pipefd[0]);
    fpipe = fdopen(pipefd[1], "w");
    if (fpipe == NULL) {
        usrerr("fdopen() failed");
        exit(EX_OSERR);
    }
    fprintf(fpipe, "To: %s\n", user);
    fputs("Auto-Submitted: auto-replied\n", fpipe);
    fputs("X-Mailer: vacation %I%\n", fpipe);

    /*
     * We used to write directly to the pipe.  But now we need to know
     * what character set to use, and we need to examine the entire
     * message to determine this.  So write to a temp file first.
     */
    tmpf_name = strdup(_PATH_TMP);
    if (tmpf_name == NULL) {
        usrerr("newstr: cannot alloc memory");
        exit(EX_OSERR);
    }
    tmpfd = -1;
    tmpfd = mkstemp(tmpf_name);
    if (tmpfd == -1) {
        usrerr("can't open temp file %s", tmpf_name);
        exit(EX_OSERR);
    }
    tmpf = fdopen(tmpfd, "w");
    if (tmpf == NULL) {
        usrerr("can't open temp file %s", tmpf_name);
        exit(EX_OSERR);
    }
    while (fgets(line, MAXLINE, f)) {
        /*
         * Check for a line with no ':' character.  If it's just \n,
         * we're at the end of the headers and all is fine.  Or if
         * it starts with white-space, then it's a continuation header.
         * Otherwise, it's the start of the body, which means the
         * header/body separator was skipped.  So output it.
         */
        if (in_header && line[0] != '\0' && strchr(line, ':') == NULL) {
            if (line[0] == '\n')
                in_header = FALSE;
            else if (!isspace(line[0])) {
                in_header = FALSE;
                fputs("\n", tmpf);
            }
        }
        p = strchr(line, '$');
        if (p && strncmp(p, "$SUBJECT", 8) == 0) {
            *p = '\0';
            seen8bitchars |= any8bitchars(line);
            fputs(line, tmpf);
            if (Subject) {
                if (in_header)
                    fputs(EncodedSubject, tmpf);
                else {
                    seen8bitchars |= any8bitchars(Subject);
                    fputs(Subject, tmpf);
                }
            }
            seen8bitchars |= any8bitchars(p+8);
            fputs(p+8, tmpf);
            continue;
        }
        seen8bitchars |= any8bitchars(line);
        fputs(line, tmpf);
    }
    fclose(f);
    fclose(tmpf);

    /*
     * If we haven't seen a funky Subject with Charset, use the default.
     * If we have and it's us-ascii, 8-bit chars in the message file will
     * still result in iso-8859-1.
     */
    if (Charset[0] == '\0')
        (void) strlcpy(Charset, (seen8bitchars) ? "iso-8859-1" :
            "us-ascii", sizeof (Charset));
    else if ((strcasecmp(Charset, "us-ascii") == 0) && seen8bitchars)
        (void) strlcpy(Charset, "iso-8859-1", sizeof (Charset));
    if (Debug)
        printf("Charset is %s\n", Charset);
    fprintf(fpipe, "Content-Type: text/plain; charset=%s\n", Charset);
    fputs("Mime-Version: 1.0\n", fpipe);

    /*
     * Now read back in from the temp file and write to the pipe.
     */
    tmpf = fopen(tmpf_name, "r");
    if (tmpf == NULL) {
        usrerr("can't open temp file %s", tmpf_name);
        exit(EX_OSERR);
    }
    while (fgets(line, MAXLINE, tmpf))
        fputs(line, fpipe);
    fclose(fpipe);
    fclose(tmpf);
    (void) unlink(tmpf_name);
    free(tmpf_name);
}

/*
 *  INITIALIZE -- initialize the database before leaving for vacation
 *
 *  Parameters:
 *      none.
 *
 *  Returns:
 *      none.
 *
 *  Side Effects:
 *      Initializes the files .vacation.{pag,dir} in the
 *      caller's home directory.
 */

static void
initialize(db_file_base)
    char *db_file_base;
{
    char *homedir;
    char buf[MAXLINE];
    DBM *db;

    setgid(getgid());
    setuid(getuid());
    homedir = getenv("HOME");
    if (homedir == NULL) {
        usrerr("No home!");
        exit(EX_NOUSER);
    }
    (void) snprintf(buf, sizeof (buf), "%s%s%s", homedir,
        (db_file_base[0] == '/') ? "" : "/", db_file_base);

    if (!(db = dbm_open(buf, O_WRONLY|O_CREAT|O_TRUNC, 0644))) {
        usrerr("%s: %s\n", buf, strerror(errno));
        exit(EX_DATAERR);
    }
    dbm_close(db);
}

/*
 *  USRERR -- print user error
 *
 *  Parameters:
 *      f -- format.
 *
 *  Returns:
 *      none.
 *
 *  Side Effects:
 *      none.
 */

/* PRINTFLIKE1 */
void
usrerr(const char *f, ...)
{
    va_list alist;

    va_start(alist, f);
    (void) fprintf(stderr, "vacation: ");
    (void) vfprintf(stderr, f, alist);
    (void) fprintf(stderr, "\n");
    va_end(alist);
}

/*
 *  NEWSTR -- copy a string
 *
 *  Parameters:
 *      s -- the string to copy.
 *
 *  Returns:
 *      A copy of the string.
 *
 *  Side Effects:
 *      none.
 */

static char *
newstr(s)
    char *s;
{
    char *p;
    size_t s_sz = strlen(s);

    p = malloc(s_sz + 1);
    if (p == NULL)
    {
        usrerr("newstr: cannot alloc memory");
        exit(EX_OSERR);
    }
    (void) strlcpy(p, s, s_sz + 1);
    return (p);
}

/*
 *  SAMEWORD -- return TRUE if the words are the same
 *
 *  Ignores case.
 *
 *  Parameters:
 *      a, b -- the words to compare.
 *
 *  Returns:
 *      TRUE if a & b match exactly (modulo case)
 *      FALSE otherwise.
 *
 *  Side Effects:
 *      none.
 */

static bool
sameword(a, b)
    register char *a, *b;
{
    char ca, cb;

    do
    {
        ca = *a++;
        cb = *b++;
        if (isascii(ca) && isupper(ca))
            ca = ca - 'A' + 'a';
        if (isascii(cb) && isupper(cb))
            cb = cb - 'A' + 'a';
    } while (ca != '\0' && ca == cb);
    return (ca == cb);
}

/*
 * When invoked with no arguments, we fall into an automatic installation
 * mode, stepping the user through a default installation.
 */

static void
AutoInstall()
{
    char file[MAXLINE];
    char forward[MAXLINE];
    char cmd[MAXLINE];
    char line[MAXLINE];
    char *editor;
    FILE *f;
    struct passwd *pw;
    extern mode_t umask(mode_t cmask);

    umask(022);
    pw = getpwuid(getuid());
    if (pw == NULL) {
        usrerr("User ID unknown");
        exit(EX_NOUSER);
    }
    myname = strdup(pw->pw_name);
    if (myname == NULL) {
        usrerr("Out of memory");
        exit(EX_OSERR);
    }
    homedir = getenv("HOME");
    if (homedir == NULL) {
        usrerr("Home directory unknown");
        exit(EX_NOUSER);
    }

    printf("This program can be used to answer your mail automatically\n");
    printf("when you go away on vacation.\n");
    (void) strlcpy(file, homedir, sizeof (file));
    (void) strlcat(file, MsgFile, sizeof (file));
    do {
        f = fopen(file, "r");
        if (f) {
            printf("You have a message file in %s.\n", file);
            if (ask("Would you like to see it")) {
                (void) snprintf(cmd, sizeof (cmd),
                    "/usr/bin/more %s", file);
                system(cmd);
            }
            if (ask("Would you like to edit it"))
                f = NULL;
        } else {
            printf("You need to create a message file"
                " in %s first.\n", file);
            f = fopen(file, "w");
            if (f == NULL) {
                usrerr("Cannot open %s", file);
                exit(EX_CANTCREAT);
            }
            fprintf(f, "Subject: away from my mail\n");
            fprintf(f, "\nI will not be reading my mail"
                " for a while.\n");
            fprintf(f, "Your mail regarding \"$SUBJECT\" will"
                " be read when I return.\n");
            fclose(f);
            f = NULL;
        }
        if (f == NULL) {
            editor = getenv("VISUAL");
            if (editor == NULL)
                editor = getenv("EDITOR");
            if (editor == NULL)
                editor = "/usr/bin/vi";
            (void) snprintf(cmd, sizeof (cmd), "%s %s", editor,
                file);
            printf("Please use your editor (%s)"
                " to edit this file.\n", editor);
            system(cmd);
        }
    } while (f == NULL);
    fclose(f);
    (void) strlcpy(forward, homedir, sizeof (forward));
    (void) strlcat(forward, "/.forward", sizeof (forward));
    f = fopen(forward, "r");
    if (f) {
        printf("You have a .forward file"
            " in your home directory containing:\n");
        while (fgets(line, MAXLINE, f))
            printf("    %s", line);
        fclose(f);
        if (!ask("Would you like to remove it and"
                " disable the vacation feature"))
            exit(EX_OK);
        if (unlink(forward))
            perror("Error removing .forward file:");
        else
            printf("Back to normal reception of mail.\n");
        exit(EX_OK);
    }

    printf("To enable the vacation feature"
        " a \".forward\" file is created.\n");
    if (!ask("Would you like to enable the vacation feature")) {
        printf("OK, vacation feature NOT enabled.\n");
        exit(EX_OK);
    }
    f = fopen(forward, "w");
    if (f == NULL) {
        perror("Error opening .forward file");
        exit(EX_CANTCREAT);
    }
    fprintf(f, "\\%s, \"|/usr/bin/vacation %s\"\n", myname, myname);
    fclose(f);
    printf("Vacation feature ENABLED."
        " Please remember to turn it off when\n");
    printf("you get back from vacation. Bon voyage.\n");

    initialize(DbFileBase);
    exit(EX_OK);
}


/*
 * Ask the user a question until we get a reasonable answer
 */

static bool
ask(prompt)
    char *prompt;
{
    char line[MAXLINE];
    char *res;

    for (;;) {
        printf("%s? ", prompt);
        fflush(stdout);
        res = fgets(line, sizeof (line), stdin);
        if (res == NULL)
            return (FALSE);
        if (res[0] == 'y' || res[0] == 'Y')
            return (TRUE);
        if (res[0] == 'n' || res[0] == 'N')
            return (FALSE);
        printf("Please reply \"yes\" or \"no\" (\'y\' or \'n\')\n");
    }
}