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      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 /* Declare a char array for use with native_handle_init */
     27 #define NATIVE_HANDLE_DECLARE_STORAGE(name, maxFds, maxInts) \
     28     alignas(native_handle_t) char (name)[                            \
     29       sizeof(native_handle_t) + sizeof(int) * ((maxFds) + (maxInts))]
     30 
     31 typedef struct native_handle
     32 {
     33     int version;        /* sizeof(native_handle_t) */
     34     int numFds;         /* number of file-descriptors at &data[0] */
     35     int numInts;        /* number of ints at &data[numFds] */
     36 #if defined(__clang__)
     37 #pragma clang diagnostic push
     38 #pragma clang diagnostic ignored "-Wzero-length-array"
     39 #endif
     40     int data[0];        /* numFds + numInts ints */
     41 #if defined(__clang__)
     42 #pragma clang diagnostic pop
     43 #endif
     44 } native_handle_t;
     45 
     46 typedef const native_handle_t* buffer_handle_t;
     47 
     48 /*
     49  * native_handle_close
     50  *
     51  * closes the file descriptors contained in this native_handle_t
     52  *
     53  * return 0 on success, or a negative error code on failure
     54  *
     55  */
     56 int native_handle_close(const native_handle_t* h);
     57 
     58 /*
     59  * native_handle_init
     60  *
     61  * Initializes a native_handle_t from storage.  storage must be declared with
     62  * NATIVE_HANDLE_DECLARE_STORAGE.  numFds and numInts must not respectively
     63  * exceed maxFds and maxInts used to declare the storage.
     64  */
     65 native_handle_t* native_handle_init(char* storage, int numFds, int numInts);
     66 
     67 /*
     68  * native_handle_create
     69  *
     70  * creates a native_handle_t and initializes it. must be destroyed with
     71  * native_handle_delete().
     72  *
     73  */
     74 native_handle_t* native_handle_create(int numFds, int numInts);
     75 
     76 /*
     77  * native_handle_clone
     78  *
     79  * creates a native_handle_t and initializes it from another native_handle_t.
     80  * Must be destroyed with native_handle_delete().
     81  *
     82  */
     83 native_handle_t* native_handle_clone(const native_handle_t* handle);
     84 
     85 /*
     86  * native_handle_delete
     87  *
     88  * frees a native_handle_t allocated with native_handle_create().
     89  * This ONLY frees the memory allocated for the native_handle_t, but doesn't
     90  * close the file descriptors; which can be achieved with native_handle_close().
     91  *
     92  * return 0 on success, or a negative error code on failure
     93  *
     94  */
     95 int native_handle_delete(native_handle_t* h);
     96 
     97 
     98 #ifdef __cplusplus
     99 }
    100 #endif
    101 
    102 #endif /* NATIVE_HANDLE_H_ */
    103