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103 lines
2.6 KiB
Python
103 lines
2.6 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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import os
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import sys
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import re
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import types
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import binascii
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class EnvBuffer():
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addr = None
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data = None # partition dump
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offset = None # ENV offset in partition
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len = 0
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max_size = None
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var = {} # key=value
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encoding = 'ascii'
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crc_prefix = True
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delim = '\x00'
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def __init__(self, data = None, delim = '\x00', crc_prefix = True, encoding = 'ascii'):
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self.encoding = encoding
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self.delim = delim
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self.crc_prefix = crc_prefix
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self.var = {}
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if data is not None:
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prefix_len = 4 if crc_prefix else 0
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if isinstance(data, str):
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self.var = self.parse_env(data, delim)
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else:
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end = data.find((delim + delim).encode(encoding), prefix_len)
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if (end > prefix_len):
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data = data[prefix_len:end+1]
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self.var = self.parse_env_b(data, delim, encoding)
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def parse_env_b(self, data, delim, encoding = 'ascii'):
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dict = {}
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self.len = len(data)
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data = data.split(delim.encode('ascii'))
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for i, s in enumerate(data):
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s = s.strip()
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if len(s) < 1:
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continue
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x = s.find(b'=')
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if x == 0:
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continue
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if x >= 1:
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key = s[0:x].decode(encoding)
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val = s[x+1:].decode(encoding)
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dict[key.strip()] = val.strip()
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else:
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key = s.decode(encoding)
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dict[key.strip()] = None
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return dict
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def parse_env(self, data, delim):
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dict = {}
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self.len = len(data)
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data = data.split(delim)
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for i, s in enumerate(data):
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s = s.strip()
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if len(s) < 1:
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continue
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x = s.find('=')
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if x == 0:
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continue
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if x >= 1:
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key = (s[0:x]).strip()
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if key:
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dict[key] = (s[x+1:]).strip()
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else:
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dict[s.strip()] = None
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return dict
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def set_env(self, key, value):
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var[key] = value
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def pack(self, bufsize, crc_prefix = None, encoding = None):
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crc_prefix = crc_prefix if crc_prefix is not None else self.crc_prefix
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encoding = encoding if encoding is not None else self.encoding
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buf = b''
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if self.var:
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for i, (k, v) in enumerate(self.var.items()):
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v = '' if (v is None) else ('=' + v)
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buf += (k + v + '\x00').encode(encoding)
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if len(buf) + 64 > bufsize:
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raise OSError("Buffer overflow")
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prefix_len = 4 if crc_prefix else 0
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buf += b'\x00' * (bufsize - len(buf) - prefix_len)
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crc = binascii.crc32(buf)
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buf = (crc).to_bytes(4, byteorder='little') + buf
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return buf
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