more work on disk format

Cargo.toml

@@ -18,6 +18,7 @@
 
 [dependencies]
 
+	byteorder = "1.1"
 	chrono = "0.4"
 	crc = "1.4"
 	flate2 = "0.2"

src/diskformat/compression.rs

@@ -0,0 +1,245 @@
+use super::prelude::*;
+
+pub fn btrfs_decompress_pages (
+	compression_type: u8,
+	raw_data: & [u8],
+	logical_size: u64,
+) -> Result <Cow <[u8]>, String> {
+
+	match compression_type {
+
+		BTRFS_EXTENT_DATA_NO_COMPRESSION =>
+			Ok (Cow::Borrowed (
+				raw_data,
+			)),
+
+		BTRFS_EXTENT_DATA_LZO_COMPRESSION => {
+
+			let mut buffer: Vec <u8> =
+				Vec::new ();
+
+			let mut position: usize = 0;
+
+			if raw_data.len () < 4 {
+
+				return Err (
+					format! (
+						"LZO paging corruption (0)"));
+
+			}
+
+			let total_compressed_size =
+				LittleEndian::read_u32 (
+					& raw_data [position .. position + 4],
+				) as usize;
+
+			if raw_data.len () < total_compressed_size {
+
+				return Err (
+					format! (
+						"LZO paging corruption (1) @ {} / {}",
+						position,
+						total_compressed_size));
+
+			}
+
+			position += 4;
+
+			while position < total_compressed_size {
+
+				// skip to next memory page if page compressed size won't fit
+
+				let bytes_left =
+					0x1000 - (position % 0x1000);
+
+				if bytes_left < 4 {
+
+					if position + bytes_left > total_compressed_size {
+
+						return Err (
+							format! (
+								"LZO paging corruption (2) @ {} / {}",
+								position,
+								total_compressed_size));
+
+					}
+
+					position += bytes_left;
+
+				}
+
+				if position == total_compressed_size {
+					break;
+				}
+
+				// read page compressed size
+
+				if position + 4 > total_compressed_size {
+
+					return Err (
+						format! (
+							"LZO paging corruption (3) @ {} / {}",
+							position,
+							total_compressed_size));
+
+				}
+
+				let page_compressed_size =
+					LittleEndian::read_u32 (
+						& raw_data [position .. position + 4],
+					) as usize;
+
+				position += 4;
+
+				// read page
+
+				if position + page_compressed_size > total_compressed_size {
+
+					return Err (
+						format! (
+							"LZO paging corruption (4) @ {} / {}",
+							position,
+							total_compressed_size));
+
+				}
+
+				buffer.extend_from_slice (
+					& minilzo::decompress (
+						& raw_data [
+							position
+						..
+							position + page_compressed_size
+						],
+						logical_size as usize,
+					).map_err (
+						|error|
+
+						format! (
+							"LZO decompression failed: {:?}",
+							error)
+
+					) ?,
+				);
+
+				position += page_compressed_size;
+
+			}
+
+			Ok (Cow::Owned (buffer))
+
+		},
+
+		BTRFS_EXTENT_DATA_ZLIB_COMPRESSION =>
+			btrfs_decompress (
+				compression_type,
+				& raw_data [8 .. ],
+				logical_size),
+
+		_ =>
+			panic! (),
+
+	}
+
+}
+
+pub fn btrfs_decompress (
+	compression_type: u8,
+	raw_data: & [u8],
+	logical_size: u64,
+) -> Result <Cow <[u8]>, String> {
+
+	match compression_type {
+
+		BTRFS_EXTENT_DATA_NO_COMPRESSION =>
+			Ok (Cow::Borrowed (
+				raw_data,
+			)),
+
+		BTRFS_EXTENT_DATA_LZO_COMPRESSION => try! (
+			minilzo::decompress (
+				raw_data,
+				logical_size as usize,
+			).map (
+				|uncompressed_data|
+
+				Ok (Cow::Owned (
+					uncompressed_data,
+				))
+
+			).or_else (
+				|error|
+
+				Err (
+					format! (
+						"LZO decompression failed: {:?}",
+						error)
+				)
+
+			)
+		),
+
+		BTRFS_EXTENT_DATA_ZLIB_COMPRESSION => {
+
+			let mut uncompressed_data =
+				Vec::with_capacity (
+					logical_size as usize);
+
+			uncompressed_data.resize (
+				logical_size as usize,
+				0u8);
+
+			let mut decompress =
+				flate2::Decompress::new (
+					false);
+
+			match (
+				decompress.decompress (
+					raw_data,
+					& mut uncompressed_data,
+					flate2::Flush::Finish,
+				).unwrap_or_else (
+					|error|
+
+					panic! (
+						"ZLIB decompression failed: {:?}",
+						error)
+
+				)
+			) {
+
+				flate2::Status::Ok =>
+					(),
+
+				_ =>
+					panic! (
+						"ZLIB decompression failed"),
+
+			}
+
+			if decompress.total_out () as usize
+				!= uncompressed_data.len () {
+
+				panic! (
+					"ZLIB decompressed size {} does not match {}",
+					decompress.total_out (),
+					uncompressed_data.len ());
+
+			}
+
+			Ok (Cow::Owned (
+					uncompressed_data
+			))
+
+		},
+
+		_ =>
+			panic! (
+				format! (
+					"Unrecognised inline extent data compression {}",
+					compression_type)),
+
+	}
+
+}
+
+// ex: noet ts=4 filetype=rust

src/diskformat/core/device_set.rs

@@ -113,14 +113,14 @@ impl <'a> BtrfsDeviceSet <'a> {
 
 			) ?;
 
-		self.system_slice_at_physical_address (
+		self.slice_at_physical_address (
 			physical_address,
 			size,
 		)
 
 	}
 
-	pub fn system_slice_at_physical_address (
+	pub fn slice_at_physical_address (
 		& self,
 		physical_address: BtrfsPhysicalAddress,
 		size: usize,