Cache

internal/cache/archive.go

@@ -0,0 +1,121 @@
+package cache
+
+import (
+	"archive/zip"
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/TheRootDaemon/tlgc/internal/upstream"
+	"github.com/TheRootDaemon/tlgc/logger"
+)
+
+// downloadArchive downloads the named archive from the given mirror
+// and verifies it against the provided hash.
+func downloadArchive(
+	ctx context.Context,
+	client *upstream.Client,
+	mirror string,
+	archiveName, hash string,
+) ([]byte, error) {
+	url := mirror + "/" + archiveName
+	return client.DownloadBytes(ctx, url, hash)
+}
+
+// extractArchive removes the existing language directory,
+// recreates it,
+// and extracts the zip archive contents into it.
+func (c *Cache) extractArchive(
+	languageDirectory string,
+	data []byte,
+) error {
+	logger.InfoStart("extracting '%s'... ", languageDirectory)
+
+	targetDirectory := filepath.Join(c.dir, languageDirectory)
+
+	if err := os.RemoveAll(targetDirectory); err != nil {
+		return err
+	}
+	if err := os.MkdirAll(targetDirectory, 0o750); err != nil {
+		return err
+	}
+
+	zipReader, err := zip.NewReader(
+		bytes.NewReader(data),
+		int64(len(data)),
+	)
+	if err != nil {
+		return fmt.Errorf("reading zip archive: %w", err)
+	}
+
+	root, err := os.OpenRoot(targetDirectory)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		_ = root.Close()
+	}()
+
+	var extracted int
+	for _, f := range zipReader.File {
+		if strings.Contains(f.Name, "..") {
+			continue
+		}
+
+		if f.FileInfo().IsDir() {
+			if err := root.MkdirAll(f.Name, 0o750); err != nil {
+				return fmt.Errorf("creating directory %s: %w", f.Name, err)
+			}
+
+			continue
+		}
+
+		if err := root.MkdirAll(filepath.Dir(f.Name), 0o750); err != nil {
+			return fmt.Errorf("creating directory for %s: %w", f.Name, err)
+		}
+
+		if err := extractFile(root, f); err != nil {
+			return err
+		}
+
+		extracted++
+	}
+
+	logger.InfoEnd("%d pages", extracted)
+	return nil
+}
+
+// extractFile writes a single zip entry to disk
+// using the given root directory.
+func extractFile(
+	root *os.Root,
+	f *zip.File,
+) error {
+	rc, err := f.Open()
+	if err != nil {
+		return fmt.Errorf("opening %s in zip: %w", f.Name, err)
+	}
+
+	out, err := root.OpenFile(
+		f.Name,
+		os.O_CREATE|os.O_WRONLY|os.O_TRUNC,
+		f.Mode(),
+	)
+	if err != nil {
+		_ = rc.Close()
+		return fmt.Errorf("creating %s: %w", f.Name, err)
+	}
+
+	_, err = out.ReadFrom(rc)
+	_ = rc.Close()
+	_ = out.Close()
+
+	if err != nil {
+		return fmt.Errorf("writing %s: %w", f.Name, err)
+	}
+
+	return nil
+}