mirror of
https://github.com/NixOS/nix.git
synced 2025-11-08 11:36:03 +01:00
c8e24491c0
Warning:
```
[39/483] Generating src/kaitai-struct-checks/kaitai-generated-sources with a custom command
../src/kaitai-struct-checks/nar.ksy: /types/padded_str/seq/1/encoding:
warning: use canonical encoding name `ASCII` instead of `ascii` (see https://doc.kaitai.io/ksy_style_guide.html#encoding-name)
```
169 lines
4.9 KiB
Text
169 lines
4.9 KiB
Text
meta:
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id: nix_nar
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title: Nix Archive (NAR)
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file-extension: nar
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endian: le
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doc: |
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Nix Archive (NAR) format. A simple, reproducible binary archive
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format used by the Nix package manager to serialize file system objects.
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doc-ref: 'https://nixos.org/manual/nix/stable/command-ref/nix-store.html#nar-format'
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seq:
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- id: magic
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type: padded_str
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doc: "Magic string, must be 'nix-archive-1'."
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valid:
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expr: _.body == 'nix-archive-1'
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- id: root_node
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type: node
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doc: "The root of the archive, which is always a single node."
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types:
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padded_str:
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doc: |
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A string, prefixed with its length (u8le) and
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padded with null bytes to the next 8-byte boundary.
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seq:
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- id: len_str
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type: u8
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- id: body
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type: str
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size: len_str
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encoding: 'ASCII'
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- id: padding
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size: (8 - (len_str % 8)) % 8
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node:
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doc: "A single filesystem node (file, directory, or symlink)."
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seq:
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- id: open_paren
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type: padded_str
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doc: "Must be '(', a token starting the node definition."
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valid:
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expr: _.body == '('
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- id: type_key
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type: padded_str
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doc: "Must be 'type'."
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valid:
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expr: _.body == 'type'
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- id: type_val
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type: padded_str
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doc: "The type of the node: 'regular', 'directory', or 'symlink'."
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- id: body
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type:
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switch-on: type_val.body
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cases:
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"'directory'": type_directory
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"'regular'": type_regular
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"'symlink'": type_symlink
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- id: close_paren
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type: padded_str
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valid:
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expr: _.body == ')'
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if: "type_val.body != 'directory'"
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doc: "Must be ')', a token ending the node definition."
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type_directory:
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doc: "A directory node, containing a list of entries. Entries must be ordered by their names."
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seq:
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- id: entries
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type: dir_entry
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repeat: until
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repeat-until: _.kind.body == ')'
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types:
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dir_entry:
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doc: "A single entry within a directory, or a terminator."
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seq:
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- id: kind
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type: padded_str
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valid:
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expr: _.body == 'entry' or _.body == ')'
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doc: "Must be 'entry' (for a child node) or '' (for terminator)."
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- id: open_paren
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type: padded_str
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valid:
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expr: _.body == '('
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if: 'kind.body == "entry"'
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- id: name_key
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type: padded_str
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valid:
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expr: _.body == 'name'
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if: 'kind.body == "entry"'
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- id: name
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type: padded_str
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if: 'kind.body == "entry"'
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- id: node_key
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type: padded_str
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valid:
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expr: _.body == 'node'
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if: 'kind.body == "entry"'
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- id: node
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type: node
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if: 'kind.body == "entry"'
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doc: "The child node, present only if kind is 'entry'."
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- id: close_paren
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type: padded_str
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valid:
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expr: _.body == ')'
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if: 'kind.body == "entry"'
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instances:
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is_terminator:
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value: kind.body == ')'
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type_regular:
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doc: "A regular file node."
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seq:
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# Read attributes (like 'executable') until we hit 'contents'
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- id: attributes
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type: reg_attribute
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repeat: until
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repeat-until: _.key.body == "contents"
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# After the 'contents' token, read the file data
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- id: file_data
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type: file_content
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instances:
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is_executable:
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value: 'attributes[0].key.body == "executable"'
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doc: "True if the file has the 'executable' attribute."
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types:
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reg_attribute:
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doc: "An attribute of the file, e.g., 'executable' or 'contents'."
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seq:
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- id: key
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type: padded_str
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doc: "Attribute key, e.g., 'executable' or 'contents'."
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valid:
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expr: _.body == 'executable' or _.body == 'contents'
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- id: value
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type: padded_str
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if: 'key.body == "executable"'
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valid:
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expr: _.body == ''
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doc: "Must be '' if key is 'executable'."
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file_content:
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doc: "The raw data of the file, prefixed by length."
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seq:
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- id: len_contents
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type: u8
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# # This relies on the property of instances that they are lazily evaluated and cached.
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- size: 0
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if: nar_offset < 0
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- id: contents
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size: len_contents
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- id: padding
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size: (8 - (len_contents % 8)) % 8
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instances:
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nar_offset:
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value: _io.pos
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type_symlink:
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doc: "A symbolic link node."
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seq:
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- id: target_key
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type: padded_str
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doc: "Must be 'target'."
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valid:
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expr: _.body == 'target'
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- id: target_val
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type: padded_str
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doc: "The destination path of the symlink."
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