SQLite3 Write-Ahead Logs (WAL)

database/sqlite3_wal.ksy

@@ -0,0 +1,67 @@
+meta:
+  id: sqlite3_wal
+  file-extension:
+    - sqlite-wal
+    - db-wal
+    - db3-wal
+    - sqlite3-wal
+  endian: be
+  license: CC0-1.0
+doc: |
+  SQLite3 is a popular serverless SQL engine, implemented as a library
+  to be used within other applications. It keeps its databases as
+  regular disk files.
+
+  Write-Ahead Logging (WAL) is a journaling mode that enhances
+  performance and allow more concurrency than the default rollback
+  journal.
+doc-ref:
+  - https://www.sqlite.org/wal.html
+  - https://sqlite.org/src/file?name=src/wal.c&ci=trunk
+seq:
+  - id: header
+    type: header
+  - id: frames
+    type: frame
+    repeat: eos
+types:
+  header:
+    seq:
+      - id: magic
+        type: u4
+        valid:
+          any-of: [0x377f0682, 0x377f0683]
+      - id: file_format_version
+        type: u4
+      - id: len_database_page
+        type: u4
+      - id: checkpoint_sequence_number
+        type: u4
+      - id: salt1
+        type: u4
+      - id: salt2
+        type: u4
+      - id: checksum1
+        type: u4
+      - id: checksum2
+        type: u4
+  frame:
+    seq:
+      - id: frame_header
+        type: frame_header
+      - id: page_data
+        size: _root.header.len_database_page
+  frame_header:
+    seq:
+      - id: page_number
+        type: u4
+      - id: commit_db_pages
+        type: u4
+      - id: salt1
+        type: u4
+      - id: salt2
+        type: u4
+      - id: checksum1
+        type: u4
+      - id: checksum2
+        type: u4

database/sqlite3_wal_index.ksy

@@ -0,0 +1,121 @@
+meta:
+  id: sqlite3_wal_index
+  file-extension:
+    - sqlite-shm
+    - db-shm
+    - db3-shm
+    - sqlite3-shm
+  license: CC0-1.0
+doc: |
+  SQLite3 is a popular serverless SQL engine, implemented as a library
+  to be used within other applications. It keeps its databases as
+  regular disk files.
+
+  Write-Ahead Logging (WAL) is a journaling mode that enhances
+  performance and allow more concurrency than the default rollback
+  journal.
+
+  The WAL Index is a shared memory object that allows faster lookup of
+  pages stored in the WAL journal. Endianness of the stored values is
+  platform-dependent.
+doc-ref:
+  - https://www.sqlite.org/wal.html
+  - https://sqlite.org/src/file?name=src/wal.c&ci=trunk
+seq:
+  - id: header
+    type: header
+  - id: header2
+    type: header
+  - id: ckpt_info
+    type: ckpt_info
+  - id: first_block
+    type: index_block_one
+  - id: index_blocks
+    type: index_block
+    repeat: eos
+types:
+  header:
+    seq:
+      - id: version
+        type: b32
+      - id: reserved
+        type: b32
+      - id: change
+        type: b32
+      - id: init
+        type: b8
+      - id: big_end_cksum
+        type: b8
+      - id: page
+        type: b16
+      - id: mx_frame
+        type: b32
+      - id: n_page
+        type: b32
+      - id: frame_cksum_0
+        type: b32
+      - id: frame_cksum_1
+        type: b32
+      - id: salt_0
+        type: b32
+      - id: salt_1
+        type: b32
+      - id: cksum_0
+        type: b32
+      - id: cksum_1
+        type: b32
+  ckpt_info:
+    seq:
+      - id: n_backfill
+        type: b32
+      - id: read_mark
+        type: read_mark_array
+      - id: lock
+        type: lock_array
+      - id: n_backfill_attempted
+        type: b32
+      - id: not_used
+        type: b32
+  lock_array:
+    seq:
+      - id: lock
+        type: b8
+        repeat: expr
+        repeat-expr: 8 # SQLITE_SHM_NLOCK
+  read_mark_array:
+    seq:
+      - id: read_mark
+        type: b32
+        repeat: expr
+        repeat-expr: 5 # WAL_NREADER
+  index_block_one:
+    seq:
+      - id: page_mapping
+        type: page_mapping_one
+      - id: hash_table
+        type: hash_table
+  page_mapping_one:
+    seq:
+      - id: page_number
+        type: b32
+        repeat: expr
+        repeat-expr: 4062 # HASHTABLE_NPAGE_ONE
+  index_block:
+    seq:
+      - id: page_mapping
+        type: page_mapping_one
+      - id: hash_table
+        type: hash_table
+  page_mapping:
+    seq:
+      - id: page_number
+        type: b32
+        repeat: expr
+        repeat-expr: 4096 # HASHTABLE_NPAGE
+  hash_table:
+    seq:
+      - id: hash
+        type: b16
+        repeat: expr
+        repeat-expr: 2*4096 # HASHTABLE_NSLOT
+