add specification for lrzip

archive/lrzip.ksy

@@ -0,0 +1,149 @@
+meta:
+  id: lrzip
+  title: lrzip 0.6
+  file-extension: lrz
+  license: CC0-1.0
+  endian: le
+doc-ref: https://github.com/ckolivas/lrzip/blob/master/doc/magic.header.txt
+seq:
+  - id: header
+    type: header
+    size: 24
+  - id: rchunks
+    type: rchunk
+    repeat: until
+    repeat-until: _.last_chunk
+    if: not header.is_encrypted
+types:
+  header:
+    seq:
+      - id: signature
+        contents: ['LRZI']
+      - id: version
+        type: version
+      - id: len_file_or_salt
+        type: u8
+      - id: unused_1
+        size: 2
+      - id: lzma_properties
+        type: lzma_properties
+      - id: md5sum_flag
+        type: u1
+      - id: encryption_flag
+        type: u1
+      - id: unused_2
+        size: 1
+    instances:
+      has_md5:
+        value: md5sum_flag & 0x01 == 1
+      is_encrypted:
+        value: encryption_flag & 0x01 == 1
+  lzma_properties:
+    seq:
+      - id: lc
+        type: u1
+      - id: lp
+        type: u1
+      - id: pb
+        type: u1
+      - id: fb
+        type: u1
+      - id: len_dictionary
+        type: u1
+  version:
+    seq:
+      - id: major
+        type: u1
+        valid: 0
+      - id: minor
+        type: u1
+        valid: 6
+  rchunk:
+    seq:
+      - id: byte_width
+        type: u1
+        valid:
+          min: 1
+          max: 4
+      - id: eof_flag
+        type: u1
+      - id: len_uncompressed
+        type:
+          switch-on: byte_width
+          cases:
+            1: u1
+            2: u2
+            3: b24le
+            4: u4
+            8: u8
+      - id: stream_0
+        type: stream_header_data(byte_width, _io.pos)
+      - id: stream_1
+        type: stream_header_data(byte_width, _io.pos - stream_0.size)
+        # oh, what an ugly hack...
+    instances:
+      last_chunk:
+        value: eof_flag == 1
+  stream_header_data:
+    params:
+      - id: byte_width
+        type: u1
+      - id: start_position
+        type: u4
+    seq:
+      - id: compressed_data_type
+        type: u1
+        enum: compression
+        valid:
+          any-of:
+            - compression::no_compression
+            - compression::bzip2
+            - compression::lzo
+            - compression::lzma
+            - compression::gzip
+            - compression::zpaq
+      - id: len_data
+        type:
+          switch-on: byte_width
+          cases:
+            1: u1
+            2: u2
+            3: b24le
+            4: u4
+            8: u8
+      - id: len_uncompressed_data
+        type:
+          switch-on: byte_width
+          cases:
+            1: u1
+            2: u2
+            3: b24le
+            4: u4
+            8: u8
+      - id: next_block_head
+        type:
+          switch-on: byte_width
+          cases:
+            1: u1
+            2: u2
+            3: b24le
+            4: u4
+            8: u8
+      - id: data
+        size: len_data
+    instances:
+      size:
+        value: 1 + 3 * byte_width
+      next:
+        pos: next_block_head + start_position
+        io: _root._io
+        type: stream_header_data(byte_width, start_position)
+        if: next_block_head != 0
+enums:
+  compression:
+    3: no_compression
+    4: bzip2
+    5: lzo
+    6: lzma
+    7: gzip
+    8: zpaq