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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 #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