add pmtiles verify command [#65]

* check the statistics and zoom levels in the header match the directories.
* if a clustered archive, verify the contents are in clustered order.

main.go

@@ -180,9 +180,10 @@ func main() {
 			logger.Fatalf("Failed to upload file, %v", err)
 		}
 	case "verify <input>":
-		// check clustered
-		// check counts (addressed tiles, tile entries, # tile contents)
-		logger.Fatalf("This command is not yet implemented.")
+		err := pmtiles.Verify(logger, cli.Verify.Input)
+		if err != nil {
+			logger.Fatalf("Failed to verify archive, %v", err)
+		}
 	case "version":
 		fmt.Printf("pmtiles %s, commit %s, built at %s\n", version, commit, date)
 	default:

pmtiles/verify.go

@@ -0,0 +1,128 @@
+package pmtiles
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"github.com/RoaringBitmap/roaring/roaring64"
+	"io"
+	"log"
+	"math"
+	"time"
+)
+
+func Verify(logger *log.Logger, file string) error {
+	start := time.Now()
+	ctx := context.Background()
+
+	bucketURL, key, err := NormalizeBucketKey("", "", file)
+
+	if err != nil {
+		return err
+	}
+
+	bucket, err := OpenBucket(ctx, bucketURL, "")
+
+	if err != nil {
+		return fmt.Errorf("Failed to open bucket for %s, %w", bucketURL, err)
+	}
+	defer bucket.Close()
+
+	r, err := bucket.NewRangeReader(ctx, key, 0, 16384)
+
+	if err != nil {
+		return fmt.Errorf("Failed to create range reader for %s, %w", key, err)
+	}
+	b, err := io.ReadAll(r)
+	if err != nil {
+		return fmt.Errorf("Failed to read %s, %w", key, err)
+	}
+	r.Close()
+
+	header, err := deserialize_header(b[0:HEADERV3_LEN_BYTES])
+
+	var CollectEntries func(uint64, uint64, func(EntryV3))
+
+	CollectEntries = func(dir_offset uint64, dir_length uint64, f func(EntryV3)) {
+		dirbytes, err := bucket.NewRangeReader(ctx, key, int64(dir_offset), int64(dir_length))
+		if err != nil {
+			panic(fmt.Errorf("I/O error"))
+		}
+		defer dirbytes.Close()
+		b, err = io.ReadAll(dirbytes)
+		if err != nil {
+			panic(fmt.Errorf("I/O Error"))
+		}
+
+		directory := deserialize_entries(bytes.NewBuffer(b))
+		for _, entry := range directory {
+			if entry.RunLength > 0 {
+				f(entry)
+			} else {
+				CollectEntries(header.LeafDirectoryOffset+entry.Offset, uint64(entry.Length), f)
+			}
+		}
+	}
+
+	var min_tile_id uint64
+	var max_tile_id uint64
+	min_tile_id = math.MaxUint64
+	max_tile_id = 0
+
+	addressed_tiles := 0
+	tile_entries := 0
+	offsets := roaring64.New()
+	var current_offset uint64
+	CollectEntries(header.RootOffset, header.RootLength, func(e EntryV3) {
+		offsets.Add(e.Offset)
+		addressed_tiles += int(e.RunLength)
+		tile_entries += 1
+
+		if e.TileId < min_tile_id {
+			min_tile_id = e.TileId
+		}
+		if e.TileId > max_tile_id {
+			max_tile_id = e.TileId
+		}
+
+		if e.Offset+uint64(e.Length) > header.TileDataLength {
+			fmt.Printf("Invalid: %v outside of tile data section", e)
+		}
+
+		if header.Clustered {
+			if !offsets.Contains(e.Offset) {
+				if e.Offset != current_offset {
+					fmt.Printf("Invalid: out-of-order entry %v in clustered archive.", e)
+				}
+				current_offset += uint64(e.Length)
+			}
+		}
+	})
+
+	if uint64(addressed_tiles) != header.AddressedTilesCount {
+		fmt.Printf("Invalid: header AddressedTilesCount=%v but %v tiles addressed.")
+	}
+
+	if uint64(tile_entries) != header.TileEntriesCount {
+		fmt.Printf("Invalid: header TileEntriesCount=%v but %v tile entries.")
+	}
+
+	if offsets.GetCardinality() != header.TileContentsCount {
+		fmt.Printf("Invalid: header TileContentsCount=%v but %v tile contents.")
+	}
+
+	if z, _, _ := IdToZxy(min_tile_id); z != header.MinZoom {
+		fmt.Printf("Invalid: header MinZoom=%v does not match min tile z %v", header.MinZoom, z)
+	}
+
+	if z, _, _ := IdToZxy(max_tile_id); z != header.MaxZoom {
+		fmt.Printf("Invalid: header MaxZoom=%v does not match max tile z %v", header.MaxZoom, z)
+	}
+
+	if !(header.CenterZoom >= header.MinZoom && header.CenterZoom <= header.MaxZoom) {
+		fmt.Printf("Invalid: header CenterZoom=%v not within MinZoom/MaxZoom.", header.CenterZoom)
+	}
+
+	fmt.Printf("Completed verify in %v.\n", time.Since(start))
+	return nil
+}