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 #include <sys/cdefs.h> 33 34 __BEGIN_DECLS 35 36 typedef struct prop_info prop_info; 37 38 #define PROP_NAME_MAX 32 39 #define PROP_VALUE_MAX 92 40 41 /* Look up a system property by name, copying its value and a 42 ** \0 terminator to the provided pointer. The total bytes 43 ** copied will be no greater than PROP_VALUE_MAX. Returns 44 ** the string length of the value. A property that is not 45 ** defined is identical to a property with a length 0 value. 46 */ 47 int __system_property_get(const char *name, char *value); 48 49 /* Set a system property by name. 50 **/ 51 int __system_property_set(const char *key, const char *value); 52 53 /* Return a pointer to the system property named name, if it 54 ** exists, or NULL if there is no such property. Use 55 ** __system_property_read() to obtain the string value from 56 ** the returned prop_info pointer. 57 ** 58 ** It is safe to cache the prop_info pointer to avoid future 59 ** lookups. These returned pointers will remain valid for 60 ** the lifetime of the system. 61 */ 62 const prop_info *__system_property_find(const char *name); 63 64 /* Read the value of a system property. Returns the length 65 ** of the value. Copies the value and \0 terminator into 66 ** the provided value pointer. Total length (including 67 ** terminator) will be no greater that PROP_VALUE_MAX. 68 ** 69 ** If name is nonzero, up to PROP_NAME_MAX bytes will be 70 ** copied into the provided name pointer. The name will 71 ** be \0 terminated. 72 */ 73 int __system_property_read(const prop_info *pi, char *name, char *value); 74 75 /* Return a prop_info for the nth system property, or NULL if 76 ** there is no nth property. Use __system_property_read() to 77 ** read the value of this property. 78 ** 79 ** Please do not call this method. It only exists to provide 80 ** backwards compatibility to NDK apps. Its implementation 81 ** is inefficient and order of results may change from call 82 ** to call. 83 */ 84 const prop_info *__system_property_find_nth(unsigned n); 85 86 /* Pass a prop_info for each system property to the provided 87 ** callback. Use __system_property_read() to read the value 88 ** of this property. 89 ** 90 ** This method is for inspecting and debugging the property 91 ** system. Please use __system_property_find() instead. 92 ** 93 ** Order of results may change from call to call. This is 94 ** not a bug. 95 */ 96 int __system_property_foreach( 97 void (*propfn)(const prop_info *pi, void *cookie), 98 void *cookie); 99 100 __END_DECLS 101 102 #endif 103