From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001
From: Vladimir Azarov <avm@intermediate-node.net>
Date: Tue, 1 Oct 2024 15:47:05 +0200
Subject: Initial version

---
 src/network/recvmmsg.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 src/network/recvmmsg.c

(limited to 'src/network/recvmmsg.c')

diff --git a/src/network/recvmmsg.c b/src/network/recvmmsg.c
new file mode 100644
index 0000000..2978e2f
--- /dev/null
+++ b/src/network/recvmmsg.c
@@ -0,0 +1,39 @@
+#define _GNU_SOURCE
+#include <sys/socket.h>
+#include <limits.h>
+#include <errno.h>
+#include <time.h>
+#include "syscall.h"
+
+#define IS32BIT(x) !((x)+0x80000000ULL>>32)
+#define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
+
+hidden void __convert_scm_timestamps(struct msghdr *, socklen_t);
+
+int recvmmsg(int fd, struct mmsghdr *msgvec, unsigned int vlen, unsigned int flags, struct timespec *timeout)
+{
+#if LONG_MAX > INT_MAX
+	struct mmsghdr *mh = msgvec;
+	unsigned int i;
+	for (i = vlen; i; i--, mh++)
+		mh->msg_hdr.__pad1 = mh->msg_hdr.__pad2 = 0;
+#endif
+#ifdef SYS_recvmmsg_time64
+	time_t s = timeout ? timeout->tv_sec : 0;
+	long ns = timeout ? timeout->tv_nsec : 0;
+	int r = __syscall_cp(SYS_recvmmsg_time64, fd, msgvec, vlen, flags,
+			timeout ? ((long long[]){s, ns}) : 0);
+	if (SYS_recvmmsg == SYS_recvmmsg_time64 || r!=-ENOSYS)
+		return __syscall_ret(r);
+	if (vlen > IOV_MAX) vlen = IOV_MAX;
+	socklen_t csize[vlen];
+	for (int i=0; i<vlen; i++) csize[i] = msgvec[i].msg_hdr.msg_controllen;
+	r = __syscall_cp(SYS_recvmmsg, fd, msgvec, vlen, flags,
+		timeout ? ((long[]){CLAMP(s), ns}) : 0);
+	for (int i=0; i<r; i++)
+		__convert_scm_timestamps(&msgvec[i].msg_hdr, csize[i]);
+	return __syscall_ret(r);
+#else
+	return syscall_cp(SYS_recvmmsg, fd, msgvec, vlen, flags, timeout);
+#endif
+}
-- 
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