Big folder refactor

bin/evmbin/src/display/config.rs

@@ -0,0 +1,40 @@
+// Copyright 2015-2020 Parity Technologies (UK) Ltd.
+// This file is part of OpenEthereum.
+
+// OpenEthereum 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.
+
+// OpenEthereum 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 OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Config used by display informants
+
+#[derive(Default, Copy, Clone)]
+pub struct Config {
+    omit_storage_output: bool,
+    omit_memory_output: bool,
+}
+
+impl Config {
+    pub fn new(omit_storage_output: bool, omit_memory_output: bool) -> Config {
+        Config {
+            omit_storage_output,
+            omit_memory_output,
+        }
+    }
+
+    pub fn omit_storage_output(&self) -> bool {
+        self.omit_storage_output
+    }
+
+    pub fn omit_memory_output(&self) -> bool {
+        self.omit_memory_output
+    }
+}

bin/evmbin/src/display/json.rs

@@ -0,0 +1,405 @@
+// Copyright 2015-2020 Parity Technologies (UK) Ltd.
+// This file is part of OpenEthereum.
+
+// OpenEthereum 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.
+
+// OpenEthereum 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 OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! JSON VM output.
+
+use std::{collections::HashMap, mem};
+
+use super::config::Config;
+use bytes::ToPretty;
+use display;
+use ethcore::trace;
+use ethereum_types::{H256, U256};
+use info as vm;
+
+/// JSON formatting informant.
+#[derive(Default)]
+pub struct Informant {
+    code: Vec<u8>,
+    depth: usize,
+    pc: usize,
+    instruction: u8,
+    gas_cost: U256,
+    gas_used: U256,
+    mem_written: Option<(usize, usize)>,
+    store_written: Option<(U256, U256)>,
+    stack: Vec<U256>,
+    memory: Vec<u8>,
+    storage: HashMap<H256, H256>,
+    traces: Vec<String>,
+    subtraces: Vec<String>,
+    subinfos: Vec<Informant>,
+    subdepth: usize,
+    unmatched: bool,
+    config: Config,
+}
+
+impl Informant {
+    pub fn new(config: Config) -> Informant {
+        let mut def = Informant::default();
+        def.config = config;
+        def
+    }
+
+    fn with_informant_in_depth<F: Fn(&mut Informant)>(
+        informant: &mut Informant,
+        depth: usize,
+        f: F,
+    ) {
+        if depth == 0 {
+            f(informant);
+        } else {
+            Self::with_informant_in_depth(
+                informant
+                    .subinfos
+                    .last_mut()
+                    .expect("prepare/done_trace are not balanced"),
+                depth - 1,
+                f,
+            );
+        }
+    }
+
+    fn informant_trace(informant: &Informant, gas_used: U256) -> String {
+        let memory = if informant.config.omit_memory_output() {
+            "".to_string()
+        } else {
+            format!("0x{}", informant.memory.to_hex())
+        };
+        let storage = if informant.config.omit_storage_output() {
+            None
+        } else {
+            Some(&informant.storage)
+        };
+        let info = ::evm::Instruction::from_u8(informant.instruction).map(|i| i.info());
+        json!({
+            "pc": informant.pc,
+            "op": informant.instruction,
+            "opName": info.map(|i| i.name).unwrap_or(""),
+            "gas": format!("{:#x}", gas_used.saturating_add(informant.gas_cost)),
+            "gasCost": format!("{:#x}", informant.gas_cost),
+            "memory": memory,
+            "stack": informant.stack,
+            "storage": storage,
+            "depth": informant.depth,
+        })
+        .to_string()
+    }
+}
+
+impl vm::Informant for Informant {
+    type Sink = Config;
+
+    fn before_test(&mut self, name: &str, action: &str) {
+        println!("{}", json!({"action": action, "test": name}));
+    }
+
+    fn set_gas(&mut self, gas: U256) {
+        self.gas_used = gas;
+    }
+
+    fn clone_sink(&self) -> Self::Sink {
+        self.config
+    }
+
+    fn finish(result: vm::RunResult<Self::Output>, config: &mut Self::Sink) {
+        match result {
+            Ok(success) => {
+                for trace in success.traces.unwrap_or_else(Vec::new) {
+                    println!("{}", trace);
+                }
+
+                let success_msg = json!({
+                    "output": format!("0x{}", success.output.to_hex()),
+                    "gasUsed": format!("{:#x}", success.gas_used),
+                    "time": display::as_micros(&success.time),
+                });
+
+                println!("{}", success_msg)
+            }
+            Err(failure) => {
+                if !config.omit_storage_output() {
+                    for trace in failure.traces.unwrap_or_else(Vec::new) {
+                        println!("{}", trace);
+                    }
+                }
+
+                let failure_msg = json!({
+                    "error": &failure.error.to_string(),
+                    "gasUsed": format!("{:#x}", failure.gas_used),
+                    "time": display::as_micros(&failure.time),
+                });
+
+                println!("{}", failure_msg)
+            }
+        }
+    }
+}
+
+impl trace::VMTracer for Informant {
+    type Output = Vec<String>;
+
+    fn trace_next_instruction(&mut self, pc: usize, instruction: u8, _current_gas: U256) -> bool {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant| {
+            informant.pc = pc;
+            informant.instruction = instruction;
+            informant.unmatched = true;
+        });
+        true
+    }
+
+    fn trace_prepare_execute(
+        &mut self,
+        pc: usize,
+        instruction: u8,
+        gas_cost: U256,
+        mem_written: Option<(usize, usize)>,
+        store_written: Option<(U256, U256)>,
+    ) {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant| {
+            informant.pc = pc;
+            informant.instruction = instruction;
+            informant.gas_cost = gas_cost;
+            informant.mem_written = mem_written;
+            informant.store_written = store_written;
+        });
+    }
+
+    fn trace_executed(&mut self, gas_used: U256, stack_push: &[U256], mem: &[u8]) {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant| {
+            let store_diff = informant.store_written.clone();
+            let info = ::evm::Instruction::from_u8(informant.instruction).map(|i| i.info());
+
+            let trace = Self::informant_trace(informant, gas_used);
+            informant.traces.push(trace);
+
+            informant.unmatched = false;
+            informant.gas_used = gas_used;
+
+            let len = informant.stack.len();
+            let info_args = info.map(|i| i.args).unwrap_or(0);
+            informant
+                .stack
+                .truncate(if len > info_args { len - info_args } else { 0 });
+            informant.stack.extend_from_slice(stack_push);
+
+            // TODO [ToDr] Align memory?
+            if let Some((pos, size)) = informant.mem_written.clone() {
+                if informant.memory.len() < (pos + size) {
+                    informant.memory.resize(pos + size, 0);
+                }
+                informant.memory[pos..(pos + size)].copy_from_slice(&mem[pos..(pos + size)]);
+            }
+
+            if let Some((pos, val)) = store_diff {
+                informant.storage.insert(pos.into(), val.into());
+            }
+
+            if !informant.subtraces.is_empty() {
+                informant
+                    .traces
+                    .extend(mem::replace(&mut informant.subtraces, vec![]));
+            }
+        });
+    }
+
+    fn prepare_subtrace(&mut self, code: &[u8]) {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant| {
+            let mut vm = Informant::default();
+            vm.config = informant.config;
+            vm.depth = informant.depth + 1;
+            vm.code = code.to_vec();
+            vm.gas_used = informant.gas_used;
+            informant.subinfos.push(vm);
+        });
+        self.subdepth += 1;
+    }
+
+    fn done_subtrace(&mut self) {
+        self.subdepth -= 1;
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant| {
+            if let Some(subtraces) = informant
+                .subinfos
+                .pop()
+                .expect("prepare/done_subtrace are not balanced")
+                .drain()
+            {
+                informant.subtraces.extend(subtraces);
+            }
+        });
+    }
+
+    fn drain(mut self) -> Option<Self::Output> {
+        if self.unmatched {
+            // print last line with final state:
+            self.gas_cost = 0.into();
+            let gas_used = self.gas_used;
+            let subdepth = self.subdepth;
+
+            Self::with_informant_in_depth(&mut self, subdepth, |informant: &mut Informant| {
+                let trace = Self::informant_trace(informant, gas_used);
+                informant.traces.push(trace);
+            });
+        } else if !self.subtraces.is_empty() {
+            self.traces
+                .extend(mem::replace(&mut self.subtraces, vec![]));
+        }
+        Some(self.traces)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use info::tests::run_test;
+    use serde_json;
+
+    #[derive(Serialize, Deserialize, Debug, PartialEq)]
+    #[serde(rename_all = "camelCase")]
+    struct TestTrace {
+        pc: usize,
+        #[serde(rename = "op")]
+        instruction: u8,
+        op_name: String,
+        #[serde(rename = "gas")]
+        gas_used: U256,
+        gas_cost: U256,
+        memory: String,
+        stack: Vec<U256>,
+        storage: HashMap<H256, H256>,
+        depth: usize,
+    }
+
+    fn assert_traces_eq(a: &[String], b: &[String]) {
+        let mut ita = a.iter();
+        let mut itb = b.iter();
+
+        loop {
+            match (ita.next(), itb.next()) {
+                (Some(a), Some(b)) => {
+                    // Compare both without worrying about the order of the fields
+                    let actual: TestTrace = serde_json::from_str(a).unwrap();
+                    let expected: TestTrace = serde_json::from_str(b).unwrap();
+                    assert_eq!(actual, expected);
+                    println!("{}", a);
+                }
+                (None, None) => return,
+                e => {
+                    panic!("Traces mismatch: {:?}", e);
+                }
+            }
+        }
+    }
+
+    fn compare_json(traces: Option<Vec<String>>, expected: &str) {
+        let expected = expected
+            .split("\n")
+            .map(|x| x.trim())
+            .map(|x| x.to_owned())
+            .filter(|x| !x.is_empty())
+            .collect::<Vec<_>>();
+        assert_traces_eq(&traces.unwrap(), &expected);
+    }
+
+    #[test]
+    fn should_trace_failure() {
+        run_test(
+            Informant::default(),
+            &compare_json,
+            "60F8d6",
+            0xffff,
+            r#"
+{"pc":0,"op":96,"opName":"PUSH1","gas":"0xffff","gasCost":"0x3","memory":"0x","stack":[],"storage":{},"depth":1}
+{"pc":2,"op":214,"opName":"","gas":"0xfffc","gasCost":"0x0","memory":"0x","stack":["0xf8"],"storage":{},"depth":1}
+			"#,
+        );
+
+        run_test(
+            Informant::default(),
+            &compare_json,
+            "F8d6",
+            0xffff,
+            r#"
+{"pc":0,"op":248,"opName":"","gas":"0xffff","gasCost":"0x0","memory":"0x","stack":[],"storage":{},"depth":1}
+			"#,
+        );
+
+        run_test(
+            Informant::default(),
+            &compare_json,
+            "5A51",
+            0xfffff,
+            r#"
+{"depth":1,"gas":"0xfffff","gasCost":"0x2","memory":"0x","op":90,"opName":"GAS","pc":0,"stack":[],"storage":{}}
+{"depth":1,"gas":"0xffffd","gasCost":"0x0","memory":"0x","op":81,"opName":"MLOAD","pc":1,"stack":["0xffffd"],"storage":{}}
+			"#,
+        );
+    }
+
+    #[test]
+    fn should_trace_create_correctly() {
+        run_test(
+            Informant::default(),
+            &compare_json,
+            "32343434345830f138343438323439f0",
+            0xffff,
+            r#"
+{"pc":0,"op":50,"opName":"ORIGIN","gas":"0xffff","gasCost":"0x2","memory":"0x","stack":[],"storage":{},"depth":1}
+{"pc":1,"op":52,"opName":"CALLVALUE","gas":"0xfffd","gasCost":"0x2","memory":"0x","stack":["0x0"],"storage":{},"depth":1}
+{"pc":2,"op":52,"opName":"CALLVALUE","gas":"0xfffb","gasCost":"0x2","memory":"0x","stack":["0x0","0x0"],"storage":{},"depth":1}
+{"pc":3,"op":52,"opName":"CALLVALUE","gas":"0xfff9","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0"],"storage":{},"depth":1}
+{"pc":4,"op":52,"opName":"CALLVALUE","gas":"0xfff7","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0","0x0"],"storage":{},"depth":1}
+{"pc":5,"op":88,"opName":"PC","gas":"0xfff5","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0","0x0","0x0"],"storage":{},"depth":1}
+{"pc":6,"op":48,"opName":"ADDRESS","gas":"0xfff3","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0","0x0","0x0","0x5"],"storage":{},"depth":1}
+{"pc":7,"op":241,"opName":"CALL","gas":"0xfff1","gasCost":"0x61d0","memory":"0x","stack":["0x0","0x0","0x0","0x0","0x0","0x5","0x0"],"storage":{},"depth":1}
+{"pc":8,"op":56,"opName":"CODESIZE","gas":"0x9e21","gasCost":"0x2","memory":"0x","stack":["0x1"],"storage":{},"depth":1}
+{"pc":9,"op":52,"opName":"CALLVALUE","gas":"0x9e1f","gasCost":"0x2","memory":"0x","stack":["0x1","0x10"],"storage":{},"depth":1}
+{"pc":10,"op":52,"opName":"CALLVALUE","gas":"0x9e1d","gasCost":"0x2","memory":"0x","stack":["0x1","0x10","0x0"],"storage":{},"depth":1}
+{"pc":11,"op":56,"opName":"CODESIZE","gas":"0x9e1b","gasCost":"0x2","memory":"0x","stack":["0x1","0x10","0x0","0x0"],"storage":{},"depth":1}
+{"pc":12,"op":50,"opName":"ORIGIN","gas":"0x9e19","gasCost":"0x2","memory":"0x","stack":["0x1","0x10","0x0","0x0","0x10"],"storage":{},"depth":1}
+{"pc":13,"op":52,"opName":"CALLVALUE","gas":"0x9e17","gasCost":"0x2","memory":"0x","stack":["0x1","0x10","0x0","0x0","0x10","0x0"],"storage":{},"depth":1}
+{"pc":14,"op":57,"opName":"CODECOPY","gas":"0x9e15","gasCost":"0x9","memory":"0x","stack":["0x1","0x10","0x0","0x0","0x10","0x0","0x0"],"storage":{},"depth":1}
+{"pc":15,"op":240,"opName":"CREATE","gas":"0x9e0c","gasCost":"0x9e0c","memory":"0x32343434345830f138343438323439f0","stack":["0x1","0x10","0x0","0x0"],"storage":{},"depth":1}
+{"pc":0,"op":50,"opName":"ORIGIN","gas":"0x210c","gasCost":"0x2","memory":"0x","stack":[],"storage":{},"depth":2}
+{"pc":1,"op":52,"opName":"CALLVALUE","gas":"0x210a","gasCost":"0x2","memory":"0x","stack":["0x0"],"storage":{},"depth":2}
+{"pc":2,"op":52,"opName":"CALLVALUE","gas":"0x2108","gasCost":"0x2","memory":"0x","stack":["0x0","0x0"],"storage":{},"depth":2}
+{"pc":3,"op":52,"opName":"CALLVALUE","gas":"0x2106","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0"],"storage":{},"depth":2}
+{"pc":4,"op":52,"opName":"CALLVALUE","gas":"0x2104","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0","0x0"],"storage":{},"depth":2}
+{"pc":5,"op":88,"opName":"PC","gas":"0x2102","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0","0x0","0x0"],"storage":{},"depth":2}
+{"pc":6,"op":48,"opName":"ADDRESS","gas":"0x2100","gasCost":"0x2","memory":"0x","stack":["0x0","0x0","0x0","0x0","0x0","0x5"],"storage":{},"depth":2}
+{"pc":7,"op":241,"opName":"CALL","gas":"0x20fe","gasCost":"0x0","memory":"0x","stack":["0x0","0x0","0x0","0x0","0x0","0x5","0xbd770416a3345f91e4b34576cb804a576fa48eb1"],"storage":{},"depth":2}
+"#,
+        );
+
+        run_test(
+            Informant::default(),
+            &compare_json,
+            "3260D85554",
+            0xffff,
+            r#"
+{"pc":0,"op":50,"opName":"ORIGIN","gas":"0xffff","gasCost":"0x2","memory":"0x","stack":[],"storage":{},"depth":1}
+{"pc":1,"op":96,"opName":"PUSH1","gas":"0xfffd","gasCost":"0x3","memory":"0x","stack":["0x0"],"storage":{},"depth":1}
+{"pc":3,"op":85,"opName":"SSTORE","gas":"0xfffa","gasCost":"0x1388","memory":"0x","stack":["0x0","0xd8"],"storage":{},"depth":1}
+{"pc":4,"op":84,"opName":"SLOAD","gas":"0xec72","gasCost":"0x0","memory":"0x","stack":[],"storage":{"0x00000000000000000000000000000000000000000000000000000000000000d8":"0x0000000000000000000000000000000000000000000000000000000000000000"},"depth":1}
+"#,
+        )
+    }
+}

bin/evmbin/src/display/mod.rs

@@ -0,0 +1,34 @@
+// Copyright 2015-2020 Parity Technologies (UK) Ltd.
+// This file is part of OpenEthereum.
+
+// OpenEthereum 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.
+
+// OpenEthereum 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 OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! VM Output display utils.
+
+use std::time::Duration;
+
+pub mod config;
+pub mod json;
+pub mod simple;
+pub mod std_json;
+
+/// Formats duration into human readable format.
+pub fn format_time(time: &Duration) -> String {
+    format!("{}.{:.9}s", time.as_secs(), time.subsec_nanos())
+}
+
+/// Formats the time as microseconds.
+pub fn as_micros(time: &Duration) -> u64 {
+    time.as_secs() * 1_000_000 + time.subsec_nanos() as u64 / 1_000
+}

bin/evmbin/src/display/simple.rs

@@ -0,0 +1,74 @@
+// Copyright 2015-2020 Parity Technologies (UK) Ltd.
+// This file is part of OpenEthereum.
+
+// OpenEthereum 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.
+
+// OpenEthereum 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 OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Simple VM output.
+
+use super::config::Config;
+use bytes::ToPretty;
+use ethcore::trace;
+
+use display;
+use info as vm;
+
+/// Simple formatting informant.
+#[derive(Default)]
+pub struct Informant {
+    config: Config,
+}
+
+impl Informant {
+    pub fn new(config: Config) -> Informant {
+        Informant { config }
+    }
+}
+
+impl vm::Informant for Informant {
+    type Sink = Config;
+
+    fn before_test(&mut self, name: &str, action: &str) {
+        println!("Test: {} ({})", name, action);
+    }
+
+    fn clone_sink(&self) -> Self::Sink {
+        self.config
+    }
+
+    fn finish(result: vm::RunResult<Self::Output>, _sink: &mut Self::Sink) {
+        match result {
+            Ok(success) => {
+                println!("Output: 0x{}", success.output.to_hex());
+                println!("Gas used: {:x}", success.gas_used);
+                println!("Time: {}", display::format_time(&success.time));
+            }
+            Err(failure) => {
+                println!("Error: {}", failure.error);
+                println!("Time: {}", display::format_time(&failure.time));
+            }
+        }
+    }
+}
+
+impl trace::VMTracer for Informant {
+    type Output = ();
+
+    fn prepare_subtrace(&mut self, _code: &[u8]) {
+        Default::default()
+    }
+    fn done_subtrace(&mut self) {}
+    fn drain(self) -> Option<()> {
+        None
+    }
+}

bin/evmbin/src/display/std_json.rs

@@ -0,0 +1,388 @@
+// Copyright 2015-2020 Parity Technologies (UK) Ltd.
+// This file is part of OpenEthereum.
+
+// OpenEthereum 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.
+
+// OpenEthereum 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 OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Standardized JSON VM output.
+
+use std::{collections::HashMap, io};
+
+use super::config::Config;
+use bytes::ToPretty;
+use display;
+use ethcore::{pod_state, trace};
+use ethereum_types::{H256, U256};
+use info as vm;
+
+pub trait Writer: io::Write + Send + Sized {
+    fn clone(&self) -> Self;
+    fn default() -> Self;
+}
+
+impl Writer for io::Stdout {
+    fn clone(&self) -> Self {
+        io::stdout()
+    }
+
+    fn default() -> Self {
+        io::stdout()
+    }
+}
+
+impl Writer for io::Stderr {
+    fn clone(&self) -> Self {
+        io::stderr()
+    }
+
+    fn default() -> Self {
+        io::stderr()
+    }
+}
+
+/// JSON formatting informant.
+pub struct Informant<Trace, Out> {
+    code: Vec<u8>,
+    instruction: u8,
+    depth: usize,
+    stack: Vec<U256>,
+    storage: HashMap<H256, H256>,
+    subinfos: Vec<Informant<Trace, Out>>,
+    subdepth: usize,
+    trace_sink: Trace,
+    out_sink: Out,
+    config: Config,
+}
+
+impl Default for Informant<io::Stderr, io::Stdout> {
+    fn default() -> Self {
+        Self::new(io::stderr(), io::stdout(), Config::default())
+    }
+}
+
+impl Informant<io::Stdout, io::Stdout> {
+    /// std json informant using out only.
+    pub fn out_only(config: Config) -> Self {
+        Self::new(io::stdout(), io::stdout(), config)
+    }
+}
+
+impl Informant<io::Stderr, io::Stderr> {
+    /// std json informant using err only.
+    pub fn err_only(config: Config) -> Self {
+        Self::new(io::stderr(), io::stderr(), config)
+    }
+}
+
+impl Informant<io::Stderr, io::Stdout> {
+    pub fn new_default(config: Config) -> Self {
+        let mut informant = Self::default();
+        informant.config = config;
+        informant
+    }
+}
+
+impl<Trace: Writer, Out: Writer> Informant<Trace, Out> {
+    pub fn new(trace_sink: Trace, out_sink: Out, config: Config) -> Self {
+        Informant {
+            code: Default::default(),
+            instruction: Default::default(),
+            depth: Default::default(),
+            stack: Default::default(),
+            storage: Default::default(),
+            subinfos: Default::default(),
+            subdepth: 0,
+            trace_sink,
+            out_sink,
+            config,
+        }
+    }
+
+    fn with_informant_in_depth<F: Fn(&mut Informant<Trace, Out>)>(
+        informant: &mut Informant<Trace, Out>,
+        depth: usize,
+        f: F,
+    ) {
+        if depth == 0 {
+            f(informant);
+        } else {
+            Self::with_informant_in_depth(
+                informant
+                    .subinfos
+                    .last_mut()
+                    .expect("prepare/done_trace are not balanced"),
+                depth - 1,
+                f,
+            );
+        }
+    }
+
+    fn dump_state_into(
+        trace_sink: &mut Trace,
+        root: H256,
+        end_state: &Option<pod_state::PodState>,
+    ) {
+        if let Some(ref end_state) = end_state {
+            let dump_data = json!({
+                "root": root,
+                "accounts": end_state,
+            });
+            writeln!(trace_sink, "{}", dump_data).expect("The sink must be writeable.");
+        }
+    }
+}
+
+impl<Trace: Writer, Out: Writer> vm::Informant for Informant<Trace, Out> {
+    type Sink = (Trace, Out, Config);
+
+    fn before_test(&mut self, name: &str, action: &str) {
+        let out_data = json!({
+            "action": action,
+            "test": name,
+        });
+
+        writeln!(&mut self.out_sink, "{}", out_data).expect("The sink must be writeable.");
+    }
+
+    fn set_gas(&mut self, _gas: U256) {}
+
+    fn clone_sink(&self) -> Self::Sink {
+        (
+            self.trace_sink.clone(),
+            self.out_sink.clone(),
+            self.config.clone(),
+        )
+    }
+    fn finish(
+        result: vm::RunResult<<Self as trace::VMTracer>::Output>,
+        (ref mut trace_sink, ref mut out_sink, _): &mut Self::Sink,
+    ) {
+        match result {
+            Ok(success) => {
+                let trace_data = json!({"stateRoot": success.state_root});
+                writeln!(trace_sink, "{}", trace_data).expect("The sink must be writeable.");
+
+                Self::dump_state_into(trace_sink, success.state_root, &success.end_state);
+
+                let out_data = json!({
+                    "output": format!("0x{}", success.output.to_hex()),
+                    "gasUsed": format!("{:#x}", success.gas_used),
+                    "time": display::as_micros(&success.time),
+                });
+
+                writeln!(out_sink, "{}", out_data).expect("The sink must be writeable.");
+            }
+            Err(failure) => {
+                let out_data = json!({
+                    "error": &failure.error.to_string(),
+                    "gasUsed": format!("{:#x}", failure.gas_used),
+                    "time": display::as_micros(&failure.time),
+                });
+
+                Self::dump_state_into(trace_sink, failure.state_root, &failure.end_state);
+
+                writeln!(out_sink, "{}", out_data).expect("The sink must be writeable.");
+            }
+        }
+    }
+}
+
+impl<Trace: Writer, Out: Writer> trace::VMTracer for Informant<Trace, Out> {
+    type Output = ();
+
+    fn trace_next_instruction(&mut self, pc: usize, instruction: u8, current_gas: U256) -> bool {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant<Trace, Out>| {
+            let info = ::evm::Instruction::from_u8(instruction).map(|i| i.info());
+            informant.instruction = instruction;
+            let trace_data = json!({
+                "pc": pc,
+                "op": instruction,
+                "opName": info.map(|i| i.name).unwrap_or(""),
+                "gas": format!("{:#x}", current_gas),
+                "stack": informant.stack,
+                "storage": informant.storage,
+                "depth": informant.depth,
+            });
+
+            writeln!(&mut informant.trace_sink, "{}", trace_data)
+                .expect("The sink must be writeable.");
+        });
+        true
+    }
+
+    fn trace_prepare_execute(
+        &mut self,
+        _pc: usize,
+        _instruction: u8,
+        _gas_cost: U256,
+        _mem_written: Option<(usize, usize)>,
+        store_written: Option<(U256, U256)>,
+    ) {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant<Trace, Out>| {
+            if let Some((pos, val)) = store_written {
+                informant.storage.insert(pos.into(), val.into());
+            }
+        });
+    }
+
+    fn trace_executed(&mut self, _gas_used: U256, stack_push: &[U256], _mem: &[u8]) {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant<Trace, Out>| {
+            let info = ::evm::Instruction::from_u8(informant.instruction).map(|i| i.info());
+
+            let len = informant.stack.len();
+            let info_args = info.map(|i| i.args).unwrap_or(0);
+            informant
+                .stack
+                .truncate(if len > info_args { len - info_args } else { 0 });
+            informant.stack.extend_from_slice(stack_push);
+        });
+    }
+
+    fn prepare_subtrace(&mut self, code: &[u8]) {
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant<Trace, Out>| {
+            let mut vm = Informant::new(
+                informant.trace_sink.clone(),
+                informant.out_sink.clone(),
+                informant.config,
+            );
+            vm.depth = informant.depth + 1;
+            vm.code = code.to_vec();
+            informant.subinfos.push(vm);
+        });
+        self.subdepth += 1;
+    }
+
+    fn done_subtrace(&mut self) {
+        self.subdepth -= 1;
+        let subdepth = self.subdepth;
+        Self::with_informant_in_depth(self, subdepth, |informant: &mut Informant<Trace, Out>| {
+            informant.subinfos.pop();
+        });
+    }
+
+    fn drain(self) -> Option<Self::Output> {
+        None
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+    use info::tests::run_test;
+    use std::sync::{Arc, Mutex};
+
+    #[derive(Debug, Clone, Default)]
+    pub struct TestWriter(pub Arc<Mutex<Vec<u8>>>);
+
+    impl Writer for TestWriter {
+        fn clone(&self) -> Self {
+            Clone::clone(self)
+        }
+        fn default() -> Self {
+            Default::default()
+        }
+    }
+
+    impl io::Write for TestWriter {
+        fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+            self.0.lock().unwrap().write(buf)
+        }
+
+        fn flush(&mut self) -> io::Result<()> {
+            self.0.lock().unwrap().flush()
+        }
+    }
+
+    pub fn informant() -> (Informant<TestWriter, TestWriter>, Arc<Mutex<Vec<u8>>>) {
+        let trace_writer: TestWriter = Default::default();
+        let out_writer: TestWriter = Default::default();
+        let res = trace_writer.0.clone();
+        (
+            Informant::new(trace_writer, out_writer, Config::default()),
+            res,
+        )
+    }
+
+    #[test]
+    fn should_trace_failure() {
+        let (inf, res) = informant();
+        run_test(
+            inf,
+            move |_, expected| {
+                let bytes = res.lock().unwrap();
+                assert_eq!(expected, &String::from_utf8_lossy(&**bytes))
+            },
+            "60F8d6",
+            0xffff,
+            r#"{"depth":1,"gas":"0xffff","op":96,"opName":"PUSH1","pc":0,"stack":[],"storage":{}}
+{"depth":1,"gas":"0xfffc","op":214,"opName":"","pc":2,"stack":["0xf8"],"storage":{}}
+"#,
+        );
+
+        let (inf, res) = informant();
+        run_test(
+            inf,
+            move |_, expected| {
+                let bytes = res.lock().unwrap();
+                assert_eq!(expected, &String::from_utf8_lossy(&**bytes))
+            },
+            "F8d6",
+            0xffff,
+            r#"{"depth":1,"gas":"0xffff","op":248,"opName":"","pc":0,"stack":[],"storage":{}}
+"#,
+        );
+    }
+
+    #[test]
+    fn should_trace_create_correctly() {
+        let (informant, res) = informant();
+        run_test(
+            informant,
+            move |_, expected| {
+                let bytes = res.lock().unwrap();
+                assert_eq!(expected, &String::from_utf8_lossy(&**bytes))
+            },
+            "32343434345830f138343438323439f0",
+            0xffff,
+            r#"{"depth":1,"gas":"0xffff","op":50,"opName":"ORIGIN","pc":0,"stack":[],"storage":{}}
+{"depth":1,"gas":"0xfffd","op":52,"opName":"CALLVALUE","pc":1,"stack":["0x0"],"storage":{}}
+{"depth":1,"gas":"0xfffb","op":52,"opName":"CALLVALUE","pc":2,"stack":["0x0","0x0"],"storage":{}}
+{"depth":1,"gas":"0xfff9","op":52,"opName":"CALLVALUE","pc":3,"stack":["0x0","0x0","0x0"],"storage":{}}
+{"depth":1,"gas":"0xfff7","op":52,"opName":"CALLVALUE","pc":4,"stack":["0x0","0x0","0x0","0x0"],"storage":{}}
+{"depth":1,"gas":"0xfff5","op":88,"opName":"PC","pc":5,"stack":["0x0","0x0","0x0","0x0","0x0"],"storage":{}}
+{"depth":1,"gas":"0xfff3","op":48,"opName":"ADDRESS","pc":6,"stack":["0x0","0x0","0x0","0x0","0x0","0x5"],"storage":{}}
+{"depth":1,"gas":"0xfff1","op":241,"opName":"CALL","pc":7,"stack":["0x0","0x0","0x0","0x0","0x0","0x5","0x0"],"storage":{}}
+{"depth":1,"gas":"0x9e21","op":56,"opName":"CODESIZE","pc":8,"stack":["0x1"],"storage":{}}
+{"depth":1,"gas":"0x9e1f","op":52,"opName":"CALLVALUE","pc":9,"stack":["0x1","0x10"],"storage":{}}
+{"depth":1,"gas":"0x9e1d","op":52,"opName":"CALLVALUE","pc":10,"stack":["0x1","0x10","0x0"],"storage":{}}
+{"depth":1,"gas":"0x9e1b","op":56,"opName":"CODESIZE","pc":11,"stack":["0x1","0x10","0x0","0x0"],"storage":{}}
+{"depth":1,"gas":"0x9e19","op":50,"opName":"ORIGIN","pc":12,"stack":["0x1","0x10","0x0","0x0","0x10"],"storage":{}}
+{"depth":1,"gas":"0x9e17","op":52,"opName":"CALLVALUE","pc":13,"stack":["0x1","0x10","0x0","0x0","0x10","0x0"],"storage":{}}
+{"depth":1,"gas":"0x9e15","op":57,"opName":"CODECOPY","pc":14,"stack":["0x1","0x10","0x0","0x0","0x10","0x0","0x0"],"storage":{}}
+{"depth":1,"gas":"0x9e0c","op":240,"opName":"CREATE","pc":15,"stack":["0x1","0x10","0x0","0x0"],"storage":{}}
+{"depth":2,"gas":"0x210c","op":50,"opName":"ORIGIN","pc":0,"stack":[],"storage":{}}
+{"depth":2,"gas":"0x210a","op":52,"opName":"CALLVALUE","pc":1,"stack":["0x0"],"storage":{}}
+{"depth":2,"gas":"0x2108","op":52,"opName":"CALLVALUE","pc":2,"stack":["0x0","0x0"],"storage":{}}
+{"depth":2,"gas":"0x2106","op":52,"opName":"CALLVALUE","pc":3,"stack":["0x0","0x0","0x0"],"storage":{}}
+{"depth":2,"gas":"0x2104","op":52,"opName":"CALLVALUE","pc":4,"stack":["0x0","0x0","0x0","0x0"],"storage":{}}
+{"depth":2,"gas":"0x2102","op":88,"opName":"PC","pc":5,"stack":["0x0","0x0","0x0","0x0","0x0"],"storage":{}}
+{"depth":2,"gas":"0x2100","op":48,"opName":"ADDRESS","pc":6,"stack":["0x0","0x0","0x0","0x0","0x0","0x5"],"storage":{}}
+{"depth":2,"gas":"0x20fe","op":241,"opName":"CALL","pc":7,"stack":["0x0","0x0","0x0","0x0","0x0","0x5","0xbd770416a3345f91e4b34576cb804a576fa48eb1"],"storage":{}}
+"#,
+        )
+    }
+}