91 lines
2.5 KiB
Python
91 lines
2.5 KiB
Python
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import hashlib
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import logging
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import tarfile
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TarError = tarfile.TarError
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logger = logging.getLogger(__name__)
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def sha256_file(fp, data=None):
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h = hashlib.sha256(data or '')
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if not fp:
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return h.hexdigest()
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while True:
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buf = fp.read(4096)
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if not buf:
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break
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h.update(buf)
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return h.hexdigest()
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def sha256_string(s):
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return hashlib.sha256(s).hexdigest()
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def compute_tarsum(fp, json_data):
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header_fields = ('name', 'mode', 'uid', 'gid', 'size', 'mtime',
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'type', 'linkname', 'uname', 'gname', 'devmajor',
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'devminor')
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tar = None
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hashes = []
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try:
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tar = tarfile.open(mode='r|*', fileobj=fp)
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for member in tar:
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header = ''
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for field in header_fields:
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value = getattr(member, field)
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if field == 'type':
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field = 'typeflag'
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elif field == 'name':
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if member.isdir() and not value.endswith('/'):
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value += '/'
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header += '{0}{1}'.format(field, value)
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h = None
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try:
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if member.size > 0:
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f = tar.extractfile(member)
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h = sha256_file(f, header)
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else:
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h = sha256_string(header)
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except KeyError:
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h = sha256_string(header)
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hashes.append(h)
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hashes.sort()
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except tarfile.ReadError as e:
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if e.message != 'empty file':
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# NOTE(samalba): ignore empty tarfiles but still let the tarsum
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# compute with json data
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raise
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finally:
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if tar:
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tar.close()
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data = json_data + ''.join(hashes)
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tarsum = 'tarsum+sha256:{0}'.format(sha256_string(data))
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logger.debug('checksums.compute_tarsum: return {0}'.format(tarsum))
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return tarsum
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def simple_checksum_handler(json_data):
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h = hashlib.sha256(json_data.encode('utf8') + '\n')
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def fn(buf):
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h.update(buf)
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return h, fn
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def compute_simple(fp, json_data):
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data = json_data + '\n'
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return 'sha256:{0}'.format(sha256_file(fp, data))
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if __name__ == '__main__':
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import sys
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if len(sys.argv) < 3:
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print 'Usage: {0} json_file layer_file'.format(sys.argv[0])
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sys.exit(1)
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json_data = file(sys.argv[1]).read()
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fp = open(sys.argv[2])
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print compute_simple(fp, json_data)
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print compute_tarsum(fp, json_data)
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