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89 lines
2.7 KiB
89 lines
2.7 KiB
# Copyright (C) 2015 The Android Open Source Project |
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# |
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# Licensed under the Apache License, Version 2.0 (the "License"); |
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# you may not use this file except in compliance with the License. |
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# You may obtain a copy of the License at |
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# |
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# http://www.apache.org/licenses/LICENSE-2.0 |
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# |
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# Unless required by applicable law or agreed to in writing, software |
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# distributed under the License is distributed on an "AS IS" BASIS, |
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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# See the License for the specific language governing permissions and |
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# limitations under the License. |
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import math |
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import os |
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import random |
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import shutil |
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import subprocess |
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import sys |
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import tempfile |
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blocksize = 4096 |
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roots = 2 |
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def corrupt(image, offset, length): |
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print "corrupting %d bytes at offset %d" % (length, offset) |
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f = os.open(image, os.O_WRONLY) |
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os.lseek(f, offset, os.SEEK_SET) |
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os.write(f, os.urandom(length)) |
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os.close(f) |
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def corruptmax(image, roots): |
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size = os.stat(image).st_size |
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blocks = int(math.ceil(float(size) / blocksize)) |
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rounds = int(math.ceil(float(blocks) / (255 - roots))) |
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max_errors = int(math.floor(rounds * roots / 2)) * blocksize |
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offset = random.randrange(0, size - max_errors) |
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corrupt(image, offset, max_errors) |
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def encode(image, fec, roots): |
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if subprocess.call([ "fec", "--roots= " + str(roots), image, fec ]) != 0: |
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raise Exception("encoding failed") |
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def decode(image, fec, output): |
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return subprocess.call([ "fec", "--decode", image, fec, output ]) |
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def compare(a, b): |
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return subprocess.call([ "cmp", "-s", a, b ]) |
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def simg2img(image, output): |
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print "creating a non-sparse copy of '%s' to '%s'" % (image, output) |
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if subprocess.call([ "simg2img", image, output]) != 0: |
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raise Exception("simg2img failed") |
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def main(argv): |
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image = argv[0] |
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temp_img = tempfile.NamedTemporaryFile() |
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temp_cor = tempfile.NamedTemporaryFile() |
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temp_fec = tempfile.NamedTemporaryFile() |
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temp_out = tempfile.NamedTemporaryFile() |
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simg2img(image, temp_img.name) |
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simg2img(image, temp_cor.name) |
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encode(image, temp_fec.name, roots) |
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corruptmax(temp_cor.name, roots) |
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if decode(temp_cor.name, temp_fec.name, temp_out.name) != 0: |
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raise Exception("FAILED: failed to correct maximum expected errors") |
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if compare(temp_img.name, temp_out.name) != 0: |
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raise Exception("FAILED: corrected file not identical") |
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else: |
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print "corrected content matches original" |
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corrupt(temp_cor.name, 0, blocksize) |
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if decode(temp_cor.name, temp_fec.name, temp_out.name) == 0: |
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raise Exception("FAILED: corrected more than maximum number of errors?") |
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print "PASSED" |
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if __name__ == '__main__': |
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main(sys.argv[1:])
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