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 */
29 #ifndef _INCLUDE_SYS__SYSTEM_PROPERTIES_H
30 #define _INCLUDE_SYS__SYSTEM_PROPERTIES_H
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>
37 typedef struct prop_msg prop_msg;
39 #define PROP_AREA_MAGIC 0x504f5250
40 #define PROP_AREA_VERSION 0xfc6ed0ab
41 #define PROP_AREA_VERSION_COMPAT 0x45434f76
43 #define PROP_SERVICE_NAME "property_service"
44 #define PROP_FILENAME "/dev/__properties__"
46 #define PA_SIZE (128 * 1024)
48 #define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
49 #define SERIAL_DIRTY(serial) ((serial) & 1)
51 __BEGIN_DECLS
53 struct prop_msg
54 {
55 unsigned cmd;
56 char name[PROP_NAME_MAX];
57 char value[PROP_VALUE_MAX];
58 };
60 #define PROP_MSG_SETPROP 1
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 */
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"
87 /*
88 ** Map the property area from the specified filename. This
89 ** method is for testing only.
90 */
91 int __system_property_set_filename(const char *filename);
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 */
98 int __system_property_area_init();
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 */
108 int __system_property_add(const char *name, unsigned int namelen,
109 const char *value, unsigned int valuelen);
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 */
119 int __system_property_update(prop_info *pi, const char *value, unsigned int len);
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 */
126 unsigned int __system_property_serial(const prop_info *pi);
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. */
131 unsigned int __system_property_wait_any(unsigned int serial);
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. */
136 const prop_info *__system_property_find_compat(const char *name);
137 int __system_property_read_compat(const prop_info *pi, char *name, char *value);
138 int __system_property_foreach_compat(
139 void (*propfn)(const prop_info *pi, void *cookie),
140 void *cookie);
142 /* Initialize the system properties area in read only mode.
143 * Should be done by all processes that need to read system
144 * properties.
145 *
146 * Returns 0 on success, -1 otherwise.
147 */
148 int __system_properties_init();
150 __END_DECLS
152 #endif
153 #endif