1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#ifndef _INCLUDE_SYS_SYSTEM_PROPERTIES_H
30#define _INCLUDE_SYS_SYSTEM_PROPERTIES_H
31
32#include <sys/cdefs.h>
33
34__BEGIN_DECLS
35
36typedef struct prop_info prop_info;
37
38#define PROP_NAME_MAX   32
39#define PROP_VALUE_MAX  92
40
41/* Look up a system property by name, copying its value and a
42** \0 terminator to the provided pointer.  The total bytes
43** copied will be no greater than PROP_VALUE_MAX.  Returns
44** the string length of the value.  A property that is not
45** defined is identical to a property with a length 0 value.
46*/
47int __system_property_get(const char *name, char *value);
48
49/* Set a system property by name.
50**/
51int __system_property_set(const char *key, const char *value);
52
53/* Return a pointer to the system property named name, if it
54** exists, or NULL if there is no such property.  Use
55** __system_property_read() to obtain the string value from
56** the returned prop_info pointer.
57**
58** It is safe to cache the prop_info pointer to avoid future
59** lookups.  These returned pointers will remain valid for
60** the lifetime of the system.
61*/
62const prop_info *__system_property_find(const char *name);
63
64/* Read the value of a system property.  Returns the length
65** of the value.  Copies the value and \0 terminator into
66** the provided value pointer.  Total length (including
67** terminator) will be no greater that PROP_VALUE_MAX.
68**
69** If name is nonzero, up to PROP_NAME_MAX bytes will be
70** copied into the provided name pointer.  The name will
71** be \0 terminated.
72*/
73int __system_property_read(const prop_info *pi, char *name, char *value);
74
75/* Return a prop_info for the nth system property, or NULL if
76** there is no nth property.  Use __system_property_read() to
77** read the value of this property.
78**
79** Please do not call this method.  It only exists to provide
80** backwards compatibility to NDK apps.  Its implementation
81** is inefficient and order of results may change from call
82** to call.
83*/
84const prop_info *__system_property_find_nth(unsigned n);
85
86/* Pass a prop_info for each system property to the provided
87** callback.  Use __system_property_read() to read the value
88** of this property.
89**
90** This method is for inspecting and debugging the property
91** system.  Please use __system_property_find() instead.
92**
93** Order of results may change from call to call.  This is
94** not a bug.
95*/
96int __system_property_foreach(
97        void (*propfn)(const prop_info *pi, void *cookie),
98        void *cookie);
99
100__END_DECLS
101
102#endif
103