Merge pull request #7097 from paritytech/panic-payload-with-msg

WASM parse payload from panics

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("<EFBFBD>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,
+			}
+		);
+	}
+}