blob: 05612b380bdf39dc1344681a93a5fd0ddf0c92f9 [file] [log] [blame]
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#pragma once
#include <sys/cdefs.h>
#include <stdint.h>
#ifndef _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#error you should #include <sys/system_properties.h> instead
#endif
#include <sys/system_properties.h>
__BEGIN_DECLS
/**
* Reads the global serial number of the system properties _area_.
*
* Called to predict if a series of cached __system_property_find()
* objects will have seen __system_property_serial() values change.
* Also aids the converse, as changes in the global serial can
* also be used to predict if a failed __system_property_find()
* could in turn now find a new object; thus preventing the
* cycles of effort to poll __system_property_find().
*
* Typically called at beginning of a cache cycle to signal if _any_ possible
* changes have occurred since last. If there is, one may check each individual
* __system_property_serial() to confirm dirty, or __system_property_find()
* to check if the property now exists. If a call to __system_property_add()
* or __system_property_update() has completed between two calls to
* __system_property_area_serial() then the second call will return a larger
* value than the first call. Beware of race conditions as changes to the
* properties are not atomic, the main value of this call is to determine
* whether the expensive __system_property_find() is worth retrying to see if
* a property now exists.
*
* Returns the serial number on success, -1 on error.
*/
uint32_t __system_property_area_serial(void);
/**
* Reads the serial number of a specific system property previously returned by
* __system_property_find(). This is a cheap way to check whether a system
* property has changed or not.
*
* Returns the serial number on success, -1 on error.
*/
uint32_t __system_property_serial(const prop_info* _Nonnull __pi);
//
// libc implementation detail.
//
/**
* Initializes the system properties area in read-only mode.
*
* This is called automatically during libc initialization,
* so user code should never need to call this.
*
* Returns 0 on success, -1 otherwise.
*/
int __system_properties_init(void);
//
// init implementation details.
//
#define PROP_SERVICE_NAME "property_service"
#define PROP_SERVICE_FOR_SYSTEM_NAME "property_service_for_system"
#define PROP_DIRNAME "/dev/__properties__"
// Messages sent to init.
#define PROP_MSG_SETPROP 1
#define PROP_MSG_SETPROP2 0x00020001
// Status codes returned by init (but not passed from libc to the caller).
#define PROP_SUCCESS 0
#define PROP_ERROR_READ_CMD 0x0004
#define PROP_ERROR_READ_DATA 0x0008
#define PROP_ERROR_READ_ONLY_PROPERTY 0x000B
#define PROP_ERROR_INVALID_NAME 0x0010
#define PROP_ERROR_INVALID_VALUE 0x0014
#define PROP_ERROR_PERMISSION_DENIED 0x0018
#define PROP_ERROR_INVALID_CMD 0x001B
#define PROP_ERROR_HANDLE_CONTROL_MESSAGE 0x0020
#define PROP_ERROR_SET_FAILED 0x0024
/**
* Initializes the area to be used to store properties.
*
* Can only be done by the process that has write access to the property area,
* typically init.
*
* See __system_properties_init() for the equivalent for all other processes.
*/
int __system_property_area_init(void);
/**
* Adds a new system property.
* Can only be done by the process that has write access to the property area --
* typically init -- which must handle sequencing to ensure that only one property is
* updated at a time.
*
* Returns 0 on success, -1 if the property area is full.
*/
int __system_property_add(const char* _Nonnull __name, unsigned int __name_length, const char* _Nonnull __value, unsigned int __value_length);
/**
* Updates the value of a system property returned by __system_property_find().
* Can only be done by the process that has write access to the property area --
* typically init -- which must handle sequencing to ensure that only one property is
* updated at a time.
*
* Returns 0 on success, -1 if the parameters are incorrect.
*/
int __system_property_update(prop_info* _Nonnull __pi, const char* _Nonnull __value, unsigned int __value_length);
/**
* Reloads the system properties from disk.
* Not intended for use by any apps except the Zygote.
* Should only be called from the main thread.
*
* Pointers received from functions such as __system_property_find()
* may be invalidated by calls to this function.
*
* Returns 0 on success, -1 otherwise.
*
* Available since API level 35.
*/
int __system_properties_zygote_reload(void) __INTRODUCED_IN(35);
//
// Deprecated functions.
//
/** Deprecated: use __system_property_wait instead. */
uint32_t __system_property_wait_any(uint32_t __old_serial);
/**
* Deprecated: previously for testing, but now that SystemProperties is its own
* testable class, there is never a reason to call this function and its
* implementation simply returns -1.
*/
int __system_property_set_filename(const char* __unused __filename);
__END_DECLS