add specification for TP-Link's minifs

filesystem/tplink_minifs.ksy

@@ -0,0 +1,112 @@
+meta:
+  id: tplink_minifs
+  title: TP-Link MINIFS
+  license: CC0-1.0
+  endian: be
+  encoding: ASCII
+doc: |
+  MINIFS is a file system found in certain TP-Link firmware files, such as
+  RE450(V4)_210531.zip, for TP-Link's own TPOS RTOS.
+
+  It consists of a header, followed by a list of file names, followed by
+  meta information for each file, meta information about the LZMA compressed
+  blobs including length, offset and uncompressed length, and then a number
+  of LZMA compressed blobs.
+
+  The LZMA blobs can contain the concatenated contents of multiple files.
+  The meta information of a file contains an offset to the directory name,
+  a file name, the LZMA blob (numbering starts at 0), the offset of the file
+  in the uncompressed data and the size of the uncompressed file.
+seq:
+  - id: header
+    size: 32
+    type: header
+  - id: filenames
+    size: header.len_filenames
+    type: filenames
+  - id: inodes
+    type: 'inode(_index != 0 ? inodes[_index - 1].cur_max_lzma_blob : 0)'
+    repeat: expr
+    repeat-expr: header.num_files
+  - id: lzma_metas
+    type: 'lzma_meta(_index != 0 ? lzma_metas[_index - 1].cur_max_lzma_blob_len : 0)'
+    repeat: expr
+    repeat-expr: inodes.last.cur_max_lzma_blob + 1
+    doc: Count starts at 0, so there is one more blob than the highest blob number
+  - id: lzma_blobs_area
+    size: lzma_metas.last.cur_max_lzma_blob_len
+    type: dummy
+instances:
+  lzma_blobs:
+    io: _root.lzma_blobs_area._io
+    type: lzma_blob(_index)
+    repeat: expr
+    repeat-expr: _root.inodes.last.cur_max_lzma_blob + 1
+types:
+  dummy: {}
+  lzma_blob:
+    params:
+      - id: index
+        type: u4
+    instances:
+      data:
+        pos: _root.lzma_metas[index].ofs_blob
+        size: _root.lzma_metas[index].len_blob
+  header:
+    seq:
+      - id: magic
+        contents: "MINIFS\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+      - id: unknown_1
+        type: u4
+      - id: num_files
+        type: u4
+      - id: unknown_2
+        type: u4
+      - id: len_filenames
+        type: u4
+  filenames:
+    seq:
+      - id: filename
+        type: strz
+        repeat: eos
+  inode:
+    params:
+      - id: prev_max_lzma_blob
+        type: u4
+    seq:
+      - id: ofs_directory
+        type: u4
+      - id: ofs_name
+        type: u4
+      - id: lzma_blob
+        type: u4
+      - id: ofs_file
+        type: u4
+      - id: size
+        type: u4
+    instances:
+      cur_max_lzma_blob:
+        value: 'lzma_blob > prev_max_lzma_blob ? lzma_blob : prev_max_lzma_blob'
+      filename:
+        io: _root.filenames._io
+        pos: ofs_name
+        type: strz
+      directory_name:
+        io: _root.filenames._io
+        pos: ofs_directory
+        type: strz
+  lzma_meta:
+    params:
+      - id: prev_max_lzma_blob_len
+        type: u4
+    seq:
+      - id: ofs_blob
+        type: u4
+        valid: prev_max_lzma_blob_len
+      - id: len_blob
+        type: u4
+      - id: len_blob_uncompressed
+        type: u4
+    instances:
+      cur_max_lzma_blob_len:
+        value: 'ofs_blob + len_blob > prev_max_lzma_blob_len ? ofs_blob + len_blob : prev_max_lzma_blob_len'