add apt gestion

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

internal/clone/apt/metadata_gen.go

@@ -0,0 +1,148 @@
+package apt
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+// InitEmptyRepo creates the directory structure for an APT mirror and writes an
+// empty Release file so APT clients don't get a 404 before the first clone.
+func InitEmptyRepo(localDir string, cfg Config) error {
+	if err := os.MkdirAll(filepath.Join(localDir, "pool"), 0o755); err != nil {
+		return err
+	}
+	for _, component := range cfg.Components {
+		for _, arch := range cfg.Architectures {
+			dir := filepath.Join(localDir, "dists", cfg.Suite, component, "binary-"+arch)
+			if err := os.MkdirAll(dir, 0o755); err != nil {
+				return err
+			}
+		}
+	}
+	releasePath := filepath.Join(localDir, "dists", cfg.Suite, "Release")
+	if _, err := os.Stat(releasePath); os.IsNotExist(err) {
+		releaseData := GenerateRelease(cfg.Suite, cfg.Suite, cfg.Components, cfg.Architectures, nil)
+		if err := atomicWrite(releasePath, releaseData); err != nil {
+			return fmt.Errorf("write empty Release: %w", err)
+		}
+	}
+	return nil
+}
+
+// RegenerateMetadata rebuilds local Packages, Packages.gz, and Release files
+// for all configured component/arch pairs, keeping only packages present on disk.
+func RegenerateMetadata(localDir string, cfg Config) error {
+	suite := cfg.Suite
+	var releaseEntries []ReleaseEntry
+
+	for _, component := range cfg.Components {
+		for _, arch := range cfg.Architectures {
+			entries, err := regenerateComponentArch(localDir, suite, component, arch)
+			if err != nil {
+				return fmt.Errorf("regenerate %s/%s: %w", component, arch, err)
+			}
+			releaseEntries = append(releaseEntries, entries...)
+		}
+	}
+
+	// Write dists/{suite}/Release.
+	releaseData := GenerateRelease(suite, suite, cfg.Components, cfg.Architectures, releaseEntries)
+	releasePath := filepath.Join(localDir, "dists", suite, "Release")
+	if err := os.MkdirAll(filepath.Dir(releasePath), 0o755); err != nil {
+		return fmt.Errorf("create dists dir: %w", err)
+	}
+	if err := atomicWrite(releasePath, releaseData); err != nil {
+		return fmt.Errorf("write Release: %w", err)
+	}
+
+	return nil
+}
+
+// regenerateComponentArch regenerates Packages and Packages.gz for one component/arch
+// and returns the two ReleaseEntry values (plain then gz) for the Release file.
+func regenerateComponentArch(localDir, suite, component, arch string) ([]ReleaseEntry, error) {
+	binDir := filepath.Join(localDir, "dists", suite, component, "binary-"+arch)
+	upstreamGzPath := filepath.Join(binDir, upstreamPackagesGz)
+
+	// 1. Read upstream Packages.gz.
+	gzData, err := os.ReadFile(upstreamGzPath)
+	if err != nil {
+		// Not cloned yet — skip silently.
+		return nil, nil
+	}
+
+	// 2. Decompress.
+	gz, err := gzip.NewReader(bytes.NewReader(gzData))
+	if err != nil {
+		return nil, fmt.Errorf("open gzip %s: %w", upstreamGzPath, err)
+	}
+	rawPackages, err := io.ReadAll(gz)
+	gz.Close()
+	if err != nil {
+		return nil, fmt.Errorf("decompress %s: %w", upstreamGzPath, err)
+	}
+
+	// 3. Parse all stanzas.
+	allPkgs, err := ParsePackages(rawPackages)
+	if err != nil {
+		return nil, fmt.Errorf("parse upstream Packages: %w", err)
+	}
+
+	// 4. Filter: keep only packages present on disk.
+	checker := diskPresenceChecker(localDir)
+	localPkgs := FilterPackages(allPkgs, checker)
+
+	// 5. Re-emit filtered stanzas.
+	plainBytes := emitPackages(localPkgs)
+
+	// 6. Gzip the filtered Packages.
+	var gzBuf bytes.Buffer
+	gzw := gzip.NewWriter(&gzBuf)
+	if _, err := gzw.Write(plainBytes); err != nil {
+		return nil, fmt.Errorf("gzip write: %w", err)
+	}
+	if err := gzw.Close(); err != nil {
+		return nil, fmt.Errorf("gzip close: %w", err)
+	}
+	gzBytes := gzBuf.Bytes()
+
+	// 7. Write Packages and Packages.gz.
+	if err := os.MkdirAll(binDir, 0o755); err != nil {
+		return nil, err
+	}
+	plainPath := filepath.Join(binDir, "Packages")
+	if err := atomicWrite(plainPath, plainBytes); err != nil {
+		return nil, fmt.Errorf("write Packages: %w", err)
+	}
+	gzPath := filepath.Join(binDir, "Packages.gz")
+	if err := atomicWrite(gzPath, gzBytes); err != nil {
+		return nil, fmt.Errorf("write Packages.gz: %w", err)
+	}
+
+	// 8. Compute SHA256 hashes.
+	plainSum := sha256.Sum256(plainBytes)
+	gzSum := sha256.Sum256(gzBytes)
+
+	// Release paths are relative to dists/{suite}/.
+	relBase := component + "/binary-" + arch + "/"
+
+	return []ReleaseEntry{
+		{
+			Hash: hex.EncodeToString(plainSum[:]),
+			Size: int64(len(plainBytes)),
+			Path: relBase + "Packages",
+		},
+		{
+			Hash: hex.EncodeToString(gzSum[:]),
+			Size: int64(len(gzBytes)),
+			Path: relBase + "Packages.gz",
+		},
+	}, nil
+}
+