From e4c234ac1569754a6aac7c6c7a0d9311e4247dc2 Mon Sep 17 00:00:00 2001
From: Mate Barany <mate.barany@qt.io>
Date: Thu, 27 Jun 2024 15:43:27 +0200
Subject: [PATCH] Remove the struct NetlinkSocket

Started with fixing a "Class with destructor should also declare a
copy or move constructor and assignment operator." warning found by an
Axivion scan.

However, the NetlinkSocket struct is used only once and the behavior
can be replicated with a qScopeGuard.

Remove the struct NetlinkSocket and use a qScopeGuard for resource
management.

Drive-by: remove a Q_UNLIKELY that's not needed (qErrnoWarning() is
already marked as Q_DECL_COLD_FUNCTION).

Task-number: QTBUG-125026
Pick-to: 6.7 6.5
Change-Id: I6b770e284fdda3ff97b8cabac205e9b5abe88b14
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 954bf6e18eb691ea95dab866831492a4494eff03)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 .../kernel/qnetworkinterface_linux.cpp        | 35 ++++++-------------
 1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/src/network/kernel/qnetworkinterface_linux.cpp b/src/network/kernel/qnetworkinterface_linux.cpp
index 89374d2c4c..a12a16d1f7 100644
--- a/src/network/kernel/qnetworkinterface_linux.cpp
+++ b/src/network/kernel/qnetworkinterface_linux.cpp
@@ -9,6 +9,7 @@
 
 #include <qendian.h>
 #include <qobjectdefs.h>
+#include <qscopeguard.h>
 #include <qvarlengtharray.h>
 
 // according to rtnetlink(7)
@@ -85,28 +86,6 @@ static QNetworkInterface::InterfaceType probeIfType(int socket, struct ifreq *re
 
 
 namespace {
-struct NetlinkSocket
-{
-    int sock;
-    Q_NODISCARD_CTOR explicit NetlinkSocket(int bufferSize)
-    {
-        sock = qt_safe_socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
-        if (Q_UNLIKELY(sock == -1))
-            qErrnoWarning("Could not create AF_NETLINK socket");
-
-        // set buffer length
-        socklen_t len = sizeof(bufferSize);
-        setsockopt(sock, SOL_SOCKET, SO_SNDBUF, &bufferSize, len);
-    }
-
-    ~NetlinkSocket()
-    {
-        if (sock != -1)
-            qt_safe_close(sock);
-    }
-
-    operator int() const { return sock; }
-};
 
 template <typename Lambda> struct ProcessNetlinkRequest
 {
@@ -406,9 +385,17 @@ QList<QNetworkInterfacePrivate *> QNetworkInterfaceManager::scan()
 {
     // open netlink socket
     QList<QNetworkInterfacePrivate *> result;
-    NetlinkSocket sock(BufferSize);
-    if (Q_UNLIKELY(sock == -1))
+    int sock = qt_safe_socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+    if (sock == -1) {
+        qErrnoWarning("Could not create AF_NETLINK socket");
         return result;
+    }
+
+    const auto sg = qScopeGuard([&] { qt_safe_close(sock); });
+
+    // set buffer length
+    const int bufferSize = BufferSize;
+    setsockopt(sock, SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
 
     QByteArray buffer(BufferSize, Qt::Uninitialized);
     char *buf = buffer.data();