From 248859c64d583b4834c74581cb9f4c457372f0c5 Mon Sep 17 00:00:00 2001
From: Markus Lehtonen <markus.lehtonen@intel.com>
Date: Wed, 20 May 2020 11:31:09 +0300
Subject: [PATCH] source: parametrise host directory paths

Specify and handle system paths we use for discovery in a unified way.
---
 Dockerfile               |  2 +-
 source/config.go         | 39 +++++++++++++++++++++++++++++++++++++++
 source/kernel/kernel.go  |  2 +-
 source/kernel/selinux.go |  4 +++-
 source/system/system.go  |  2 +-
 5 files changed, 45 insertions(+), 4 deletions(-)
 create mode 100644 source/config.go

diff --git a/Dockerfile b/Dockerfile
index ac5107ba5..e7cd1e639 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -14,7 +14,7 @@ COPY . /go/node-feature-discovery
 ARG NFD_VERSION
 
 RUN go install \
-  -ldflags "-s -w -X sigs.k8s.io/node-feature-discovery/pkg/version.version=$NFD_VERSION" \
+  -ldflags "-s -w -X sigs.k8s.io/node-feature-discovery/pkg/version.version=$NFD_VERSION -X sigs.k8s.io/node-feature-discovery/source.pathPrefix=/host-" \
   ./cmd/*
 RUN install -D -m644 nfd-worker.conf.example /etc/kubernetes/node-feature-discovery/nfd-worker.conf
 
diff --git a/source/config.go b/source/config.go
new file mode 100644
index 000000000..1047c4314
--- /dev/null
+++ b/source/config.go
@@ -0,0 +1,39 @@
+/*
+Copyright 2020 The Kubernetes 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 source
+
+import (
+	"path/filepath"
+)
+
+var (
+	pathPrefix = "/"
+	// BootPath is where the /boot directory of the system to be inspected is located
+	BootDir = HostDir(pathPrefix + "boot")
+	// EtcPath is where the /etc directory of the system to be inspected is located
+	EtcDir = HostDir(pathPrefix + "etc")
+	// SysfsPath is where the /sys directory of the system to be inspected is located
+	SysfsDir = HostDir(pathPrefix + "sys")
+)
+
+// HostDir is a helper for handling host system directories
+type HostDir string
+
+// Path returns a full path to a file under HostDir
+func (d HostDir) Path(elem ...string) string {
+	return filepath.Join(append([]string{string(d)}, elem...)...)
+}
diff --git a/source/kernel/kernel.go b/source/kernel/kernel.go
index e2b9a34e0..37c301c77 100644
--- a/source/kernel/kernel.go
+++ b/source/kernel/kernel.go
@@ -167,7 +167,7 @@ func parseKconfig() (map[string]string, error) {
 			return nil, err
 		}
 		// Read kconfig
-		raw, err = ioutil.ReadFile("/host-boot/config-" + uname)
+		raw, err = ioutil.ReadFile(source.BootDir.Path("config-" + uname))
 		if err != nil {
 			return nil, err
 		}
diff --git a/source/kernel/selinux.go b/source/kernel/selinux.go
index bf34ebe7d..9a67d3b45 100644
--- a/source/kernel/selinux.go
+++ b/source/kernel/selinux.go
@@ -19,11 +19,13 @@ package kernel
 import (
 	"fmt"
 	"io/ioutil"
+
+	"sigs.k8s.io/node-feature-discovery/source"
 )
 
 // Detect if selinux has been enabled in the kernel
 func SelinuxEnabled() (bool, error) {
-	status, err := ioutil.ReadFile("/host-sys/fs/selinux/enforce")
+	status, err := ioutil.ReadFile(source.SysfsDir.Path("fs/selinux/enforce"))
 	if err != nil {
 		return false, fmt.Errorf("Failed to detect the status of selinux, please check if the system supports selinux and make sure /sys on the host is mounted into the container: %s", err.Error())
 	}
diff --git a/source/system/system.go b/source/system/system.go
index 750a5d824..dab3ce89e 100644
--- a/source/system/system.go
+++ b/source/system/system.go
@@ -66,7 +66,7 @@ func (s Source) Discover() (source.Features, error) {
 func parseOSRelease() (map[string]string, error) {
 	release := map[string]string{}
 
-	f, err := os.Open("/host-etc/os-release")
+	f, err := os.Open(source.EtcDir.Path("os-release"))
 	if err != nil {
 		return nil, err
 	}