mark platforms as Linux-only

Related to #1270.

PiperOrigin-RevId: 411648212

runsc/boot/platforms/BUILD

@@ -1,15 +1,32 @@
-load("//tools:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library", "select_system")
 
 package(licenses = ["notice"])
 
+# Don't rewrite the deps attribute of :platforms.
+# @unused
+glaze_ignore = [
+    "platforms.go",
+    "platforms_darwin.go",
+]
+
 go_library(
     name = "platforms",
-    srcs = ["platforms.go"],
+    srcs = [
+        "platforms.go",
+        "platforms_darwin.go",
+    ],
+    # Nothing needs to be stateified, and stateify has trouble when select is
+    # used to choose deps.
+    stateify = False,
     visibility = [
         "//runsc:__subpackages__",
     ],
-    deps = [
-        "//pkg/sentry/platform/kvm",
-        "//pkg/sentry/platform/ptrace",
-    ],
+    deps = select_system(
+        darwin = [],
+        linux = [
+            "//pkg/sentry/platform/kvm",
+            "//pkg/sentry/platform/ptrace",
+            "//runsc/boot/platforms/nonstandard",
+        ],
+    ),
 )

runsc/boot/platforms/nonstandard/BUILD

@@ -0,0 +1,11 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "nonstandard",
+    srcs = ["nonstandard.go"],
+    visibility = [
+        "//runsc:__subpackages__",
+    ],
+)

runsc/boot/platforms/nonstandard/nonstandard.go

@@ -0,0 +1,16 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package nonstandard provides a place for nonstandard platforms.
+package nonstandard

runsc/boot/platforms/platforms.go

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build linux
+// +build linux
+
 // Package platforms imports all available platform packages.
 package platforms
 
@@ -19,6 +22,7 @@ import (
 	// Import platforms that runsc might use.
 	_ "gvisor.dev/gvisor/pkg/sentry/platform/kvm"
 	_ "gvisor.dev/gvisor/pkg/sentry/platform/ptrace"
+	_ "gvisor.dev/gvisor/runsc/boot/platforms/nonstandard"
 )
 
 const (

runsc/boot/platforms/platforms_darwin.go

@@ -0,0 +1,20 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build darwin
+// +build darwin
+
+package platforms
+
+// This file makes the platforms package buildable on Darwin.

tools/bazeldefs/defs.bzl

@@ -27,8 +27,11 @@ def select_arch(amd64 = "amd64", arm64 = "arm64", default = None, **kwargs):
         values["//conditions:default"] = default
     return select(values, **kwargs)
 
-def select_system(linux = ["__linux__"], **kwargs):
-    return linux  # Only Linux supported.
+def select_system(linux = ["__linux__"], darwin = [], **kwargs):
+    return select({
+        "@bazel_tools//src/conditions:darwin": darwin,
+        "//conditions:default": linux,
+    })
 
 def default_installer():
     return None

tools/bazeldefs/go.bzl

@@ -156,4 +156,7 @@ def select_goarch():
     return select_arch(amd64 = "amd64", arm64 = "arm64")
 
 def select_goos():
-    return select_system(linux = "linux")
+    return select_system(
+        linux = "linux",
+        darwin = "darwin",
+    )