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File: [cvs.NetBSD.org] / src / lib / libc / gen / devname.c (download)

Revision 1.22, Sun Jun 3 21:42:46 2012 UTC (2 years, 6 months ago) by joerg
Branch: MAIN
CVS Tags: yamt-pagecache-base9, yamt-pagecache-base8, yamt-pagecache-base7, yamt-pagecache-base6, tls-maxphys-base, tls-maxphys, tls-earlyentropy-base, tls-earlyentropy, riastradh-xf86-video-intel-2-7-1-pre-2-21-15, riastradh-drm2-base3, riastradh-drm2-base2, riastradh-drm2-base1, riastradh-drm2-base, riastradh-drm2, netbsd-7-base, netbsd-7, agc-symver-base, agc-symver, HEAD
Changes since 1.21: +121 -152 lines

Switch device database to cdb(5). Rework ttyname(3) and ttyname_r(3) to
depend on new devname_r(3) as heart. Add /dev/pts magic directly to
devname(3). While it can lead to returning non-existing paths, the
behavior is more consistent that way. Drop caching layer in devname(3),
it doesn't buy anything for the common case of having access to the
database. Teach devname(3) proper fallback behavior of scanning /dev.
Create both old-style and new-style database for now in /etc/rc.d/sysdb.

/*	$NetBSD: devname.c,v 1.22 2012/06/03 21:42:46 joerg 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 1.22 2012/06/03 21:42:46 joerg 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;
}