1e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/* 2e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Copyright (C) 2017 The Android Open Source Project 3e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 4e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Licensed under the Apache License, Version 2.0 (the "License"); 5e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * you may not use this file except in compliance with the License. 6e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * You may obtain a copy of the License at 7e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 8e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * http://www.apache.org/licenses/LICENSE-2.0 9e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 10e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Unless required by applicable law or agreed to in writing, software 11e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * distributed under the License is distributed on an "AS IS" BASIS, 12e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * See the License for the specific language governing permissions and 14e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * limitations under the License. 15e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 16e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 17e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** 18e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * @addtogroup Memory 19e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * @{ 20e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 21e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 22e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** 23e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * @file sharedmem.h 24e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 25e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 26e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#ifndef ANDROID_SHARED_MEMORY_H 27e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#define ANDROID_SHARED_MEMORY_H 28e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 29e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#include <stddef.h> 30e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 31e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/****************************************************************** 32e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 33e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * IMPORTANT NOTICE: 34e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 35e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * This file is part of Android's set of stable system headers 36e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * exposed by the Android NDK (Native Development Kit). 37e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 38e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Third-party source AND binary code relies on the definitions 39e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * here to be FROZEN ON ALL UPCOMING PLATFORM RELEASES. 40e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 41e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * - DO NOT MODIFY ENUMS (EXCEPT IF YOU ADD NEW 32-BIT VALUES) 42e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * - DO NOT MODIFY CONSTANTS OR FUNCTIONAL MACROS 43e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * - DO NOT CHANGE THE SIGNATURE OF FUNCTIONS IN ANY WAY 44e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * - DO NOT CHANGE THE LAYOUT OR SIZE OF STRUCTURES 45e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 46e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 47e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** 48e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Structures and functions for a shared memory buffer that can be shared across process. 49e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 50e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 51e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#ifdef __cplusplus 52e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xuextern "C" { 53e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#endif 54e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 55e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#if __ANDROID_API__ >= __ANDROID_API_O__ 56e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 57e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** 58e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Create a shared memory region. 59e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 60e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Create shared memory region and returns an file descriptor. The resulting file descriptor can be 61e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * mmap'ed to process memory space with PROT_READ | PROT_WRITE | PROT_EXEC. Access to shared memory 62e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * region can be restricted with {@link ASharedMemory_setProt}. 63e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 64e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Use close() to release the shared memory region. 65e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 66e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \param name an optional name. 67e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \param size size of the shared memory region 68e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \return file descriptor that denotes the shared memory; error code on failure. 69e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 70e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xuint ASharedMemory_create(const char *name, size_t size); 71e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 72e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** 73e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Get the size of the shared memory region. 74e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 75e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \param fd file descriptor of the shared memory region 76e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \return size in bytes; 0 if fd is not a valid shared memory file descriptor. 77e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 78e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xusize_t ASharedMemory_getSize(int fd); 79e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 80e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** 81e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * Restrict access of shared memory region. 82e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 83e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * This function restricts access of a shared memory region. Access can only be removed. The effect 84e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * applies globally to all file descriptors in all processes across the system that refer to this 85e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * shared memory region. Existing memory mapped regions are not affected. 86e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 87e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * It is a common use case to create a shared memory region, map it read/write locally to intialize 88e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * content, and then send the shared memory to another process with read only access. Code example 895163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * as below (error handling omited). 90e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 91e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 925163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * int fd = ASharedMemory_create("memory", 128); 93e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 945163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * // By default it has PROT_READ | PROT_WRITE | PROT_EXEC. 955163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * char *buffer = (char *) mmap(NULL, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 96e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 975163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * strcpy(buffer, "This is an example."); // trivially initialize content 98e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 995163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * // limit access to read only 1005163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * ASharedMemory_setProt(fd, PROT_READ); 1015163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * 1025163357fc094cefaf08c6d50a933fdfee13ab76dQuddus Chong * // share fd with another process here and the other process can only map with PROT_READ. 103e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * 104e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \param fd file descriptor of the shared memory region. 105e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \param prot any bitwise-or'ed combination of PROT_READ, PROT_WRITE, PROT_EXEC denoting 106e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * updated access. Note access can only be removed, but not added back. 107e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu * \return 0 for success, error code on failure. 108e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu */ 109e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xuint ASharedMemory_setProt(int fd, int prot); 110e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 111e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#endif 112e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 113e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#ifdef __cplusplus 114e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu}; 115e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#endif 116e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 117e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu#endif // ANDROID_SHARED_MEMORY_H 118e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu 119e1e7e3877a7ca37b20745774638d8b3a87feec2dPeng Xu/** @} */ 120