do not overwrite existing files when doing `tendermint init` (Fixes #410)

cmd/tendermint/init.go

@@ -1,24 +1,35 @@
 package main
 
 import (
-	. "github.com/tendermint/go-common"
+	"os"
+
+	cmn "github.com/tendermint/go-common"
 	"github.com/tendermint/tendermint/types"
 )
 
 func init_files() {
-	privValidator := types.GenPrivValidator()
-	privValidator.SetFile(config.GetString("priv_validator_file"))
-	privValidator.Save()
+	privValFile := config.GetString("priv_validator_file")
+	if _, err := os.Stat(privValFile); os.IsNotExist(err) {
+		privValidator := types.GenPrivValidator()
+		privValidator.SetFile(privValFile)
+		privValidator.Save()
 
-	genDoc := types.GenesisDoc{
-		ChainID: Fmt("test-chain-%v", RandStr(6)),
-	}
-	genDoc.Validators = []types.GenesisValidator{types.GenesisValidator{
-		PubKey: privValidator.PubKey,
-		Amount: 10,
-	}}
+		genFile := config.GetString("genesis_file")
 
-	genDoc.SaveAs(config.GetString("genesis_file"))
+		if _, err := os.Stat(genFile); os.IsNotExist(err) {
+			genDoc := types.GenesisDoc{
+				ChainID: cmn.Fmt("test-chain-%v", cmn.RandStr(6)),
+			}
+			genDoc.Validators = []types.GenesisValidator{types.GenesisValidator{
+				PubKey: privValidator.PubKey,
+				Amount: 10,
+			}}
 
-	log.Notice("Initialized tendermint", "genesis", config.GetString("genesis_file"), "priv_validator", config.GetString("priv_validator_file"))
+			genDoc.SaveAs(genFile)
+		}
+
+		log.Notice("Initialized tendermint", "genesis", config.GetString("genesis_file"), "priv_validator", config.GetString("priv_validator_file"))
+	} else {
+		log.Notice("Already initialized", "priv_validator", config.GetString("priv_validator_file"))
+	}
 }