test(initrd): assert contents of CPIO archive (#953)

Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>
Approved-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>

initrd/directory_test.go

@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2023, Unikraft GmbH and The KraftKit Authors.
+// Licensed under the BSD-3-Clause License (the "License").
+// You may not use this file except in compliance with the License.
+package initrd_test
+
+import (
+	"context"
+	"io"
+	"os"
+	"testing"
+
+	"github.com/cavaliergopher/cpio"
+
+	"kraftkit.sh/initrd"
+)
+
+func TestNewFromDirectory(t *testing.T) {
+	const rootDir = "testdata/rootfs"
+
+	ctx := context.Background()
+
+	ird, err := initrd.NewFromDirectory(ctx, rootDir)
+	if err != nil {
+		t.Fatal("NewFromDirectory:", err)
+	}
+
+	irdPath, err := ird.Build(ctx)
+	if err != nil {
+		t.Fatal("Build:", err)
+	}
+	t.Cleanup(func() {
+		if err := os.Remove(irdPath); err != nil {
+			t.Fatal("Failed to remove initrd file:", err)
+		}
+	})
+
+	irdFiles := ird.Files()
+
+	const expectFiles = 4 // only regular and symlink files are indexed
+	if gotFiles := len(irdFiles); gotFiles != expectFiles {
+		t.Errorf("Expected %d files in InitrdConfig, got %d: %v", expectFiles, gotFiles, irdFiles)
+	}
+
+	r := cpio.NewReader(openFile(t, irdPath))
+
+	expectHeaders := map[string]cpio.Header{
+		"/entrypoint.sh": {
+			Mode: cpio.TypeReg,
+			Size: 25,
+		},
+		"/etc": {
+			Mode: cpio.TypeDir,
+		},
+		"/etc/app.conf": {
+			Mode: cpio.TypeReg,
+			Size: 16,
+		},
+		"/lib": {
+			Mode: cpio.TypeDir,
+		},
+		"/lib/libtest.so.1": {
+			Mode:     cpio.TypeSymlink,
+			Linkname: "libtest.so.1.0.0",
+		},
+		"/lib/libtest.so.1.0.0": {
+			Mode: cpio.TypeReg,
+			Size: 9,
+		},
+	}
+
+	for {
+		hdr, err := r.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			t.Fatal("Failed to read next cpio header:", err)
+		}
+
+		expectHdr, ok := expectHeaders[hdr.Name]
+		if !ok {
+			t.Error("Encountered unexpected file in cpio archive:", hdr.Name)
+			continue
+		}
+
+		if gotMode := hdr.Mode & cpio.ModeType; gotMode != expectHdr.Mode {
+			t.Errorf("file [%s]: got mode %s, expected %s", hdr.Name, gotMode, expectHdr.Mode)
+		}
+		if hdr.Linkname != expectHdr.Linkname {
+			t.Errorf("file [%s]: got linkname %q, expected %q", hdr.Name, hdr.Linkname, expectHdr.Linkname)
+		}
+		if hdr.Size != expectHdr.Size {
+			t.Errorf("file [%s]: got size %d, expected %d", hdr.Name, hdr.Size, expectHdr.Size)
+		}
+	}
+}
+
+// openFile opens a file for reading, and closes it when the test completes.
+func openFile(t *testing.T, path string) io.Reader {
+	t.Helper()
+
+	f, err := os.Open(path)
+	if err != nil {
+		t.Fatal("Failed to open file for reading:", err)
+	}
+	t.Cleanup(func() {
+		if err := f.Close(); err != nil {
+			t.Error("Failed to close file:", err)
+		}
+	})
+
+	return f
+}

initrd/testdata/rootfs/entrypoint.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env sh
+exit 0

initrd/testdata/rootfs/etc/app.conf

@@ -0,0 +1,2 @@
+[app]
+key=value

initrd/testdata/rootfs/lib/libtest.so.1

@@ -0,0 +1 @@
+libtest.so.1.0.0

initrd/testdata/rootfs/lib/libtest.so.1.0.0

@@ -0,0 +1 @@
+#fakelib