Refactor path manipulation around named types

Author: zombiezen

aptblob.go

@@ -35,7 +35,7 @@ import (
 	"zombiezen.com/go/aptblob/internal/deb"
 )
 
-func cmdInit(ctx context.Context, bucket *blob.Bucket, dist string, keyID string) error {
+func cmdInit(ctx context.Context, bucket *blob.Bucket, dist distribution, keyID string) error {
 	fmt.Fprintln(os.Stderr, "aptblob: reading Release from stdin...")
 	newRelease, err := deb.ParseReleaseIndex(os.Stdin)
 	if err != nil {
@@ -58,8 +58,8 @@ func cmdInit(ctx context.Context, bucket *blob.Bucket, dist string, keyID string
 	return nil
 }
 
-func downloadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist string) (deb.Paragraph, error) {
-	key := releaseIndexPath(dist)
+func downloadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist distribution) (deb.Paragraph, error) {
+	key := dist.indexPath()
 	blob, err := bucket.NewReader(ctx, key, nil)
 	if err != nil {
 		if gcerrors.Code(err) == gcerrors.NotFound {
@@ -77,7 +77,7 @@ func downloadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist string)
 
 const componentName = "main"
 
-func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID string, debPath string) error {
+func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist distribution, keyID string, debPath string) error {
 	// Extract package metadata.
 	debFile, err := os.Open(debPath)
 	if err != nil {
@@ -96,11 +96,12 @@ func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID stri
 		}
 	}
 	newPackage := p.Paragraph()
+	promotePackageField(newPackage)
 	arch := newPackage.Get("Architecture")
 	if arch == "" {
 		return fmt.Errorf("%s: no Architecture", debPath)
 	}
-	poolPath := "pool/" + filepath.Base(debPath)
+	poolPath := poolPath(filepath.Base(debPath))
 	packageHashes, err := upload(ctx, bucket, poolPath, "application/vnd.debian.binary-package", "immutable", debFile)
 	if err != nil {
 		return err
@@ -113,24 +114,25 @@ func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID stri
 
 	// List existing packages.
 	var packages []deb.Paragraph
-	if packagesReader, err := bucket.NewReader(ctx, binaryPackagesIndexPath(dist, componentName, arch), nil); err == nil {
+	comp := component{dist: dist, name: componentName}
+	if packagesReader, err := bucket.NewReader(ctx, comp.binaryIndexPath(arch), nil); err == nil {
 		p := deb.NewParser(packagesReader)
 		p.Fields = deb.ControlFields
 		for p.Next() {
 			packages = append(packages, p.Paragraph())
 		}
 		packagesReader.Close()
 		if err := p.Err(); err != nil {
-			return fmt.Errorf("%s: %w", binaryPackagesIndexPath(dist, componentName, arch), err)
+			return fmt.Errorf("%s: %w", comp.binaryIndexPath(arch), err)
 		}
 	} else if gcerrors.Code(err) != gcerrors.NotFound {
 		return err
 	}
 
 	// Append package to index.
 	packages = append(packages, newPackage)
-	packageIndexHashes, packageIndexGzipHashes, err := uploadPackageIndex(
-		ctx, bucket, dist, componentName, arch, packages)
+	packageIndexHashes, packageIndexGzipHashes, err :=
+		uploadPackageIndex(ctx, bucket, comp, arch, packages)
 	if err != nil {
 		return err
 	}
@@ -140,14 +142,8 @@ func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID stri
 	if err != nil {
 		return err
 	}
-	packagesDistPath := strings.TrimPrefix(
-		binaryPackagesIndexPath(dist, componentName, arch),
-		distDirPath(dist)+"/",
-	)
-	packagesGzipDistPath := strings.TrimPrefix(
-		binaryPackagesGzipIndexPath(dist, componentName, arch),
-		distDirPath(dist)+"/",
-	)
+	packagesDistPath := strings.TrimPrefix(comp.binaryIndexPath(arch), dist.dir()+"/")
+	packagesGzipDistPath := strings.TrimPrefix(comp.binaryIndexGzipPath(arch), dist.dir()+"/")
 	err = updateSignature(&release, "MD5Sum",
 		deb.IndexSignature{
 			Filename: packagesDistPath,
@@ -161,7 +157,7 @@ func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID stri
 		},
 	)
 	if err != nil {
-		return fmt.Errorf("%s: %w", releaseIndexPath(dist), err)
+		return fmt.Errorf("%s: %w", dist.indexPath(), err)
 	}
 	err = updateSignature(&release, "SHA1",
 		deb.IndexSignature{
@@ -176,7 +172,7 @@ func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID stri
 		},
 	)
 	if err != nil {
-		return fmt.Errorf("%s: %w", releaseIndexPath(dist), err)
+		return fmt.Errorf("%s: %w", dist.indexPath(), err)
 	}
 	err = updateSignature(&release, "SHA256",
 		deb.IndexSignature{
@@ -191,7 +187,7 @@ func cmdUpload(ctx context.Context, bucket *blob.Bucket, dist string, keyID stri
 		},
 	)
 	if err != nil {
-		return fmt.Errorf("%s: %w", releaseIndexPath(dist), err)
+		return fmt.Errorf("%s: %w", dist.indexPath(), err)
 	}
 	if err := uploadReleaseIndex(ctx, bucket, dist, release, keyID); err != nil {
 		return err
@@ -238,6 +234,20 @@ func updateSignature(para *deb.Paragraph, key string, newSigs ...deb.IndexSignat
 	return nil
 }
 
+// promotePackageField ensures the Package field is the first in the paragraph.
+// It modifies the paragraph in-place.
+//
+// This is necessary for Packages and Sources paragraphs to be spec-compliant.
+func promotePackageField(para deb.Paragraph) {
+	for i, f := range para {
+		if f.Name == "Package" {
+			copy(para[1:], para[:i])
+			para[0] = f
+			return
+		}
+	}
+}
+
 func main() {
 	rootCmd := &cobra.Command{
 		Use:           "aptblob",
@@ -265,7 +275,7 @@ func main() {
 			if err != nil {
 				return err
 			}
-			return cmdInit(cmd.Context(), bucket, args[1], *keyID)
+			return cmdInit(cmd.Context(), bucket, distribution(args[1]), *keyID)
 		},
 	})
 	rootCmd.AddCommand(&cobra.Command{
@@ -280,7 +290,7 @@ func main() {
 			if err != nil {
 				return err
 			}
-			return cmdUpload(cmd.Context(), bucket, args[1], *keyID, args[2])
+			return cmdUpload(cmd.Context(), bucket, distribution(args[1]), *keyID, args[2])
 		},
 	})
 	if err := rootCmd.Execute(); err != nil {

upload.go

@@ -36,34 +36,45 @@ func poolPath(name string) string {
 	return "pool/" + name
 }
 
-func distDirPath(dist string) string {
-	return "dists/" + dist
+type distribution string
+
+func (dist distribution) dir() string {
+	return "dists/" + string(dist)
+}
+
+func (dist distribution) indexPath() string {
+	return dist.dir() + "/Release"
+}
+
+func (dist distribution) signedIndexPath() string {
+	return dist.dir() + "/InRelease"
 }
 
-func releaseIndexPath(dist string) string {
-	return distDirPath(dist) + "/Release"
+func (dist distribution) indexSignaturePath() string {
+	return dist.dir() + "/Release.gpg"
 }
 
-func signedReleaseIndexPath(dist string) string {
-	return distDirPath(dist) + "/InRelease"
+type component struct {
+	dist distribution
+	name string
 }
 
-func releaseSignatureIndexPath(dist string) string {
-	return distDirPath(dist) + "/Release.gpg"
+func (comp component) dir() string {
+	return comp.dist.dir() + "/" + comp.name
 }
 
-func binaryPackagesIndexPath(dist, component, arch string) string {
-	return distDirPath(dist) + "/" + component + "/binary-" + arch + "/Packages"
+func (comp component) binaryIndexPath(arch string) string {
+	return comp.dir() + "/binary-" + arch + "/Packages"
 }
 
-func binaryPackagesGzipIndexPath(dist, component, arch string) string {
-	return distDirPath(dist) + "/" + component + "/binary-" + arch + "/Packages.gz"
+func (comp component) binaryIndexGzipPath(arch string) string {
+	return comp.binaryIndexPath(arch) + ".gz"
 }
 
-func uploadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist string, release deb.Paragraph, keyID string) error {
+func uploadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist distribution, release deb.Paragraph, keyID string) error {
 	data := new(bytes.Buffer)
 	deb.Save(data, []deb.Paragraph{release})
-	err := bucket.WriteAll(ctx, releaseIndexPath(dist), data.Bytes(), &blob.WriterOptions{
+	err := bucket.WriteAll(ctx, dist.indexPath(), data.Bytes(), &blob.WriterOptions{
 		ContentType: "text/plain; charset=utf-8",
 	})
 	if err != nil {
@@ -82,7 +93,7 @@ func uploadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist string, r
 	if err := clearSign.Run(); err != nil {
 		return fmt.Errorf("generate InRelease: %w", err)
 	}
-	err = bucket.WriteAll(ctx, signedReleaseIndexPath(dist), clearSignOutput.Bytes(), &blob.WriterOptions{
+	err = bucket.WriteAll(ctx, dist.signedIndexPath(), clearSignOutput.Bytes(), &blob.WriterOptions{
 		ContentType: "text/plain; charset=utf-8",
 	})
 	if err != nil {
@@ -97,7 +108,7 @@ func uploadReleaseIndex(ctx context.Context, bucket *blob.Bucket, dist string, r
 	if err := detachSign.Run(); err != nil {
 		return fmt.Errorf("generate Release.gpg: %w", err)
 	}
-	err = bucket.WriteAll(ctx, releaseSignatureIndexPath(dist), detachSignOutput.Bytes(), &blob.WriterOptions{
+	err = bucket.WriteAll(ctx, dist.indexSignaturePath(), detachSignOutput.Bytes(), &blob.WriterOptions{
 		ContentType: "text/plain; charset=utf-8",
 	})
 	if err != nil {
@@ -113,12 +124,12 @@ type indexHashes struct {
 	sha256 [sha256.Size]byte
 }
 
-func uploadPackageIndex(ctx context.Context, bucket *blob.Bucket, dist, component, arch string, packages []deb.Paragraph) (uncompressed, compressed indexHashes, err error) {
+func uploadPackageIndex(ctx context.Context, bucket *blob.Bucket, comp component, arch string, packages []deb.Paragraph) (uncompressed, compressed indexHashes, err error) {
 	buf := new(bytes.Buffer)
 	if err := deb.Save(buf, packages); err != nil {
 		return indexHashes{}, indexHashes{}, err
 	}
-	key := binaryPackagesIndexPath(dist, component, arch)
+	key := comp.binaryIndexPath(arch)
 	uncompressed, err = upload(ctx, bucket, key, "text/plain; charset=utf-8", "", bytes.NewReader(buf.Bytes()))
 	if err != nil {
 		return indexHashes{}, indexHashes{}, err
@@ -131,7 +142,7 @@ func uploadPackageIndex(ctx context.Context, bucket *blob.Bucket, dist, componen
 	if err := zw.Close(); err != nil {
 		return indexHashes{}, indexHashes{}, fmt.Errorf("compress %s: %w", key, err)
 	}
-	compressed, err = upload(ctx, bucket, binaryPackagesGzipIndexPath(dist, component, arch), "application/gzip", "", bytes.NewReader(gzipBuf.Bytes()))
+	compressed, err = upload(ctx, bucket, comp.binaryIndexGzipPath(arch), "application/gzip", "", bytes.NewReader(gzipBuf.Bytes()))
 	if err != nil {
 		return indexHashes{}, indexHashes{}, err
 	}