eth, internal/web3ext: add optional first and last arguments to the ...

eth, internal/web3ext: add optional first and last arguments to the  `admin_exportChain` RPC. (#20107)

eth/api.go

@@ -166,8 +166,16 @@ func NewPrivateAdminAPI(eth *Ethereum) *PrivateAdminAPI {
 	return &PrivateAdminAPI{eth: eth}
 }
 
-// ExportChain exports the current blockchain into a local file.
-func (api *PrivateAdminAPI) ExportChain(file string) (bool, error) {
+// ExportChain exports the current blockchain into a local file,
+// or a range of blocks if first and last are non-nil
+func (api *PrivateAdminAPI) ExportChain(file string, first *uint64, last *uint64) (bool, error) {
+	if first == nil && last != nil {
+		return false, errors.New("last cannot be specified without first")
+	}
+	if first != nil && last == nil {
+		head := api.eth.BlockChain().CurrentHeader().Number.Uint64()
+		last = &head
+	}
 	if _, err := os.Stat(file); err == nil {
 		// File already exists. Allowing overwrite could be a DoS vecotor,
 		// since the 'file' may point to arbitrary paths on the drive
@@ -187,7 +195,11 @@ func (api *PrivateAdminAPI) ExportChain(file string) (bool, error) {
 	}
 
 	// Export the blockchain
-	if err := api.eth.BlockChain().Export(writer); err != nil {
+	if first != nil {
+		if err := api.eth.BlockChain().ExportN(writer, *first, *last); err != nil {
+			return false, err
+		}
+	} else if err := api.eth.BlockChain().Export(writer); err != nil {
 		return false, err
 	}
 	return true, nil

internal/web3ext/web3ext.go

@@ -172,8 +172,8 @@ web3._extend({
 		new web3._extend.Method({
 			name: 'exportChain',
 			call: 'admin_exportChain',
-			params: 1,
-			inputFormatter: [null]
+			params: 3,
+			inputFormatter: [null, null, null]
 		}),
 		new web3._extend.Method({
 			name: 'importChain',