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"""
See "The Purely Functional Software Deployment Model", fig. 5.2 [1].
[1]: E. Dolstra, “The purely functional software deployment model,” Ph.D., Universeit Utrecht, Utrecht, NL, 2006. [Online]. Available: https://edolstra.github.io/pubs/phd-thesis.pdf
"""
from abc import ABCMeta, abstractmethod
import dataclasses
import struct
from typing import Protocol, ClassVar
class Writable(Protocol):
"""Realistically could just be IOBase but this is more constrained"""
def write(self, data: bytes, /) -> int: ...
@dataclasses.dataclass
class NarListener:
data: Writable
def literal(self, data: bytes):
self.data.write(data)
def int_(self, v: int):
self.literal(struct.pack("<Q", v))
def add_pad(self, data_len: int):
npad = 8 - data_len % 8
if npad == 8:
npad = 0
# FIXME(Jade): implement nonzero padding
self.literal(b"\0" * npad)
def str_(self, data: bytes):
self.int_(len(data))
self.literal(data)
self.add_pad(len(data))
class NarItem(metaclass=ABCMeta):
type_: bytes
def serialize(self, out: NarListener):
out.str_(b"type")
out.str_(self.type_)
self.serialize_type(out)
@abstractmethod
def serialize_type(self, out: NarListener):
pass
@dataclasses.dataclass
class Regular(NarItem):
executable: bool
contents: bytes
type_: ClassVar[bytes] = b"regular"
def serialize_type(self, out: NarListener):
if self.executable:
out.str_(b"executable")
out.str_(b"")
out.str_(b"contents")
out.str_(self.contents)
@dataclasses.dataclass
class DirectoryUnordered(NarItem):
entries: list[tuple[bytes, NarItem]]
"""Entries in the directory, not required to be in order because this nar is evil"""
type_: ClassVar[bytes] = b"directory"
@staticmethod
def entry(out: NarListener, name: bytes, item: "NarItem"):
# lol this format
out.str_(b"entry")
out.str_(b"(")
out.str_(b"name")
out.str_(name)
out.str_(b"node")
out.str_(b"(")
item.serialize(out)
out.str_(b")")
out.str_(b")")
def serialize_type(self, out: NarListener):
for name, entry in self.entries:
self.entry(out, name, entry)
@dataclasses.dataclass
class Directory(NarItem):
entries: dict[bytes, NarItem]
def serialize_type(self, out: NarListener):
for name, item in sorted(self.entries.items(), key=lambda v: v[0]):
DirectoryUnordered.entry(out, name, item)
@dataclasses.dataclass
class Symlink(NarItem):
target: bytes
type_: ClassVar[bytes] = b"symlink"
def serialize_type(self, out: NarListener):
out.str_(b"target")
out.str_(self.target)
def serialize_nar(toplevel: NarItem, out: NarListener):
out.str_(b"nix-archive-1")
out.str_(b"(")
toplevel.serialize(out)
out.str_(b")")
def write_with_export_header(nar: NarItem, name: bytes, out: NarListener):
# n.b. this is *not* actually a nar serialization, it just happens that nix
# used exactly the same format for ints and strings in its protocol (and
# nix-store --export) as it did in NARs lol
export_magic = 0x4558494E
# Store::exportPaths
# For each path, put 1 then exportPath
out.int_(1)
# Store::exportPath
serialize_nar(nar, out)
out.int_(export_magic)
# Due to `nix` setting the store using chroots /nix/store is still the test-local store and not the global one
store_path = b"/nix/store"
out.str_(store_path + b"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-" + name)
# no references
out.int_(0)
# no deriver
out.str_(b"")
# end of path
out.int_(0)
out.int_(0)
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