From f9c866231b4124ffedf6481b6ff772b3cdb4ad09 Mon Sep 17 00:00:00 2001
From: Shaohua Tong <shaohua.tong@stud.hs-emden-leer.de>
Date: Fri, 8 Nov 2019 18:30:27 +0100
Subject: [PATCH] getShareMemory(char *address, int size, int offset)
 hinzufuegen, ob man es braucht.

---
 src/SharedMemoryAccess.cpp | 17 +++++++++++++++++
 src/SharedMemoryAccess.h   | 13 +++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/SharedMemoryAccess.cpp b/src/SharedMemoryAccess.cpp
index 0fd13dd..412d54b 100644
--- a/src/SharedMemoryAccess.cpp
+++ b/src/SharedMemoryAccess.cpp
@@ -61,10 +61,27 @@ void writeSharedMemory(char *data, int size, int offset) {
         return;
         /* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/
     } else {
+        std::cout << "writing" << std::endl;
         char *shm_pointer = (char *) shmat(shmId, NULL, 0);
         semaphoreOperation(LOCK);
         memcpy(shm_pointer + offset, data, size);
+        shmdt(shm_pointer);                                     //close shm_pointer
         semaphoreOperation(UNLOCK);
+        std::cout << "writing successed" << std::endl;
+    }
+}
+
+void getSharedMemory(char *address, int size, int offset) {
+    int shmId = shmget(impl.sharedMemoryKey, NULL, 0);
+    if(shmId < 0) {
+        return;
+    } else {
+        char *shm_pointer = (char *) shmat(shmId, NULL, 0);
+        semaphoreOperation(LOCK);
+        memcpy(address, shm_pointer + offset, size);
+        shmdt(shm_pointer);                             //close shm_pointer
+        semaphoreOperation(UNLOCK);
+        return;
     }
 }
 
diff --git a/src/SharedMemoryAccess.h b/src/SharedMemoryAccess.h
index 949307b..f50dffb 100644
--- a/src/SharedMemoryAccess.h
+++ b/src/SharedMemoryAccess.h
@@ -12,6 +12,15 @@
  */
 char *getSharedMemory();
 
+/**
+ * use lock and unlock when writing,
+ * set content to the address
+ * @param *address target address
+ * @param size of data
+ * @param offset where the data is written on the shared memory
+ */
+void getSharedMemory(char *address, int size, int offset);
+
 /**
  *
  * @return the size of the shared memory
@@ -24,10 +33,10 @@ void unlockSharedMemory();
 
 /**
  *
- * @param data poiter to data
+ * @param data pointer 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);
+void writeSharedMemory(char *date, int size, int offset);
 
 #endif //LIBRARY_SHAREDMEMORYACCESSS_H