From: Dmitry V. Levin <ldv@altlinux.org>
Date: Mon, 18 Jul 2016 16:25:25 +0000 (+0000)
Subject: Print unsent messages of sendmmsg syscall
X-Git-Tag: v4.13~25
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3a161d19021710dd8c746655c45eb97aeba93051;p=strace

Print unsent messages of sendmmsg syscall

* defs.h (decode_mmsgvec): Add int argument.
* mmsghdr.c (print_struct_mmsghdr_config): Add msg_len_vlen field.
(print_struct_mmsghdr): Print struct mmsghdr.msg_len only for
msg_len_vlen first elements of struct mmsghdr array.
(decode_mmsgvec): Add msg_len_vlen argument.
(SYS_FUNC(sendmmsg), SYS_FUNC(recvmmsg)): Pass to decode_mmsgvec
the number of elements of struct mmsghdr array that contain meaningful
struct mmsghdr.msg_len.
* tests/mmsg_name.c (test_mmsg_name): Check it.
---

diff --git a/mmsghdr.c b/mmsghdr.c
index 9ef0f080..d310a767 100644
--- a/mmsghdr.c
+++ b/mmsghdr.c
@@ -47,6 +47,7 @@ fetch_struct_mmsghdr_or_printaddr(struct tcb *tcp, const long addr,
 
 struct print_struct_mmsghdr_config {
 	const int *p_user_msg_namelen;
+	unsigned int msg_len_vlen;
 	unsigned int count;
 	bool use_msg_len;
 };
@@ -67,7 +68,11 @@ print_struct_mmsghdr(struct tcb *tcp, void *elem_buf,
 	tprints("{msg_hdr=");
 	print_struct_msghdr(tcp, &mmsg->msg_hdr, c->p_user_msg_namelen,
 			    c->use_msg_len ? mmsg->msg_len : -1UL);
-	tprintf(", msg_len=%u}", mmsg->msg_len);
+	if (c->msg_len_vlen) {
+		tprintf(", msg_len=%u", mmsg->msg_len);
+		--c->msg_len_vlen;
+	}
+	tprints("}");
 
 	if (c->p_user_msg_namelen)
 		++c->p_user_msg_namelen;
@@ -120,10 +125,12 @@ save_mmsgvec_namelen(struct tcb *tcp, unsigned long addr,
 
 static void
 decode_mmsgvec(struct tcb *tcp, const unsigned long addr,
-	       const unsigned int len, const bool use_msg_len)
+	       const unsigned int vlen, const unsigned int msg_len_vlen,
+	       const bool use_msg_len)
 {
 	struct mmsghdr mmsg;
 	struct print_struct_mmsghdr_config c = {
+		.msg_len_vlen = msg_len_vlen,
 		.count = IOV_MAX,
 		.use_msg_len = use_msg_len
 	};
@@ -135,7 +142,7 @@ decode_mmsgvec(struct tcb *tcp, const unsigned long addr,
 		c.p_user_msg_namelen = data->namelen;
 	}
 
-	print_array(tcp, addr, len, &mmsg, sizeof_struct_mmsghdr(),
+	print_array(tcp, addr, vlen, &mmsg, sizeof_struct_mmsghdr(),
 		    fetch_struct_mmsghdr_or_printaddr,
 		    print_struct_mmsghdr, &c);
 }
@@ -173,7 +180,8 @@ SYS_FUNC(sendmmsg)
 			return RVAL_DECODED;
 		}
 	} else {
-		decode_mmsgvec(tcp, tcp->u_arg[1], tcp->u_rval, false);
+		decode_mmsgvec(tcp, tcp->u_arg[1], tcp->u_arg[2],
+			       tcp->u_rval, false);
 		/* vlen */
 		tprintf(", %u, ", (unsigned int) tcp->u_arg[2]);
 		/* flags */
@@ -202,7 +210,8 @@ SYS_FUNC(recvmmsg)
 		return 0;
 	} else {
 		if (verbose(tcp)) {
-			decode_mmsgvec(tcp, tcp->u_arg[1], tcp->u_rval, true);
+			decode_mmsgvec(tcp, tcp->u_arg[1], tcp->u_rval,
+				       tcp->u_rval, true);
 			/* vlen */
 			tprintf(", %u, ", (unsigned int) tcp->u_arg[2]);
 			/* flags */
diff --git a/tests/mmsg_name.c b/tests/mmsg_name.c
index e90cafdb..466b602d 100644
--- a/tests/mmsg_name.c
+++ b/tests/mmsg_name.c
@@ -104,19 +104,22 @@ test_mmsg_name(const int send_fd, const int recv_fd)
 		perror_msg_and_skip("sendmmsg");
 
 	printf("sendmmsg(%d, [", send_fd);
-	for (i = 0; i < rc; ++i) {
+	for (i = 0; i < IOV_MAX1; ++i) {
 		if (i)
 			printf(", ");
+		if (i >= IOV_MAX
 #ifndef VERBOSE_MMSGHDR
-		if (i >= DEFAULT_STRLEN) {
+			|| i >= DEFAULT_STRLEN
+#endif
+		   ) {
 			printf("...");
 			break;
 		}
-#endif
 		printf("{msg_hdr={msg_name=NULL, msg_namelen=0"
 		       ", msg_iov=[{iov_base=\"%c\", iov_len=1}]"
-		       ", msg_iovlen=1, msg_controllen=0, msg_flags=0}"
-		       ", msg_len=1}", '0' + i % 10);
+		       ", msg_iovlen=1, msg_controllen=0, msg_flags=0}%s}",
+		       '0' + i % 10,
+		       i < rc ? ", msg_len=1" : "");
 	}
 	printf("], %u, MSG_DONTWAIT) = %d\n", IOV_MAX1, rc);