tests: test that path names longer than 108 bytes are rejected

These would either overflow the struct sockaddr_un, or
be truncated and leave a non-null-terminated string.

tests/socket-test.c

@@ -0,0 +1,82 @@
+/*
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/un.h>
+
+#include "wayland-client.h"
+#include "wayland-server.h"
+#include "test-runner.h"
+
+/* Paths longer than what the .sun_path array can contain must be rejected.
+   This is a hard limitation of assigning a name to AF_UNIX/AF_LOCAL sockets.
+   See `man 7 unix`. */
+
+static const struct sockaddr_un example_sockaddr_un;
+
+#define TOO_LONG (1 + sizeof example_sockaddr_un.sun_path)
+
+TEST(socket_path_overflow_client_connect)
+{
+	char path[TOO_LONG];
+	struct wl_display *d;
+	int ret;
+
+	/* Ensure the connection doesn't fail due to lack of
+	   XDG_RUNTIME_DIR. Don't use setenv(), as that allocates
+	   memory and creates a spurious memory leak failure. */
+	ret = putenv("XDG_RUNTIME_DIR=.");
+	assert(ret == 0);
+
+	memset(path, 'a', sizeof path);
+	path[sizeof path - 1] = '\0';
+
+	d = wl_display_connect(path);
+	assert(d == NULL);
+	assert(errno == ENAMETOOLONG);
+}
+
+TEST(socket_path_overflow_server_create)
+{
+	char path[TOO_LONG];
+	struct wl_display *d;
+	int ret;
+
+	/* Ensure the connection doesn't fail due to lack of
+	   XDG_RUNTIME_DIR. Don't use setenv(), as that allocates
+	   memory and creates a spurious memory leak failure. */
+	ret = putenv("XDG_RUNTIME_DIR=.");
+	assert(ret == 0);
+
+	memset(path, 'a', sizeof path);
+	path[sizeof path - 1] = '\0';
+
+	d = wl_display_create();
+	assert(d != NULL);
+
+	ret = wl_display_add_socket(d, path);
+	assert(ret < 0);
+	assert(errno == ENAMETOOLONG);
+
+	wl_display_destroy(d);
+}