Fix getsockopt option_value initial initialization

On some platforms, some of the options we're getting the value
for may be a single byte, so attempting to read the full int
produces garbage.

Found with IP_MULTICAST_TTL and IP_MULTICAST_LOOP on QNX. See:
https://www.qnx.com/developers/docs/7.1/index.html#com.qnx.doc.neutrino.lib_ref/topic/g/getsockopt.html#getsockopt__IP_MULTICAST_TTL

Pick-to: 5.15 6.2 6.3
Change-Id: Id9f7f249c6c4be0c3f94c5904d402b4ec4e17b59
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/network/socket/qnativesocketengine_unix.cpp b/src/network/socket/qnativesocketengine_unix.cpp
index e6704a3ca4..61fa8edbe9 100644
--- a/src/network/socket/qnativesocketengine_unix.cpp
+++ b/src/network/socket/qnativesocketengine_unix.cpp
@@ -46,6 +46,7 @@
 #include "qelapsedtimer.h"
 #include "qvarlengtharray.h"
 #include "qnetworkinterface.h"
+#include "qendian.h"
 #include <time.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -329,12 +330,12 @@ int QNativeSocketEnginePrivate::option(QNativeSocketEngine::SocketOption opt) co
     }
 
     int n, level;
-    int v = -1;
+    int v = 0;
     QT_SOCKOPTLEN_T len = sizeof(v);
 
     convertToLevelAndOption(opt, socketProtocol, level, n);
     if (n != -1 && ::getsockopt(socketDescriptor, level, n, (char *) &v, &len) != -1)
-        return v;
+        return len == 1 ? qFromUnaligned<quint8>(&v) : v;
 
     return -1;
 }