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1 /*
2  * Copyright (C) 2017 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 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
30 #include <sys/_system_properties.h>
31 
32 #include <async_safe/CHECK.h>
33 #include <system_properties/prop_area.h>
34 #include <system_properties/system_properties.h>
35 
36 #include "private/bionic_defs.h"
37 
38 static SystemProperties system_properties;
39 static_assert(__is_trivially_constructible(SystemProperties),
40               "System Properties must be trivially constructable");
41 
42 // This is public because it was exposed in the NDK. As of 2017-01, ~60 apps reference this symbol.
43 // It is set to nullptr and never modified.
44 __BIONIC_WEAK_VARIABLE_FOR_NATIVE_BRIDGE
45 prop_area* __system_property_area__ = nullptr;
46 
47 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_properties_init()48 int __system_properties_init() {
49   return system_properties.Init(PROP_DIRNAME) ? 0 : -1;
50 }
51 
52 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_set_filename(const char *)53 int __system_property_set_filename(const char*) {
54   return -1;
55 }
56 
57 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_area_init()58 int __system_property_area_init() {
59   bool fsetxattr_fail = false;
60   return system_properties.AreaInit(PROP_DIRNAME, &fsetxattr_fail) && !fsetxattr_fail ? 0 : -1;
61 }
62 
63 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_area_serial()64 uint32_t __system_property_area_serial() {
65   return system_properties.AreaSerial();
66 }
67 
68 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_find(const char * name)69 const prop_info* __system_property_find(const char* name) {
70   return system_properties.Find(name);
71 }
72 
73 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_read(const prop_info * pi,char * name,char * value)74 int __system_property_read(const prop_info* pi, char* name, char* value) {
75   return system_properties.Read(pi, name, value);
76 }
77 
78 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_read_callback(const prop_info * pi,void (* callback)(void * cookie,const char * name,const char * value,uint32_t serial),void * cookie)79 void __system_property_read_callback(const prop_info* pi,
80                                      void (*callback)(void* cookie, const char* name,
81                                                       const char* value, uint32_t serial),
82                                      void* cookie) {
83   return system_properties.ReadCallback(pi, callback, cookie);
84 }
85 
86 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_get(const char * name,char * value)87 int __system_property_get(const char* name, char* value) {
88   return system_properties.Get(name, value);
89 }
90 
91 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_update(prop_info * pi,const char * value,unsigned int len)92 int __system_property_update(prop_info* pi, const char* value, unsigned int len) {
93   return system_properties.Update(pi, value, len);
94 }
95 
96 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_add(const char * name,unsigned int namelen,const char * value,unsigned int valuelen)97 int __system_property_add(const char* name, unsigned int namelen, const char* value,
98                           unsigned int valuelen) {
99   return system_properties.Add(name, namelen, value, valuelen);
100 }
101 
102 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_serial(const prop_info * pi)103 uint32_t __system_property_serial(const prop_info* pi) {
104   // N.B. a previous version of this function was much heavier-weight
105   // and enforced acquire semantics, so give our load here acquire
106   // semantics just in case somebody depends on
107   // __system_property_serial enforcing memory order, e.g., in case
108   // someone spins on the result of this function changing before
109   // loading some value.
110   return atomic_load_explicit(&pi->serial, memory_order_acquire);
111 }
112 
113 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_wait_any(uint32_t old_serial)114 uint32_t __system_property_wait_any(uint32_t old_serial) {
115   return system_properties.WaitAny(old_serial);
116 }
117 
118 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_wait(const prop_info * pi,uint32_t old_serial,uint32_t * new_serial_ptr,const timespec * relative_timeout)119 bool __system_property_wait(const prop_info* pi, uint32_t old_serial, uint32_t* new_serial_ptr,
120                             const timespec* relative_timeout) {
121   return system_properties.Wait(pi, old_serial, new_serial_ptr, relative_timeout);
122 }
123 
124 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_find_nth(unsigned n)125 const prop_info* __system_property_find_nth(unsigned n) {
126   return system_properties.FindNth(n);
127 }
128 
129 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_property_foreach(void (* propfn)(const prop_info * pi,void * cookie),void * cookie)130 int __system_property_foreach(void (*propfn)(const prop_info* pi, void* cookie), void* cookie) {
131   return system_properties.Foreach(propfn, cookie);
132 }
133 
134 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
__system_properties_zygote_reload(void)135 int __system_properties_zygote_reload(void) {
136   CHECK(getpid() == gettid());
137   return system_properties.Reload(false) ? 0 : -1;
138 }
139