Cleanup host UDS support

This change fixes several issues with the fsgofer host UDS support. Notably, it
adds support for SOCK_SEQPACKET and SOCK_DGRAM sockets [1]. It also fixes
unsafe use of unet.Socket, which could cause a panic if Socket.FD is called
when err != nil, and calls to Socket.FD with nothing to prevent the garbage
collector from destroying and closing the socket.

A set of tests is added to exercise host UDS access. This required extracting
most of the syscall test runner into a library that can be used by custom
tests.

Updates #235
Updates #1003

[1] N.B. SOCK_DGRAM sockets are likely not particularly useful, as a server can
only reply to a client that binds first. We don't allow bind, so these are
unlikely to be used.

PiperOrigin-RevId: 275558502

1 files changed, 17 insertions, 0 deletions

diff --git a/test/uds/BUILD b/test/uds/BUILD
new file mode 100644
index 000000000..a3843e699
--- /dev/null
+++ b/test/uds/BUILD
@@ -0,0 +1,17 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+package(
+    default_visibility = ["//:sandbox"],
+    licenses = ["notice"],
+)
+
+go_library(
+    name = "uds",
+    testonly = 1,
+    srcs = ["uds.go"],
+    importpath = "gvisor.dev/gvisor/test/uds",
+    deps = [
+        "//pkg/log",
+        "//pkg/unet",
+    ],
+)