b843791b61
HIDL requires file descriptors to be wrapped in native_handle_t. We want
a low overhead way to do that when the number of file descriptors is known
at compile time. Instead of
// wrap an fd in native_handle_t
native_handle_t* fd_handle = native_handle_create(1, 0);
if (!fd_handle) {
// clean up and return error
}
fd_handle->data[0] = fd;
hidl_cb(..., fd_handle);
native_handle_delete(fd_handle);
this change adds native_handle_init to allow for
// wrap an fd in native_handle_t
NATIVE_HANDLE_DECLARE_STORAGE(fd_storage, 1, 0);
native_handle_t* fd_handle = native_handle_init(fd_storage, 1, 0);
fd_handle->data[0] = fd;
hidl_cb(..., fd_handle);
Test: make libcutils
Bug: 32021609
Change-Id: If1fd07482243d37492fdea57c602a1b13c8953cc
100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef NATIVE_HANDLE_H_
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#define NATIVE_HANDLE_H_
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#include <stdalign.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Declare a char array for use with native_handle_init */
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#define NATIVE_HANDLE_DECLARE_STORAGE(name, maxFds, maxInts) \
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alignas(native_handle_t) char name[ \
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sizeof(native_handle_t) + sizeof(int) * (maxFds + maxInts)]
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typedef struct native_handle
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{
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int version; /* sizeof(native_handle_t) */
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int numFds; /* number of file-descriptors at &data[0] */
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int numInts; /* number of ints at &data[numFds] */
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#if defined(__clang__)
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#pragma clang diagnostic push
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#pragma clang diagnostic ignored "-Wzero-length-array"
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#endif
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int data[0]; /* numFds + numInts ints */
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#if defined(__clang__)
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#pragma clang diagnostic pop
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#endif
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} native_handle_t;
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/*
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* native_handle_close
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*
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* closes the file descriptors contained in this native_handle_t
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*
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* return 0 on success, or a negative error code on failure
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*
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*/
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int native_handle_close(const native_handle_t* h);
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/*
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* native_handle_init
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*
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* Initializes a native_handle_t from storage. storage must be declared with
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* NATIVE_HANDLE_DECLARE_STORAGE. numFds and numInts must not respectively
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* exceed maxFds and maxInts used to declare the storage.
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*/
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native_handle_t* native_handle_init(char* storage, int numFds, int numInts);
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/*
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* native_handle_create
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*
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* creates a native_handle_t and initializes it. must be destroyed with
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* native_handle_delete().
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*
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*/
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native_handle_t* native_handle_create(int numFds, int numInts);
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/*
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* native_handle_clone
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*
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* creates a native_handle_t and initializes it from another native_handle_t.
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* Must be destroyed with native_handle_delete().
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*
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*/
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native_handle_t* native_handle_clone(const native_handle_t* handle);
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/*
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* native_handle_delete
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*
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* frees a native_handle_t allocated with native_handle_create().
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* This ONLY frees the memory allocated for the native_handle_t, but doesn't
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* close the file descriptors; which can be achieved with native_handle_close().
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*
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* return 0 on success, or a negative error code on failure
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*
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*/
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int native_handle_delete(native_handle_t* h);
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#ifdef __cplusplus
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}
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#endif
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#endif /* NATIVE_HANDLE_H_ */
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