From a807dceca5ccfaf283aedaca3d998f83db8fe1fa Mon Sep 17 00:00:00 2001
From: Masatake YAMATO <yamato@redhat.com>
Date: Fri, 7 Nov 2014 01:23:26 +0900
Subject: [PATCH] Add functions for dumping iovecs in mmsghdr used in sendmmsg
 and recvmmsg

This patch is similar to what I did in commit
02f9f6b386741a52f58e1b31ad4e7fff60781ef8.
That commit was for sendmsg and recvmsg system calls.
This one is for sendmmsg and recvmmsg system calls.

* defs.h (dumpiov_in_mmsghdr): New declaration.
* net.c (extractmmsghdr): New function derived from printmmsghdr.
(printmmsghdr): Use it.
(dumpiov_in_mmsghdr): New function.
* syscall.c (dumpio) [HAVE_SENDMSG]: Call dumpiov_in_mmsghdr
for recvmmsg and sendmmsg syscalls.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
 defs.h    |  1 +
 net.c     | 73 ++++++++++++++++++++++++++++++++++---------------------
 syscall.c |  4 +++
 3 files changed, 50 insertions(+), 28 deletions(-)

diff --git a/defs.h b/defs.h
index 8a10e035..708adf61 100644
--- a/defs.h
+++ b/defs.h
@@ -673,6 +673,7 @@ extern void addflags(const struct xlat *, int);
 extern int printflags(const struct xlat *, int, const char *);
 extern const char *sprintflags(const char *, const struct xlat *, int);
 extern void dumpiov_in_msghdr(struct tcb *, long);
+extern void dumpiov_in_mmsghdr(struct tcb *, long);
 extern void dumpiov(struct tcb *, int, long);
 extern void dumpstr(struct tcb *, long, int);
 extern void printstr(struct tcb *, long, long);
diff --git a/net.c b/net.c
index 9e9e1591..f3f102e4 100644
--- a/net.c
+++ b/net.c
@@ -467,6 +467,29 @@ extractmsghdr(struct tcb *tcp, long addr, struct msghdr *msg)
 	return true;
 }
 
+static bool
+extractmmsghdr(struct tcb *tcp, long addr, unsigned int idx, struct mmsghdr *mmsg)
+{
+#if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
+	if (current_wordsize == 4) {
+		struct mmsghdr32 mmsg32;
+
+		addr += sizeof(struct mmsghdr32) * idx;
+		if (umove(tcp, addr, &mmsg32) < 0)
+			return false;
+
+		copy_from_msghdr32(&mmsg->msg_hdr, &mmsg32.msg_hdr);
+		mmsg->msg_len = mmsg32.msg_len;
+	} else
+#endif
+	{
+		addr += sizeof(*mmsg) * idx;
+		if (umove(tcp, addr, mmsg) < 0)
+			return false;
+	}
+	return true;
+}
+
 static void
 printmsghdr(struct tcb *tcp, long addr, unsigned long data_size)
 {
@@ -492,35 +515,13 @@ printmmsghdr(struct tcb *tcp, long addr, unsigned int idx, unsigned long msg_len
 {
 	struct mmsghdr mmsg;
 
-#if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
-	if (current_wordsize == 4) {
-		struct mmsghdr32 mmsg32;
-
-		addr += sizeof(mmsg32) * idx;
-		if (umove(tcp, addr, &mmsg32) < 0) {
-			tprintf("%#lx", addr);
-			return;
-		}
-		mmsg.msg_hdr.msg_name       = (void*)(long)mmsg32.msg_hdr.msg_name;
-		mmsg.msg_hdr.msg_namelen    =              mmsg32.msg_hdr.msg_namelen;
-		mmsg.msg_hdr.msg_iov        = (void*)(long)mmsg32.msg_hdr.msg_iov;
-		mmsg.msg_hdr.msg_iovlen     =              mmsg32.msg_hdr.msg_iovlen;
-		mmsg.msg_hdr.msg_control    = (void*)(long)mmsg32.msg_hdr.msg_control;
-		mmsg.msg_hdr.msg_controllen =              mmsg32.msg_hdr.msg_controllen;
-		mmsg.msg_hdr.msg_flags      =              mmsg32.msg_hdr.msg_flags;
-		mmsg.msg_len                =              mmsg32.msg_len;
-	} else
-#endif
-	{
-		addr += sizeof(mmsg) * idx;
-		if (umove(tcp, addr, &mmsg) < 0) {
-			tprintf("%#lx", addr);
-			return;
-		}
+	if (extractmmsghdr(tcp, addr, idx, &mmsg)) {
+		tprints("{");
+		do_msghdr(tcp, &mmsg.msg_hdr, msg_len ? msg_len : mmsg.msg_len);
+		tprintf(", %u}", mmsg.msg_len);
 	}
-	tprints("{");
-	do_msghdr(tcp, &mmsg.msg_hdr, msg_len ? msg_len : mmsg.msg_len);
-	tprintf(", %u}", mmsg.msg_len);
+	else
+		tprintf("%#lx", addr);
 }
 
 static void
@@ -547,6 +548,22 @@ decode_mmsg(struct tcb *tcp, unsigned long msg_len)
 	printflags(msg_flags, tcp->u_arg[3], "MSG_???");
 }
 
+void
+dumpiov_in_mmsghdr(struct tcb *tcp, long addr)
+{
+	unsigned int len = tcp->u_rval;
+	unsigned int i;
+	struct mmsghdr mmsg;
+
+	for (i = 0; i < len; ++i) {
+		if (extractmmsghdr(tcp, addr, i, &mmsg)) {
+			tprintf(" = %lu buffers in vector %u\n",
+				(unsigned long)mmsg.msg_hdr.msg_iovlen, i);
+			dumpiov(tcp, mmsg.msg_hdr.msg_iovlen,
+				(long)mmsg.msg_hdr.msg_iov);
+		}
+	}
+}
 #endif /* HAVE_SENDMSG */
 
 /*
diff --git a/syscall.c b/syscall.c
index fa761a95..091626ce 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2500,6 +2500,8 @@ dumpio(struct tcb *tcp)
 #if HAVE_SENDMSG
 		else if (func == sys_recvmsg)
 			dumpiov_in_msghdr(tcp, tcp->u_arg[1]);
+		else if (func == sys_recvmmsg)
+			dumpiov_in_mmsghdr(tcp, tcp->u_arg[1]);
 #endif
 		return;
 	}
@@ -2514,6 +2516,8 @@ dumpio(struct tcb *tcp)
 #if HAVE_SENDMSG
 		else if (func == sys_sendmsg)
 			dumpiov_in_msghdr(tcp, tcp->u_arg[1]);
+		else if (func == sys_sendmmsg)
+			dumpiov_in_mmsghdr(tcp, tcp->u_arg[1]);
 #endif
 		return;
 	}
-- 
2.40.0