examples/dwarf_die_tree.py

   1 #-------------------------------------------------------------------------------
   2 # elftools example: dwarf_die_tree.py
   3 #
   4 # In the .debug_info section, Dwarf Information Entries (DIEs) form a tree.
   5 # pyelftools provides easy access to this tree, as demonstrated here.
   6 #
   7 # Eli Bendersky (eliben@gmail.com)
   8 # This code is in the public domain
   9 #-------------------------------------------------------------------------------
  10 from __future__ import print_function
  11 import sys
  12
  13 # If pyelftools is not installed, the example can also run from the root or
  14 # examples/ dir of the source distribution.
  15 sys.path[0:0] = ['.', '..']
  16
  17 from elftools.elf.elffile import ELFFile
  18
  19
  20 def process_file(filename):
  21     print('Processing file:', filename)
  22     with open(filename, 'rb') as f:
  23         elffile = ELFFile(f)
  24
  25         if not elffile.has_dwarf_info():
  26             print('  file has no DWARF info')
  27             return
  28
  29         # get_dwarf_info returns a DWARFInfo context object, which is the
  30         # starting point for all DWARF-based processing in pyelftools.
  31         dwarfinfo = elffile.get_dwarf_info()
  32
  33         for CU in dwarfinfo.iter_CUs():
  34             # DWARFInfo allows to iterate over the compile units contained in
  35             # the .debug_info section. CU is a CompileUnit object, with some
  36             # computed attributes (such as its offset in the section) and
  37             # a header which conforms to the DWARF standard. The access to
  38             # header elements is, as usual, via item-lookup.
  39             print('  Found a compile unit at offset %s, length %s' % (
  40                 CU.cu_offset, CU['unit_length']))
  41
  42             # Start with the top DIE, the root for this CU's DIE tree
  43             top_DIE = CU.get_top_DIE()
  44             print('    Top DIE with tag=%s' % top_DIE.tag)
  45
  46             # We're interested in the filename...
  47             print('    name=%s' % top_DIE.get_full_path())
  48
  49             # Display DIEs recursively starting with top_DIE
  50             die_info_rec(top_DIE)
  51
  52
  53 def die_info_rec(die, indent_level='    '):
  54     """ A recursive function for showing information about a DIE and its
  55         children.
  56     """
  57     print(indent_level + 'DIE tag=%s' % die.tag)
  58     child_indent = indent_level + '  '
  59     for child in die.iter_children():
  60         die_info_rec(child, child_indent)
  61
  62
  63 if __name__ == '__main__':
  64     if sys.argv[1] == '--test':
  65         for filename in sys.argv[2:]:
  66             process_file(filename)