diff --git a/include/reHDD.h b/include/reHDD.h
index 893b0bd..ad23206 100644
--- a/include/reHDD.h
+++ b/include/reHDD.h
@@ -31,7 +31,7 @@
 #endif
 
 // Logic
-// #define DRYRUN    // don't touch the drives
+#define DRYRUN    // don't touch the drives
 #define FROZEN_ALERT // show alert if drive is frozen
 #define ZERO_CHECK   // check drive after shred if all bytes are zero, show alert if this fails
 
diff --git a/src/drive.cpp b/src/drive.cpp
index 1ca3e61..5ae0b7e 100644
--- a/src/drive.cpp
+++ b/src/drive.cpp
@@ -62,8 +62,12 @@ string Drive::sCapacityToText()
         dSize /= 1000;
         u16UnitIndex++;
     }
-
-    sprintf(acBuffer, "%.*f %s", u16UnitIndex - 3, dSize, units[u16UnitIndex]);
+    if (u16UnitIndex >= 9)
+    {
+        u16UnitIndex = 8;
+    }
+    int precision = (u16UnitIndex >= 3) ? (u16UnitIndex - 3) : 0;
+    sprintf(acBuffer, "%.*f %s", precision, dSize, units[u16UnitIndex]);
     return acBuffer;
 }
 
@@ -148,12 +152,20 @@ void Drive::setDriveSMARTData(string modelFamily,
 
 void Drive::setTimestamp()
 {
-    time(&this->u32Timestamp);
+    if (time(&this->u32Timestamp) == -1)
+    {
+        // handle error
+        this->u32Timestamp = 0U;
+    }
 }
 
 void Drive::setActionStartTimestamp()
 {
-    time(&this->u32TimestampTaskStart);
+    if (time(&this->u32TimestampTaskStart) == -1)
+    {
+        // handle error
+        this->u32TimestampTaskStart = 0U;
+    }
 }
 
 time_t Drive::getActionStartTimestamp()
@@ -164,7 +176,11 @@ time_t Drive::getActionStartTimestamp()
 void Drive::calculateTaskDuration()
 {
     time_t u32localtime;
-    time(&u32localtime);
+    if (time(&u32localtime) == -1)
+    {
+        // handle error
+        u32localtime = 0U;
+    }
 
     this->u32TaskDuration = u32localtime - this->u32TimestampTaskStart;
 }
@@ -178,6 +194,11 @@ void Drive::checkFrozenDrive(void)
 {
     time_t u32localtime;
     time(&u32localtime);
+    if (time(&u32localtime) == -1)
+    {
+        // handle error
+        u32localtime = 0U;
+    }
 
     if ((u32localtime - this->u32Timestamp) >= (FROZEN_TIMEOUT * 60) && (this->u32Timestamp > 0) && (this->getTaskPercentage() < 100.0))
     {
diff --git a/src/main.cpp b/src/main.cpp
index 30441e1..5b1798d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -16,7 +16,7 @@ int main(void)
 {
     // cout << "refurbishingHddTool" << endl;
 
-    reHDD *app = new reHDD();
-    app->app_logic();
+    reHDD app;
+    app.app_logic();
     return EXIT_SUCCESS;
 }
\ No newline at end of file
diff --git a/src/reHDD.cpp b/src/reHDD.cpp
index 5852628..defcb5a 100644
--- a/src/reHDD.cpp
+++ b/src/reHDD.cpp
@@ -43,8 +43,15 @@ void reHDD::app_logic(void)
     ui = new TUI();
     ui->initTUI();
 
-    pipe(fdNewDrivesInformPipe);
-    pipe(fdShredInformPipe);
+    if (pipe(fdNewDrivesInformPipe) == -1)
+    {
+        Logger::logThis()->error("Unable to open pipe 'fdNewDrivesInformPipe'");
+    }
+
+    if (pipe(fdShredInformPipe) == -1)
+    {
+        Logger::logThis()->error("Unable to open pipe 'fdShredInformPipe'");
+    }
 
     thread thDevices(ThreadScanDevices);                 // start thread that scans for drives
     thread thUserInput(ThreadUserInput);                 // start thread that reads user input
@@ -94,7 +101,7 @@ Drive *reHDD::getSelectedDrive()
     else
     {
         Logger::logThis()->warning("selected drive not present");
-        return {};
+        return nullptr;
     }
 }
 
@@ -135,6 +142,8 @@ void reHDD::ThreadUserInput()
 {
     while (true)
     {
+        Drive *tmpSelectedDrive = getSelectedDrive();
+
         // cout << TUI::readUserInput() << endl;
         switch (TUI::readUserInput())
         {
@@ -159,11 +168,11 @@ void reHDD::ThreadUserInput()
         case TUI::UserInput::Delete:
             // cout << "Delete" << endl;
 
-            if (getSelectedDrive() != nullptr)
+            if (tmpSelectedDrive != nullptr)
             {
-                if (getSelectedDrive()->state == Drive::NONE)
+                if (tmpSelectedDrive->state == Drive::NONE)
                 {
-                    getSelectedDrive()->state = Drive::DELETE_SELECTED;
+                    tmpSelectedDrive->state = Drive::DELETE_SELECTED;
                 }
             }
 
@@ -171,15 +180,13 @@ void reHDD::ThreadUserInput()
             break;
         case TUI::UserInput::Shred:
             // cout << "Shred" << endl;
-
-            if (getSelectedDrive() != nullptr)
+            if (tmpSelectedDrive != nullptr)
             {
-                if (getSelectedDrive()->state == Drive::NONE)
+                if (tmpSelectedDrive->state == Drive::NONE)
                 {
-                    getSelectedDrive()->state = Drive::SHRED_SELECTED;
+                    tmpSelectedDrive->state = Drive::SHRED_SELECTED;
                 }
             }
-
             ui->updateTUI(&listDrives, u8SelectedEntry);
             break;
         case TUI::UserInput::ShredAll:
@@ -224,13 +231,14 @@ void reHDD::ThreadShred(Drive *const pDrive)
 
 void reHDD::ThreadDelete()
 {
-    if (getSelectedDrive() != nullptr)
+    Drive *tmpSelectedDrive = getSelectedDrive();
+    if (tmpSelectedDrive != nullptr)
     {
-        getSelectedDrive()->setActionStartTimestamp();      // save timestamp at start of deleting
-        Delete::deleteDrive(getSelectedDrive());            // blocking, no thread
-        getSelectedDrive()->state = Drive::TaskState::NONE; // delete finished
-        getSelectedDrive()->bWasDeleted = true;
-        Logger::logThis()->info("Finished delete for: " + getSelectedDrive()->getModelName() + "-" + getSelectedDrive()->getSerial());
+        tmpSelectedDrive->setActionStartTimestamp();      // save timestamp at start of deleting
+        Delete::deleteDrive(tmpSelectedDrive);            // blocking, no thread
+        tmpSelectedDrive->state = Drive::TaskState::NONE; // delete finished
+        tmpSelectedDrive->bWasDeleted = true;
+        Logger::logThis()->info("Finished delete for: " + tmpSelectedDrive->getModelName() + "-" + tmpSelectedDrive->getSerial());
         ui->updateTUI(&listDrives, u8SelectedEntry);
     }
 }
@@ -326,28 +334,28 @@ void reHDD::searchDrives(std::list<Drive> *plistDrives)
         if (devName.empty())
             continue;
 
-        Drive *tmpDrive = new Drive("/dev/" + devName);
-        tmpDrive->state = Drive::NONE;
-        tmpDrive->bIsOffline = false;
+        Drive tmpDrive("/dev/" + devName);
+        tmpDrive.state = Drive::NONE;
+        tmpDrive.bIsOffline = false;
 
         // Set connection type
         if (transport == "sata")
-            tmpDrive->connectionType = Drive::SATA;
+            tmpDrive.connectionType = Drive::SATA;
         else if (transport == "usb")
-            tmpDrive->connectionType = Drive::USB;
+            tmpDrive.connectionType = Drive::USB;
         else if (transport == "nvme")
-            tmpDrive->connectionType = Drive::NVME;
+            tmpDrive.connectionType = Drive::NVME;
         else
-            tmpDrive->connectionType = Drive::UNKNOWN;
+            tmpDrive.connectionType = Drive::UNKNOWN;
 
-        plistDrives->push_back(*tmpDrive);
+        plistDrives->push_back(tmpDrive);
 
         Logger::logThis()->info(
-            "Drive found: " + tmpDrive->getPath() +
+            "Drive found: " + tmpDrive.getPath() +
             " (type: " +
-            (tmpDrive->connectionType == Drive::USB ? "USB" : tmpDrive->connectionType == Drive::SATA ? "SATA"
-                                                          : tmpDrive->connectionType == Drive::NVME   ? "NVME"
-                                                                                                      : "UNKNOWN") +
+            (tmpDrive.connectionType == Drive::USB ? "USB" : tmpDrive.connectionType == Drive::SATA ? "SATA"
+                                                         : tmpDrive.connectionType == Drive::NVME   ? "NVME"
+                                                                                                    : "UNKNOWN") +
             ")");
     }
 
@@ -376,7 +384,6 @@ void reHDD::filterIgnoredDrives(list<Drive> *plistDrives)
                 Logger::logThis()->info("system drive found --> ignore this drive: " + it->getPath());
 #endif
                 it = plistDrives->erase(it);
-                it--;
             }
         }
     }
@@ -419,6 +426,7 @@ void reHDD::filterIgnoredDrives(list<Drive> *plistDrives)
                     // cout << "blkid uuid:" << sUUID << endl;
                 }
             }
+            free(cLine);
             pclose(outputfileBlkid);
             // cout << "blkid uuid:" << sUUID << endl;
 
@@ -429,7 +437,6 @@ void reHDD::filterIgnoredDrives(list<Drive> *plistDrives)
                 Logger::logThis()->info("same uuid found than in ignore file --> ignore this drive: " + it->getPath());
 #endif
                 it = plistDrives->erase(it);
-                it--;
             }
         }
     }
@@ -451,7 +458,6 @@ void reHDD::filterInvalidDrives(list<Drive> *plistDrives)
             Logger::logThis()->info("Drive reports zero capacity --> ignore this drive: " + it->getPath());
 #endif
             it = plistDrives->erase(it);
-            it--;
         }
     }
 }
@@ -619,22 +625,21 @@ void reHDD::handleArrowKey(TUI::UserInput userInput)
 
 void reHDD::handleEnter()
 {
-
-    if (getSelectedDrive() != nullptr)
+    Drive *tmpSelectedDrive = getSelectedDrive();
+    if (tmpSelectedDrive != nullptr)
     {
-        if (getSelectedDrive()->state == Drive::TaskState::SHRED_SELECTED)
+        if (tmpSelectedDrive->state == Drive::TaskState::SHRED_SELECTED)
         {
-            Logger::logThis()->info("Started shred/check for: " + getSelectedDrive()->getModelName() + "-" + getSelectedDrive()->getSerial());
-            getSelectedDrive()->state = Drive::TaskState::SHRED_ACTIVE;
-            // task for drive is running --> don't show  more task options
-            Drive *pTmpDrive = getSelectedDrive();
-            thread(ThreadShred, pTmpDrive).detach();
+            Logger::logThis()->info("Started shred/check for: " + tmpSelectedDrive->getModelName() + "-" + tmpSelectedDrive->getSerial());
+            tmpSelectedDrive->state = Drive::TaskState::SHRED_ACTIVE;
+            // task for drive is running --> don't show  more task option
+            thread(ThreadShred, tmpSelectedDrive).detach();
         }
 
-        if (getSelectedDrive()->state == Drive::TaskState::DELETE_SELECTED)
+        if (tmpSelectedDrive->state == Drive::TaskState::DELETE_SELECTED)
         {
-            Logger::logThis()->info("Started delete for: " + getSelectedDrive()->getModelName() + "-" + getSelectedDrive()->getSerial());
-            getSelectedDrive()->state = Drive::TaskState::DELETE_ACTIVE;
+            Logger::logThis()->info("Started delete for: " + tmpSelectedDrive->getModelName() + "-" + tmpSelectedDrive->getSerial());
+            tmpSelectedDrive->state = Drive::TaskState::DELETE_ACTIVE;
             // task for drive is running --> don't show  more task options
             thread(ThreadDelete).detach();
         }
@@ -643,17 +648,18 @@ void reHDD::handleEnter()
 
 void reHDD::handleESC()
 {
-    if (getSelectedDrive() != nullptr)
+    Drive *tmpSelectedDrive = getSelectedDrive();
+    if (tmpSelectedDrive != nullptr)
     {
-        if (getSelectedDrive()->state == Drive::TaskState::SHRED_SELECTED)
+        if (tmpSelectedDrive->state == Drive::TaskState::SHRED_SELECTED)
         {
-            getSelectedDrive()->state = Drive::TaskState::NONE;
+            tmpSelectedDrive->state = Drive::TaskState::NONE;
             // task for drive is selected --> remove selection
         }
 
-        if (getSelectedDrive()->state == Drive::TaskState::DELETE_SELECTED)
+        if (tmpSelectedDrive->state == Drive::TaskState::DELETE_SELECTED)
         {
-            getSelectedDrive()->state = Drive::TaskState::NONE;
+            tmpSelectedDrive->state = Drive::TaskState::NONE;
             // task for drive is selected --> remove selection
         }
     }
@@ -661,12 +667,13 @@ void reHDD::handleESC()
 
 void reHDD::handleAbort()
 {
-    if (getSelectedDrive() != nullptr)
+    Drive *tmpSelectedDrive = getSelectedDrive();
+    if (tmpSelectedDrive != nullptr)
     {
-        if (getSelectedDrive()->state == Drive::SHRED_ACTIVE || getSelectedDrive()->state == Drive::DELETE_ACTIVE)
+        if (tmpSelectedDrive->state == Drive::SHRED_ACTIVE || tmpSelectedDrive->state == Drive::DELETE_ACTIVE)
         {
-            getSelectedDrive()->state = Drive::NONE;
-            Logger::logThis()->info("Abort-Shred-Signal for: " + getSelectedDrive()->getModelName() + "-" + getSelectedDrive()->getSerial());
+            tmpSelectedDrive->state = Drive::NONE;
+            Logger::logThis()->info("Abort-Shred-Signal for: " + tmpSelectedDrive->getModelName() + "-" + tmpSelectedDrive->getSerial());
             // task for drive is running --> remove selection
         }
     }
diff --git a/src/shred.cpp b/src/shred.cpp
index 2255310..8fd3fae 100644
--- a/src/shred.cpp
+++ b/src/shred.cpp
@@ -36,7 +36,7 @@ int Shred::shredDrive(Drive *drive, int *ipSignalFd)
     ostringstream address;
     address << (void const *)&(*drive);
     Logger::logThis()->info("Shred-Task started - Drive: " + drive->getModelName() + "-" + drive->getSerial() + " @" + address.str());
-    drive->bWasShredStarted = true; //Mark drive as partly shredded
+    drive->bWasShredStarted = true; // Mark drive as partly shredded
 
 #ifdef DRYRUN
     for (int i = 0; i <= 500; i++)
@@ -60,7 +60,7 @@ int Shred::shredDrive(Drive *drive, int *ipSignalFd)
     randomSrcFileDiscr = open(randomsrc, O_RDONLY | O_LARGEFILE);
     if (randomSrcFileDiscr == -1)
     {
-        std::string errorMsg(strerror(randomSrcFileDiscr));
+        std::string errorMsg(strerror(errno));
         Logger::logThis()->error("Shred-Task: Open random source failed! " + errorMsg + " - Drive: " + drive->getSerial());
         perror(randomsrc);
         cleanup();
@@ -71,7 +71,7 @@ int Shred::shredDrive(Drive *drive, int *ipSignalFd)
     driveFileDiscr = open(cpDrivePath, O_RDWR | O_LARGEFILE);
     if (driveFileDiscr == -1)
     {
-        std::string errorMsg(strerror(driveFileDiscr));
+        std::string errorMsg(strerror(errno));
         Logger::logThis()->error("Shred-Task: Open drive failed! " + errorMsg + " - Drive: " + drive->getSerial());
         perror(cpDrivePath);
         cleanup();
@@ -82,7 +82,7 @@ int Shred::shredDrive(Drive *drive, int *ipSignalFd)
     ssize_t readRet = read(randomSrcFileDiscr, ucKey, sizeof(ucKey));
     if (readRet <= 0)
     {
-        std::string errorMsg(strerror(readRet));
+        std::string errorMsg(strerror(errno));
         Logger::logThis()->error("Shred-Task: Read random key failed! " + errorMsg + " - Drive: " + drive->getSerial());
         perror(randomsrc);
         cleanup();
@@ -93,7 +93,7 @@ int Shred::shredDrive(Drive *drive, int *ipSignalFd)
 
     this->ulDriveByteSize = getDriveSizeInBytes(driveFileDiscr);
     drive->sShredSpeed.chronoShredTimestamp = std::chrono::system_clock::now(); // set inital timestamp for speed metric
-    drive->sShredSpeed.ulSpeedMetricBytesWritten = 0U; // uses to calculate speed metric
+    drive->sShredSpeed.ulSpeedMetricBytesWritten = 0U;                          // uses to calculate speed metric
 
 #ifdef LOG_LEVEL_HIGH
     Logger::logThis()->info("Shred-Task: Bytes-Size of Drive: " + to_string(this->ulDriveByteSize) + " - Drive: " + drive->getSerial());
@@ -132,7 +132,7 @@ int Shred::shredDrive(Drive *drive, int *ipSignalFd)
 
             if (iByteShredded <= 0)
             {
-                std::string errorMsg(strerror(iByteShredded));
+                std::string errorMsg(strerror(errno));
                 Logger::logThis()->error("Shred-Task: Write to drive failed! " + errorMsg + " - Drive: " + drive->getSerial());
                 perror("unable to write random data");
                 cleanup();