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