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@@ -1,3 +1,5 @@
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+import os, struct
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+
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class NotELFFileError(Exception):
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pass
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@@ -10,6 +12,8 @@ class ELFFile:
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EI_OSABI = 7
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EI_ABIVERSION = 8
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+ E_MACHINE = 0x12
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+
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# possible values for EI_CLASS
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ELFCLASSNONE = 0
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ELFCLASS32 = 1
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@@ -23,6 +27,8 @@ class ELFFile:
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ELFDATA2LSB = 1
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ELFDATA2MSB = 2
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+ PT_INTERP = 3
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+
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def my_assert(self, expectation, result):
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if not expectation == result:
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#print "'%x','%x' %s" % (ord(expectation), ord(result), self.name)
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@@ -38,9 +44,12 @@ class ELFFile:
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raise NotELFFileError("%s is not a normal file" % self.name)
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self.file = file(self.name, "r")
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- self.data = self.file.read(ELFFile.EI_NIDENT+4)
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+ # Read 4k which should cover most of the headers we're after
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+ self.data = self.file.read(4096)
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+
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+ if len(self.data) < ELFFile.EI_NIDENT + 4:
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+ raise NotELFFileError("%s is not an ELF" % self.name)
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- self.my_assert(len(self.data), ELFFile.EI_NIDENT+4)
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self.my_assert(self.data[0], chr(0x7f) )
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self.my_assert(self.data[1], 'E')
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self.my_assert(self.data[2], 'L')
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@@ -86,14 +95,33 @@ class ELFFile:
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def isBigEndian(self):
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return self.sex == ">"
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+ def getShort(self, offset):
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+ return struct.unpack_from(self.sex+"H", self.data, offset)[0]
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+
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+ def getWord(self, offset):
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+ return struct.unpack_from(self.sex+"i", self.data, offset)[0]
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+
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+ def isDynamic(self):
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+ """
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+ Return True if there is a .interp segment (therefore dynamically
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+ linked), otherwise False (statically linked).
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+ """
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+ offset = self.getWord(self.bits == 32 and 0x1C or 0x20)
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+ size = self.getShort(self.bits == 32 and 0x2A or 0x36)
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+ count = self.getShort(self.bits == 32 and 0x2C or 0x38)
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+
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+ for i in range(0, count):
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+ p_type = self.getWord(offset + i * size)
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+ if p_type == ELFFile.PT_INTERP:
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+ return True
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+ return False
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+
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def machine(self):
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"""
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We know the sex stored in self.sex and we
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know the position
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"""
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- import struct
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- (a,) = struct.unpack(self.sex+"H", self.data[18:20])
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- return a
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+ return self.getShort(ELFFile.E_MACHINE)
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def run_objdump(self, cmd, d):
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import bb.process
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@@ -115,3 +143,9 @@ class ELFFile:
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except Exception as e:
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bb.note("%s %s %s failed: %s" % (objdump, cmd, self.name, e))
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return ""
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+
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+if __name__ == "__main__":
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+ import sys
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+ elf = ELFFile(sys.argv[1])
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+ elf.open()
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+ print elf.isDynamic()
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