From 35eb03fdf74b67c558b2eef11a041e99a2ae5dd9 Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Mon, 11 Jan 2016 00:17:36 +0000
Subject: [PATCH] mmsg.test: check memory access by sendmmsg and recvmmsg
 decoders

* tests/tests.h (tail_memdup): New prototype.
* tests/tail_alloc.c (tail_memdup): New function.
* tests/mmsg.c (main): Place all objects passed to sendmmsg and recvmmsg
at the end of memory pages followed by inaccessible pages.
---
 tests/mmsg.c       | 52 ++++++++++++++++++++--------------------------
 tests/tail_alloc.c |  8 +++++++
 tests/tests.h      |  3 +++
 3 files changed, 34 insertions(+), 29 deletions(-)

diff --git a/tests/mmsg.c b/tests/mmsg.c
index 4dae0286..630ad1dd 100644
--- a/tests/mmsg.c
+++ b/tests/mmsg.c
@@ -33,7 +33,6 @@
 
 # include <assert.h>
 # include <errno.h>
-# include <fcntl.h>
 # include <unistd.h>
 # include <sys/socket.h>
 
@@ -81,64 +80,59 @@ int
 main(void)
 {
 	const int R = 0, W = 1;
-	int fd;
 	int sv[2];
-	char one[] = "one";
-	char two[] = "two";
-	char three[] = "three";
+
+	(void) close(0);
+	(void) close(1);
+	if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sv))
+		perror_msg_and_skip("socketpair");
+	assert(R == sv[0]);
+	assert(W == sv[1]);
+
+	static const char const one[] = "one";
+	static const char const two[] = "two";
+	static const char const three[] = "three";
+	void *copy_one = tail_memdup(one, sizeof(one) - 1);
+	void *copy_two = tail_memdup(two, sizeof(two) - 1);
+	void *copy_three = tail_memdup(three, sizeof(three) - 1);
 
 	struct iovec iov[] = {
 		{
-			.iov_base = one,
+			.iov_base = copy_one,
 			.iov_len = sizeof(one) - 1
 		}, {
-			.iov_base = two,
+			.iov_base = copy_two,
 			.iov_len = sizeof(two) - 1
 		}, {
-			.iov_base = three,
+			.iov_base = copy_three,
 			.iov_len = sizeof(three) - 1
 		}
 	};
+	struct iovec *copy_iov = tail_memdup(iov, sizeof(iov));
 
 	struct mmsghdr mmh[] = {
 		{
 			.msg_hdr = {
-				.msg_iov = iov + 0,
+				.msg_iov = copy_iov + 0,
 				.msg_iovlen = 2,
 			}
 		}, {
 			.msg_hdr = {
-				.msg_iov = iov + 2,
+				.msg_iov = copy_iov + 2,
 				.msg_iovlen = 1,
 			}
 		}
 	};
+	void *copy_mmh = tail_memdup(mmh, sizeof(mmh));
 # define n_mmh (sizeof(mmh)/sizeof(mmh[0]))
 
-	/*
-	 * Following open/dup2/close calls make the output of strace
-	 * more predictable, so we can just compare the output and
-	 * expected output (mmsg.expected) for testing purposes.
-	 */
-	while ((fd = open("/dev/null", O_RDWR)) < 3)
-		assert(fd >= 0);
-	(void) close(3);
-
-	if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sv))
-		perror_msg_and_skip("socketpair");
-
-	assert(dup2(sv[W], W) == W);
-	assert(close(sv[W]) == 0);
-	assert(dup2(sv[R], R) == R);
-	assert(close(sv[R]) == 0);
-
-	int r = send_mmsg(W, mmh, n_mmh, MSG_DONTROUTE | MSG_NOSIGNAL);
+	int r = send_mmsg(W, copy_mmh, n_mmh, MSG_DONTROUTE | MSG_NOSIGNAL);
 	if (r < 0 && errno == ENOSYS)
 		perror_msg_and_skip("sendmmsg");
 	assert((size_t)r == n_mmh);
 	assert(close(W) == 0);
 
-	assert(recv_mmsg(R, mmh, n_mmh, MSG_DONTWAIT, NULL) == n_mmh);
+	assert(recv_mmsg(R, copy_mmh, n_mmh, MSG_DONTWAIT, NULL) == n_mmh);
 	assert(close(R) == 0);
 
 	return 0;
diff --git a/tests/tail_alloc.c b/tests/tail_alloc.c
index 2b8b14ed..82e1aacb 100644
--- a/tests/tail_alloc.c
+++ b/tests/tail_alloc.c
@@ -50,3 +50,11 @@ tail_alloc(const size_t size)
 	memset(start_work, 0xff, len);
 	return tail_guard - size;
 }
+
+void *
+tail_memdup(const void *p, const size_t size)
+{
+	void *dest = tail_alloc(size);
+	memcpy(dest, p, size);
+	return dest;
+}
diff --git a/tests/tests.h b/tests/tests.h
index 91fa24ef..36ddea31 100644
--- a/tests/tests.h
+++ b/tests/tests.h
@@ -55,6 +55,9 @@ void perror_msg_and_skip(const char *, ...)
  */
 void *tail_alloc(const size_t)
 	ATTRIBUTE_MALLOC ATTRIBUTE_ALLOC_SIZE((1));
+/* Allocate memory using tail_alloc, then memcpy. */
+void *tail_memdup(const void *, const size_t)
+	ATTRIBUTE_MALLOC ATTRIBUTE_ALLOC_SIZE((2));
 
 # define SKIP_MAIN_UNDEFINED(arg) \
 	int main(void) { error_msg_and_skip("undefined: %s", arg); }
-- 
2.40.0