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118
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1 import struct
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2
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3 classes = {1:'ELF32', 2:'ELF64'}
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4
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5 class ElfFile:
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6 def __init__(self, f):
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7 self.f = f
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8 self.parse()
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9 def parse(self):
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10 self.parseHeader()
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11 self.parseSections()
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12 self.parsePrograms()
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13 @property
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14 def ElfClass(self):
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15 return classes[self.ei_class]
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16 def parseHeader(self):
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17 # Parse identifier
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18 e_ident = self.f.read(16)
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19 ELFMAGIC = bytes([0x7f]) + b'ELF'
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20 assert e_ident[0:4] == ELFMAGIC
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21 self.ei_class = e_ident[4]
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22 print('ELF class: ', self.ElfClass)
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23 assert self.ei_class in classes.keys()
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24 self.ei_data = e_ident[5]
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25 print('ei_data:', self.ei_data)
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26 ei_version = e_ident[6]
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27 assert ei_version == 1
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28
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29 # rest of the ELF header:
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30 e_type = self.readHalf()
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31 e_machine = self.readHalf()
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32 e_version = self.readWord()
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33 e_entry = self.readAddr()
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34 e_phoff = self.readOff()
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35 e_shoff = self.readOff()
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36 e_flags = self.readWord()
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37 e_ehsize = self.readHalf()
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38 e_phentsize = self.readHalf()
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39 e_phnum = self.readHalf()
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40 e_shentsize = self.readHalf()
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41 e_shnum = self.readHalf()
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42 e_shstrndx = self.readHalf()
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43
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44 if self.ei_class == 1:
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45 assert e_ehsize == 52
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46 elif self.ei_class == 2:
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47 assert e_ehsize == 64
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48 print('program header size', e_phentsize, e_phnum)
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49 print('section header size', e_shentsize, e_shnum, e_shstrndx)
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50 def readFmt(self, fmt):
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51 size = struct.calcsize(fmt)
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52 return struct.unpack(fmt, self.f.read(size))
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53 def readHalf(self):
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54 return self.readFmt('<H')[0]
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55 def readWord(self):
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56 return self.readFmt('<I')[0]
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57 def readAddr(self):
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58 if self.ei_class == 1:
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59 fmt = '<I'
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60 elif self.ei_class == 2:
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61 fmt = '<Q'
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62 else:
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63 raise Exception()
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64 return self.readFmt(fmt)[0]
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65 readOff = readAddr
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66
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67 def printProgramHeaders(self):
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68 pass
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