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py_fpff.py
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py_fpff.py
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"""Provides operations for working with FPFF.
"""
import os
import shutil
import time
import struct
from typing import Any, BinaryIO, Union
from enum import IntEnum
class SectionType(IntEnum):
"""Enum types for FPFF section types.
Example:
>>> t = SectionType.ASCII
"""
ASCII = 1
UTF8 = 2
WORDS = 3
DWORDS = 4
DOUBLES = 5
COORD = 6
REF = 7
PNG = 8
GIF87 = 9
GIF89 = 10
class FPFF:
"""FPFF file.
Attributes:
version (int): FPFF version number. Only accepts 1.
timestamp (int): UNIX timestamp indicating time of creation.
author (str): Author name.
nsects (int): Number of sections in the FPFF.
stypes (List[SectionType]): List of section types indexed by section.
svalues (List[Any]): List of section values indexed by section.
"""
def __init__(self, file: Union[BinaryIO, None] = None, author: str = ''):
"""Initializes new FPFF.
Args:
file (BinaryIO): Optional FPFF input byte stream. Provided if reading FPFF.
author (str): Author name. Defaults to ''.
Example:
>>> with open('./input.fpff', 'rb') as f:
>>> fpff = FPFF(f)
"""
self.version = 1
self.timestamp = int(time.time())
self.author = author
self.nsects = 0
self.stypes = list()
self.svalues = list()
# Read FPFF file if supplied
if file != None:
self.read(file)
def read(self, file: BinaryIO):
"""Reads in FPFF from byte stream.
Args:
file (BinaryIO): FPFF input byte stream.
Raises:
ValueError: Magic did not match FPFF magic.
ValueError: Unsupported version. Only version 1 is supported.
ValueError: Section length must be greater than 0.
ValueError: Improper section length.
ValueError: Reference value is out of bounds.
ValueError: File contained an unsupported type.
Example:
>>> with open('./input.fpff', 'rb') as f:
>>> fpff = FPFF()
>>> fpff.read(f)
"""
data = file.read(24)
magic = data[0:4][::-1]
self.version = int.from_bytes(data[4:8], 'little')
self.timestamp = int.from_bytes(data[8:12], 'little')
self.author = data[12:20][::-1].decode('ascii').strip('\0')
self.nsects = int.from_bytes(data[20:24], 'little')
self.stypes = []
self.svalues = []
# Metadata checks
if magic != b'\xBE\xFE\xDA\xDE':
raise ValueError("Magic did not match FPFF magic.")
if self.version != 1:
raise ValueError(
"Unsupported version. Only version 1 is supported."
)
# Read each section
for _ in range(self.nsects):
# Read section header and data
data = file.read(8)
stype = int.from_bytes(data[0:4], 'little')
slen = int.from_bytes(data[4:8], 'little')
if slen <= 0:
raise ValueError("Section length must be greater than 0.")
svalue = file.read(slen)
# Decode section data
if stype == 0x1:
# ASCII
self.stypes.append(SectionType.ASCII)
self.svalues.append(svalue.decode('ascii'))
elif stype == 0x2:
# UTF-8
self.stypes.append(SectionType.UTF8)
self.svalues.append(svalue.decode('utf8'))
elif stype == 0x3:
# Words
if slen % 4 != 0:
raise ValueError("Improper section length.")
self.stypes.append(SectionType.WORDS)
self.svalues.append(
[svalue[j:j+4] for j in range(0, slen, 4)]
)
elif stype == 0x4:
# DWords
if slen % 8 != 0:
raise ValueError("Improper section length.")
self.stypes.append(SectionType.DWORDS)
self.svalues.append(
[svalue[j:j+8] for j in range(0, slen, 8)]
)
elif stype == 0x5:
# Doubles
if slen % 8 != 0:
raise ValueError("Improper section length.")
self.stypes.append(SectionType.DOUBLES)
self.svalues.append(
[struct.unpack("<d", svalue[j:j+8])[0]
for j in range(0, slen, 8)]
)
elif stype == 0x6:
# Coord
if slen != 16:
raise ValueError("Improper section length.")
self.stypes.append(SectionType.COORD)
lat = struct.unpack("<d", svalue[0:8])[0]
lng = struct.unpack("<d", svalue[8:16])[0]
# TODO: validate lat and lng
self.svalues.append((lat, lng))
elif stype == 0x7:
# Reference
if slen != 4:
raise ValueError("Improper section length.")
ref = int.from_bytes(svalue[0:4], 'little')
if ref < 0 or ref >= self.nsects:
raise ValueError("Reference value is out of bounds.")
self.stypes.append(SectionType.REF)
self.svalues.append(ref)
elif stype == 0x8:
# PNG
self.stypes.append(SectionType.PNG)
sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
out = sig + svalue[0:slen]
self.svalues.append(out)
elif stype == 0x9:
# GIF87a
self.stypes.append(SectionType.GIF87)
sig = b'\x47\x49\x46\x38\x37\x61'
out = sig + svalue[0:slen]
self.svalues.append(out)
elif stype == 0xA:
# GIF89a
self.stypes.append(SectionType.GIF89)
sig = b'\x47\x49\x46\x38\x39\x61'
out = sig + svalue[0:slen]
self.svalues.append(out)
else:
raise ValueError("File contained an unsupported type.")
def write(self, file: BinaryIO):
"""Writes FPFF to byte stream.
Args:
file (BinaryIO): FPFF output byte stream.
Raises:
ValueError: Word needs to be 4 bytes.
ValueError: DWord needs to be 8 bytes.
Example:
>>> with open('./output.fpff', 'wb') as out_f:
>>> fpff = FPFF()
>>> fpff.append(SectionType.ASCII, 'Hello, world!')
>>> fpff.write(out_f)
"""
# Write FPFF header
file.write(b'\xDE\xDA\xFE\xBE')
file.write(self.version.to_bytes(4, 'little'))
file.write(self.timestamp.to_bytes(4, 'little'))
author_bytes = self.author.encode('ascii')[::-1]
file.write(author_bytes)
file.write(b'\x00'*(8-len(author_bytes)))
file.write(self.nsects.to_bytes(4, 'little'))
# Write each section
for i in range(self.nsects):
section_bytes = b''
if self.stypes[i] == SectionType.ASCII:
# ASCII
section_bytes = self.svalues[i].encode('ascii')
elif self.stypes[i] == SectionType.UTF8:
# UTF-8
section_bytes = self.svalues[i].encode('utf8')
elif self.stypes[i] == SectionType.WORDS:
# Words
for w in self.svalues[i]:
if len(w) != 4:
raise ValueError("Word needs to be 4 bytes.")
section_bytes += w
elif self.stypes[i] == SectionType.DWORDS:
# DWords
for w in self.svalues[i]:
if len(w) != 8:
raise ValueError("DWord needs to be 8 bytes.")
section_bytes += w
elif self.stypes[i] == SectionType.DOUBLES:
# Doubles
section_bytes = b''.join(
[struct.pack("<d", w) for w in self.svalues[i]]
)
elif self.stypes[i] == SectionType.COORD:
# Coords
section_bytes = struct.pack("<d", self.svalues[i][0])
section_bytes += struct.pack("<d", self.svalues[i][1])
elif self.stypes[i] == SectionType.REF:
# Reference
section_bytes = self.svalues[i].to_bytes(4, 'little')
elif self.stypes[i] == SectionType.PNG:
# PNG
section_bytes = self.svalues[i][8:]
elif self.stypes[i] == SectionType.GIF87:
# GIF87a
section_bytes = self.svalues[i][6:]
elif self.stypes[i] == SectionType.GIF89:
# GIF89a
section_bytes = self.svalues[i][6:]
# Write to file
file.write(self.stypes[i].to_bytes(4, 'little'))
file.write(len(section_bytes).to_bytes(4, 'little'))
file.write(section_bytes)
def export(self, output_path: str):
"""Exports FPFF sections to directory.
Args:
output_path (str): Path to export directory.
Example:
>>> with open('./input.fpff') as f:
>>> fpff = FPFF(f)
>>> fpff.export('./exported')
"""
# Ensure output path exists
if os.path.exists(output_path):
shutil.rmtree(output_path)
os.mkdir(output_path)
# Export files
for i in range(self.nsects):
if self.stypes[i] not in [SectionType.PNG, SectionType.GIF87, SectionType.GIF89]:
# Non-media section
file_name = f'section-{i}.txt'
output = ''
if self.stypes[i] == SectionType.ASCII:
output = self.svalues[i]
elif self.stypes[i] == SectionType.UTF8:
output = self.svalues[i]
elif self.stypes[i] == SectionType.WORDS:
output = ', '.join(
[val.hex() for val in self.svalues[i]]
)
elif self.stypes[i] == SectionType.DWORDS:
output = ', '.join(
[val.hex() for val in self.svalues[i]]
)
elif self.stypes[i] == SectionType.DOUBLES:
output = ', '.join(
[str(val) for val in self.svalues[i]]
)
elif self.stypes[i] == SectionType.COORD:
output = f'LAT: {str(self.svalues[i][0])}\nLNG: {str(self.svalues[i][1])}'
elif self.stypes[i] == SectionType.REF:
output = f'REF: {str(self.svalues[i])}'
with open(os.path.join(output_path, file_name), 'w', encoding='utf8') as f:
f.write(output)
else:
# Media section
if self.stypes[i] == SectionType.PNG:
file_name = f'section-{i}.png'
with open(os.path.join(output_path, file_name), 'wb') as f:
f.write(self.svalues[i])
elif self.stypes[i] == SectionType.GIF87:
file_name = f'section-{i}.gif'
with open(os.path.join(output_path, file_name), 'wb') as f:
f.write(self.svalues[i])
elif self.stypes[i] == SectionType.GIF89:
file_name = f'section-{i}.gif'
with open(os.path.join(output_path, file_name), 'wb') as f:
f.write(self.svalues[i])
def insert(self, section_idx: int, obj_type: SectionType, obj_data: Any):
"""Inserts section before indicated index.
Args:
section_idx (int): Section index to insert in front of.
obj_type (int): Section type of new section.
obj_data (Any): Section value of new section.
Raises:
TypeError: Object data not valid for object type.
Example:
>>> fpff.insert(0, SectionType.ASCII, 'Hello, world!')
"""
if obj_type == SectionType.ASCII and type(obj_data) == str:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.UTF8 and type(obj_data) == str:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.WORDS and type(obj_data) == list:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.DWORDS and type(obj_data) == list:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.DOUBLES and type(obj_data) == list:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.COORD and type(obj_data) == tuple:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.REF and type(obj_data) == int:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.PNG and type(obj_data) in [bytes, bytearray]:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.GIF87 and type(obj_data) in [bytes, bytearray]:
self.svalues.insert(section_idx, obj_data)
elif obj_type == SectionType.GIF89 and type(obj_data) in [bytes, bytearray]:
self.svalues.insert(section_idx, obj_data)
else:
raise TypeError("Object data not valid for object type.")
self.stypes.insert(section_idx, obj_type)
self.nsects += 1
def append(self, obj_type: SectionType, obj_data: Any):
"""Appends section.
Args:
obj_type (int): Section type of new section.
obj_data (Any): Section value of new section.
Example:
>>> fpff.append(SectionType.ASCII, 'Hello, world!')
"""
self.insert(self.nsects, obj_type, obj_data)
def remove(self, section_idx: int):
"""Removes section at index.
Args:
section_idx (int): Index of section to remove.
Example:
>>> fpff.remove(0)
"""
del self.svalues[section_idx]
del self.stypes[section_idx]
self.nsects -= 1
def __repr__(self) -> str:
"""String representation of FPFF.
Returns:
string: String representation of FPFF.
"""
return str(self.stypes)