Add GreggyBits support

This commit is contained in:
Elliot Nunn 2020-01-19 14:52:26 +08:00
parent aa185339bc
commit 800cfbf040
4 changed files with 264 additions and 1 deletions

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@ -58,6 +58,10 @@ deprecated `Rez` and `DeRez` utilities. They convert between raw resource forks
and Rez-style `.rdump` files. To access a raw resource fork under Mac OS X, you
can append `/..namedfork/rsrc` to a filename.
Commands implementing Apple's [undocumented resource compression scheme](http://preserve.mactech.com/articles/mactech/Vol.09/09.01/ResCompression/index.html):
- `greggybits` (in Python: `from greggybits import pack, unpack`)
All utilities have online help.

71
bin/greggybits Executable file
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@ -0,0 +1,71 @@
#!/usr/bin/env python3
HELP = '''GreggyBits: (un)pack resources in the Macintosh System file (7.1)
Algorithm by Greg Mariott <http://www.greggybits.com>
Reimplemented by Maxim Poliakovski and Elliot Nunn
Use the 'rfx' wrapper command to access resources inside a file'''
def debug_round_trip(filename, packed):
print(filename.split('/')[-1], end=' ')
unpacked = unpack(packed)
repacked = pack(unpacked)
if packed == repacked:
print('good', end=' ')
elif packed[17] != repacked[17]:
print('WRONGMODE', repacked[17], 'not', packed[17], end=' ')
if pack_with_flags(unpacked, packed[17]) == packed:
print('(correct when mode is forced)', end=' ')
elif packed[:14] == repacked[:14] and packed[16:] == repacked[16:]:
print('sloppy', hex(struct.unpack_from('>H', repacked, 14)[0]), 'not', hex(struct.unpack_from('>H', packed, 14)[0]), end=' ')
else:
print('other', end=' ')
print()
if __name__ == '__main__':
# Some cheeky debug code for testing... rfx greggybits --debug System//
from macresources.greggybits import pack, pack_with_flags, unpack
import struct
import sys
import argparse
parser = argparse.ArgumentParser(
description=HELP, formatter_class=argparse.RawTextHelpFormatter,
)
parser.prog = '[rfx] ' + parser.prog
parser.add_argument('path', nargs='+', metavar='file', action='store', help='Resource data')
parser.add_argument('-x', dest='do_compress', action='store_false', help='extract (default: compress)')
parser.add_argument('--debug', action='store_true', help='attempt to round-trip resources')
args = parser.parse_args()
for el in args.path:
from macresources.greggybits import pack, unpack
with open(el, 'r+b') as f:
already_compressed = (f.read(4) == b'\xA8\x9Fer')
if already_compressed == args.do_compress: continue
f.seek(0)
data = f.read()
try:
if args.do_compress:
data = pack(data)
if args.debug: debug_round_trip(el, data)
else:
if args.debug: debug_round_trip(el, data)
data = unpack(data)
f.seek(0)
f.write(data)
f.truncate()
except ValueError:
raise
print('some kind of error')

188
macresources/greggybits.py Normal file
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@ -0,0 +1,188 @@
import struct
# predefined lookup table of the most frequent words
TABLE = (
0x0000, 0x0008, 0x4EBA, 0x206E, 0x4E75, 0x000C, 0x0004, 0x7000,
0x0010, 0x0002, 0x486E, 0xFFFC, 0x6000, 0x0001, 0x48E7, 0x2F2E,
0x4E56, 0x0006, 0x4E5E, 0x2F00, 0x6100, 0xFFF8, 0x2F0B, 0xFFFF,
0x0014, 0x000A, 0x0018, 0x205F, 0x000E, 0x2050, 0x3F3C, 0xFFF4,
0x4CEE, 0x302E, 0x6700, 0x4CDF, 0x266E, 0x0012, 0x001C, 0x4267,
0xFFF0, 0x303C, 0x2F0C, 0x0003, 0x4ED0, 0x0020, 0x7001, 0x0016,
0x2D40, 0x48C0, 0x2078, 0x7200, 0x588F, 0x6600, 0x4FEF, 0x42A7,
0x6706, 0xFFFA, 0x558F, 0x286E, 0x3F00, 0xFFFE, 0x2F3C, 0x6704,
0x598F, 0x206B, 0x0024, 0x201F, 0x41FA, 0x81E1, 0x6604, 0x6708,
0x001A, 0x4EB9, 0x508F, 0x202E, 0x0007, 0x4EB0, 0xFFF2, 0x3D40,
0x001E, 0x2068, 0x6606, 0xFFF6, 0x4EF9, 0x0800, 0x0C40, 0x3D7C,
0xFFEC, 0x0005, 0x203C, 0xFFE8, 0xDEFC, 0x4A2E, 0x0030, 0x0028,
0x2F08, 0x200B, 0x6002, 0x426E, 0x2D48, 0x2053, 0x2040, 0x1800,
0x6004, 0x41EE, 0x2F28, 0x2F01, 0x670A, 0x4840, 0x2007, 0x6608,
0x0118, 0x2F07, 0x3028, 0x3F2E, 0x302B, 0x226E, 0x2F2B, 0x002C,
0x670C, 0x225F, 0x6006, 0x00FF, 0x3007, 0xFFEE, 0x5340, 0x0040,
0xFFE4, 0x4A40, 0x660A, 0x000F, 0x4EAD, 0x70FF, 0x22D8, 0x486B,
0x0022, 0x204B, 0x670E, 0x4AAE, 0x4E90, 0xFFE0, 0xFFC0, 0x002A,
0x2740, 0x6702, 0x51C8, 0x02B6, 0x487A, 0x2278, 0xB06E, 0xFFE6,
0x0009, 0x322E, 0x3E00, 0x4841, 0xFFEA, 0x43EE, 0x4E71, 0x7400,
0x2F2C, 0x206C, 0x003C, 0x0026, 0x0050, 0x1880, 0x301F, 0x2200,
0x660C, 0xFFDA, 0x0038, 0x6602, 0x302C, 0x200C, 0x2D6E, 0x4240,
0xFFE2, 0xA9F0, 0xFF00, 0x377C, 0xE580, 0xFFDC, 0x4868, 0x594F,
0x0034, 0x3E1F, 0x6008, 0x2F06, 0xFFDE, 0x600A, 0x7002, 0x0032,
0xFFCC, 0x0080, 0x2251, 0x101F, 0x317C, 0xA029, 0xFFD8, 0x5240,
0x0100, 0x6710, 0xA023, 0xFFCE, 0xFFD4, 0x2006, 0x4878, 0x002E,
0x504F, 0x43FA, 0x6712, 0x7600, 0x41E8, 0x4A6E, 0x20D9, 0x005A,
0x7FFF, 0x51CA, 0x005C, 0x2E00, 0x0240, 0x48C7, 0x6714, 0x0C80,
0x2E9F, 0xFFD6, 0x8000, 0x1000, 0x4842, 0x4A6B, 0xFFD2, 0x0048,
0x4A47, 0x4ED1, 0x206F, 0x0041, 0x600C, 0x2A78, 0x422E, 0x3200,
0x6574, 0x6716, 0x0044, 0x486D, 0x2008, 0x486C, 0x0B7C, 0x2640,
0x0400, 0x0068, 0x206D, 0x000D, 0x2A40, 0x000B, 0x003E, 0x0220
)
TABLE_DICT = {word: idx for (idx, word) in enumerate(TABLE)}
def unpack(src, _calculate_slop=False):
dst = bytearray()
pos = 0
magic, hdrLen, vers, iscmp, unpackSize, _dcmp, _slop, tabSize, comprFlags = struct.unpack_from(">LHBBLHHBB", src, pos)
pos += 18
hasDynamicTab = comprFlags & 1
isBitmapped = comprFlags & 2
if hasDynamicTab:
nEntries = tabSize + 1
dynamicLUT = struct.unpack_from(">" + str(nEntries) + "H", src, pos)
pos += nEntries * 2
# dump dynamic LUT
if 0:
for idx, elem in enumerate(dynamicLUT):
if idx and not idx & 3:
print(",")
else:
print(", ", end="")
print("0x%04X" % elem, end="")
print("")
LUT = dynamicLUT if hasDynamicTab else TABLE
nWords = unpackSize >> 1
hasExtraByte = unpackSize & 1
LUT = [word.to_bytes(2, 'big') for word in LUT]
slop = 0
slop = max(slop, len(dst) + (len(src) - pos) - unpackSize)
if isBitmapped:
evenUnpackLen = unpackSize - (unpackSize % 2)
while len(dst) < evenUnpackLen:
if not len(dst) & 0xF:
mask = src[pos]; pos += 1
if mask & 0x80:
dst.extend(LUT[src[pos]]); pos += 1
else:
dst.append(src[pos]); pos += 1
dst.append(src[pos]); pos += 1
mask <<= 1
slop = max(slop, len(dst) + (len(src) - pos) - unpackSize)
else:
while len(dst) < unpackSize & ~1:
dst.extend(LUT[src[pos]]); pos += 1
slop = max(slop, len(dst) + (len(src) - pos) - unpackSize)
if hasExtraByte: # have a got an extra byte at the end?
dst.append(src[pos]) # copy it over
pos += 1
if _calculate_slop: return slop
return(dst)
def pack_with_flags(src, flags, _defer_slop=False):
nWords = len(src) >> 1
inWords = struct.unpack(">" + str(nWords) + "H", src[:nWords*2])
dst = bytearray(b'\xA8\x9Fer')
dst.extend(struct.pack('>HBBLH', 0x12, 9, 1, len(src), 2)) # magic, hdrlen, 9=gregg, 1=compressed, size, 2=dcmp
dst.extend(bytes(4)) # to fill in later
dst[17] = flags
# Create a custom lookup table instead of the one at the beginning of the file
LUT = TABLE_DICT
if flags & 1:
import collections
wordsCounts = collections.Counter(inWords)
customTab = sorted(wordsCounts, reverse=True, key=lambda word: (wordsCounts[word], word))
if len(customTab) > 256:
# The table has 8-bit indices. The Apple compressor short circuits inappropriately in this case.
del customTab[256:]
elif flags & 2:
# If we are able to encode words not in the table, then save space
# by removing remove rarely used entries from the table
while customTab and wordsCounts[customTab[-1]] <= 2:
del customTab[-1]
# Put the table after the header
dst[16] = len(customTab) - 1
dst.extend(struct.pack('>' + str(len(customTab)) + 'H', *customTab))
# Use our custom function for looking up words
LUT = {word: idx for (idx, word) in enumerate(customTab)}
if flags & 2:
# Use bitmaps to distinguish between verbatim copies and table lookupss
LUT = LUT.get
for pos, word in enumerate(inWords):
if not (pos & 7):
mask = len(dst)
dst.append(0)
result = LUT(word, None)
if result is None:
dst.append(word >> 8)
dst.append(word & 0xFF)
else:
dst.append(result)
dst[mask] |= 0x80 >> (pos & 7)
else:
# Table lookups only
dst.extend(LUT[word] for word in inWords) # triggers https://bugs.python.org/issue37417
if len(src) & 1: # copy over last byte in the case of odd length
dst.append(src[-1])
if not _defer_slop:
slop = unpack(dst, _calculate_slop=True)
struct.pack_into('>H', dst, 14, slop)
return dst
def pack(src):
if len(src) < 18: return src
bestCompress = src
bestSize = len(src)
for flags in (0, 1, 2, 3):
try:
thisCompress = pack_with_flags(src, flags, _defer_slop=True)
except:
continue
thisSize = len(thisCompress)
# thisSize += struct.unpack_from('>H', thisCompress, 14)[0]
if thisSize < bestSize:
bestCompress = thisCompress
bestSize = thisSize
if bestCompress is not src:
slop = unpack(bestCompress, _calculate_slop=True)
struct.pack_into('>H', bestCompress, 14, slop)
return bestCompress

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@ -18,5 +18,5 @@ setup(
'Development Status :: 3 - Alpha',
],
packages=['macresources'],
scripts=['bin/SimpleRez', 'bin/SimpleDeRez', 'bin/hexrez', 'bin/rezhex', 'bin/sortrez', 'bin/rfx'],
scripts=['bin/SimpleRez', 'bin/SimpleDeRez', 'bin/hexrez', 'bin/rezhex', 'bin/sortrez', 'bin/rfx', 'bin/greggybits'],
)