1 files changed, 68 insertions, 1 deletions

diff --git a/cmd/geth/chaincmd.go b/cmd/geth/chaincmd.go
index 12bc1d7c6..4a9a7b11b 100644
--- a/cmd/geth/chaincmd.go
+++ b/cmd/geth/chaincmd.go
@@ -31,7 +31,9 @@ import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/trie"
 	"github.com/syndtr/goleveldb/leveldb/util"
@@ -71,7 +73,7 @@ It expects the genesis file as argument.`,
 The import command imports blocks from an RLP-encoded form. The form can be one file
 with several RLP-encoded blocks, or several files can be used.
 
-If only one file is used, import error will result in failure. If several files are used, 
+If only one file is used, import error will result in failure. If several files are used,
 processing will proceed even if an individual RLP-file import failure occurs.`,
 	}
 	exportCommand = cli.Command{
@@ -91,6 +93,23 @@ Optional second and third arguments control the first and
 last block to write. In this mode, the file will be appended
 if already existing.`,
 	}
+	copydbCommand = cli.Command{
+		Action:    utils.MigrateFlags(copyDb),
+		Name:      "copydb",
+		Usage:     "Create a local chain from a target chaindata folder",
+		ArgsUsage: "<sourceChaindataDir>",
+		Flags: []cli.Flag{
+			utils.DataDirFlag,
+			utils.CacheFlag,
+			utils.SyncModeFlag,
+			utils.FakePoWFlag,
+			utils.TestnetFlag,
+			utils.RinkebyFlag,
+		},
+		Category: "BLOCKCHAIN COMMANDS",
+		Description: `
+The first argument must be the directory containing the blockchain to download from`,
+	}
 	removedbCommand = cli.Command{
 		Action:    utils.MigrateFlags(removeDB),
 		Name:      "removedb",
@@ -268,6 +287,54 @@ func exportChain(ctx *cli.Context) error {
 	return nil
 }
 
+func copyDb(ctx *cli.Context) error {
+	// Ensure we have a source chain directory to copy
+	if len(ctx.Args()) != 1 {
+		utils.Fatalf("Source chaindata directory path argument missing")
+	}
+	// Initialize a new chain for the running node to sync into
+	stack := makeFullNode(ctx)
+	chain, chainDb := utils.MakeChain(ctx, stack)
+
+	syncmode := *utils.GlobalTextMarshaler(ctx, utils.SyncModeFlag.Name).(*downloader.SyncMode)
+	dl := downloader.New(syncmode, chainDb, new(event.TypeMux), chain, nil, nil)
+
+	// Create a source peer to satisfy downloader requests from
+	db, err := ethdb.NewLDBDatabase(ctx.Args().First(), ctx.GlobalInt(utils.CacheFlag.Name), 256)
+	if err != nil {
+		return err
+	}
+	hc, err := core.NewHeaderChain(db, chain.Config(), chain.Engine(), func() bool { return false })
+	if err != nil {
+		return err
+	}
+	peer := downloader.NewFakePeer("local", db, hc, dl)
+	if err = dl.RegisterPeer("local", 63, peer); err != nil {
+		return err
+	}
+	// Synchronise with the simulated peer
+	start := time.Now()
+
+	currentHeader := hc.CurrentHeader()
+	if err = dl.Synchronise("local", currentHeader.Hash(), hc.GetTd(currentHeader.Hash(), currentHeader.Number.Uint64()), syncmode); err != nil {
+		return err
+	}
+	for dl.Synchronising() {
+		time.Sleep(10 * time.Millisecond)
+	}
+	fmt.Printf("Database copy done in %v\n", time.Since(start))
+
+	// Compact the entire database to remove any sync overhead
+	start = time.Now()
+	fmt.Println("Compacting entire database...")
+	if err = chainDb.(*ethdb.LDBDatabase).LDB().CompactRange(util.Range{}); err != nil {
+		utils.Fatalf("Compaction failed: %v", err)
+	}
+	fmt.Printf("Compaction done in %v.\n\n", time.Since(start))
+
+	return nil
+}
+
 func removeDB(ctx *cli.Context) error {
 	stack, _ := makeConfigNode(ctx)