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_VENDOR_BUILD "/vendor/build.prop"
85 #define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop"
86 #define PROP_PATH_FACTORY "/factory/factory.prop"
88 /*
89 ** Map the property area from the specified filename. This
90 ** method is for testing only.
91 */
92 int __system_property_set_filename(const char *filename);
94 /*
95 ** Initialize the area to be used to store properties. Can
96 ** only be done by a single process that has write access to
97 ** the property area.
98 */
99 int __system_property_area_init();
101 /* Add a new system property. Can only be done by a single
102 ** process that has write access to the property area, and
103 ** that process must handle sequencing to ensure the property
104 ** does not already exist and that only one property is added
105 ** or updated at a time.
106 **
107 ** Returns 0 on success, -1 if the property area is full.
108 */
109 int __system_property_add(const char *name, unsigned int namelen,
110 const char *value, unsigned int valuelen);
112 /* Update the value of a system property returned by
113 ** __system_property_find. Can only be done by a single process
114 ** that has write access to the property area, and that process
115 ** must handle sequencing to ensure that only one property is
116 ** updated at a time.
117 **
118 ** Returns 0 on success, -1 if the parameters are incorrect.
119 */
120 int __system_property_update(prop_info *pi, const char *value, unsigned int len);
122 /* Read the serial number of a system property returned by
123 ** __system_property_find.
124 **
125 ** Returns the serial number on success, -1 on error.
126 */
127 unsigned int __system_property_serial(const prop_info *pi);
129 /* Wait for any system property to be updated. Caller must pass
130 ** in 0 the first time, and the previous return value on each
131 ** successive call. */
132 unsigned int __system_property_wait_any(unsigned int serial);
134 /* Compatibility functions to support using an old init with a new libc,
135 ** mostly for the OTA updater binary. These can be deleted once OTAs from
136 ** a pre-K release no longer needed to be supported. */
137 const prop_info *__system_property_find_compat(const char *name);
138 int __system_property_read_compat(const prop_info *pi, char *name, char *value);
139 int __system_property_foreach_compat(
140 void (*propfn)(const prop_info *pi, void *cookie),
141 void *cookie);
143 /* Initialize the system properties area in read only mode.
144 * Should be done by all processes that need to read system
145 * properties.
146 *
147 * Returns 0 on success, -1 otherwise.
148 */
149 int __system_properties_init();
151 __END_DECLS
153 #endif
154 #endif