From f2aac995e790d240b8ab8bf915e8283e8ba531f0 Mon Sep 17 00:00:00 2001
From: Waldemar Brodkorb <wbrodkorb@conet.de>
Date: Sat, 20 Oct 2018 16:25:49 +0200
Subject: do not expose recvmmsg/sendmmsg for unsupported kernels

---
 libc/inet/socketcalls.c                          | 5 +++++
 libc/sysdeps/linux/common/bits/kernel-features.h | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/libc/inet/socketcalls.c b/libc/inet/socketcalls.c
index 1b92609d0..edb5ab87e 100644
--- a/libc/inet/socketcalls.c
+++ b/libc/inet/socketcalls.c
@@ -8,6 +8,7 @@
 #include <sys/syscall.h>
 #include <sys/socket.h>
 #include <cancel.h>
+#include <bits/kernel-features.h>
 
 #ifdef __NR_socketcall
 /* Various socketcall numbers */
@@ -267,6 +268,7 @@ lt_libc_hidden(recvmsg)
 #endif
 
 #ifdef L_recvmmsg
+#ifdef __ASSUME_RECVMMSG_SYSCALL
 static ssize_t __NC(recvmmsg)(int sockfd, struct mmsghdr *msg, size_t vlen,
 			      int flags, struct timespec *tmo)
 {
@@ -289,6 +291,7 @@ CANCELLABLE_SYSCALL(ssize_t, recvmmsg,
 		    (sockfd, msg, vlen, flags, tmo))
 lt_libc_hidden(recvmmsg)
 #endif
+#endif
 
 #ifdef L_send
 static ssize_t __NC(send)(int sockfd, const void *buffer, size_t len, int flags)
@@ -332,6 +335,7 @@ lt_libc_hidden(sendmsg)
 #endif
 
 #ifdef L_sendmmsg
+#ifdef __ASSUME_SENDMMSG_SYSCALL
 static ssize_t __NC(sendmmsg)(int sockfd, struct mmsghdr *msg, size_t vlen,
 			      int flags)
 {
@@ -352,6 +356,7 @@ CANCELLABLE_SYSCALL(ssize_t, sendmmsg,
 		    (sockfd, msg, vlen, flags))
 lt_libc_hidden(sendmmsg)
 #endif
+#endif
 
 #ifdef L_sendto
 ssize_t __NC(sendto)(int sockfd, const void *buffer, size_t len, int flags,
diff --git a/libc/sysdeps/linux/common/bits/kernel-features.h b/libc/sysdeps/linux/common/bits/kernel-features.h
index e0195e405..f1ebe0204 100644
--- a/libc/sysdeps/linux/common/bits/kernel-features.h
+++ b/libc/sysdeps/linux/common/bits/kernel-features.h
@@ -461,6 +461,12 @@
 # define __ASSUME_ACCEPT4       1
 #endif
 
+/* Support for the recvmmsg/sendmmsg syscall was added in 2.6.33  */
+#if __LINUX_KERNEL_VERSION >= 0x020621
+#define __ASSUME_RECVMMSG_SYSCALL       1
+#define __ASSUME_SENDMMSG_SYSCALL       1
+#endif
+
 /* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29.  */
 #if __LINUX_KERNEL_VERSION >= 0x02061d
 # define __ASSUME_FUTEX_CLOCK_REALTIME	1
-- 
cgit v1.2.3