Fix SquashFS extraction when it contains directory symlinks

internal/pkg/build/sources/conveyorPacker_local.go

@@ -16,20 +16,14 @@ import (
 	"github.com/sylabs/singularity/v4/pkg/sylog"
 )
 
-// LocalConveyor only needs to hold the conveyor to have the needed data to pack
-type LocalConveyor struct {
-	src string
-}
-
 // LocalPacker ...
 type LocalPacker interface {
 	Pack(context.Context) (*types.Bundle, error)
 }
 
 // LocalConveyorPacker only needs to hold the conveyor to have the needed data to pack
 type LocalConveyorPacker struct {
-	LocalConveyor
-	LocalPacker
+	localPacker LocalPacker
 }
 
 // GetLocalPacker ...
@@ -104,13 +98,29 @@ func GetLocalPacker(ctx context.Context, src string, b *types.Bundle) (LocalPack
 
 // Get just stores the source.
 func (cp *LocalConveyorPacker) Get(ctx context.Context, b *types.Bundle) (err error) {
-	// insert base metadata before unpacking fs
+	src := filepath.Clean(b.Recipe.Header["from"])
+
+	cp.localPacker, err = GetLocalPacker(ctx, src, b)
+	return err
+}
+
+// Delegate to local packer then insert base env
+func (cp *LocalConveyorPacker) Pack(ctx context.Context) (*types.Bundle, error) {
+	sylog.Infof("Extracting local image...")
+	b, err := cp.localPacker.Pack(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("while unpacking local image: %v", err)
+	}
+
+	// insert base metadata AFTER unpacking fs to avoid conflicts with contained files/symlinks
 	if err = makeBaseEnv(b.RootfsPath); err != nil {
-		return fmt.Errorf("while inserting base environment: %v", err)
+		return nil, fmt.Errorf("while inserting base environment: %v", err)
 	}
 
-	cp.src = filepath.Clean(b.Recipe.Header["from"])
+	sylog.Infof("Inserting Singularity configuration...")
+	if err = makeBaseEnv(b.RootfsPath); err != nil {
+		return nil, fmt.Errorf("while inserting base environment: %v", err)
+	}
 
-	cp.LocalPacker, err = GetLocalPacker(ctx, cp.src, b)
-	return err
+	return b, nil
 }

internal/pkg/build/sources/conveyorPacker_local_test.go

@@ -0,0 +1,124 @@
+// Copyright (c) 2018-2024, Sylabs Inc. All rights reserved.
+// This software is licensed under a 3-clause BSD license. Please consult the
+// LICENSE.md file distributed with the sources of this project regarding your
+// rights to use or distribute this software.
+
+package sources_test
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/sylabs/singularity/v4/internal/pkg/build/sources"
+	"github.com/sylabs/singularity/v4/internal/pkg/image/packer"
+	"github.com/sylabs/singularity/v4/internal/pkg/util/fs"
+	"github.com/sylabs/singularity/v4/pkg/build/types"
+)
+
+func createArchiveFromDir(dir string, t *testing.T) *os.File {
+	mk, err := exec.LookPath("mksquashfs")
+	if err != nil {
+		t.SkipNow()
+	}
+	f, err := os.CreateTemp("", "archive-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	cmd := exec.Command(mk, dir, f.Name(), "-noappend", "-no-progress")
+	if err := cmd.Run(); err != nil {
+		t.Fatal(err)
+	}
+	return f
+}
+
+func makeDir(path string, t *testing.T) {
+	if err := os.MkdirAll(path, 0o755); err != nil {
+		t.Fatalf("while creating directory %s: %v", path, err)
+	}
+}
+
+func isExist(path string) bool {
+	result, _ := fs.PathExists(path)
+	return result
+}
+
+func TestSquashfsInput(t *testing.T) {
+	if s := packer.NewSquashfs(); !s.HasMksquashfs() {
+		t.Skip("mksquashfs not found, skipping")
+	}
+
+	dir, err := os.MkdirTemp(os.TempDir(), "test-localpacker-squashfs-")
+	if err != nil {
+		t.Fatalf("while creating tmpdir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	// Check that folder symlinks in the image to common folders (in base env) work
+	inputDir := filepath.Join(dir, "input")
+
+	makeDir(filepath.Join(dir, "var", "tmp"), t)
+	// Symlink /var/tmp -> /tmp in image
+	makeDir(filepath.Join(inputDir, "tmp"), t)
+	makeDir(filepath.Join(inputDir, "var"), t)
+	if err := os.Symlink("../tmp", filepath.Join(inputDir, "var", "tmp")); err != nil {
+		t.Fatalf("while creating symlink: %v", err)
+	}
+	// And a file we can check for
+	testfile := "conveyorPacker_local_test.go"
+	data, err := os.ReadFile(testfile)
+	if err != nil {
+		t.Fatalf("while reading test file: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(inputDir, testfile), data, 0o644); err != nil {
+		t.Fatalf("while writing test file: %v", err)
+	}
+	archive := createArchiveFromDir(inputDir, t)
+	defer os.Remove(archive.Name())
+
+	bundleTmp, _ := os.MkdirTemp(os.TempDir(), "bundle-tmp-")
+	b, err := types.NewBundle(dir, bundleTmp)
+	if err != nil {
+		t.Fatalf("while creating bundle: %v", err)
+	}
+	b.Recipe, _ = types.NewDefinitionFromURI("localimage://" + archive.Name())
+
+	lcp := &sources.LocalConveyorPacker{}
+	if err := lcp.Get(context.Background(), b); err != nil {
+		t.Fatalf("while getting local packer: %v", err)
+	}
+
+	_, err = lcp.Pack(context.Background())
+	if err != nil {
+		t.Fatalf("failed to Pack from %s: %v\n", archive.Name(), err)
+	}
+	rootfs := b.RootfsPath
+
+	// check if testfile was extracted
+	path := filepath.Join(rootfs, testfile)
+	if !isExist(path) {
+		t.Errorf("extraction failed, %s is missing", path)
+	}
+	// Check folders and symlinks
+	path = filepath.Join(rootfs, "tmp")
+	if !fs.IsDir(path) {
+		t.Errorf("extraction failed, %s is missing", path)
+	}
+	path = filepath.Join(rootfs, "var")
+	if !fs.IsDir(path) {
+		t.Errorf("extraction failed, %s is missing", path)
+	}
+	path = filepath.Join(rootfs, "var", "tmp")
+	if !isExist(path) {
+		t.Errorf("extraction failed, %s is missing", path)
+	} else if !fs.IsLink(path) {
+		t.Errorf("extraction failed, %s is not a symlink", path)
+	} else {
+		tgt, _ := os.Readlink(path)
+		if tgt != "../tmp" {
+			t.Errorf("extraction failed, %s wrongly points to %s", path, tgt)
+		}
+	}
+}