WASM parse payload from panics

ethcore/wasm/src/lib.rs

@@ -31,6 +31,7 @@ mod result;
 #[cfg(test)]
 mod tests;
 mod env;
+mod panic_payload;
 
 const DEFAULT_STACK_SPACE: u32 = 5 * 1024 * 1024;
 

ethcore/wasm/src/panic_payload.rs

@@ -0,0 +1,168 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity 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.
+
+// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+use byteorder::{LittleEndian, ReadBytesExt};
+use std::io::{self, Read};
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct PanicPayload {
+	pub msg: Option<String>,
+	pub file: Option<String>,
+	pub line: Option<u32>,
+	pub col: Option<u32>,
+}
+
+fn read_string(rdr: &mut io::Cursor<&[u8]>) -> io::Result<Option<String>> {
+	let string_len = rdr.read_u32::<LittleEndian>()?;
+	let string = if string_len == 0 {
+		None
+	} else {
+		let mut content = vec![0; string_len as usize];
+		rdr.read_exact(&mut content)?;
+		Some(String::from_utf8_lossy(&content).into_owned())
+	};
+	Ok(string)
+}
+
+pub fn decode(raw: &[u8]) -> PanicPayload {
+	let mut rdr = io::Cursor::new(raw);
+	let msg = read_string(&mut rdr).ok().and_then(|x| x);
+	let file = read_string(&mut rdr).ok().and_then(|x| x);
+	let line = rdr.read_u32::<LittleEndian>().ok();
+	let col = rdr.read_u32::<LittleEndian>().ok();
+	PanicPayload {
+		msg: msg,
+		file: file,
+		line: line,
+		col: col,
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use byteorder::WriteBytesExt;
+
+	fn write_u32(payload: &mut Vec<u8>, val: u32) {
+		payload.write_u32::<LittleEndian>(val).unwrap();
+	}
+
+	fn write_bytes(payload: &mut Vec<u8>, bytes: &[u8]) {
+		write_u32(payload, bytes.len() as u32);
+		payload.extend(bytes);
+	}
+
+	#[test]
+	fn it_works() {
+		let mut raw = Vec::new();
+		write_bytes(&mut raw, b"msg");
+		write_bytes(&mut raw, b"file");
+		write_u32(&mut raw, 1);
+		write_u32(&mut raw, 2);
+
+		let payload = decode(&raw);
+
+		assert_eq!(
+			payload,
+			PanicPayload {
+				msg: Some("msg".to_string()),
+				file: Some("file".to_string()),
+				line: Some(1),
+				col: Some(2),
+			}
+		);
+	}
+
+	#[test]
+	fn only_msg() {
+		let mut raw = Vec::new();
+		write_bytes(&mut raw, b"msg");
+
+		let payload = decode(&raw);
+
+		assert_eq!(
+			payload,
+			PanicPayload {
+				msg: Some("msg".to_string()),
+				file: None,
+				line: None,
+				col: None,
+			}
+		);
+	}
+
+	#[test]
+	fn invalid_utf8() {
+		let mut raw = Vec::new();
+		write_bytes(&mut raw, b"\xF0\x90\x80msg");
+		write_bytes(&mut raw, b"file");
+		write_u32(&mut raw, 1);
+		write_u32(&mut raw, 2);
+
+		let payload = decode(&raw);
+
+		assert_eq!(
+			payload,
+			PanicPayload {
+				msg: Some("�msg".to_string()),
+				file: Some("file".to_string()),
+				line: Some(1),
+				col: Some(2),
+			}
+		);
+	}
+
+	#[test]
+	fn trailing_data() {
+		let mut raw = Vec::new();
+		write_bytes(&mut raw, b"msg");
+		write_bytes(&mut raw, b"file");
+		write_u32(&mut raw, 1);
+		write_u32(&mut raw, 2);
+		write_u32(&mut raw, 0xdeadbeef);
+
+		let payload = decode(&raw);
+
+		assert_eq!(
+			payload,
+			PanicPayload {
+				msg: Some("msg".to_string()),
+				file: Some("file".to_string()),
+				line: Some(1),
+				col: Some(2),
+			}
+		);
+	}
+
+	#[test]
+	fn empty_str_is_none() {
+		let mut raw = Vec::new();
+		write_bytes(&mut raw, b"msg");
+		write_bytes(&mut raw, b"");
+
+		let payload = decode(&raw);
+
+		assert_eq!(
+			payload,
+			PanicPayload {
+				msg: Some("msg".to_string()),
+				file: None,
+				line: None,
+				col: None,
+			}
+		);
+	}
+}

ethcore/wasm/src/runtime.rs

@@ -21,6 +21,7 @@ use std::sync::Arc;
 use byteorder::{LittleEndian, ByteOrder};
 
 use vm;
+use panic_payload;
 use parity_wasm::interpreter;
 use wasm_utils::rules;
 use bigint::prelude::U256;
@@ -626,12 +627,26 @@ impl<'a, 'b> Runtime<'a, 'b> {
 	fn user_panic(&mut self, context: InterpreterCallerContext)
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
-		let msg_len = context.value_stack.pop_as::<i32>()? as u32;
-		let msg_ptr = context.value_stack.pop_as::<i32>()? as u32;
-
-		let msg = String::from_utf8(self.memory.get(msg_ptr, msg_len as usize)?)
-			.map_err(|_| UserTrap::BadUtf8)?;
-
+		let payload_len = context.value_stack.pop_as::<i32>()? as u32;
+		let payload_ptr = context.value_stack.pop_as::<i32>()? as u32;
+
+		let raw_payload = self.memory.get(payload_ptr, payload_len as usize)?;
+		let payload = panic_payload::decode(&raw_payload);
+		let msg = format!(
+			"{msg}, {file}:{line}:{col}",
+			msg = payload
+				.msg
+				.as_ref()
+				.map(String::as_ref)
+				.unwrap_or("<msg was stripped>"),
+			file = payload
+				.file
+				.as_ref()
+				.map(String::as_ref)
+				.unwrap_or("<unknown>"),
+			line = payload.line.unwrap_or(0),
+			col = payload.col.unwrap_or(0)
+		);
 		trace!(target: "wasm", "Contract custom panic message: {}", msg);
 
 		Err(UserTrap::Panic(msg).into())

ethcore/wasm/src/tests.rs

@@ -180,7 +180,7 @@ fn dispersion() {
 		result,
 		vec![0u8, 0, 125, 11, 197, 7, 255, 8, 19, 0]
 	);
-	assert_eq!(gas_left, U256::from(99_469));
+	assert_eq!(gas_left, U256::from(96_961));
 }
 
 #[test]
@@ -208,7 +208,7 @@ fn suicide_not() {
 		result,
 		vec![0u8]
 	);
-	assert_eq!(gas_left, U256::from(99_724));
+	assert_eq!(gas_left, U256::from(97_290));
 }
 
 #[test]
@@ -240,7 +240,7 @@ fn suicide() {
 	};
 
 	assert!(ext.suicides.contains(&refund));
-	assert_eq!(gas_left, U256::from(99_663));
+	assert_eq!(gas_left, U256::from(97_249));
 }
 
 #[test]
@@ -312,7 +312,7 @@ fn call_code() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Call,
-			gas: U256::from(98_709),
+			gas: U256::from(98_713),
 			sender_address: Some(sender),
 			receive_address: Some(receiver),
 			value: None,
@@ -324,7 +324,7 @@ fn call_code() {
 	// siphash result
 	let res = LittleEndian::read_u32(&result[..]);
 	assert_eq!(res, 4198595614);
-	assert_eq!(gas_left, U256::from(93_851));
+	assert_eq!(gas_left, U256::from(93_855));
 }
 
 #[test]
@@ -357,7 +357,7 @@ fn call_static() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Call,
-			gas: U256::from(98_709),
+			gas: U256::from(98_713),
 			sender_address: Some(sender),
 			receive_address: Some(receiver),
 			value: None,
@@ -370,7 +370,7 @@ fn call_static() {
 	let res = LittleEndian::read_u32(&result[..]);
 	assert_eq!(res, 317632590);
 
-	assert_eq!(gas_left, U256::from(93_851));
+	assert_eq!(gas_left, U256::from(93_855));
 }
 
 // Realloc test
@@ -393,7 +393,7 @@ fn realloc() {
 		}
 	};
 	assert_eq!(result, vec![0u8; 2]);
-	assert_eq!(gas_left, U256::from(99_787));
+	assert_eq!(gas_left, U256::from(97_278));
 }
 
 // Tests that contract's ability to read from a storage
@@ -419,7 +419,7 @@ fn storage_read() {
 	};
 
 	assert_eq!(Address::from(&result[12..32]), address);
-	assert_eq!(gas_left, U256::from(99_702));
+	assert_eq!(gas_left, U256::from(99_706));
 }
 
 // Tests keccak calculation
@@ -445,7 +445,7 @@ fn keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(84_520));
+	assert_eq!(gas_left, U256::from(82_009));
 }
 
 // memcpy test.
@@ -477,7 +477,7 @@ fn memcpy() {
 	};
 
 	assert_eq!(result, test_payload);
-	assert_eq!(gas_left, U256::from(75_324));
+	assert_eq!(gas_left, U256::from(72_773));
 }
 
 // memmove test.
@@ -509,7 +509,7 @@ fn memmove() {
 	};
 
 	assert_eq!(result, test_payload);
-	assert_eq!(gas_left, U256::from(75_324));
+	assert_eq!(gas_left, U256::from(72_773));
 }
 
 // memset test
@@ -534,7 +534,7 @@ fn memset() {
 	};
 
 	assert_eq!(result, vec![228u8; 8192]);
-	assert_eq!(gas_left, U256::from(75_324));
+	assert_eq!(gas_left, U256::from(72_763));
 }
 
 macro_rules! reqrep_test {
@@ -591,7 +591,7 @@ fn math_add() {
 		U256::from_dec_str("1888888888888888888888888888887").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(98_576));
+	assert_eq!(gas_left, U256::from(96_084));
 }
 
 // multiplication
@@ -613,7 +613,7 @@ fn math_mul() {
 		U256::from_dec_str("888888888888888888888888888887111111111111111111111111111112").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(97_726));
+	assert_eq!(gas_left, U256::from(95_234));
 }
 
 // subtraction
@@ -635,7 +635,7 @@ fn math_sub() {
 		U256::from_dec_str("111111111111111111111111111111").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(98_568));
+	assert_eq!(gas_left, U256::from(96_076));
 }
 
 // subtraction with overflow
@@ -677,7 +677,7 @@ fn math_div() {
 		U256::from_dec_str("1125000").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(91_564));
+	assert_eq!(gas_left, U256::from(89_074));
 }
 
 // This test checks the ability of wasm contract to invoke
@@ -765,7 +765,7 @@ fn externs() {
 		"Gas limit requested and returned does not match"
 	);
 
-	assert_eq!(gas_left, U256::from(97_740));
+	assert_eq!(gas_left, U256::from(95_291));
 }
 
 #[test]
@@ -791,7 +791,7 @@ fn embedded_keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(84_520));
+	assert_eq!(gas_left, U256::from(82_009));
 }
 
 /// This test checks the correctness of log extern
@@ -826,5 +826,5 @@ fn events() {
 	assert_eq!(&log_entry.data, b"gnihtemos");
 
 	assert_eq!(&result, b"gnihtemos");
-	assert_eq!(gas_left, U256::from(82_721));
+	assert_eq!(gas_left, U256::from(80_199));
 }