use ZST error type for snappy, use new snappy compression methods

ethcore/src/error.rs

@@ -229,7 +229,7 @@ pub enum Error {
 	/// Io error.
 	Io(::std::io::Error),
 	/// Snappy error.
-	Snappy(::util::snappy::Error),
+	Snappy(::util::snappy::InvalidInput),
 }
 
 impl fmt::Display for Error {
@@ -321,8 +321,8 @@ impl From<::std::io::Error> for Error {
 	}
 }
 
-impl From<::util::snappy::Error> for Error {
-	fn from(err: ::util::snappy::Error) -> Error {
+impl From<::util::snappy::InvalidInput> for Error {
+	fn from(err: ::util::snappy::InvalidInput) -> Error {
 		Error::Snappy(err)
 	}
 }

ethcore/src/snapshot/mod.rs

@@ -40,41 +40,10 @@ mod block;
 // Try to have chunks be around 16MB (before compression)
 const PREFERRED_CHUNK_SIZE: usize = 16 * 1024 * 1024;
 
-// compresses the data into the buffer, resizing if necessary.
-fn compression_helper(input: &[u8], output: &mut Vec<u8>) -> usize {
-	let max_size = snappy::max_compressed_len(input.len());
-	let buf_len = output.len();
-
-	// resize if necessary, but in reality this will probably almost never happen.
-	if max_size > buf_len {
-		output.resize(max_size, 0);
-	}
-
-	match snappy::compress_into(&input, output) {
-		Ok(size) => size,
-		Err(snappy::Error::BufferTooSmall) => panic!("buffer too small although capacity ensured?"),
-		Err(snappy::Error::InvalidInput) => panic!("invalid input error impossible in snappy_compress"),
-	}
-}
-
-// decompresses the data into the buffer, resizing if necessary.
-// may return invalid input error.
-fn decompression_helper(input: &[u8], output: &mut Vec<u8>) -> Result<usize, snappy::Error> {
-	let size = try!(snappy::decompressed_len(input));
-	let buf_len = output.len();
-
-	// resize if necessary, slow path.
-	if size > buf_len {
-		output.resize(size, 0);
-	}
-
-	snappy::decompress_into(&input, output)
-}
-
 // shared portion of write_chunk
 // returns either a (hash, compressed_size) pair or an io error.
 fn write_chunk(raw_data: &[u8], compression_buffer: &mut Vec<u8>, path: &Path) -> Result<(H256, usize), Error> {
-	let compressed_size = compression_helper(raw_data, compression_buffer);
+	let compressed_size = snappy::compress_into(raw_data, compression_buffer);
 	let compressed = &compression_buffer[..compressed_size];
 	let hash = compressed.sha3();
 
@@ -320,7 +289,7 @@ impl<'a> StateRebuilder<'a> {
 
 	/// Feed a compressed state chunk into the rebuilder.
 	pub fn feed(&mut self, compressed: &[u8]) -> Result<(), Error> {
-		let len = try!(decompression_helper(compressed, &mut self.snappy_buffer));
+		let len = try!(snappy::decompress_into(compressed, &mut self.snappy_buffer));
 		let rlp = UntrustedRlp::new(&self.snappy_buffer[..len]);
 
 		for account_pair in rlp.iter() {

util/src/error.rs

@@ -66,7 +66,7 @@ pub enum UtilError {
 	/// Error from a bad input size being given for the needed output.
 	BadSize,
 	/// Error from snappy.
-	Snappy(::snappy::Error),
+	Snappy(::snappy::InvalidInput),
 }
 
 impl fmt::Display for UtilError {
@@ -182,8 +182,8 @@ impl From<String> for UtilError {
 	}
 }
 
-impl From<::snappy::Error> for UtilError {
-	fn from(err: ::snappy::Error) -> UtilError {
+impl From<::snappy::InvalidInput> for UtilError {
+	fn from(err: ::snappy::InvalidInput) -> UtilError {
 		UtilError::Snappy(err)
 	}
 }

util/src/snappy.rs

@@ -53,23 +53,13 @@ extern {
 	) -> c_int;
 }
 
-/// Errors that can occur during usage of snappy.
+/// Attempted to decompress an uncompressed buffer.
 #[derive(Debug)]
-pub enum Error {
-	/// An invalid input was supplied. Usually means that you tried to decompress an uncompressed
-	/// buffer.
-	InvalidInput,
-	/// The output buffer supplied was too small. Make sure to provide buffers large enough to hold
-	/// all the output data.
-	BufferTooSmall,
-}
+pub struct InvalidInput;
 
-impl fmt::Display for Error {
+impl fmt::Display for InvalidInput {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-		match *self {
-			Error::InvalidInput => write!(f, "Snappy error (invalid input)"),
-			Error::BufferTooSmall => write!(f, "Snappy error (buffer too small)"),
-		}
+		write!(f, "Attempted snappy decompression with invalid input")
 	}
 }
 
@@ -79,30 +69,30 @@ pub fn max_compressed_len(len: usize) -> usize {
 }
 
 /// How large the given data will be when decompressed.
-pub fn decompressed_len(compressed: &[u8]) -> Result<usize, Error> {
+pub fn decompressed_len(compressed: &[u8]) -> Result<usize, InvalidInput> {
 	let mut size: size_t = 0;
 	let len = compressed.len() as size_t;
 
 	let status = unsafe { snappy_uncompressed_length(compressed.as_ptr() as *const c_char, len, &mut size) };
 
 	if status == SNAPPY_INVALID_INPUT {
-		Err(Error::InvalidInput)
+		Err(InvalidInput)
 	} else {
-		Ok(len)
+		Ok(size)
 	}
 }
 
 /// Compress a buffer using snappy.
 pub fn compress(input: &[u8]) -> Vec<u8> {
 	let mut buf = Vec::new();
-	compress_into(input, &mut buf).expect("snappy compression failed");
+	compress_into(input, &mut buf);
 	buf
 }
 
 /// Compress a buffer using snappy, writing the result into
 /// the given output buffer, growing it if necessary.
 /// Otherwise, returns the length of the compressed data.
-pub fn compress_into(input: &[u8], output: &mut Vec<u8>) -> Result<usize, Error> {
+pub fn compress_into(input: &[u8], output: &mut Vec<u8>) -> usize {
 	let mut len = max_compressed_len(input.len());
 
 	if output.len() < len {
@@ -119,15 +109,15 @@ pub fn compress_into(input: &[u8], output: &mut Vec<u8>) -> Result<usize, Error>
 	};
 
 	match status {
-		SNAPPY_OK => Ok(len),
-		SNAPPY_INVALID_INPUT => Err(Error::InvalidInput), // should never happen, but can't hurt!
+		SNAPPY_OK => len,
+		SNAPPY_INVALID_INPUT => panic!("snappy compression has no concept of invalid input"),
 		SNAPPY_BUFFER_TOO_SMALL => panic!("buffer cannot be too small, the capacity was just ensured."),
 		_ => panic!("snappy returned unspecified status"),
 	}
 }
 
 /// Decompress a buffer using snappy. Will return an error if the buffer is not snappy-compressed.
-pub fn decompress(input: &[u8]) -> Result<Vec<u8>, Error> {
+pub fn decompress(input: &[u8]) -> Result<Vec<u8>, InvalidInput> {
 	let mut v = Vec::new();
 	decompress_into(input, &mut v).map(|_| v)
 }
@@ -136,7 +126,7 @@ pub fn decompress(input: &[u8]) -> Result<Vec<u8>, Error> {
 /// the given output buffer, growing it if necessary.
 /// Will error if the input buffer is not snappy-compressed.
 /// Otherwise, returns the length of the decompressed data.
-pub fn decompress_into(input: &[u8], output: &mut Vec<u8>) -> Result<usize, Error> {
+pub fn decompress_into(input: &[u8], output: &mut Vec<u8>) -> Result<usize, InvalidInput> {
 	let mut len = try!(decompressed_len(input));
 
 	if output.len() < len {
@@ -154,7 +144,7 @@ pub fn decompress_into(input: &[u8], output: &mut Vec<u8>) -> Result<usize, Erro
 
 	match status {
 		SNAPPY_OK => Ok(len as usize),
-		SNAPPY_INVALID_INPUT => Err(Error::InvalidInput),
+		SNAPPY_INVALID_INPUT => Err(InvalidInput),
 		SNAPPY_BUFFER_TOO_SMALL => panic!("buffer cannot be too small, size was just set to large enough."),
 		_ => panic!("snappy returned unspecified status"),
 	}