2 files changed, 39 insertions, 1 deletions
diff --git a/libc/inet/Makefile.in b/libc/inet/Makefile.in
index bed76c30c..91c417cc2 100644
--- a/libc/inet/Makefile.in
+++ b/libc/inet/Makefile.in
@@ -50,7 +50,7 @@ socketcalls_CSRC-y += \
 	sendto.c setsockopt.c shutdown.c socket.c socketpair.c \
 	recvmmsg.c sendmmsg.c
 socketcalls_CSRC-$(UCLIBC_LINUX_SPECIFIC) += accept4.c
-CSRC-$(UCLIBC_HAS_SOCKET) += $(socketcalls_CSRC-y) opensock.c
+CSRC-$(UCLIBC_HAS_SOCKET) += $(socketcalls_CSRC-y) opensock.c sockatmark.c
 
 CSRC-$(findstring y,$(UCLIBC_HAS_SOCKET)$(V4_OR_V6)) += ethers.c ether_addr.c
 
diff --git a/libc/inet/sockatmark.c b/libc/inet/sockatmark.c
new file mode 100644
index 000000000..6c6e29422
--- /dev/null
+++ b/libc/inet/sockatmark.c
@@ -0,0 +1,38 @@
+/*
+ * Copyright © 2005-2020 Rich Felker, et al.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Imported from musl C library
+ */
+
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+
+/* Determine whether socket is at a out-of-band mark.  */
+int sockatmark(int fd)
+{
+	int ret;
+
+	if (ioctl(fd, SIOCATMARK, &ret) < 0)
+		return -1;
+
+	return ret;
+}