Further work-in-progress, basic packing and inspecting

cmd/htpacker/inspector.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/lwithers/htpack/internal/packed"
+)
+
+// Inspect a packfile.
+//  TODO: verify etag; verify integrity of compressed data.
+//  TODO: skip Gzip/Brotli if not present; print ratio.
+func Inspect(filename string) error {
+	f, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	hdr, dir, err := packed.Load(f)
+	if hdr != nil {
+		fmt.Printf("Header: %#v\n", hdr)
+	}
+	if dir != nil {
+		fmt.Printf("%d files:\n", len(dir.Files))
+		for path, info := range dir.Files {
+			fmt.Printf(" • %s\n"+
+				"    · Etag:         %s\n"+
+				"    · Content type: %s\n"+
+				"    · Uncompressed: %s (offset %d)\n"+
+				"    · Gzipped:      %s (offset %d)\n"+
+				"    · Brotli:       %s (offset %d)\n",
+				path, info.Etag, info.ContentType,
+				printSize(info.Uncompressed.Length), info.Uncompressed.Offset,
+				printSize(info.Gzip.Length), info.Gzip.Offset,
+				printSize(info.Brotli.Length), info.Brotli.Offset,
+			)
+		}
+	}
+	return err
+}
+
+func printSize(size uint64) string {
+	switch {
+	case size < 1<<10:
+		return fmt.Sprintf("%d bytes", size)
+	case size < 1<<15:
+		return fmt.Sprintf("%.2f KiB", float64(size)/(1<<10))
+	case size < 1<<20:
+		return fmt.Sprintf("%.1f KiB", float64(size)/(1<<10))
+	case size < 1<<25:
+		return fmt.Sprintf("%.2f MiB", float64(size)/(1<<20))
+	case size < 1<<30:
+		return fmt.Sprintf("%.1f MiB", float64(size)/(1<<20))
+	case size < 1<<35:
+		return fmt.Sprintf("%.2f GiB", float64(size)/(1<<30))
+	default:
+		return fmt.Sprintf("%.1f GiB", float64(size)/(1<<30))
+	}
+}