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#-------------------------------------------------------------------------------
# elftools example: dwarf_range_lists.py
#
# Examine DIE entries which have range list values, and decode these range
# lists.
#
# Eli Bendersky (eliben@gmail.com)
# This code is in the public domain
#-------------------------------------------------------------------------------
from __future__ import print_function
import sys
# If pyelftools is not installed, the example can also run from the root or
# examples/ dir of the source distribution.
sys.path[0:0] = ['.', '..']
from elftools.common.py3compat import itervalues
from elftools.elf.elffile import ELFFile
from elftools.dwarf.descriptions import (
describe_DWARF_expr, set_global_machine_arch)
from elftools.dwarf.ranges import RangeEntry
def process_file(filename):
print('Processing file:', filename)
with open(filename, 'rb') as f:
elffile = ELFFile(f)
if not elffile.has_dwarf_info():
print(' file has no DWARF info')
return
# get_dwarf_info returns a DWARFInfo context object, which is the
# starting point for all DWARF-based processing in pyelftools.
dwarfinfo = elffile.get_dwarf_info()
# The range lists are extracted by DWARFInfo from the .debug_ranges
# section, and returned here as a RangeLists object.
range_lists = dwarfinfo.range_lists()
if range_lists is None:
print(' file has no .debug_ranges section')
return
for CU in dwarfinfo.iter_CUs():
# DWARFInfo allows to iterate over the compile units contained in
# the .debug_info section. CU is a CompileUnit object, with some
# computed attributes (such as its offset in the section) and
# a header which conforms to the DWARF standard. The access to
# header elements is, as usual, via item-lookup.
print(' Found a compile unit at offset %s, length %s' % (
CU.cu_offset, CU['unit_length']))
# A CU provides a simple API to iterate over all the DIEs in it.
for DIE in CU.iter_DIEs():
# Go over all attributes of the DIE. Each attribute is an
# AttributeValue object (from elftools.dwarf.die), which we
# can examine.
for attr in itervalues(DIE.attributes):
if attribute_has_range_list(attr):
# This is a range list. Its value is an offset into
# the .debug_ranges section, so we can use the range
# lists object to decode it.
rangelist = range_lists.get_range_list_at_offset(
attr.value)
print(' DIE %s. attr %s.\n%s' % (
DIE.tag,
attr.name,
rangelist))
def attribute_has_range_list(attr):
""" Only some attributes can have range list values, if they have the
required DW_FORM (rangelistptr "class" in DWARF spec v3)
"""
if attr.name == 'DW_AT_ranges':
if attr.form in ('DW_FORM_data4', 'DW_FORM_data8'):
return True
return False
if __name__ == '__main__':
if sys.argv[1] == '--test':
for filename in sys.argv[2:]:
process_file(filename)
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