/*	$NetBSD: getdiskrawname.c,v 1.6 2019/08/22 20:23:43 brad Exp $	*/

/*-
 * Copyright (c) 2012 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__RCSID("$NetBSD: getdiskrawname.c,v 1.6 2019/08/22 20:23:43 brad Exp $");

#include <sys/stat.h>

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <util.h>
#include <limits.h>
#include <unistd.h>

static const char *
resolve_link(char *buf, size_t bufsiz, const char *name)
{
	const char *dp;
	size_t nlen;
	ssize_t dlen;

	dlen = readlink(name, buf, bufsiz - 1);
	if (dlen == -1)
		return name;

	buf[dlen] = '\0';

	if (buf[0] != '/') {
		dp = strrchr(name, '/');
		if (dp != NULL) {
			nlen = dp - name + 1;
			if (nlen + 1 > bufsiz)
				return NULL;
			if (nlen + dlen + 1 > bufsiz)
				return NULL;

			memmove(buf + nlen, buf, (size_t)dlen + 1);
			memcpy(buf, name, nlen);
		}
	}

	return buf;
}

/*
 * zvol device names look like:
 * /dev/zvol/dsk/pool_name/.../volume_name
 * /dev/zvol/rdsk/pool_name/.../volume_name
 *
 * ZFS pools can be divided nearly to infinity
 *
 * This allows for 16 pool names, which one would hope would be enough
 */
#define DISKMAXPARTS 20
static int
calc_zvol_name(char *buf, size_t bufsiz, const char *name, const char *raw)
{
	char copyname[PATH_MAX];
	char *names[DISKMAXPARTS];
	char *last, *p;
	size_t i = 0;

	strlcpy(copyname, name, sizeof(copyname));
	for (p = strtok_r(copyname, "/", &last); p;
	     p = strtok_r(NULL, "/", &last)) {
		if (i >= DISKMAXPARTS) {
			errno =  ENOSPC;
			return -1;
		}
		names[i++] = p;
	}

	if (i < 4) {
		errno = EINVAL;
		return -1;
	}

	snprintf(buf, bufsiz, "/dev/zvol/%sdsk", raw);
	for (size_t j = 3; j < i; j++) {
		strlcat(buf, "/", bufsiz);
		strlcat(buf, names[j], bufsiz);
	}
	return 0;
}

static int
calc_name(char *buf, size_t bufsiz, const char *name, const char *raw)
{
	int skip = 1;

	if (strncmp("/dev/zvol/", name, 10) == 0)
		return calc_zvol_name(buf, bufsiz, name, raw);

	const char *dp = strrchr(name, '/');
	if (!*raw && ((dp != NULL && dp[1] != 'r')
		|| (dp == NULL && name[0] != 'r'))) {
		errno = EINVAL;
		return -1;
	}
	if (raw[0] != 'r')
		skip = 2;
	if (dp != NULL)
		snprintf(buf, bufsiz, "%.*s/%s%s", (int)(dp - name),
		    name, raw, dp + skip);
	else
		snprintf(buf, bufsiz, "%s%s", raw, name);
	return 0;
}

const char *
getdiskrawname(char *buf, size_t bufsiz, const char *name)
{
	struct stat st;
	char dest[PATH_MAX];

	if ((name = resolve_link(dest, sizeof(dest), name)) == NULL) {
		errno = EINVAL;
		return NULL;
	}

	if (stat(name, &st) == -1)
		return NULL;

	if (!S_ISBLK(st.st_mode)) {
		errno = EFTYPE;
		return NULL;
	}

	if (calc_name(buf, bufsiz, name, "r") == -1)
		return NULL;

	return buf;
}

const char *
getdiskcookedname(char *buf, size_t bufsiz, const char *name)
{
	struct stat st;
	char dest[PATH_MAX];

	if ((name = resolve_link(dest, sizeof(dest), name)) == NULL) {
		errno = EINVAL;
		return NULL;
	}

	if (stat(name, &st) == -1)
		return NULL;

	if (!S_ISCHR(st.st_mode)) {
		errno = EFTYPE;
		return NULL;
	}

	if (calc_name(buf, bufsiz, name, "") == -1)
		return NULL;

	return buf;
}