/*-
 * Copyright (c) 2000  Peter Wemm <peter@freebsd.org>
 *
 * 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 AUTHORS 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 AUTHORS 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/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/sysctl.h>
#include <err.h>
#include <kenv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void	usage(void);
static int	kdumpenv(void);
static int	kgetenv(const char *);
static int	ksetenv(const char *, char *);
static int	kunsetenv(const char *);

static int hflag = 0;
static int Nflag = 0;
static int qflag = 0;
static int uflag = 0;
static int vflag = 0;

static void
usage(void)
{
	(void)fprintf(stderr, "%s\n%s\n%s\n",
	    "usage: kenv [-hNq]",
	    "       kenv [-qv] variable[=value]",
	    "       kenv [-q] -u variable");
	exit(1);
}

int
main(int argc, char **argv)
{
	char *env, *eq, *val;
	int ch, error;

	val = NULL;
	env = NULL;
	while ((ch = getopt(argc, argv, "hNquv")) != -1) {
		switch (ch) {
		case 'h':
			hflag++;
			break;
		case 'N':
			Nflag++;
			break;
		case 'q':
			qflag++;
			break;
		case 'u':
			uflag++;
			break;
		case 'v':
			vflag++;
			break;
		default:
			usage();
		}
	}
	argc -= optind;
	argv += optind;
	if (argc > 0) {
		env = argv[0];
		eq = strchr(env, '=');
		if (eq != NULL) {
			*eq++ = '\0';
			val = eq;
		}
		argv++;
		argc--;
	}
	if ((hflag || Nflag) && env != NULL)
		usage();
	if (argc > 0 || ((uflag || vflag) && env == NULL))
		usage();
	if (env == NULL) {
		error = kdumpenv();
		if (error && !qflag)
			warn("kdumpenv");
	} else if (val == NULL) {
		if (uflag) {
			error = kunsetenv(env);
			if (error && !qflag)
				warnx("unable to unset %s", env);
		} else {
			error = kgetenv(env);
			if (error && !qflag)
				warnx("unable to get %s", env);
		}
	} else {
		error = ksetenv(env, val);
		if (error && !qflag)
			warnx("unable to set %s to %s", env, val);
	}
	return (error);
}

static int
kdumpenv(void)
{
	char *buf, *bp, *cp;
	int buflen, envlen;

	envlen = kenv(KENV_DUMP, NULL, NULL, 0);
	if (envlen < 0)
		return (-1);
	for (;;) {
		buflen = envlen * 120 / 100;
		buf = calloc(1, buflen + 1);
		if (buf == NULL)
			return (-1);
		envlen = kenv(KENV_DUMP, NULL, buf, buflen);
		if (envlen < 0) {
			free(buf);
			return (-1);
		}
		if (envlen > buflen)
			free(buf);
		else
			break;
	}

	for (bp = buf; *bp != '\0'; bp += strlen(bp) + 1) {
		if (hflag) {
			if (strncmp(bp, "hint.", 5) != 0)
				continue;
		}
		cp = strchr(bp, '=');
		if (cp == NULL)
			continue;
		*cp++ = '\0';
		if (Nflag)
			printf("%s\n", bp);
		else
			printf("%s=\"%s\"\n", bp, cp);
		bp = cp;
	}

	free(buf);
	return (0);
}

static int
kgetenv(const char *env)
{
	char buf[1024];
	int ret;

	ret = kenv(KENV_GET, env, buf, sizeof(buf));
	if (ret == -1)
		return (ret);
	if (vflag)
		printf("%s=\"%s\"\n", env, buf);
	else
		printf("%s\n", buf);
	return (0);
}

static int
ksetenv(const char *env, char *val)
{
	int ret;

	ret = kenv(KENV_SET, env, val, strlen(val) + 1);
	if (ret == 0)
		printf("%s=\"%s\"\n", env, val);
	return (ret);
}

static int
kunsetenv(const char *env)
{
	int ret;

	ret = kenv(KENV_UNSET, env, NULL, 0);
	return (ret);
}