Adds export-state subcommand (#5842)

* Export state cli

* More work

* Fix tests

* Make it work

* Fix compilation

* Apply suggestions from code review

substrate/client/cli/src/commands/export_state_cmd.rs

@@ -0,0 +1,81 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+	CliConfiguration, error, params::{PruningParams, SharedParams, BlockNumberOrHash},
+};
+use log::info;
+use sc_service::{Configuration, ServiceBuilderCommand};
+use sp_runtime::traits::{Block as BlockT, NumberFor};
+use std::{fmt::Debug, str::FromStr};
+use structopt::StructOpt;
+
+/// The `export-state` command used to export the state of a given block into
+/// a chain spec.
+#[derive(Debug, StructOpt, Clone)]
+pub struct ExportStateCmd {
+	/// Block hash or number.
+	#[structopt(value_name = "HASH or NUMBER")]
+	pub input: Option<BlockNumberOrHash>,
+
+	#[allow(missing_docs)]
+	#[structopt(flatten)]
+	pub shared_params: SharedParams,
+
+	#[allow(missing_docs)]
+	#[structopt(flatten)]
+	pub pruning_params: PruningParams,
+}
+
+impl ExportStateCmd {
+	/// Run the `export-state` command
+	pub fn run<B, BC, BB>(
+		&self,
+		config: Configuration,
+		builder: B,
+	) -> error::Result<()>
+	where
+		B: FnOnce(Configuration) -> Result<BC, sc_service::error::Error>,
+		BC: ServiceBuilderCommand<Block = BB> + Unpin,
+		BB: BlockT + Debug,
+		<NumberFor<BB> as FromStr>::Err: std::fmt::Debug,
+		BB::Hash: FromStr,
+		<BB::Hash as FromStr>::Err: std::fmt::Debug,
+	{
+		info!("Exporting raw state...");
+		let mut input_spec = config.chain_spec.cloned_box();
+		let block_id = self.input.clone().map(|b| b.parse()).transpose()?;
+		let raw_state = builder(config)?.export_raw_state(block_id)?;
+		input_spec.set_storage(raw_state);
+
+		info!("Generating new chain spec...");
+		let json = sc_service::chain_ops::build_spec(&*input_spec, true)?;
+
+		print!("{}", json);
+
+		Ok(())
+	}
+}
+
+impl CliConfiguration for ExportStateCmd {
+	fn shared_params(&self) -> &SharedParams {
+		&self.shared_params
+	}
+
+	fn pruning_params(&self) -> Option<&PruningParams> {
+		Some(&self.pruning_params)
+	}
+}