From 38d0d0d6b02d3fb290617fa7d803bcb1350cb4f1 Mon Sep 17 00:00:00 2001
From: Jan Fajerski <jfajersk@redhat.com>
Date: Fri, 16 Apr 2021 17:01:41 +0200
Subject: [PATCH] sysfs/net_class: filter devices by name

This adds regexp-based device filtering to the NetClass function in order to avoid
parsing devices files that are uninteresting.

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>
---
 sysfs/net_class.go      | 10 +++++++---
 sysfs/net_class_test.go | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/sysfs/net_class.go b/sysfs/net_class.go
index e6e223984..ab1e3356b 100644
--- a/sysfs/net_class.go
+++ b/sysfs/net_class.go
@@ -20,6 +20,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"regexp"
 
 	"github.com/prometheus/procfs/internal/util"
 )
@@ -63,7 +64,7 @@ type NetClassIface struct {
 type NetClass map[string]NetClassIface
 
 // NetClassDevices scans /sys/class/net for devices and returns them as a list of names.
-func (fs FS) NetClassDevices() ([]string, error) {
+func (fs FS) NetClassDevices(ignoredDevicesPattern *regexp.Regexp) ([]string, error) {
 	var res []string
 	path := fs.sys.Path(netclassPath)
 
@@ -76,6 +77,9 @@ func (fs FS) NetClassDevices() ([]string, error) {
 		if deviceDir.Mode().IsRegular() {
 			continue
 		}
+		if ignoredDevicesPattern.MatchString(deviceDir.Name()) {
+			continue
+		}
 		res = append(res, deviceDir.Name())
 	}
 
@@ -83,8 +87,8 @@ func (fs FS) NetClassDevices() ([]string, error) {
 }
 
 // NetClass returns info for all net interfaces (iface) read from /sys/class/net/<iface>.
-func (fs FS) NetClass() (NetClass, error) {
-	devices, err := fs.NetClassDevices()
+func (fs FS) NetClass(ignoredDevicesPattern *regexp.Regexp) (NetClass, error) {
+	devices, err := fs.NetClassDevices(ignoredDevicesPattern)
 	if err != nil {
 		return nil, err
 	}
diff --git a/sysfs/net_class_test.go b/sysfs/net_class_test.go
index bc219f340..ca6e38e79 100644
--- a/sysfs/net_class_test.go
+++ b/sysfs/net_class_test.go
@@ -17,6 +17,7 @@ package sysfs
 
 import (
 	"reflect"
+	"regexp"
 	"testing"
 )
 
@@ -26,7 +27,12 @@ func TestNewNetClassDevices(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	devices, err := fs.NetClassDevices()
+	re, err := regexp.Compile("^$")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	devices, err := fs.NetClassDevices(re)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -39,13 +45,39 @@ func TestNewNetClassDevices(t *testing.T) {
 	}
 }
 
+func TestNewNetClassDevicesFilter(t *testing.T) {
+	fs, err := NewFS(sysTestFixtures)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	re, err := regexp.Compile("eth")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	devices, err := fs.NetClassDevices(re)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(devices) != 0 {
+		t.Errorf("Unexpected number of devices, want %d, have %d", 0, len(devices))
+	}
+}
+
 func TestNetClass(t *testing.T) {
 	fs, err := NewFS(sysTestFixtures)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	nc, err := fs.NetClass()
+	re, err := regexp.Compile("^$")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	nc, err := fs.NetClass(re)
 	if err != nil {
 		t.Fatal(err)
 	}