+ shared memory access cleanup

src/SharedMemoryAccess.cpp

@@ -12,8 +12,18 @@
 #include <unistd.h>
 #include <cstring>
 
+#include "internal.h"
 #include "SharedMemoryAccess.h"  /* header is important for the shmID. name could be different. maybe not needed cause: (shmget(memory_access_key, NULL, 0)) */
 
+#define PERM 0666      /* Zugriffsrechte */
+#define LOCK       -1
+#define UNLOCK      1
+#define SEM_KEY  123458L
+
+//int memoryAccessKey; /* var type is int. but could be another type. */ //TODO: look after type in sharedmemory group
+int semId;
+struct sembuf semaphore;
+
 int initSemaphore (void) {
     /* Testen, ob das Semaphor bereits existiert */
     semId = semget (SEM_KEY, 0, IPC_PRIVATE);
@@ -43,21 +53,21 @@ int semaphoreOperation (int op) {
     return 1;
 }
 
-void writeToShm(char* text, int size) {
-    int shmId = shmget(memoryAccessKey, NULL, 0); // dont init just get the ID if already existing.
+void writeSharedMemory(char *data, int size, int offset) {
+    int shmId = shmget(impl.sharedMemoryKey, NULL, 0); // dont init just get the ID if already existing.
     if(shmId < 0 ) {
         exit(EXIT_FAILURE);
         /* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/
     } else {
         char *shm_pointer = (char *) shmat(shmId, NULL, 0);
         semaphoreOperation(LOCK);
-        memcpy(shm_pointer, text, size);
+        memcpy(shm_pointer + offset, data, size);
         semaphoreOperation(UNLOCK);
     }
 }
 
-char* getShmPointer() {
-    int shmId = shmget(memoryAccessKey, NULL, 0);
+const char* getSharedMemory() {
+    int shmId = shmget(impl.sharedMemoryKey, NULL, 0);
     if(shmId < 0) {
         exit(EXIT_FAILURE);
         /* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/

src/SharedMemoryAccess.h

@@ -5,17 +5,25 @@
 #ifndef LIBRARY_SHAREDMEMORYACCESSS_H
 #define LIBRARY_SHAREDMEMORYACCESSS_H
 
-#define PERM 0666      /* Zugriffsrechte */
-#define LOCK       -1
-#define UNLOCK      1
-#define SEM_KEY  123458L
 
-int memoryAccessKey; /* var type is int. but could be another type. */ //TODO: look after type in sharedmemory group
-int semId;
-struct sembuf semaphore;
-int initSemaphore (void);
-int semaphoreOperation (int op);
-char* getShmPointer(void);
-void writeToShm(char* text, int size);
+/**
+ * only to read the shared memory
+ * @return pointer to the shared memory
+ */
+const char *getSharedMemory();
+
+/**
+ *
+ * @return the size of the shared memory
+ */
+int getSharedMemorySize();
+
+/**
+ *
+ * @param data poiter to data
+ * @param size of data
+ * @param offset where the data is written on the shared memory
+ */
+void writeSharedMemory(char *data, int size, int offset);
 
 #endif //LIBRARY_SHAREDMEMORYACCESSS_H

src/internal.h

@@ -55,10 +55,6 @@ struct Impl {
 
 extern Impl impl;
 
-void *getSharedMemory();
-
-int getSharedMemorySize();
-
 /**
  * send a signal to a process
  * @param pid of the process to which the signal is send