[PATCH v2 08/11] VSOCK: add vsock_get_local_cid() test utility

[Stefano Garzarella <sgarzare@xxxxxxxxxx>]

This patch adds utility to get local CID, useful to
understand if we are in the host or guest.

Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
---
 tools/testing/vsock/util.c | 17 +++++++++++++++++
 tools/testing/vsock/util.h |  1 +
 2 files changed, 18 insertions(+)

diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
index d46a6e079b96..41b94495ecb1 100644
--- a/tools/testing/vsock/util.c
+++ b/tools/testing/vsock/util.c
@@ -13,6 +13,7 @@
 #include <stdlib.h>
 #include <signal.h>
 #include <unistd.h>
+#include <assert.h>
 
 #include "timeout.h"
 #include "control.h"
@@ -44,6 +45,22 @@ unsigned int parse_cid(const char *str)
 	return n;
 }
 
+/* Get the local CID */
+unsigned int vsock_get_local_cid(int fd)
+{
+	struct sockaddr_vm svm;
+	socklen_t svm_len = sizeof(svm);
+
+	if (getsockname(fd, (struct sockaddr *) &svm, &svm_len)) {
+		perror("getsockname");
+		exit(EXIT_FAILURE);
+	}
+
+	assert(svm.svm_family == AF_VSOCK);
+
+	return svm.svm_cid;
+}
+
 /* Connect to <cid, port> and return the file descriptor. */
 int vsock_stream_connect(unsigned int cid, unsigned int port)
 {
diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
index fe524d393d67..379e02ab59bb 100644
--- a/tools/testing/vsock/util.h
+++ b/tools/testing/vsock/util.h
@@ -36,6 +36,7 @@ unsigned int parse_cid(const char *str);
 int vsock_stream_connect(unsigned int cid, unsigned int port);
 int vsock_stream_accept(unsigned int cid, unsigned int port,
 			struct sockaddr_vm *clientaddrp);
+unsigned int vsock_get_local_cid(int fd);
 void send_byte(int fd, int expected_ret);
 void recv_byte(int fd, int expected_ret);
 void run_tests(const struct test_case *test_cases,
-- 
2.20.1