/*      $NetBSD: devname.c,v 1.23 2019/02/18 20:27:20 christos Exp $    */

/*-
* Copyright (c) 2012 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Simon Burge.
*
* 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: devname.c,v 1.23 2019/02/18 20:27:20 christos Exp $");

#include "namespace.h"
#include "reentrant.h"
#include <sys/stat.h>

#include <cdbr.h>
#include <errno.h>
#include <fts.h>
#include <limits.h>
#include <paths.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#ifdef __weak_alias
__weak_alias(devname_r,_devname_r)
#endif

static once_t db_opened = ONCE_INITIALIZER;
static struct cdbr *db;
static devmajor_t pts;

static void
devname_dbopen(void)
{
       db = cdbr_open(_PATH_DEVCDB, CDBR_DEFAULT);
       pts = getdevmajor("pts", S_IFCHR);
}

__CTASSERT(sizeof(dev_t) == 8);

static int
devname_dblookup(dev_t dev, mode_t type, char *path, size_t len)
{
       const void *data;
       size_t datalen;
       uint8_t key[10];

       le64enc(key, dev);
       le16enc(key + 8, type);
       if (cdbr_find(db, key, sizeof(key), &data, &datalen) != 0)
               return ENOENT;
       if (datalen <= sizeof(key))
               return ENOENT;
       if (memcmp(key, data, sizeof(key)) != 0)
               return ENOENT;
       data = (const char *)data + sizeof(key);
       datalen -= sizeof(key);
       if (memchr(data, '\0', datalen) != (const char *)data + datalen - 1)
               return ENOENT;
       if (datalen > len)
               return ERANGE;
       memcpy(path, data, datalen);
       return 0;
}

static int
devname_ptslookup(dev_t dev, mode_t type, char *path, size_t len)
{
       int rv;

       if (type != S_IFCHR || pts == NODEVMAJOR || major(dev) != pts)
               return ENOENT;

       rv = snprintf(path, len, "%s%d", &_PATH_DEV_PTS[sizeof(_PATH_DEV) - 1],
           minor(dev));
       if (rv < 0 || (size_t)rv >= len)
               return ERANGE;
       return 0;
}

static int
devname_fts(dev_t dev, mode_t type, char *path, size_t len)
{
       FTS *ftsp;
       FTSENT *fe;
       static const char path_dev[] = _PATH_DEV;
       static char * const dirs[2] = { __UNCONST(path_dev), NULL };
       const size_t len_dev = strlen(path_dev);
       int rv;

       if ((ftsp = fts_open(dirs, FTS_NOCHDIR | FTS_PHYSICAL, NULL)) == NULL)
               return ENOENT;

       rv = ENOENT;
       while ((fe = fts_read(ftsp)) != NULL) {
               if (fe->fts_info != FTS_DEFAULT)
                       continue;
               if (fe->fts_statp->st_rdev != dev)
                       continue;
               if ((type & S_IFMT) != (fe->fts_statp->st_mode & S_IFMT))
                       continue;
               if (strncmp(fe->fts_path, path_dev, len_dev))
                       continue;
               if (strlcpy(path, fe->fts_path + len_dev, len) < len) {
                       rv = 0;
                       break;
               }
       }

       fts_close(ftsp);
       return rv;
}

int
devname_r(dev_t dev, mode_t type, char *path, size_t len)
{
       int rv;

       thr_once(&db_opened, devname_dbopen);

       if (db != NULL) {
               rv = devname_dblookup(dev, type, path, len);
               if (rv == 0 || rv == ERANGE)
                       return rv;
       }

       rv = devname_ptslookup(dev, type, path, len);
       if (rv == 0 || rv == ERANGE)
               return rv;

       if (db != NULL)
               return ENOENT;
       rv = devname_fts(dev, type, path, len);
       return rv;
}

char *
devname(dev_t dev, mode_t type)
{
       static char path[PATH_MAX];

       return devname_r(dev, type, path, sizeof(path)) == 0 ? path : NULL;
}