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 37 typedef struct prop_area prop_area; 38 typedef struct prop_msg prop_msg; 39 40 #define PROP_AREA_MAGIC 0x504f5250 41 #define PROP_AREA_VERSION 0x45434f76 42 43 #define PROP_SERVICE_NAME "property_service" 44 #define PROP_FILENAME "/dev/__properties__" 45 46 /* #define PROP_MAX_ENTRIES 247 */ 47 /* 247 -> 32620 bytes (<32768) */ 48 49 #define TOC_NAME_LEN(toc) ((toc) >> 24) 50 #define TOC_TO_INFO(area, toc) ((prop_info*) (((char*) area) + ((toc) & 0xFFFFFF))) 51 52 struct prop_area { 53 unsigned volatile count; 54 unsigned volatile serial; 55 unsigned magic; 56 unsigned version; 57 unsigned reserved[4]; 58 unsigned toc[1]; 59 }; 60 61 #define SERIAL_VALUE_LEN(serial) ((serial) >> 24) 62 #define SERIAL_DIRTY(serial) ((serial) & 1) 63 64 struct prop_info { 65 char name[PROP_NAME_MAX]; 66 unsigned volatile serial; 67 char value[PROP_VALUE_MAX]; 68 }; 69 70 struct prop_msg 71 { 72 unsigned cmd; 73 char name[PROP_NAME_MAX]; 74 char value[PROP_VALUE_MAX]; 75 }; 76 77 #define PROP_MSG_SETPROP 1 78 79 /* 80 ** Rules: 81 ** 82 ** - there is only one writer, but many readers 83 ** - prop_area.count will never decrease in value 84 ** - once allocated, a prop_info's name will not change 85 ** - once allocated, a prop_info's offset will not change 86 ** - reading a value requires the following steps 87 ** 1. serial = pi->serial 88 ** 2. if SERIAL_DIRTY(serial), wait*, then goto 1 89 ** 3. memcpy(local, pi->value, SERIAL_VALUE_LEN(serial) + 1) 90 ** 4. if pi->serial != serial, goto 2 91 ** 92 ** - writing a value requires the following steps 93 ** 1. pi->serial = pi->serial | 1 94 ** 2. memcpy(pi->value, local_value, value_len) 95 ** 3. pi->serial = (value_len << 24) | ((pi->serial + 1) & 0xffffff) 96 ** 97 ** Improvements: 98 ** - maintain the toc sorted by pi->name to allow lookup 99 ** by binary search 100 ** 101 */ 102 103 #define PROP_PATH_RAMDISK_DEFAULT "/default.prop" 104 #define PROP_PATH_SYSTEM_BUILD "/system/build.prop" 105 #define PROP_PATH_SYSTEM_DEFAULT "/system/default.prop" 106 #define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop" 107 #define PROP_PATH_FACTORY "/factory/factory.prop" 108 109 #endif 110 #endif 111