178 lines
6.5 KiB
C
178 lines
6.5 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_msg prop_msg;
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#define PROP_AREA_MAGIC 0x504f5250
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#define PROP_AREA_VERSION 0xfc6ed0ab
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#define PROP_AREA_VERSION_COMPAT 0x45434f76
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#define PROP_SERVICE_NAME "property_service"
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#define PROP_FILENAME "/dev/__properties__"
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#define PA_SIZE (128 * 1024)
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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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__BEGIN_DECLS
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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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#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_VENDOR_BUILD "/vendor/build.prop"
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#define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop"
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#define PROP_PATH_FACTORY "/factory/factory.prop"
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/*
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** Map the property area from the specified filename. This
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** method is for testing only.
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*/
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int __system_property_set_filename(const char *filename);
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/*
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** Initialize the area to be used to store properties. Can
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** only be done by a single process that has write access to
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** the property area.
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*/
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int __system_property_area_init();
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/* Read the global serial number of the system properties
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**
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** Called to predict if a series of cached __system_property_find
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** objects will have seen __system_property_serial values change.
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** But also aids the converse, as changes in the global serial can
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** also be used to predict if a failed __system_property_find
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** could in-turn now find a new object; thus preventing the
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** cycles of effort to poll __system_property_find.
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**
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** Typically called at beginning of a cache cycle to signal if _any_ possible
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** changes have occurred since last. If there is, one may check each individual
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** __system_property_serial to confirm dirty, or __system_property_find
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** to check if the property now exists. If a call to __system_property_add
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** or __system_property_update has completed between two calls to
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** __system_property_area_serial then the second call will return a larger
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** value than the first call. Beware of race conditions as changes to the
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** properties are not atomic, the main value of this call is to determine
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** whether the expensive __system_property_find is worth retrying to see if
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** a property now exists.
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**
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** Returns the serial number on success, -1 on error.
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*/
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unsigned int __system_property_area_serial();
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/* Add a new system property. Can only be done by a single
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** process that has write access to the property area, and
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** that process must handle sequencing to ensure the property
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** does not already exist and that only one property is added
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** or updated at a time.
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**
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** Returns 0 on success, -1 if the property area is full.
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*/
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int __system_property_add(const char *name, unsigned int namelen,
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const char *value, unsigned int valuelen);
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/* Update the value of a system property returned by
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** __system_property_find. Can only be done by a single process
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** that has write access to the property area, and that process
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** must handle sequencing to ensure that only one property is
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** updated at a time.
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**
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** Returns 0 on success, -1 if the parameters are incorrect.
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*/
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int __system_property_update(prop_info *pi, const char *value, unsigned int len);
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/* Read the serial number of a system property returned by
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** __system_property_find.
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**
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** Returns the serial number on success, -1 on error.
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*/
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unsigned int __system_property_serial(const prop_info *pi);
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/* Wait for any system property to be updated. Caller must pass
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** in 0 the first time, and the previous return value on each
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** successive call. */
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unsigned int __system_property_wait_any(unsigned int serial);
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/* Compatibility functions to support using an old init with a new libc,
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** mostly for the OTA updater binary. These can be deleted once OTAs from
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** a pre-K release no longer needed to be supported. */
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const prop_info *__system_property_find_compat(const char *name);
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int __system_property_read_compat(const prop_info *pi, char *name, char *value);
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int __system_property_foreach_compat(
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void (*propfn)(const prop_info *pi, void *cookie),
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void *cookie);
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/* Initialize the system properties area in read only mode.
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* Should be done by all processes that need to read system
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* properties.
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*
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* Returns 0 on success, -1 otherwise.
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*/
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int __system_properties_init();
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__END_DECLS
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#endif
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#endif
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