/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2014 The FreeBSD Foundation
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 */

/*
 * All the "defined" stuff is for handling variables,
 * such as ${OSNAME}, in maps.
 */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/linker.h>
#include <sys/mount.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/utsname.h>
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <libutil.h>
#include <netdb.h>
#include <signal.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "common.h"

static TAILQ_HEAD(, defined_value)      defined_values;

static const char *
defined_find(const char *name)
{
        struct defined_value *d;

        TAILQ_FOREACH(d, &defined_values, d_next) {
                if (strcmp(d->d_name, name) == 0)
                        return (d->d_value);
        }

        return (NULL);
}

char *
defined_expand(const char *string)
{
        const char *value;
        char c, *expanded, *name;
        int i, ret, before_len = 0, name_off = 0, name_len = 0, after_off = 0;
        bool backslashed = false, bracketed = false;

        expanded = checked_strdup(string);

        for (i = 0; string[i] != '\0'; i++) {
                c = string[i];
                if (c == '\\' && backslashed == false) {
                        backslashed = true;
                        continue;
                }
                if (backslashed) {
                        backslashed = false;
                        continue;
                }
                backslashed = false;
                if (c != '$')
                        continue;

                /*
                 * The 'before_len' variable contains the number
                 * of characters before the '$'.
                 */
                before_len = i;
                assert(i + 1 < (int)strlen(string));
                if (string[i + 1] == '{')
                        bracketed = true;

                if (string[i + 1] == '\0') {
                        log_warnx("truncated variable");
                        return (NULL);
                }

                /*
                 * Skip '$'.
                 */
                i++;

                if (bracketed) {
                        if (string[i + 1] == '\0') {
                                log_warnx("truncated variable");
                                return (NULL);
                        }

                        /*
                         * Skip '{'.
                         */
                        i++;
                }

                /*
                 * The 'name_off' variable contains the number
                 * of characters before the variable name,
                 * including the "$" or "${".
                 */
                name_off = i;

                for (; string[i] != '\0'; i++) {
                        c = string[i];
                        /*
                         * XXX: Decide on the set of characters that can be
                         *      used in a variable name.
                         */
                        if (isalnum(c) || c == '_')
                                continue;

                        /*
                         * End of variable name.
                         */
                        if (bracketed) {
                                if (c != '}')
                                        continue;

                                /*
                                 * The 'after_off' variable contains the number
                                 * of characters before the rest of the string,
                                 * i.e. after the variable name.
                                 */
                                after_off = i + 1;
                                assert(i > 1);
                                assert(i - 1 > name_off);
                                name_len = i - name_off;
                                break;
                        }

                        after_off = i;
                        assert(i > 1);
                        assert(i > name_off);
                        name_len = i - name_off;
                        break;
                }

                name = strndup(string + name_off, name_len);
                if (name == NULL)
                        log_err(1, "strndup");
                value = defined_find(name);
                if (value == NULL) {
                        log_warnx("undefined variable ${%s}", name);
                        return (NULL);
                }

                /*
                 * Concatenate it back.
                 */
                ret = asprintf(&expanded, "%.*s%s%s",
                    before_len, string, value, string + after_off);
                if (ret < 0)
                        log_err(1, "asprintf");

                //log_debugx("\"%s\" expanded to \"%s\"", string, expanded);
                free(name);

                /*
                 * Figure out where to start searching for next variable.
                 */
                string = expanded;
                i = before_len + strlen(value);
                backslashed = bracketed = false;
                before_len = name_off = name_len = after_off = 0;
                assert(i <= (int)strlen(string));
        }

        if (before_len != 0 || name_off != 0 || name_len != 0 || after_off != 0) {
                log_warnx("truncated variable");
                return (NULL);
        }

        return (expanded);
}

static void
defined_add(const char *name, const char *value)
{
        struct defined_value *d;
        const char *found;

        found = defined_find(name);
        if (found != NULL)
                log_errx(1, "variable %s already defined", name);

        log_debugx("defining variable %s=%s", name, value);

        d = calloc(1, sizeof(*d));
        if (d == NULL)
                log_err(1, "calloc");
        d->d_name = checked_strdup(name);
        d->d_value = checked_strdup(value);

        TAILQ_INSERT_TAIL(&defined_values, d, d_next);
}

void
defined_parse_and_add(char *def)
{
        char *name, *value;

        value = def;
        name = strsep(&value, "=");

        if (value == NULL || value[0] == '\0')
                log_errx(1, "missing variable value");
        if (name == NULL || name[0] == '\0')
                log_errx(1, "missing variable name");

        defined_add(name, value);
}

void
defined_init(void)
{
        struct utsname name;
        int error;

        TAILQ_INIT(&defined_values);

        error = uname(&name);
        if (error != 0)
                log_err(1, "uname");

        defined_add("ARCH", name.machine);
        defined_add("CPU", name.machine);
        defined_add("DOLLAR", "$");
        defined_add("HOST", name.nodename);
        defined_add("OSNAME", name.sysname);
        defined_add("OSREL", name.release);
        defined_add("OSVERS", name.version);
}