1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
23/*	  All Rights Reserved  	*/
24
25
26/*
27 * Copyright (c) 1997, by Sun Microsystems, Inc.
28 * All rights reserved.
29 */
30
31#pragma	ident	"%Z%%M%	%I%	%E% SMI"	/* SVr4.0 1.2 */
32
33/*LINTLIBRARY*/
34
35/*
36 *  devattr.c
37 *
38 *  Contents:
39 *	devattr()	Get the value of a attribute for a specific device
40 */
41
42/*
43 *  Header files needed
44 *	<sys/types.h>		System Data Types
45 *	<stdio.h>		Standard I/O Definitions
46 *	<errno.h>		Error-value definitions
47 *	<string.h>		String function and constant definitions
48 *	<devmgmt.h>		Device table definitions available to the world
49 *	"devtab.h"		Local device table definitions
50 */
51
52#include	<sys/types.h>
53#include	<stdio.h>
54#include	<errno.h>
55#include	<string.h>
56#include	<stdlib.h>
57#include	<devmgmt.h>
58#include	"devtab.h"
59
60/*
61 *  Local constant definitions
62 */
63
64
65/*
66 *  Local static data
67 */
68
69/*
70 *  char *devattr(device, attr)
71 *
72 *	This function searches the device table, looking for the device
73 *	specified by <device>.  If it finds a record corresponding to that
74 *	device (see below for a definition of that correspondence), it
75 *	extracts the value of the field <attr> from that record, if any.
76 *	It returns a pointer to that value, or (char *) NULL if none.
77 *
78 *  Arguments:
79 *	device		Pointer to the character-string that describes the
80 *			device whose record is to be looked for
81 *	attr		The device's attribute to be looked for
82 *
83 *  Returns:  char *
84 *	A pointer to the character-string containing the value of the
85 *	attribute <attr> for the device <device>, or (char *) NULL if none
86 *	was found.  If the function returns (char *) NULL and the error was
87 *	detected by this function, it sets "errno" to indicate the problem.
88 *
89 *  "errno" Values:
90 *	EPERM		Permissions deny reading access of the device-table
91 *			file
92 *	ENOENT		The specified device-table file could not be found
93 *	ENODEV		Device not found in the device table
94 *	EINVAL		The device does not have that attribute defined
95 *	ENOMEM		No memory available
96 */
97
98char *
99devattr(
100	char   *device,		/* The device ) we're to look for */
101	char   *attribute)	/* The attribute to extract */
102{
103	/* Automatic data */
104	struct devtabent	*record;	/* Retrieved record */
105	struct attrval		*p;		/* attr/val records */
106	char			*val;		/* Extracted value */
107	char			*rtnval;	/* Value to return */
108	int			found;		/* TRUE if attribute found */
109
110
111	/* Get the record for the specified device */
112	if (!(record = _getdevrec(device))) {
113		_enddevtab();
114		return (NULL);
115	}
116
117	/* Search the record for the specified attribute */
118	found = FALSE;
119
120	/* Did they ask for the device alias? */
121	if (strcmp(attribute, DTAB_ALIAS) == 0) {
122	    val = (record->alias != NULL) ? record->alias : "";
123	    found = TRUE;
124	}
125
126	/* Did they ask for the character-special device? */
127	else if (strcmp(attribute, DTAB_CDEVICE) == 0) {
128	    val = (record->cdevice != NULL) ? record->cdevice : "";
129	    found = TRUE;
130	}
131
132	/* Did they ask for the block-special device? */
133	else if (strcmp(attribute, DTAB_BDEVICE) == 0) {
134	    val = (record->bdevice != NULL) ? record->bdevice : "";
135	    found = TRUE;
136	}
137
138	/* Did they ask for the pathname? */
139	else if (strcmp(attribute, DTAB_PATHNAME) == 0) {
140	    val = (record->pathname != NULL) ? record->pathname : "";
141	    found = TRUE;
142	}
143
144	else {
145
146	/*
147	 * Didn't ask for one of the easy ones, search the attr/val
148	 * structure
149	 */
150
151	    p = record->attrlist;
152	    while (!found && (p)) {
153		if (strcmp(p->attr, attribute) == 0) {
154		    val = p->val;
155		    found = TRUE;
156		} else p = p->next;
157	    }
158	}
159
160	/*
161	 * If the attribute was found, copy it into malloc()ed space.
162	 * If not, set errno appropriately; we'll return NULL
163	 */
164
165	if (found) {
166	    if (rtnval = malloc(strlen(val)+1))
167		(void) strcpy(rtnval, val);
168	    else errno = ENOMEM;
169	} else {
170	    rtnval = NULL;
171	    errno = EINVAL;
172	}
173
174	/* Free the space allocated to the struct devtabent structure */
175	_freedevtabent(record);
176
177	_enddevtab();
178
179	/* Fini */
180	return (rtnval);
181}
182