104 lines
3.0 KiB
C++
104 lines
3.0 KiB
C++
#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <iostream>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <sys/shm.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "SharedMemoryAccess.hpp" /* header is important for the shmID. name could be different. maybe not needed cause: (shmget(memory_access_key, NULL, 0)) */
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#include "internal.hpp"
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#include "log.hpp"
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namespace vkvm {
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constexpr int PERM = 0666; /* access rights */
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constexpr int LOCK = -1;
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constexpr int UNLOCK = 1;
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constexpr int SEM_KEY = 123458L;
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//int memoryAccessKey; /* var type is int. but could be another type. */ //TODO: look after type in sharedmemory group
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int semId;
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struct sembuf semaphore;
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std::vector<char> localSharedMemory;
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auto initSemaphore() -> int {
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/* Testen, ob das Semaphor bereits existiert */
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semId = semget(SEM_KEY, 0, IPC_PRIVATE);
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if (semId < 0) {
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/* ... existiert noch nicht, also anlegen */
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/* Alle Zugriffsrechte der Dateikreierungsmaske */
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/* erlauben */
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umask(0);
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semId = semget(SEM_KEY, 1, IPC_CREAT | IPC_EXCL | PERM);
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if (semId < 0) {
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return -1;
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}
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/* Semaphor mit 1 initialisieren */
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if (semctl(semId, 0, SETVAL, 1) == -1) {
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return -1;
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}
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}
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return 1;
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}
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auto semaphoreOperation(int op) -> int {
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semaphore.sem_op = static_cast<int16_t>(op);
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semaphore.sem_flg = SEM_UNDO;
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if (semop(semId, &semaphore, 1) == -1) {
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perror(" semop ");
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return -1;
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}
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return 1;
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}
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auto writeSharedMemory(char *data, int size, int offset) -> void {
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lockSharedMemory();
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memcpy(getSharedMemory() + offset, data, size);
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unlockSharedMemory();
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}
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char *getLocalMemory(){
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if (localSharedMemory.empty()) {
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constexpr int kilo = 1024;
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localSharedMemory.resize(impl.sharedMemorySize);
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}
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return &localSharedMemory[0];
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}
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auto getSharedMemory() -> char * {
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int shmId = shmget(impl.sharedMemoryKey, 0, 0);
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if (shmId < 0) {
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//using a local buffer for shared memory testing
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return getLocalMemory();
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}
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char *ptr = static_cast<char *>(shmat(shmId, nullptr, 0));
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if((size_t)ptr == (size_t)-1){
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return getLocalMemory();
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}else{
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return ptr;
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}
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}
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auto getSharedMemory(char *address, int size, int offset) -> void {
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lockSharedMemory();
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memcpy(address, getSharedMemory() + offset, size);
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unlockSharedMemory();
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}
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auto getSharedMemorySize() -> int {
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return impl.sharedMemorySize;
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}
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auto lockSharedMemory() -> void {
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semaphoreOperation(LOCK);
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}
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auto unlockSharedMemory() -> void {
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semaphoreOperation(UNLOCK);
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}
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} |