Created
August 20, 2015 16:27
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A FAT32 fragmenter, because I am a horrible person.
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#!/usr/bin/env python | |
import random | |
import struct | |
import sys | |
# Most of the Fat32 class was cribbed from https://gist.github.com/jonte/4577833 | |
def ppNum(num): | |
return "%s (%s)" % (hex(num), num) | |
class Fat32: | |
def __init__(self, filename): | |
self.fs = open(filename, 'r+b') | |
def getRawBytes(self, pos, numBytes): | |
self.fs.seek(pos) | |
return self.fs.read(numBytes) | |
def putRawBytes(self, pos, data): | |
self.fs.seek(pos) | |
self.fs.write(data) | |
def putUInt32(self, pos, n): | |
print 'write %10s@%08x' % (n, pos) | |
self.fs.seek(pos) | |
self.putRawBytes(pos, struct.pack('<i', n)) | |
def putUInt16(self, pos, n): | |
self.fs.seek(pos) | |
self.putRawBytes(pos, struct.pack('<H', n)) | |
def putUInt8(self, pos, n): | |
self.fs.seek(pos) | |
self.putRawBytes(pos, struct.pack('<B', n)) | |
def getBytes(self, pos, numBytes): | |
byte = self.getRawBytes(pos, numBytes) | |
if (numBytes == 2): | |
formatString = "H" | |
elif (numBytes == 1): | |
formatString = "B" | |
elif (numBytes == 4): | |
formatString = "i" | |
else: | |
raise Exception("Not implemented") | |
return struct.unpack("<"+formatString, byte)[0] | |
def getString(self, pos, numBytes): | |
raw = self.getRawBytes(pos, numBytes) | |
return struct.unpack(str(numBytes)+"s", raw)[0] | |
@property | |
def bytesPerSector(self): | |
return self.getBytes(11,2) | |
@property | |
def sectorsPerCluster(self): | |
return self.getBytes(13,1) | |
@property | |
def bytesPerCluster(self): | |
return self.bytesPerSector * self.sectorsPerCluster | |
@property | |
def reservedSectorCount(self): | |
return self.getBytes(14,2) | |
@property | |
def numberOfFATs(self): | |
return self.getBytes(16,1) | |
def FATStart(self, numFat): | |
return self.reservedSectorCount * self.bytesPerSector + (self.FATSize * self.bytesPerSector * (numFat - 1)) | |
def FATEnd(self, numFat): | |
return self.FATStart(numFat+1) | |
@property | |
def FATSize(self): | |
return self.getBytes(36,4) | |
@property | |
def rootStart(self): | |
return self.FATStart(1) + (self.FATSize * self.numberOfFATs * self.bytesPerSector) | |
@property | |
def fsIdentityString(self): | |
return self.getString(82,8) | |
class ClEntry: | |
def __init__(self, offset, length, nextclidx, prevclidx=None): | |
self.offset = offset | |
self.length = length | |
self.next = nextclidx | |
self.prev = prevclidx | |
def __repr__(self): | |
return 'ClEnt(%s, %s, %s, %s)' % (self.offset, self.length, self.next, self.prev) | |
class Clusters: | |
def __init__(self, fs): | |
self.fs = fs | |
self.fat = [] | |
self.free = set() | |
self.fs.fs.seek(0, 2) | |
eof = self.fs.fs.tell() | |
for pos in range(self.fs.FATStart(1), self.fs.FATEnd(1), 4): | |
clidx = (pos - self.fs.FATStart(1)) / 4 | |
# not entirely sure why -2 is required here | |
offset = self.fs.rootStart + (clidx-2) * self.fs.bytesPerCluster | |
if offset + self.fs.bytesPerCluster >= eof: | |
break | |
nextcluster = self.fs.getBytes(pos, 4) | |
self.fat.append(ClEntry(offset, self.fs.bytesPerCluster, nextcluster)) | |
if nextcluster == 0: | |
self.free.add(clidx) | |
for clidx in xrange(0, len(self.fat)): | |
cluster = self.fat[clidx] | |
if cluster.next > 2 and cluster.next < 0xffffff8: | |
self.fat[cluster.next].prev = clidx | |
def setNextCluster(self, target, value): | |
if value is None: | |
value = 0 | |
if target is not None: | |
writeOffset = self.fs.FATStart(1) + target * 4 | |
self.fs.putUInt32(writeOffset, value) | |
self.fat[target].next = value | |
if value == 0: | |
# clear the previous cluster reference | |
self.fat[target].prev = None | |
# add cluster to the free list | |
self.free.add(target) | |
else: | |
if value < 0xffffff8: | |
# set the previous cluster reference | |
self.fat[value].prev = target | |
# remove cluster from the free list | |
self.free.discard(target) | |
def swap(self, clidx1, clidx2): | |
c1 = self.fat[clidx1] | |
c2 = self.fat[clidx2] | |
n1 = c1.next | |
n2 = c2.next | |
p1 = c1.prev | |
p2 = c2.prev | |
o1 = c1.offset | |
o2 = c2.offset | |
d1 = self.fs.getRawBytes(o1, c1.length) | |
d2 = self.fs.getRawBytes(o2, c2.length) | |
self.setNextCluster(p1, clidx2) | |
self.setNextCluster(clidx2, n1) | |
self.setNextCluster(p2, clidx1) | |
self.setNextCluster(clidx1, n2) | |
print o1 | |
print o2 | |
self.fs.putRawBytes(o1, d2) | |
self.fs.putRawBytes(o2, d1) | |
fs = Fat32(sys.argv[1]) | |
print "Bytes per sector:", ppNum(fs.bytesPerSector) | |
print "Sectors per cluster:", ppNum(fs.sectorsPerCluster) | |
print "Reserved sector count:", ppNum(fs.reservedSectorCount) | |
print "Size of FAT (sectors):", ppNum(fs.FATSize) | |
print "Number of FATs:", ppNum(fs.numberOfFATs) | |
print "Start of FAT1:", ppNum(fs.FATStart(1)) | |
print "Start of root directory:", ppNum(fs.rootStart) | |
print "Identity string:", fs.fsIdentityString | |
clusters = Clusters(fs) | |
if 0: | |
clusters.swap(4, 6) | |
clusters.fs.fs.flush() | |
sys.exit(0) | |
for arg in sys.argv[2:]: | |
clidx = clusters.fat[int(arg)].next | |
while clidx > 2 and clidx < 0xffffff8: | |
free = random.sample(clusters.free, 1)[0] | |
nextidx = clusters.fat[clidx].next | |
print 'swap %10s <=> %10s next %10s' % (clidx, free, nextidx) | |
clusters.swap(clidx, free) | |
clidx = nextidx | |
#print clusters.fat | |
#clusters.swap(5, 9) | |
#clusters.swap(6, 10) | |
clusters.fs.fs.flush() |
That is a thing of beauty!
@FesterCluck Maximal fragmentation of a single file (It currently can't move the first cluster, though).
No jQuery :c.
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Themes, that is an interesting idea .. making one that could display ascii art into the older windows or dos defragmenter would be an interesting theme ...