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1/* $OpenBSD: opendev.c,v 1.18 2025/08/25 14:59:13 claudio Exp $ */
2
3/*
4 * Copyright (c) 2000, Todd C. Miller. All rights reserved.
5 * Copyright (c) 1996, Jason Downs. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
17 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT,
20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <errno.h>
30#include <fcntl.h>
31#include <limits.h>
32#include <paths.h>
33#include <stdio.h>
34#include <string.h>
35#include <unistd.h>
36
37#include <sys/ioctl.h>
38#include <sys/limits.h>
39#include <sys/disk.h>
40#include <sys/dkio.h>
41
42#include "util.h"
43
44/*
45 * This routine is a generic rewrite of the original code found in
46 * disklabel(8).
47 */
48int
49opendev(const char *path, int oflags, int dflags, char **realpath)
50{
51 static char namebuf[PATH_MAX];
52 struct dk_diskmap dm;
53 char *slash, *prefix;
54 int fd, ret;
55
56 /* Initial state */
57 fd = -1;
58 errno = ENOENT;
59
60 if (dflags & OPENDEV_BLCK)
61 prefix = ""; /* block device */
62 else
63 prefix = "r"; /* character device */
64
65 if ((slash = strchr(path, '/'))) {
66 strlcpy(namebuf, path, sizeof(namebuf));
67 fd = open(namebuf, oflags);
68 } else if (isduid(path, dflags)) {
69 strlcpy(namebuf, path, sizeof(namebuf));
70 if ((fd = open("/dev/diskmap", oflags)) != -1) {
71 bzero(&dm, sizeof(struct dk_diskmap));
72 dm.device = namebuf;
73 dm.fd = fd;
74 if (dflags & OPENDEV_PART)
75 dm.flags |= DM_OPENPART;
76 if (dflags & OPENDEV_BLCK)
77 dm.flags |= DM_OPENBLCK;
78
79 if (ioctl(fd, DIOCMAP, &dm) == -1) {
80 close(fd);
81 fd = -1;
82 errno = ENOENT;
83 }
84 }
85 }
86 if (!slash && fd == -1 && errno == ENOENT) {
87 if (dflags & OPENDEV_PART) {
88 /*
89 * First try raw partition (for removable drives)
90 */
91 ret = snprintf(namebuf, sizeof(namebuf), "%s%s%s%c",
92 _PATH_DEV, prefix, path, 'a' + getrawpartition());
93 if (ret < 0 || (size_t)ret >= sizeof(namebuf))
94 errno = ENAMETOOLONG;
95 else
96 fd = open(namebuf, oflags);
97 }
98 if (fd == -1 && errno == ENOENT) {
99 ret = snprintf(namebuf, sizeof(namebuf), "%s%s%s",
100 _PATH_DEV, prefix, path);
101 if (ret < 0 || (size_t)ret >= sizeof(namebuf))
102 errno = ENAMETOOLONG;
103 else
104 fd = open(namebuf, oflags);
105 }
106 }
107 if (realpath)
108 *realpath = namebuf;
109
110 return (fd);
111}