/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysctl.h>

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ttyent.h>

static char zapchar;
static FILE *tf;
static size_t lbsize;
static char *line;

#define MALLOCCHUNK     100

static char *skip(char *);
static char *value(char *);

struct ttyent *
getttynam(const char *tty)
{
        struct ttyent *t;

        if (strncmp(tty, "/dev/", 5) == 0)
                tty += 5;
        setttyent();
        while ( (t = getttyent()) )
                if (!strcmp(tty, t->ty_name))
                        break;
        endttyent();
        return (t);
}

static int
auto_tty_status(const char *ty_name)
{
        size_t len;
        char *buf, *cons, *nextcons;
        int rv;

        rv = TTY_IFCONSOLE;

        /* Check if this is an enabled kernel console line */
        buf = NULL;
        if (sysctlbyname("kern.console", NULL, &len, NULL, 0) == -1)
                return (rv); /* Errors mean don't enable */
        buf = malloc(len);
        if (sysctlbyname("kern.console", buf, &len, NULL, 0) == -1)
                goto done;

        if ((cons = strchr(buf, '/')) == NULL)
                goto done;
        *cons = '\0';
        nextcons = buf;
        while ((cons = strsep(&nextcons, ",")) != NULL && strlen(cons) != 0) {
                if (strcmp(cons, ty_name) == 0) {
                        rv |= TTY_ON;
                        break;
                }
        }

done:
        free(buf);
        return (rv);
}

static int
auto_exists_status(const char *ty_name)
{
        struct stat sb;
        char *dev;
        int rv;

        rv = TTY_IFEXISTS;
        if (*ty_name == '/')
                asprintf(&dev, "%s", ty_name);
        else
                asprintf(&dev, "/dev/%s", ty_name);
        if (dev != NULL && stat(dev, &sb) == 0)
                rv |= TTY_ON;
        free(dev);
        return (rv);
}

struct ttyent *
getttyent(void)
{
        static struct ttyent tty;
        char *p;
        int c;
        size_t i;

        if (!tf && !setttyent())
                return (NULL);
        for (;;) {
                if (!fgets(p = line, lbsize, tf))
                        return (NULL);
                /* extend buffer if line was too big, and retry */
                while (!strchr(p, '\n') && !feof(tf)) {
                        i = strlen(p);
                        lbsize += MALLOCCHUNK;
                        if ((p = realloc(line, lbsize)) == NULL) {
                                (void)endttyent();
                                return (NULL);
                        }
                        line = p;
                        if (!fgets(&line[i], lbsize - i, tf))
                                return (NULL);
                }
                while (isspace((unsigned char)*p))
                        ++p;
                if (*p && *p != '#')
                        break;
        }

#define scmp(e) !strncmp(p, e, sizeof(e) - 1) && isspace((unsigned char)p[sizeof(e) - 1])
#define vcmp(e) !strncmp(p, e, sizeof(e) - 1) && p[sizeof(e) - 1] == '='

        zapchar = 0;
        tty.ty_name = p;
        tty.ty_status = 0;
        tty.ty_window = NULL;
        tty.ty_group  = _TTYS_NOGROUP;

        p = skip(p);
        if (!*(tty.ty_getty = p))
                tty.ty_getty = tty.ty_type = NULL;
        else {
                p = skip(p);
                if (!*(tty.ty_type = p))
                        tty.ty_type = NULL;
                else {
                        /* compatibility kludge: handle network/dialup specially */
                        if (scmp(_TTYS_DIALUP))
                                tty.ty_status |= TTY_DIALUP;
                        else if (scmp(_TTYS_NETWORK))
                                tty.ty_status |= TTY_NETWORK;
                        p = skip(p);
                }
        }

        for (; *p; p = skip(p)) {
                if (scmp(_TTYS_OFF))
                        tty.ty_status &= ~TTY_ON;
                else if (scmp(_TTYS_ON))
                        tty.ty_status |= TTY_ON;
                else if (scmp(_TTYS_ONIFCONSOLE))
                        tty.ty_status |= auto_tty_status(tty.ty_name);
                else if (scmp(_TTYS_ONIFEXISTS))
                        tty.ty_status |= auto_exists_status(tty.ty_name);
                else if (scmp(_TTYS_SECURE))
                        tty.ty_status |= TTY_SECURE;
                else if (scmp(_TTYS_INSECURE))
                        tty.ty_status &= ~TTY_SECURE;
                else if (scmp(_TTYS_DIALUP))
                        tty.ty_status |= TTY_DIALUP;
                else if (scmp(_TTYS_NETWORK))
                        tty.ty_status |= TTY_NETWORK;
                else if (vcmp(_TTYS_WINDOW))
                        tty.ty_window = value(p);
                else if (vcmp(_TTYS_GROUP))
                        tty.ty_group = value(p);
                else
                        break;
        }

        if (zapchar == '#' || *p == '#')
                while ((c = *++p) == ' ' || c == '\t')
                        ;
        tty.ty_comment = p;
        if (*p == 0)
                tty.ty_comment = 0;
        if ((p = strchr(p, '\n')))
                *p = '\0';
        return (&tty);
}

#define QUOTED  1

/*
 * Skip over the current field, removing quotes, and return a pointer to
 * the next field.
 */
static char *
skip(char *p)
{
        char *t;
        int c, q;

        for (q = 0, t = p; (c = *p) != '\0'; p++) {
                if (c == '"') {
                        q ^= QUOTED;    /* obscure, but nice */
                        continue;
                }
                if (q == QUOTED && *p == '\\' && *(p+1) == '"')
                        p++;
                *t++ = *p;
                if (q == QUOTED)
                        continue;
                if (c == '#') {
                        zapchar = c;
                        *p = 0;
                        break;
                }
                if (c == '\t' || c == ' ' || c == '\n') {
                        zapchar = c;
                        *p++ = 0;
                        while ((c = *p) == '\t' || c == ' ' || c == '\n')
                                p++;
                        break;
                }
        }
        *--t = '\0';
        return (p);
}

static char *
value(char *p)
{

        return ((p = strchr(p, '=')) ? ++p : NULL);
}

int
setttyent(void)
{

        if (line == NULL) {
                if ((line = malloc(MALLOCCHUNK)) == NULL)
                        return (0);
                lbsize = MALLOCCHUNK;
        }
        if (tf) {
                rewind(tf);
                return (1);
        } else if ( (tf = fopen(_PATH_TTYS, "re")) )
                return (1);
        return (0);
}

int
endttyent(void)
{
        int rval;

        /*
         * NB: Don't free `line' because getttynam()
         * may still be referencing it
         */
        if (tf) {
                rval = (fclose(tf) != EOF);
                tf = NULL;
                return (rval);
        }
        return (1);
}

static int
isttystat(const char *tty, int flag)
{
        struct ttyent *t;

        return ((t = getttynam(tty)) == NULL) ? 0 : !!(t->ty_status & flag);
}


int
isdialuptty(const char *tty)
{

        return isttystat(tty, TTY_DIALUP);
}

int
isnettty(const char *tty)
{

        return isttystat(tty, TTY_NETWORK);
}