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 typedef struct prop_info prop_info; 33 34 #define PROP_NAME_MAX 32 35 #define PROP_VALUE_MAX 92 36 37 /* Look up a system property by name, copying its value and a 38 ** \0 terminator to the provided pointer. The total bytes 39 ** copied will be no greater than PROP_VALUE_MAX. Returns 40 ** the string length of the value. A property that is not 41 ** defined is identical to a property with a length 0 value. 42 */ 43 int __system_property_get(const char *name, char *value); 44 45 /* Return a pointer to the system property named name, if it 46 ** exists, or NULL if there is no such property. Use 47 ** __system_property_read() to obtain the string value from 48 ** the returned prop_info pointer. 49 ** 50 ** It is safe to cache the prop_info pointer to avoid future 51 ** lookups. These returned pointers will remain valid for 52 ** the lifetime of the system. 53 */ 54 const prop_info *__system_property_find(const char *name); 55 56 /* Read the value of a system property. Returns the length 57 ** of the value. Copies the value and \0 terminator into 58 ** the provided value pointer. Total length (including 59 ** terminator) will be no greater that PROP_VALUE_MAX. 60 ** 61 ** If name is nonzero, up to PROP_NAME_MAX bytes will be 62 ** copied into the provided name pointer. The name will 63 ** be \0 terminated. 64 */ 65 int __system_property_read(const prop_info *pi, char *name, char *value); 66 67 /* Return a prop_info for the nth system property, or NULL if 68 ** there is no nth property. Use __system_property_read() to 69 ** read the value of this property. 70 ** 71 ** This method is for inspecting and debugging the property 72 ** system. Please use __system_property_find() instead. 73 ** 74 ** Order of results may change from call to call. This is 75 ** not a bug. 76 */ 77 const prop_info *__system_property_find_nth(unsigned n); 78 79 #endif 80