jade
3571817e3a
This also rewrites a lot of the command handling in the fixtures
library, since we want to more precisely control which way that the nix
store is set up in the tests, rather than the previous method of
renaming /nix/store to some temp dir (which allows builds but does not
allow any /nix/store paths or stability across runs, which is a
significant issue for snapshot testing).
It uses a builder to reduce the amount of state carelessly thrown
around.
The evil NARs are inspired by CVE-2024-45593
(https://github.com/NixOS/nix/security/advisories/GHSA-h4vv-h3jq-v493).
No bugs were found in this endeavor.
Change-Id: Iee41b055fa96529c5a3c761f680ed1d0667ba5da
133 lines
3.3 KiB
Python
133 lines
3.3 KiB
Python
"""
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See "The Purely Functional Software Deployment Model", fig. 5.2 [1].
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[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
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"""
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from abc import ABCMeta, abstractmethod
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import dataclasses
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import struct
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from pathlib import Path
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from typing import Protocol
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import unicodedata
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class Writable(Protocol):
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"""Realistically could just be IOBase but this is more constrained"""
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def write(self, data: bytes, /) -> int: ...
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@dataclasses.dataclass
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class NarListener:
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data: Writable
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def literal(self, data: bytes):
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self.data.write(data)
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def int_(self, v: int):
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self.literal(struct.pack('<Q', v))
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def add_pad(self, data_len: int):
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npad = 8 - data_len % 8
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if npad == 8:
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npad = 0
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# FIXME: implement nonzero padding
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self.literal(b'\0' * npad)
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def str_(self, data: bytes):
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self.int_(len(data))
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self.literal(data)
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self.add_pad(len(data))
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class NarItem(metaclass=ABCMeta):
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type_: bytes
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def serialize(self, out: NarListener):
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out.str_(b'type')
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out.str_(self.type_)
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self.serialize_type(out)
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@abstractmethod
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def serialize_type(self, out: NarListener):
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pass
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@dataclasses.dataclass
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class Regular(NarItem):
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executable: bool
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contents: bytes
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type_ = b'regular'
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def serialize_type(self, out: NarListener):
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if self.executable:
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out.str_(b'executable')
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out.str_(b'')
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out.str_(b'contents')
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out.str_(self.contents)
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@dataclasses.dataclass
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class Directory(NarItem):
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entries: list[tuple[bytes, NarItem]]
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"""Entries in the directory, not required to be in order because this nar is evil"""
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type_ = b'directory'
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@staticmethod
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def entry(out: NarListener, name: bytes, item: 'NarItem'):
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# lol this format
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out.str_(b'entry')
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out.str_(b'(')
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out.str_(b'name')
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out.str_(name)
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out.str_(b'node')
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out.str_(b'(')
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item.serialize(out)
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out.str_(b')')
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out.str_(b')')
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def serialize_type(self, out: NarListener):
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for (name, entry) in self.entries:
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self.entry(out, name, entry)
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@dataclasses.dataclass
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class Symlink(NarItem):
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target: bytes
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type_ = b'symlink'
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def serialize_type(self, out: NarListener):
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out.str_(b'target')
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out.str_(self.target)
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def serialize_nar(toplevel: NarItem, out: NarListener):
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out.str_(b'nix-archive-1')
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out.str_(b'(')
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toplevel.serialize(out)
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out.str_(b')')
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def write_with_export_header(nar: NarItem, name: bytes, out: NarListener):
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# n.b. this is *not* actually a nar serialization, it just happens that nix
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# used exactly the same format for ints and strings in its protocol (and
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# nix-store --export) as it did in NARs lol
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EXPORT_MAGIC = 0x4558494e
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# Store::exportPaths
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# For each path, put 1 then exportPath
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out.int_(1)
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# Store::exportPath
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serialize_nar(nar, out)
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out.int_(EXPORT_MAGIC)
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out.str_(b'/nix/store/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-' + name)
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# no references
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out.int_(0)
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# no deriver
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out.str_(b'')
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# end of path
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out.int_(0)
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out.int_(0)
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