ext/kgio/kgio_ext.c in kgio-2.7.4 vs ext/kgio/kgio_ext.c in kgio-2.8.0

@@ -1,8 +1,43 @@
 #include "kgio.h"
+#include <sys/utsname.h>
+#include <stdio.h>
+/* true if TCP Fast Open is usable */
+unsigned kgio_tfo;
 
+static void tfo_maybe(void)
+{
+	VALUE mKgio = rb_define_module("Kgio");
+
+	/* Deal with the case where system headers have not caught up */
+	if (KGIO_TFO_MAYBE) {
+		/* Ensure Linux 3.7 or later for TCP_FASTOPEN */
+		struct utsname buf;
+		unsigned maj, min;
+
+		if (uname(&buf) != 0)
+			rb_sys_fail("uname");
+		if (sscanf(buf.release, "%u.%u", &maj, &min) != 2)
+			return;
+		if (maj < 3 || (maj == 3 && min < 7))
+			return;
+	}
+
+	/*
+	 * KGIO_TFO_MAYBE will be false if a distro backports TFO
+	 * to a pre-3.7 kernel, but includes the necessary constants
+	 * in system headers
+	 */
+#if defined(MSG_FASTOPEN) && defined(TCP_FASTOPEN)
+	rb_define_const(mKgio, "TCP_FASTOPEN", INT2NUM(TCP_FASTOPEN));
+	rb_define_const(mKgio, "MSG_FASTOPEN", INT2NUM(MSG_FASTOPEN));
+	kgio_tfo = 1;
+#endif
+}
+
 void Init_kgio_ext(void)
 {
+	tfo_maybe();
 	init_kgio_wait();
 	init_kgio_read_write();
 	init_kgio_connect();
 	init_kgio_accept();
 	init_kgio_autopush();