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Update IOUtools. Ref #1627
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@@ -37,19 +37,19 @@ optional arguments:
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-h, --help show this help message and exit
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"""
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import argparse
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import sys
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import struct
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# Uncompress data in .Z file format.
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# Ported from dynamips' fs_nvram.c to python
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# Adapted from 7zip's ZDecoder.cpp, which is licensed under LGPL 2.1.
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# Uncompress data in LZC format, .Z file format
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# LZC uses the LZW compression algorithm with a variable dictionary size
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# For LZW see https://en.wikipedia.org/wiki/Lempel–Ziv–Welch
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# Performance: about 1 MByte/sec, 15-50 times slower than C implementation
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def uncompress_LZC(data):
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LZC_NUM_BITS_MIN = 9
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LZC_NUM_BITS_MAX = 16
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in_data = bytearray(data)
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in_len = len(in_data)
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in_data = bytearray(data)
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in_len = len(in_data)
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out_data = bytearray()
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if in_len == 0:
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@@ -59,143 +59,144 @@ def uncompress_LZC(data):
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if in_data[0] != 0x1F or in_data[1] != 0x9D:
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raise ValueError('invalid header')
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maxbits = in_data[2] & 0x1F
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numItems = 1 << maxbits
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blockMode = (in_data[2] & 0x80) != 0
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if maxbits < LZC_NUM_BITS_MIN or maxbits > LZC_NUM_BITS_MAX:
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max_bits = in_data[2] & 0x1F
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if max_bits < LZC_NUM_BITS_MIN or max_bits > LZC_NUM_BITS_MAX:
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raise ValueError('not supported')
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num_items = 1 << max_bits
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blockmode = (in_data[2] & 0x80) != 0
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parents = [0] * numItems
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suffixes = [0] * numItems
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in_pos = 3
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numBits = LZC_NUM_BITS_MIN
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head = 256
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if blockMode:
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in_pos = 3
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start_pos = in_pos
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num_bits = LZC_NUM_BITS_MIN
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dict_size = 1 << num_bits
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head = 256
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if blockmode:
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head += 1
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first_sym = True
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needPrev = 0
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bitPos = 0
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numBufBits = 0
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# initialize dictionary
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comp_dict = [None] * num_items
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for i in range(0, 256):
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comp_dict[i] = bytes(bytearray([i]))
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parents[256] = 0
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suffixes[256] = 0
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buf_extend = bytearray([0] * 3)
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while True:
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# fill buffer, when empty
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if numBufBits == bitPos:
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buf_len = min(in_len - in_pos, numBits)
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buf = in_data[in_pos:in_pos + buf_len] + buf_extend
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numBufBits = buf_len << 3
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bitPos = 0
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in_pos += buf_len
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# extract next symbol
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bytePos = bitPos >> 3
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symbol = buf[bytePos] | buf[bytePos + 1] << 8 | buf[bytePos + 2] << 16
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symbol >>= bitPos & 7
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symbol &= (1 << numBits) - 1
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bitPos += numBits
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# check for special conditions: end, bad data, re-initialize dictionary
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if bitPos > numBufBits:
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break
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if symbol >= head:
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buf = buf_bits = 0
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while in_pos < in_len:
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# get next symbol
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try:
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while buf_bits < num_bits:
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buf |= in_data[in_pos] << buf_bits
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buf_bits += 8
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in_pos += 1
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buf, symbol = divmod(buf, dict_size)
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buf_bits -= num_bits
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except IndexError:
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raise ValueError('invalid data')
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if blockMode and symbol == 256:
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numBufBits = bitPos = 0
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numBits = LZC_NUM_BITS_MIN
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# re-initialize dictionary
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if blockmode and symbol == 256:
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# skip to next buffer boundary
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buf = buf_bits = 0
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in_pos += (start_pos - in_pos) % num_bits
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# reset to LZC_NUM_BITS_MIN
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head = 257
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needPrev = 0
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num_bits = LZC_NUM_BITS_MIN
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dict_size = 1 << num_bits
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start_pos = in_pos
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first_sym = True
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continue
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# convert symbol to string
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stack = []
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cur = symbol
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while cur >= 256:
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stack.append(suffixes[cur])
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cur = parents[cur]
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stack.append(cur)
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if needPrev:
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suffixes[head - 1] = cur
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if symbol == head - 1:
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stack[0] = cur
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stack.reverse()
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out_data.extend(stack)
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# first symbol
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if first_sym:
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first_sym = False
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if symbol >= 256:
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raise ValueError('invalid data')
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prev = symbol
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out_data.extend(comp_dict[symbol])
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continue
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# update parents, check for numBits change
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if head < numItems:
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needPrev = 1
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parents[head] = symbol
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head += 1
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if head > (1 << numBits):
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if numBits < maxbits:
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numBufBits = bitPos = 0
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numBits += 1
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# dictionary full
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if head >= num_items:
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out_data.extend(comp_dict[symbol])
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continue
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# update compression dictionary
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if symbol < head:
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comp_dict[head] = comp_dict[prev] + comp_dict[symbol][0:1]
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elif symbol == head:
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comp_dict[head] = comp_dict[prev] + comp_dict[prev][0:1]
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else:
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needPrev = 0
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raise ValueError('invalid data')
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prev = symbol
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# output symbol
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out_data.extend(comp_dict[symbol])
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# update head, check for num_bits change
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head += 1
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if head >= dict_size and num_bits < max_bits:
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num_bits += 1
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dict_size = 1 << num_bits
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start_pos = in_pos
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return out_data
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# extract 16 bit unsigned int from data
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def get_uint16(data, off):
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return data[off] << 8 | data[off + 1]
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# extract 32 bit unsigned int from data
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def get_uint32(data, off):
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return data[off] << 24 | data[off + 1] << 16 | data[off + 2] << 8 | data[off + 3]
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# export IOU NVRAM
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# NVRAM format: https://github.com/ehlers/IOUtools/blob/master/NVRAM.md
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def nvram_export(nvram):
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nvram = bytearray(nvram)
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# extract startup config
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offset = 0
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if len(nvram) < offset + 36:
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# extract startup config
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try:
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(magic, data_format, _, _, _, _, length, _, _, _, _, _) = \
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struct.unpack_from('>HHHHIIIIIHHI', nvram, offset=offset)
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offset += 36
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if magic != 0xABCD:
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raise ValueError('no startup config')
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if len(nvram) < offset+length:
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raise ValueError('invalid length')
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startup = nvram[offset:offset+length]
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except struct.error:
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raise ValueError('invalid length')
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if get_uint16(nvram, offset + 0) != 0xABCD:
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raise ValueError('no startup config')
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format = get_uint16(nvram, offset + 2)
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length = get_uint32(nvram, offset + 16)
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offset += 36
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if len(nvram) < offset + length:
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raise ValueError('invalid length')
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startup = nvram[offset:offset + length]
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# compressed startup config
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if format == 2:
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# uncompress startup config
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if data_format == 2:
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try:
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startup = uncompress_LZC(startup)
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except ValueError as err:
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raise ValueError('uncompress startup: ' + str(err))
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offset += length
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# alignment to multiple of 4
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offset = (offset + 3) & ~3
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# check for additonal offset of 4
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if len(nvram) >= offset + 8 and \
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get_uint16(nvram, offset + 4) == 0xFEDC and \
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get_uint16(nvram, offset + 6) == 1:
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offset += 4
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# extract private config
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private = None
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if len(nvram) >= offset + 16 and get_uint16(nvram, offset + 0) == 0xFEDC:
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length = get_uint32(nvram, offset + 12)
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try:
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# calculate offset of private header
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length += (4 - length % 4) % 4 # alignment to multiple of 4
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offset += length
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# check for additonal offset of 4
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(magic, data_format) = struct.unpack_from('>HH', nvram, offset=offset+4)
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if magic == 0xFEDC and data_format == 1:
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offset += 4
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# extract private config
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(magic, data_format, _, _, length) = \
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struct.unpack_from('>HHIII', nvram, offset=offset)
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offset += 16
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if len(nvram) >= offset + length:
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private = nvram[offset:offset + length]
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if magic == 0xFEDC and data_format == 1:
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if len(nvram) < offset+length:
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raise ValueError('invalid length')
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private = nvram[offset:offset+length]
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# missing private header is not an error
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except struct.error:
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pass
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return (startup, private)
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if __name__ == '__main__':
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# Main program
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import argparse
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import sys
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parser = argparse.ArgumentParser(description='%(prog)s exports startup/private configuration from IOU NVRAM file.')
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parser.add_argument('nvram', metavar='NVRAM',
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