Enable FD_CLOEXEC.

PostgreSQL enables this option when available which seems like a good idea since we also do not share connections between processes.

Note that as in PostgreSQL there is no way to disable this option.

src/common/io/socket/common.c

@@ -3,6 +3,8 @@ Socket Common Functions
 ***********************************************************************************************************************************/
 #include "build.auto.h"
 
+#include <fcntl.h>
+
 #ifdef __FreeBSD__
 #include <netinet/in.h>
 #endif
@@ -72,6 +74,12 @@ sckOptionSet(int fd)
         setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &socketValue, sizeof(int)) == -1, ProtocolError, "unable set TCP_NODELAY");
 #endif
 
+    // Automatically close the socket (in the child process) on a successful execve() call. Connections are never shared between
+    // processes so there is no reason to leave them open.
+#ifdef F_SETFD
+	THROW_ON_SYS_ERROR(fcntl(fd, F_SETFD, FD_CLOEXEC) == -1, ProtocolError, "unable set FD_CLOEXEC");
+#endif
+
     // Enable TCP keepalives
     if (socketLocal.keepAlive)
     {

test/src/module/common/ioTlsTest.c

@@ -1,6 +1,7 @@
 /***********************************************************************************************************************************
 Test Tls Client
 ***********************************************************************************************************************************/
+#include <fcntl.h>
 #include <unistd.h>
 
 #include "common/time.h"
@@ -130,6 +131,8 @@ testRun(void)
             sckInit(true, 32, 3113, 818);
             sckOptionSet(fd);
 
+            TEST_RESULT_INT(fcntl(fd, F_GETFD), FD_CLOEXEC, "check FD_CLOEXEC");
+
             socklen_t socketValueSize = sizeof(int);
             int noDelayValue = 0;