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Mitigate scratch consumption

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As an old file is copied in for future disposale, delete
it as we go by fallocate
to punch holes in it.
This commit is contained in:
Jarrod Johnson 2021-07-26 09:19:33 -04:00
parent 663f8fc085
commit 0ad59436ec
1 changed files with 19 additions and 6 deletions
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25
imgutil/imgutil
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@ -30,6 +30,11 @@ MS_BIND = 4096
MS_REC = 16384
MS_PRIVATE = 1<<18
fallocate = libc.fallocate
fallocate.argtypes = [ctypes.c_int, ctypes.c_int, ctypes.c_int64, ctypes.c_int64]
fallocate.restype = ctypes.c_int
FALLOC_FL_KEEP_SIZE = 1
FALLOC_FL_PUNCH_HOLE = 2
numregex = re.compile('([0-9]+)')
@ -259,11 +264,14 @@ def capture_system_back(args):
if pad:
outimg.write(b'\x00' * pad)
outimg.write(struct.pack('!Q', isize))
with open(fname + '.sfs', 'rb') as imgin:
currchunk = imgin.read(32768)
with open(fname + '.sfs', 'rb+') as imgin:
lastoffset = 0
currchunk = imgin.read(2097152)
while currchunk:
fallocate(imgin.fileno(), FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, lastoffset, len(currchunk))
lastoffset = imgin.tell()
outimg.write(currchunk)
currchunk = imgin.read(32768)
currchunk = imgin.read(2097152)
pad = 4096 - (outimg.tell() % 4096)
if pad < 4096:
outimg.write(b'\x00' * pad)
@ -289,11 +297,16 @@ def encrypt_image(plainfile, cryptfile, keyfile):
subprocess.check_call(['losetup', loopdev, cryptfile])
subprocess.check_call(['dmsetup', 'create', dmname, '--table', '0 {} crypt aes-xts-plain64 {} 0 {} 8'.format(neededblocks, key, loopdev)])
with open('/dev/mapper/{}'.format(dmname), 'wb') as cryptout:
with open(plainfile, 'rb') as plainin:
chunk = plainin.read(65536)
with open(plainfile, 'rb+') as plainin:
lastoffset = 0
chunk = plainin.read(2097152)
while chunk:
fallocate(plainin.fileno(), FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, lastoffset, len(chunk))
lastoffset = plainin.tell()
cryptout.write(chunk)
chunk = plainin.read(65536)
chunk = plainin.read(2097152)
subprocess.check_call(['dmsetup', 'remove', dmname])
subprocess.check_call(['losetup', '-d', loopdev])
oum = os.umask(0o077)
with open(keyfile, 'w') as keyout:
keyout.write('aes-xts-plain64\n{}\n'.format(key))