oaknut-file 12.7.2

Acorn file metadata handling: INF sidecars, filename encoding, xattrs, and access flags

oaknut-file

Acorn file metadata handling for the oaknut package family.

oaknut-file is the shared metadata layer used across the oaknut family — by oaknut-dfs, oaknut-adfs, oaknut-afs, oaknut-zip, and the disc CLI. It provides:

• The Access IntFlag enum for Acorn file attribute bytes
• The AcornMeta dataclass for load/exec addresses and attributes
• INF sidecar file parsing and formatting (traditional and PiEconetBridge variants)
• Filename metadata encoding (,xxx, ,llllllll,eeeeeeee, ,load-exec)
• Extended attribute read/write under user.acorn.* and user.econet_*

Installation

Using uv (recommended):

uv add oaknut-file

pip install oaknut-file also works.

The xattr package is automatically installed on macOS, where it is required for extended attribute support. Linux uses os.setxattr from the standard library and needs no additional dependency. Windows does not support extended attributes; the xattr functions will raise on use.

Quick start

Access flags

The Access IntFlag enum represents the standard Acorn OSFILE attribute byte. Bit values match the filing system API convention used by PiEconetBridge and the user.acorn.attr extended attribute.

from oaknut.file import Access

# Compose flags with bitwise OR
flags = Access.R | Access.W | Access.L
print(repr(flags))   # <Access.LWR: 11>
print(hex(flags))    # 0xb

Flag	Value	Meaning
Access.R	0x01	Owner read
Access.W	0x02	Owner write
Access.E	0x04	Execute only
Access.L	0x08	Locked — prevents delete, overwrite, and rename on the disc filing systems
Access.PR	0x10	Public read
Access.PW	0x20	Public write
Access.X	0x40	*RUN-only — may be *RUN but not *LOADed (CFS/ROMFS copy protection)

Access.X (*RUN-only) is a distinct axis from Access.L (locked): X is the cassette/ROM copy-protection bit and does not map to or from the disc filing systems' delete-lock. Access.WR and Access.LWR are provided as convenience composites for the common owner-read+write and locked-owner-read+write cases.

INF sidecar files

Two INF sidecar formats are supported. parse_inf_line() auto-detects which format a line uses, while format_trad_inf_line() and format_pieb_inf_line() let you choose explicitly when writing.

from oaknut.file import (
    Access, format_trad_inf_line, format_pieb_inf_line, parse_inf_line,
)

# Traditional INF: filename load exec length [attr]
trad = format_trad_inf_line(
    filename="HELLO",
    load_address=0x1900,
    exec_address=0x8023,
    length=0x100,
    attr=int(Access.R | Access.W),
)
print(trad)
# HELLO       00001900 00008023 00000100 03

# PiEconetBridge INF: owner load exec perm
pieb = format_pieb_inf_line(
    load_address=0xFFFFDD00,
    exec_address=0xFFFFDD00,
    attr=int(Access.R | Access.W | Access.L | Access.PR),
)
print(pieb)
# 0 ffffdd00 ffffdd00 1b

# Auto-detect format on parse (returns (source_label, AcornMeta))
source, meta = parse_inf_line(trad)
print(meta.load_address, meta.exec_address, meta.access)
# 6400 32803 3

source, meta = parse_inf_line(pieb)
print(hex(meta.load_address), hex(meta.access), hex(meta.infer_filetype()))
# 0xffffdd00 0x1b 0xfdd

Filename metadata encoding

Three filename suffix conventions are supported for embedding load/exec addresses or RISC OS filetypes in host filenames.

from oaknut.file import parse_encoded_filename

# RISC OS filetype suffix (3 hex digits)
clean, meta = parse_encoded_filename("PROG,ffb")
print(clean, meta.infer_filetype())
# ('PROG', filetype=0xFFB)

# MOS load-exec suffix (variable-width hex)
clean, meta = parse_encoded_filename("PROG,1900-801f")
print(clean, hex(meta.load_address), hex(meta.exec_address))
# PROG 0x1900 0x801f

Filetype-stamped load addresses

When a load address has its top 12 bits set to 0xFFF, the next 12 bits encode a RISC OS filetype.

from oaknut.file import AcornMeta

meta = AcornMeta(load_address=0xFFFF0E10)
print(meta.is_filetype_stamped, hex(meta.infer_filetype()))
# True 0xf0e

Extended attributes

from oaknut.file import write_acorn_xattrs, read_acorn_xattrs

# Write to user.acorn.* namespace
write_acorn_xattrs(
    "myfile.bin",
    load_address=0x1900,
    exec_address=0x8023,
    attr=0x03,
)

# Read back (falls through to user.econet_* if user.acorn.* is absent)
meta = read_acorn_xattrs("myfile.bin")
print(meta.load_address, meta.exec_address, meta.access)

Public API

Module	Exports
oaknut.file.access	Access, format_access_hex, format_access_text
oaknut.file.meta	AcornMeta
oaknut.file.formats	MetaFormat, SOURCE_* labels
oaknut.file.inf	parse_inf_line, format_trad_inf_line, format_pieb_inf_line, read_inf_file, write_inf_file
oaknut.file.filename_encoding	parse_encoded_filename, build_filename_suffix, build_mos_filename_suffix
oaknut.file.xattr	read_acorn_xattrs, write_acorn_xattrs, read_econet_xattrs, write_econet_xattrs

All public symbols are also re-exported from the top-level oaknut.file package.

License

MIT