test: add file descriptor exhaustion regression test

fix: use correct file flags for oci installer
Signed-off-by: anushkagupta200615-jpg <anushkagupta200615@gmail.com>

internal/plugin/installer/oci_installer.go

@@ -216,7 +216,7 @@ func extractFile(path string, mode int64, src io.Reader) error {
 		return err
 	}
 
-	outFile, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, os.FileMode(mode))
+	outFile, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.FileMode(mode))
 	if err != nil {
 		return err
 	}

internal/plugin/installer/oci_installer_unix_test.go

@@ -0,0 +1,79 @@
+//go:build !windows
+
+/*
+Copyright The Helm 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 installer
+
+import (
+	"archive/tar"
+	"bytes"
+	"fmt"
+	"syscall"
+	"testing"
+)
+
+func TestExtractTarFileDescriptorLeak(t *testing.T) {
+	var rLimit syscall.Rlimit
+	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+	if err != nil {
+		t.Skipf("Skipping test because Getrlimit failed: %v", err)
+	}
+
+	// Lower the limit to 50
+	oldLimit := rLimit
+	rLimit.Cur = 50
+	if rLimit.Max < 50 {
+		rLimit.Max = 50
+	}
+
+	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
+	if err != nil {
+		t.Skipf("Skipping test because Setrlimit failed: %v", err)
+	}
+	defer func() {
+		// Restore the original limit
+		if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &oldLimit); err != nil {
+			t.Logf("Failed to restore RLIMIT_NOFILE: %v", err)
+		}
+	}()
+
+	// Create a dummy tar archive with 100 files (more than the limit of 50)
+	var buf bytes.Buffer
+	tw := tar.NewWriter(&buf)
+	for i := 0; i < 100; i++ {
+		hdr := &tar.Header{
+			Name:     fmt.Sprintf("file_%d.txt", i),
+			Mode:     0600,
+			Size:     0,
+			Typeflag: tar.TypeReg,
+		}
+		if err := tw.WriteHeader(hdr); err != nil {
+			t.Fatalf("Failed to write header: %v", err)
+		}
+		if _, err := tw.Write([]byte{}); err != nil {
+			t.Fatalf("Failed to write content: %v", err)
+		}
+	}
+	if err := tw.Close(); err != nil {
+		t.Fatalf("Failed to close tar writer: %v", err)
+	}
+
+	// Extract the tar archive
+	tempDir := t.TempDir()
+	if err := extractTar(&buf, tempDir); err != nil {
+		t.Fatalf("extractTar failed, likely due to file descriptor exhaustion: %v", err)
+	}
+}