108 lines
3.5 KiB
C
108 lines
3.5 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _INCLUDE_SYS__SYSTEM_PROPERTIES_H
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#define _INCLUDE_SYS__SYSTEM_PROPERTIES_H
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#ifndef _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
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#error you should #include <sys/system_properties.h> instead
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#else
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#include <sys/system_properties.h>
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typedef struct prop_area prop_area;
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typedef struct prop_msg prop_msg;
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#define PROP_AREA_MAGIC 0x504f5250
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#define PROP_AREA_VERSION 0x45434f76
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#define PROP_SERVICE_NAME "property_service"
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/* #define PROP_MAX_ENTRIES 247 */
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/* 247 -> 32620 bytes (<32768) */
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#define TOC_NAME_LEN(toc) ((toc) >> 24)
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#define TOC_TO_INFO(area, toc) ((prop_info*) (((char*) area) + ((toc) & 0xFFFFFF)))
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struct prop_area {
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unsigned volatile count;
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unsigned volatile serial;
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unsigned magic;
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unsigned version;
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unsigned reserved[4];
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unsigned toc[1];
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};
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#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
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#define SERIAL_DIRTY(serial) ((serial) & 1)
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struct prop_info {
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char name[PROP_NAME_MAX];
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unsigned volatile serial;
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char value[PROP_VALUE_MAX];
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};
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struct prop_msg
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{
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unsigned cmd;
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char name[PROP_NAME_MAX];
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char value[PROP_VALUE_MAX];
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};
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#define PROP_MSG_SETPROP 1
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/*
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** Rules:
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**
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** - there is only one writer, but many readers
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** - prop_area.count will never decrease in value
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** - once allocated, a prop_info's name will not change
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** - once allocated, a prop_info's offset will not change
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** - reading a value requires the following steps
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** 1. serial = pi->serial
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** 2. if SERIAL_DIRTY(serial), wait*, then goto 1
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** 3. memcpy(local, pi->value, SERIAL_VALUE_LEN(serial) + 1)
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** 4. if pi->serial != serial, goto 2
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**
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** - writing a value requires the following steps
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** 1. pi->serial = pi->serial | 1
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** 2. memcpy(pi->value, local_value, value_len)
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** 3. pi->serial = (value_len << 24) | ((pi->serial + 1) & 0xffffff)
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**
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** Improvements:
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** - maintain the toc sorted by pi->name to allow lookup
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** by binary search
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**
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*/
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#define PROP_PATH_RAMDISK_DEFAULT "/default.prop"
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#define PROP_PATH_SYSTEM_BUILD "/system/build.prop"
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#define PROP_PATH_SYSTEM_DEFAULT "/system/default.prop"
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#define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop"
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#endif
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#endif
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