From 7b6ecccf385f16a7e139faad522566300e972def Mon Sep 17 00:00:00 2001
From: Ayoub Mrini <ayoubmrini424@gmail.com>
Date: Tue, 5 Mar 2024 14:45:50 +0100
Subject: [PATCH] chore: class_fibrechannel: support optional attributes (#607)

Signed-off-by: machine424 <ayoubmrini424@gmail.com>
---
 sysfs/class_fibrechannel.go      |  5 ++
 sysfs/class_fibrechannel_test.go | 20 ++++++++
 testdata/fixtures.ttar           | 81 ++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+)

diff --git a/sysfs/class_fibrechannel.go b/sysfs/class_fibrechannel.go
index d7e62784b..ded07a881 100644
--- a/sysfs/class_fibrechannel.go
+++ b/sysfs/class_fibrechannel.go
@@ -93,6 +93,11 @@ func (fs FS) parseFibreChannelHost(name string) (*FibreChannelHost, error) {
 		name := filepath.Join(path, f)
 		value, err := util.SysReadFile(name)
 		if err != nil {
+			// drivers can choose not to expose some attributes to sysfs.
+			// See: https://github.com/prometheus/node_exporter/issues/2919.
+			if os.IsNotExist(err) {
+				continue
+			}
 			return nil, fmt.Errorf("failed to read file %q: %w", name, err)
 		}
 
diff --git a/sysfs/class_fibrechannel_test.go b/sysfs/class_fibrechannel_test.go
index 7181795c9..55f728c2e 100644
--- a/sysfs/class_fibrechannel_test.go
+++ b/sysfs/class_fibrechannel_test.go
@@ -64,6 +64,26 @@ func TestFibreChannelClass(t *testing.T) {
 				FCPPacketAborts:       0x13,
 			},
 		},
+		"host1": FibreChannelHost{
+			Name:      "host1",
+			PortState: "Online",
+			Counters: FibreChannelCounters{
+				DumpedFrames:          0,
+				ErrorFrames:           ^uint64(0),
+				InvalidCRCCount:       0x20,
+				RXFrames:              0x30,
+				RXWords:               0x40,
+				TXFrames:              0x50,
+				TXWords:               0x60,
+				SecondsSinceLastReset: 0x70,
+				InvalidTXWordCount:    0x80,
+				LinkFailureCount:      0x90,
+				LossOfSyncCount:       0x100,
+				LossOfSignalCount:     0x110,
+				NosCount:              0x120,
+				FCPPacketAborts:       0x130,
+			},
+		},
 	}
 
 	if diff := cmp.Diff(want, got); diff != "" {
diff --git a/testdata/fixtures.ttar b/testdata/fixtures.ttar
index 3fdfc5b45..c5d9a6dc7 100644
--- a/testdata/fixtures.ttar
+++ b/testdata/fixtures.ttar
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