/*      $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;
}