From: Masatake YAMATO <yamato@redhat.com>
Date: Wed, 15 Oct 2014 13:11:43 +0000 (+0900)
Subject: Add a function for dumping iovec in msghdr used in sendmsg and recvmsg
X-Git-Tag: v4.10~376
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=02f9f6b386741a52f58e1b31ad4e7fff60781ef8;p=strace

Add a function for dumping iovec in msghdr used in sendmsg and recvmsg

Here is an example session:

    $ ./strace -e write=all ip link change dev enp0s25 mtu 1501 > /dev/null
    sendmsg(3, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"(...
     * 40 bytes in buffer 0
     | 00000  28 00 00 00 10 00 05 00  d0 d9 aa 53 00 00 00 00  (..........S.... |
     | 00010  00 00 00 00 02 00 00 00  00 00 00 00 00 00 00 00  ................ |
     | 00020  08 00 04 00 dd 05 00 00                           ........         |
    ...

    $ ./strace -e read=all ip link show > /dev/null
    recvmsg(3, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"...
     * 8192 bytes in buffer 0
     | 00000  34 00 00 00 02 00 00 00  00 00 00 00 ff 23 00 00  4............#.. |
     | 00010  ff ff ff ff 20 00 00 00  10 00 05 00 00 00 00 00  .... ........... |
    ...

* defs.h (dumpiov_in_msghdr): New prototype.
* net.c (extractmsghdr): New function derived from printmsghdr.
(printmsghdr): Use extractmsghdr.
(dumpiov_in_msghdr): New function.
* syscall.c (dumpio) [HAVE_SENDMSG]: Call dumpiov_in_msghdr for recvmsg
and sendmsg syscalls.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---

diff --git a/defs.h b/defs.h
index 5bfeb6b4..d41af968 100644
--- a/defs.h
+++ b/defs.h
@@ -673,6 +673,7 @@ extern int printargs_ld(struct tcb *);
 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(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 46c491f8..a0e90a8f 100644
--- a/net.c
+++ b/net.c
@@ -392,33 +392,47 @@ struct mmsghdr32 {
 	uint32_t /* unsigned */ msg_len;
 };
 
-static void
-printmsghdr(struct tcb *tcp, long addr, unsigned long data_size)
+static bool
+extractmsghdr(struct tcb *tcp, long addr, struct msghdr *msg)
 {
-	struct msghdr msg;
-
 #if SUPPORTED_PERSONALITIES > 1 && SIZEOF_LONG > 4
 	if (current_wordsize == 4) {
 		struct msghdr32 msg32;
 
-		if (umove(tcp, addr, &msg32) < 0) {
-			tprintf("%#lx", addr);
-			return;
-		}
-		msg.msg_name       = (void*)(long)msg32.msg_name;
-		msg.msg_namelen    =              msg32.msg_namelen;
-		msg.msg_iov        = (void*)(long)msg32.msg_iov;
-		msg.msg_iovlen     =              msg32.msg_iovlen;
-		msg.msg_control    = (void*)(long)msg32.msg_control;
-		msg.msg_controllen =              msg32.msg_controllen;
-		msg.msg_flags      =              msg32.msg_flags;
+		if (umove(tcp, addr, &msg32) < 0)
+			return false;
+		msg->msg_name       = (void*)(long)msg32.msg_name;
+		msg->msg_namelen    =              msg32.msg_namelen;
+		msg->msg_iov        = (void*)(long)msg32.msg_iov;
+		msg->msg_iovlen     =              msg32.msg_iovlen;
+		msg->msg_control    = (void*)(long)msg32.msg_control;
+		msg->msg_controllen =              msg32.msg_controllen;
+		msg->msg_flags      =              msg32.msg_flags;
 	} else
 #endif
-	if (umove(tcp, addr, &msg) < 0) {
+	if (umove(tcp, addr, msg) < 0)
+		return false;
+	return true;
+}
+
+static void
+printmsghdr(struct tcb *tcp, long addr, unsigned long data_size)
+{
+	struct msghdr msg;
+
+	if (extractmsghdr(tcp, addr, &msg))
+		do_msghdr(tcp, &msg, data_size);
+	else
 		tprintf("%#lx", addr);
-		return;
-	}
-	do_msghdr(tcp, &msg, data_size);
+}
+
+void
+dumpiov_in_msghdr(struct tcb *tcp, long addr)
+{
+	struct msghdr msg;
+
+	if (extractmsghdr(tcp, addr, &msg))
+		dumpiov(tcp, msg.msg_iovlen, (long)msg.msg_iov);
 }
 
 static void
diff --git a/syscall.c b/syscall.c
index 135221bb..fa761a95 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2497,6 +2497,10 @@ dumpio(struct tcb *tcp)
 			dumpstr(tcp, tcp->u_arg[1], tcp->u_rval);
 		else if (func == sys_readv)
 			dumpiov(tcp, tcp->u_arg[2], tcp->u_arg[1]);
+#if HAVE_SENDMSG
+		else if (func == sys_recvmsg)
+			dumpiov_in_msghdr(tcp, tcp->u_arg[1]);
+#endif
 		return;
 	}
 	if (qual_flags[tcp->u_arg[0]] & QUAL_WRITE) {
@@ -2507,6 +2511,10 @@ dumpio(struct tcb *tcp)
 			dumpstr(tcp, tcp->u_arg[1], tcp->u_arg[2]);
 		else if (func == sys_writev)
 			dumpiov(tcp, tcp->u_arg[2], tcp->u_arg[1]);
+#if HAVE_SENDMSG
+		else if (func == sys_sendmsg)
+			dumpiov_in_msghdr(tcp, tcp->u_arg[1]);
+#endif
 		return;
 	}
 }