Support output from MakeHFS to device files

Takes advantage of the 'sparse' feature to minimise writes (in all
cases).

Does some binary-search magic to find the size of a block device, on a
Unix-like OS from Apple that I will not name.

At some point this should be exported through the Python API.
This commit is contained in:
Elliot Nunn 2018-12-10 16:10:06 +08:00
parent eb61c947de
commit dbc950c5d6

View File

@ -3,6 +3,7 @@
import argparse
from datetime import datetime
from machfs import Volume
import os
########################################################################
@ -58,7 +59,7 @@ args.add_argument('dest', metavar='OUTPUT', nargs=1, help='Destination file')
args.add_argument('-n', '--name', default='untitled', action='store', help='volume name (default: untitled)')
args.add_argument('-i', '--dir', action='store', help='folder to copy into the image')
args.add_argument('-a', '--app', default=None, type=hfspathtpl, help='Path:To:Startup:App')
args.add_argument('-s', '--size', default='800k', type=imgsize, action='store', help='volume size (default: size of OUTPUT)')
args.add_argument('-s', '--size', default=None, type=imgsize, action='store', help='volume size (default: sized for OUTPUT, or 800k)')
args.add_argument('-d', '--date', default='1994', type=hfsdat, action='store', help='creation & mod date (ISO-8601 or "now")')
args.add_argument('--mpw-dates', action='store_true', help='''
preserve the modification order of files by setting on-disk dates
@ -70,11 +71,67 @@ args = args.parse_args()
########################################################################
integral_sizes = [800*1024, 1024*1024]
while integral_sizes[-1] < 2 * 1024**4: # absolute max = 2TB
integral_sizes.append(integral_sizes[-1] * 2)
integral_sizes = [x // 512 for x in integral_sizes]
def is_at_least(f, size):
try:
f.seek(size - 512)
if len(f.read(512)) == 512:
return True
except:
pass
return False
def hack_file_size(f):
size = f.seek(0, 2) # seek to the end of the file
if size: # this should work most of the time, but...
size -= size % 512
return size
f.seek(0)
if len(f.read(1)) == 0: return 0
# exponentially increase the size...
left_ge = 0
for trysize in integral_sizes:
if is_at_least(f, trysize * 512):
left_ge = trysize
else:
right_lt = trysize
break
else:
return integral_sizes[-1] # reached max size
if left_ge == 0: return 0 # never got anywhere
# then refine with binary search
while left_ge + 1 < right_lt:
midpoint = left_ge + (right_lt - left_ge)//2
if is_at_least(f, midpoint * 512):
left_ge = midpoint
else:
right_lt = midpoint
return left_ge * 512
vol = Volume()
vol.name = args.name
if args.dir: vol.read_folder(args.dir, date=args.date, mpw_dates=args.mpw_dates)
image = vol.write(args.size, startapp=args.app)
with open(args.dest[0], 'wb') as f:
f.write(image)
with open(args.dest[0], 'ab+') as f:
if args.size is None: args.size = hack_file_size(f)
if args.size == 0: args.size = 800 * 1024
with open(args.dest[0], 'rb+') as f:
left, gap, right = vol.write(args.size, startapp=args.app, sparse=True)
f.write(left)
f.seek(gap, 1)
problem = len(left) + gap - f.tell()
if problem > 0:
f.write(bytes(problem))
f.write(right)
f.truncate()