#5 add python script for csv decoding

xtRLE.py

@@ -0,0 +1,128 @@
+import argparse, os
+
+XTRLE_MAGIC = 'xtRLE'
+KEY_ONE = 0xA5
+KEY_TWO = 0x00
+
+def bytes_to_int(arr):
+    size = len(arr)
+    res = 0
+    for i in range(0, 4):
+        res |= (int(arr[i]) << ((size - 1 - i) * 8))
+    return res
+
+def decompress(file):
+    magic = file.read(len(XTRLE_MAGIC))
+    if magic.decode('ascii') != XTRLE_MAGIC:
+        file.close()
+        raise ValueError('Infile is not encoded with {}'.format(XTRLE_MAGIC))
+
+    # skip magic end (0x00)
+    file.read(1)
+    # unknown value
+    file.read(4)
+
+    # recover size
+    size = bytes_to_int(file.read(4)[::-1])
+
+    data = [0] * size
+    data_ptr = 0
+
+    c = file.read(1)
+    while c and c[0] != 0x0:
+        if c[0] == 0x0:
+            file.seek(0x0E + num)
+        else:
+            num = c[0] & 0x7F
+
+            if c[0] & 0x80:
+                # read whole num-chunk from file
+                new_data = file.read(num)
+                if not new_data:
+                    file.close()
+                    raise ValueError('Error reading input file')
+                else:
+                    for i in range(0, num):
+                        data[data_ptr + i] = new_data[i]
+            else:
+                # copy next byte num-times
+                c = file.read(1)
+                if c[0] == 0x0:
+                    file.close()
+                    raise ValueError('Error reading input file')
+                for i in range(0, num):
+                    data[data_ptr + i] = c[0]
+
+            data_ptr += num
+        c = file.read(1)
+
+    return data, size
+
+def decrypt(data, size):
+    if not size:
+        return
+
+    res = data.copy()
+    c = data[0]
+    i = 1
+
+    while True:
+        d = res[i]
+        if d == c:
+            while i < size:
+                d = res[i]
+                res[i - 1] = c ^ KEY_TWO
+                if d != c:
+                    break
+                i += 1
+        else:
+            res[i - 1] = c ^ KEY_ONE
+
+        if i >= size - 1:
+            res[size - 1] = d ^ (KEY_TWO if c == d else KEY_ONE)
+            break
+
+        c = d
+        i += 1
+
+    return res
+
+def run(key1, key2, infile, outfile):
+    if infile == outfile:
+        raise ValueError('Input and output files are the same')
+
+    if not os.path.exists(infile):
+        raise FileNotFoundError("Input file does not exist")
+    f_in = open(infile, 'rb')
+
+    if not outfile:
+        outfile = './' + infile.split('.')[0][::-1].split('/')[0][::-1] + '.csv'
+        print('Output not given, using {}'.format(outfile))
+        f_out = open(outfile, 'w')
+    else:
+        if os.path.exists(outfile):
+            os.remove(outfile)
+            print('Overwriting {}'.format(outfile))
+        f_out = open(outfile, 'w')
+
+    data, size = decompress(f_in)
+    if not data:
+        raise ValueError('Decompressed file appears to be empty')
+
+    res = decrypt(data, size)
+    for x in res:
+        f_out.write(chr(x))
+
+    f_in.close()
+    f_out.close()
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="xtRLE decoder")
+    parser.add_argument('--key1', '-k1', type=int, required=False, help='Key 1')
+    parser.add_argument('--key2', '-k2', type=int, required=False, help='Key 2')
+    parser.add_argument('--infile', '-i', type=str, required=True, help='Input file')
+    parser.add_argument('--outfile', '-o', type=str, required=False, help='Output file')
+    args = parser.parse_args()
+
+    run(args.key1, args.key2, args.infile, args.outfile)
+