1 /*
2  * Copyright (C) 2009 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef NATIVE_HANDLE_H_
18 #define NATIVE_HANDLE_H_
19 
20 #include <stdalign.h>
21 
22 #ifdef __cplusplus
23 extern "C" {
24 #endif
25 
26 #define NATIVE_HANDLE_MAX_FDS 1024
27 #define NATIVE_HANDLE_MAX_INTS 1024
28 
29 /* Declare a char array for use with native_handle_init */
30 #define NATIVE_HANDLE_DECLARE_STORAGE(name, maxFds, maxInts) \
31     alignas(native_handle_t) char (name)[                            \
32       sizeof(native_handle_t) + sizeof(int) * ((maxFds) + (maxInts))]
33 
34 typedef struct native_handle
35 {
36     int version;        /* sizeof(native_handle_t) */
37     int numFds;         /* number of file-descriptors at &data[0] */
38     int numInts;        /* number of ints at &data[numFds] */
39 #if defined(__clang__)
40 #pragma clang diagnostic push
41 #pragma clang diagnostic ignored "-Wzero-length-array"
42 #endif
43     int data[0];        /* numFds + numInts ints */
44 #if defined(__clang__)
45 #pragma clang diagnostic pop
46 #endif
47 } native_handle_t;
48 
49 typedef const native_handle_t* buffer_handle_t;
50 
51 /*
52  * native_handle_close
53  *
54  * closes the file descriptors contained in this native_handle_t
55  *
56  * return 0 on success, or a negative error code on failure
57  *
58  */
59 int native_handle_close(const native_handle_t* h);
60 
61 /*
62  * native_handle_init
63  *
64  * Initializes a native_handle_t from storage.  storage must be declared with
65  * NATIVE_HANDLE_DECLARE_STORAGE.  numFds and numInts must not respectively
66  * exceed maxFds and maxInts used to declare the storage.
67  */
68 native_handle_t* native_handle_init(char* storage, int numFds, int numInts);
69 
70 /*
71  * native_handle_create
72  *
73  * creates a native_handle_t and initializes it. must be destroyed with
74  * native_handle_delete(). Note that numFds must be <= NATIVE_HANDLE_MAX_FDS,
75  * numInts must be <= NATIVE_HANDLE_MAX_INTS, and both must be >= 0.
76  *
77  */
78 native_handle_t* native_handle_create(int numFds, int numInts);
79 
80 /*
81  * native_handle_clone
82  *
83  * creates a native_handle_t and initializes it from another native_handle_t.
84  * Must be destroyed with native_handle_delete().
85  *
86  */
87 native_handle_t* native_handle_clone(const native_handle_t* handle);
88 
89 /*
90  * native_handle_delete
91  *
92  * frees a native_handle_t allocated with native_handle_create().
93  * This ONLY frees the memory allocated for the native_handle_t, but doesn't
94  * close the file descriptors; which can be achieved with native_handle_close().
95  *
96  * return 0 on success, or a negative error code on failure
97  *
98  */
99 int native_handle_delete(native_handle_t* h);
100 
101 
102 #ifdef __cplusplus
103 }
104 #endif
105 
106 #endif /* NATIVE_HANDLE_H_ */
107