151 lines
3.1 KiB
C++
151 lines
3.1 KiB
C++
#pragma once
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#include <semaphore.h>
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#include <sys/mman.h>
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namespace nall {
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struct shared_memory {
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shared_memory() = default;
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shared_memory(const shared_memory&) = delete;
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auto operator=(const shared_memory&) -> shared_memory& = delete;
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~shared_memory() {
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reset();
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}
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explicit operator bool() const {
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return _mode != mode::inactive;
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}
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auto empty() const -> bool {
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return _mode == mode::inactive;
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}
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auto size() const -> unsigned {
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return _size;
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}
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auto acquired() const -> bool {
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return _acquired;
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}
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auto acquire() -> uint8_t* {
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if(!acquired()) {
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sem_wait(_semaphore);
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_acquired = true;
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}
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return _data;
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}
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auto release() -> void {
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if(acquired()) {
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sem_post(_semaphore);
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_acquired = false;
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}
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}
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auto reset() -> void {
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release();
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if(_mode == mode::server) return remove();
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if(_mode == mode::client) return close();
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}
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auto create(const string& name, unsigned size) -> bool {
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reset();
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_name = {"/nall-", string{name}.transform("/:", "--")};
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_size = size;
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//O_CREAT | O_EXCL seems to throw ENOENT even when semaphore does not exist ...
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_semaphore = sem_open(_name, O_CREAT, 0644, 1);
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if(_semaphore == SEM_FAILED) return remove(), false;
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_descriptor = shm_open(_name, O_CREAT | O_TRUNC | O_RDWR, 0644);
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if(_descriptor < 0) return remove(), false;
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if(ftruncate(_descriptor, _size) != 0) return remove(), false;
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_data = (uint8_t*)mmap(nullptr, _size, PROT_READ | PROT_WRITE, MAP_SHARED, _descriptor, 0);
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if(_data == MAP_FAILED) return remove(), false;
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memory::fill(_data, _size);
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_mode = mode::server;
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return true;
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}
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auto remove() -> void {
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if(_data) {
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munmap(_data, _size);
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_data = nullptr;
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}
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if(_descriptor) {
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::close(_descriptor);
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shm_unlink(_name);
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_descriptor = -1;
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}
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if(_semaphore) {
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sem_close(_semaphore);
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sem_unlink(_name);
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_semaphore = nullptr;
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}
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_mode = mode::inactive;
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_name = "";
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_size = 0;
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}
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auto open(const string& name, unsigned size) -> bool {
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reset();
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_name = {"/nall-", string{name}.transform("/:", "--")};
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_size = size;
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_semaphore = sem_open(_name, 0, 0644);
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if(_semaphore == SEM_FAILED) return close(), false;
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_descriptor = shm_open(_name, O_RDWR, 0644);
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if(_descriptor < 0) return close(), false;
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_data = (uint8_t*)mmap(nullptr, _size, PROT_READ | PROT_WRITE, MAP_SHARED, _descriptor, 0);
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if(_data == MAP_FAILED) return close(), false;
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_mode = mode::client;
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return true;
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}
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auto close() -> void {
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if(_data) {
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munmap(_data, _size);
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_data = nullptr;
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}
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if(_descriptor) {
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::close(_descriptor);
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_descriptor = -1;
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}
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if(_semaphore) {
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sem_close(_semaphore);
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_semaphore = nullptr;
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}
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_mode = mode::inactive;
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_name = "";
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_size = 0;
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}
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private:
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enum class mode : unsigned { server, client, inactive } _mode = mode::inactive;
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string _name;
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sem_t* _semaphore = nullptr;
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signed _descriptor = -1;
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uint8_t* _data = nullptr;
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unsigned _size = 0;
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bool _acquired = false;
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};
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}
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