Shorten long directory names with e2e pod logs

In a downstream test job, I've seen an e2e test failing to create a
directory for Pod logs when running an e2e test. Shorten them to 255
characters.

For example, consider this test: "[sig-storage] CSI Mock selinux on mount metrics and SELinuxWarningController SELinuxMount metrics [LinuxOnly] [Feature:SELinux] [Serial] error is not bumped on two Pods with a different policy RWX volume (MountOption + MountOption) [FeatureGate:SELinuxMountReadWriteOncePod] [Beta] [FeatureGate:SELinuxChangePolicy] [Beta] [FeatureGate:SELinuxMount] [Beta] [Feature:OffByDefault] [sig-storage, Feature:SELinux, Serial, FeatureGate:SELinuxMountReadWriteOncePod, Beta, FeatureGate:SELinuxChangePolicy, FeatureGate:SELinuxMount, Feature:OffByDefault, BetaOffByDefault]"

During execution, the test will create a directory
`error_is_not_bumped_on_two_Pods_with_Recursive_policy_and_a_different_context_on_RWX_volume_FeatureGate_SELinuxMountReadWriteOncePod_Beta_FeatureGate_SELinuxChangePolicy_Beta_FeatureGate_SELinuxMount_Beta_Feature_OffByDefault_`,
which has 226 characters and it's close to the limit (256).

Author: jsafrane

test/e2e/storage/utils/file.go

@@ -0,0 +1,41 @@
+/*
+Copyright 2025 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 utils
+
+import (
+	"fmt"
+	"hash/crc32"
+)
+
+// The max length for ntfs, ext4, xfs and btrfs.
+const maxFileNameLength = 255
+
+// Shorten a file name to size allowed by the most common filesystems.
+// If the filename is too long, cut it + add a short hash (crc32) that makes it unique.
+// Note that the input should be a single file / directory name, not a path
+// composed of several directories.
+func ShortenFileName(filename string) string {
+	if len(filename) <= maxFileNameLength {
+		return filename
+	}
+
+	hash := crc32.ChecksumIEEE([]byte(filename))
+	hashString := fmt.Sprintf("%x", hash)
+	hashLen := len(hashString)
+
+	return fmt.Sprintf("%s-%s", filename[:maxFileNameLength-1-hashLen], hashString)
+}

test/e2e/storage/utils/file_test.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2025 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 utils
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestShortenFileName(t *testing.T) {
+	tests := []struct {
+		name     string
+		filename string
+		expected string
+	}{
+		{
+			name:     "Shorter than max length",
+			filename: "short file name",
+			expected: "short file name",
+		},
+		{
+			name:     "Longer than max length, truncated",
+			filename: "a very long string that has exactly 256 characters a very long string that has exactly 256 characters a very long string that has exactly 256 characters a very long string that has exactly 256 characters a very long string that has exactly 256 characters..",
+			expected: "a very long string that has exactly 256 characters a very long string that has exactly 256 characters a very long string that has exactly 256 characters a very long string that has exactly 256 characters a very long string that has exactly 256 ch-ad31f675",
+		},
+		{
+			name:     "Exactly max length, not truncated",
+			filename: "a very long string that has exactly 255 characters a very long string that has exactly 255 characters a very long string that has exactly 255 characters a very long string that has exactly 255 characters a very long string that has exactly 255 characters.",
+			expected: "a very long string that has exactly 255 characters a very long string that has exactly 255 characters a very long string that has exactly 255 characters a very long string that has exactly 255 characters a very long string that has exactly 255 characters.",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := ShortenFileName(tt.filename)
+			assert.Equal(t, tt.expected, result)
+			assert.LessOrEqual(t, len(result), maxFileNameLength)
+		})
+	}
+}

test/e2e/storage/utils/pod.go

@@ -22,8 +22,8 @@ import (
 	"io"
 	"os"
 	"path"
+	"path/filepath"
 	"regexp"
-	"strings"
 
 	"github.com/onsi/ginkgo/v2"
 	"github.com/onsi/gomega"
@@ -68,6 +68,12 @@ func StartPodLogs(ctx context.Context, f *framework.Framework, driverNamespace *
 				testName = append(testName, reg.ReplaceAllString(test.LeafNodeText, "_"))
 			}
 		}
+
+		// Make sure each directory name is short enough for Linux + Windows
+		for i, testNameComponent := range testName {
+			testName[i] = ShortenFileName(testNameComponent)
+		}
+
 		// We end the prefix with a slash to ensure that all logs
 		// end up in a directory named after the current test.
 		//
@@ -76,7 +82,7 @@ func StartPodLogs(ctx context.Context, f *framework.Framework, driverNamespace *
 		// keeps each directory name smaller (the full test
 		// name at one point exceeded 256 characters, which was
 		// too much for some filesystems).
-		logDir := framework.TestContext.ReportDir + "/" + strings.Join(testName, "/")
+		logDir := filepath.Join(framework.TestContext.ReportDir, filepath.Join(testName...))
 		to.LogPathPrefix = logDir + "/"
 
 		err := os.MkdirAll(logDir, 0755)