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#ifndef _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
33#error you should #include <sys/system_properties.h> instead
34#else
35#include <sys/system_properties.h>
36
37typedef struct prop_msg prop_msg;
38
39#define PROP_AREA_MAGIC   0x504f5250
40#define PROP_AREA_VERSION 0xfc6ed0ab
41#define PROP_AREA_VERSION_COMPAT 0x45434f76
42
43#define PROP_SERVICE_NAME "property_service"
44#define PROP_FILENAME "/dev/__properties__"
45
46#define PA_SIZE         (128 * 1024)
47
48#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
49#define SERIAL_DIRTY(serial) ((serial) & 1)
50
51__BEGIN_DECLS
52
53struct prop_msg
54{
55    unsigned cmd;
56    char name[PROP_NAME_MAX];
57    char value[PROP_VALUE_MAX];
58};
59
60#define PROP_MSG_SETPROP 1
61
62/*
63** Rules:
64**
65** - there is only one writer, but many readers
66** - prop_area.count will never decrease in value
67** - once allocated, a prop_info's name will not change
68** - once allocated, a prop_info's offset will not change
69** - reading a value requires the following steps
70**   1. serial = pi->serial
71**   2. if SERIAL_DIRTY(serial), wait*, then goto 1
72**   3. memcpy(local, pi->value, SERIAL_VALUE_LEN(serial) + 1)
73**   4. if pi->serial != serial, goto 2
74**
75** - writing a value requires the following steps
76**   1. pi->serial = pi->serial | 1
77**   2. memcpy(pi->value, local_value, value_len)
78**   3. pi->serial = (value_len << 24) | ((pi->serial + 1) & 0xffffff)
79*/
80
81#define PROP_PATH_RAMDISK_DEFAULT  "/default.prop"
82#define PROP_PATH_SYSTEM_BUILD     "/system/build.prop"
83#define PROP_PATH_SYSTEM_DEFAULT   "/system/default.prop"
84#define PROP_PATH_LOCAL_OVERRIDE   "/data/local.prop"
85#define PROP_PATH_FACTORY          "/factory/factory.prop"
86
87/*
88** Map the property area from the specified filename.  This
89** method is for testing only.
90*/
91int __system_property_set_filename(const char *filename);
92
93/*
94** Initialize the area to be used to store properties.  Can
95** only be done by a single process that has write access to
96** the property area.
97*/
98int __system_property_area_init();
99
100/* Add a new system property.  Can only be done by a single
101** process that has write access to the property area, and
102** that process must handle sequencing to ensure the property
103** does not already exist and that only one property is added
104** or updated at a time.
105**
106** Returns 0 on success, -1 if the property area is full.
107*/
108int __system_property_add(const char *name, unsigned int namelen,
109			const char *value, unsigned int valuelen);
110
111/* Update the value of a system property returned by
112** __system_property_find.  Can only be done by a single process
113** that has write access to the property area, and that process
114** must handle sequencing to ensure that only one property is
115** updated at a time.
116**
117** Returns 0 on success, -1 if the parameters are incorrect.
118*/
119int __system_property_update(prop_info *pi, const char *value, unsigned int len);
120
121/* Read the serial number of a system property returned by
122** __system_property_find.
123**
124** Returns the serial number on success, -1 on error.
125*/
126unsigned int __system_property_serial(const prop_info *pi);
127
128/* Wait for any system property to be updated.  Caller must pass
129** in 0 the first time, and the previous return value on each
130** successive call. */
131unsigned int __system_property_wait_any(unsigned int serial);
132
133/*  Compatibility functions to support using an old init with a new libc,
134 ** mostly for the OTA updater binary.  These can be deleted once OTAs from
135 ** a pre-K release no longer needed to be supported. */
136const prop_info *__system_property_find_compat(const char *name);
137int __system_property_read_compat(const prop_info *pi, char *name, char *value);
138int __system_property_foreach_compat(
139        void (*propfn)(const prop_info *pi, void *cookie),
140        void *cookie);
141
142__END_DECLS
143
144#endif
145#endif
146