1 # Copyright (C) 2015 The Android Open Source Project 2 # 3 # Licensed under the Apache License, Version 2.0 (the "License"); 4 # you may not use this file except in compliance with the License. 5 # You may obtain a copy of the License at 6 # 7 # http://www.apache.org/licenses/LICENSE-2.0 8 # 9 # Unless required by applicable law or agreed to in writing, software 10 # distributed under the License is distributed on an "AS IS" BASIS, 11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 # See the License for the specific language governing permissions and 13 # limitations under the License. 14 15 import math 16 import os 17 import random 18 import shutil 19 import subprocess 20 import sys 21 import tempfile 22 23 blocksize = 4096 24 roots = 2 25 26 def corrupt(image, offset, length): 27 print "corrupting %d bytes at offset %d" % (length, offset) 28 f = os.open(image, os.O_WRONLY) 29 os.lseek(f, offset, os.SEEK_SET) 30 os.write(f, os.urandom(length)) 31 os.close(f) 32 33 def corruptmax(image, roots): 34 size = os.stat(image).st_size 35 36 blocks = int(math.ceil(float(size) / blocksize)) 37 rounds = int(math.ceil(float(blocks) / (255 - roots))) 38 39 max_errors = int(math.floor(rounds * roots / 2)) * blocksize 40 offset = random.randrange(0, size - max_errors) 41 42 corrupt(image, offset, max_errors) 43 44 def encode(image, fec, roots): 45 if subprocess.call([ "fec", "--roots= " + str(roots), image, fec ]) != 0: 46 raise Exception("encoding failed") 47 48 def decode(image, fec, output): 49 return subprocess.call([ "fec", "--decode", image, fec, output ]) 50 51 def compare(a, b): 52 return subprocess.call([ "cmp", "-s", a, b ]) 53 54 def simg2img(image, output): 55 print "creating a non-sparse copy of '%s' to '%s'" % (image, output) 56 if subprocess.call([ "simg2img", image, output]) != 0: 57 raise Exception("simg2img failed") 58 59 def main(argv): 60 image = argv[0] 61 62 temp_img = tempfile.NamedTemporaryFile() 63 temp_cor = tempfile.NamedTemporaryFile() 64 temp_fec = tempfile.NamedTemporaryFile() 65 temp_out = tempfile.NamedTemporaryFile() 66 67 simg2img(image, temp_img.name) 68 simg2img(image, temp_cor.name) 69 70 encode(image, temp_fec.name, roots) 71 corruptmax(temp_cor.name, roots) 72 73 if decode(temp_cor.name, temp_fec.name, temp_out.name) != 0: 74 raise Exception("FAILED: failed to correct maximum expected errors") 75 76 if compare(temp_img.name, temp_out.name) != 0: 77 raise Exception("FAILED: corrected file not identical") 78 else: 79 print "corrected content matches original" 80 81 corrupt(temp_cor.name, 0, blocksize) 82 83 if decode(temp_cor.name, temp_fec.name, temp_out.name) == 0: 84 raise Exception("FAILED: corrected more than maximum number of errors?") 85 86 print "PASSED" 87 88 if __name__ == '__main__': 89 main(sys.argv[1:]) 90
