/usr/lib/python2.7/dist-packages/elftools/elf/elffile.py is in python-pyelftools 0.24-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 | #-------------------------------------------------------------------------------
# elftools: elf/elffile.py
#
# ELFFile - main class for accessing ELF files
#
# Eli Bendersky (eliben@gmail.com)
# This code is in the public domain
#-------------------------------------------------------------------------------
import io
import struct
import zlib
try:
import resource
PAGESIZE = resource.getpagesize()
except ImportError:
# Windows system
import mmap
PAGESIZE = mmap.PAGESIZE
from ..common.py3compat import BytesIO
from ..common.exceptions import ELFError
from ..common.utils import struct_parse, elf_assert
from .structs import ELFStructs
from .sections import (
Section, StringTableSection, SymbolTableSection,
SUNWSyminfoTableSection, NullSection, NoteSection)
from .dynamic import DynamicSection, DynamicSegment
from .relocation import RelocationSection, RelocationHandler
from .gnuversions import (
GNUVerNeedSection, GNUVerDefSection,
GNUVerSymSection)
from .segments import Segment, InterpSegment, NoteSegment
from ..dwarf.dwarfinfo import DWARFInfo, DebugSectionDescriptor, DwarfConfig
class ELFFile(object):
""" Creation: the constructor accepts a stream (file-like object) with the
contents of an ELF file.
Accessible attributes:
stream:
The stream holding the data of the file - must be a binary
stream (bytes, not string).
elfclass:
32 or 64 - specifies the word size of the target machine
little_endian:
boolean - specifies the target machine's endianness
header:
the complete ELF file header
e_ident_raw:
the raw e_ident field of the header
"""
def __init__(self, stream):
self.stream = stream
self._identify_file()
self.structs = ELFStructs(
little_endian=self.little_endian,
elfclass=self.elfclass)
self.header = self._parse_elf_header()
self.stream.seek(0)
self.e_ident_raw = self.stream.read(16)
self._file_stringtable_section = self._get_file_stringtable()
self._section_name_map = None
def num_sections(self):
""" Number of sections in the file
"""
return self['e_shnum']
def get_section(self, n):
""" Get the section at index #n from the file (Section object or a
subclass)
"""
section_header = self._get_section_header(n)
return self._make_section(section_header)
def get_section_by_name(self, name):
""" Get a section from the file, by name. Return None if no such
section exists.
"""
# The first time this method is called, construct a name to number
# mapping
#
if self._section_name_map is None:
self._section_name_map = {}
for i, sec in enumerate(self.iter_sections()):
self._section_name_map[sec.name] = i
secnum = self._section_name_map.get(name, None)
return None if secnum is None else self.get_section(secnum)
def iter_sections(self):
""" Yield all the sections in the file
"""
for i in range(self.num_sections()):
yield self.get_section(i)
def num_segments(self):
""" Number of segments in the file
"""
return self['e_phnum']
def get_segment(self, n):
""" Get the segment at index #n from the file (Segment object)
"""
segment_header = self._get_segment_header(n)
return self._make_segment(segment_header)
def iter_segments(self):
""" Yield all the segments in the file
"""
for i in range(self.num_segments()):
yield self.get_segment(i)
def address_offsets(self, start, size=1):
""" Yield a file offset for each ELF segment containing a memory region.
A memory region is defined by the range [start...start+size). The
offset of the region is yielded.
"""
end = start + size
for seg in self.iter_segments():
if (start >= seg['p_vaddr'] and
end <= seg['p_vaddr'] + seg['p_filesz']):
yield start - seg['p_vaddr'] + seg['p_offset']
def has_dwarf_info(self):
""" Check whether this file appears to have debugging information.
We assume that if it has the .debug_info or .zdebug_info section, it
has all the other required sections as well.
"""
return bool(self.get_section_by_name('.debug_info')) or \
bool(self.get_section_by_name('.zdebug_info'))
def get_dwarf_info(self, relocate_dwarf_sections=True):
""" Return a DWARFInfo object representing the debugging information in
this file.
If relocate_dwarf_sections is True, relocations for DWARF sections
are looked up and applied.
"""
# Expect that has_dwarf_info was called, so at least .debug_info is
# present.
# Sections that aren't found will be passed as None to DWARFInfo.
#
section_names = ('.debug_info', '.debug_aranges', '.debug_abbrev', '.debug_str',
'.debug_line', '.debug_frame',
'.debug_loc', '.debug_ranges')
compressed = bool(self.get_section_by_name('.zdebug_info'))
if compressed:
section_names = tuple(map(lambda x: '.z' + x[1:], section_names))
debug_info_sec_name, debug_aranges_sec_name, debug_abbrev_sec_name, debug_str_sec_name, \
debug_line_sec_name, debug_frame_sec_name, debug_loc_sec_name, \
debug_ranges_sec_name = section_names
debug_sections = {}
for secname in section_names:
section = self.get_section_by_name(secname)
if section is None:
debug_sections[secname] = None
else:
dwarf_section = self._read_dwarf_section(
section,
relocate_dwarf_sections)
if compressed:
dwarf_section = self._decompress_dwarf_section(dwarf_section)
debug_sections[secname] = dwarf_section
return DWARFInfo(
config=DwarfConfig(
little_endian=self.little_endian,
default_address_size=self.elfclass // 8,
machine_arch=self.get_machine_arch()),
debug_info_sec=debug_sections[debug_info_sec_name],
debug_aranges_sec=debug_sections[debug_aranges_sec_name],
debug_abbrev_sec=debug_sections[debug_abbrev_sec_name],
debug_frame_sec=debug_sections[debug_frame_sec_name],
# TODO(eliben): reading of eh_frame is not hooked up yet
eh_frame_sec=None,
debug_str_sec=debug_sections[debug_str_sec_name],
debug_loc_sec=debug_sections[debug_loc_sec_name],
debug_ranges_sec=debug_sections[debug_ranges_sec_name],
debug_line_sec=debug_sections[debug_line_sec_name])
def get_machine_arch(self):
""" Return the machine architecture, as detected from the ELF header.
Not all architectures are supported at the moment.
"""
if self['e_machine'] == 'EM_X86_64':
return 'x64'
elif self['e_machine'] in ('EM_386', 'EM_486'):
return 'x86'
elif self['e_machine'] == 'EM_ARM':
return 'ARM'
elif self['e_machine'] == 'EM_AARCH64':
return 'AArch64'
elif self['e_machine'] == 'EM_MIPS':
return 'MIPS'
else:
return '<unknown>'
#-------------------------------- PRIVATE --------------------------------#
def __getitem__(self, name):
""" Implement dict-like access to header entries
"""
return self.header[name]
def _identify_file(self):
""" Verify the ELF file and identify its class and endianness.
"""
# Note: this code reads the stream directly, without using ELFStructs,
# since we don't yet know its exact format. ELF was designed to be
# read like this - its e_ident field is word-size and endian agnostic.
#
self.stream.seek(0)
magic = self.stream.read(4)
elf_assert(magic == b'\x7fELF', 'Magic number does not match')
ei_class = self.stream.read(1)
if ei_class == b'\x01':
self.elfclass = 32
elif ei_class == b'\x02':
self.elfclass = 64
else:
raise ELFError('Invalid EI_CLASS %s' % repr(ei_class))
ei_data = self.stream.read(1)
if ei_data == b'\x01':
self.little_endian = True
elif ei_data == b'\x02':
self.little_endian = False
else:
raise ELFError('Invalid EI_DATA %s' % repr(ei_data))
def _section_offset(self, n):
""" Compute the offset of section #n in the file
"""
return self['e_shoff'] + n * self['e_shentsize']
def _segment_offset(self, n):
""" Compute the offset of segment #n in the file
"""
return self['e_phoff'] + n * self['e_phentsize']
def _make_segment(self, segment_header):
""" Create a Segment object of the appropriate type
"""
segtype = segment_header['p_type']
if segtype == 'PT_INTERP':
return InterpSegment(segment_header, self.stream)
elif segtype == 'PT_DYNAMIC':
return DynamicSegment(segment_header, self.stream, self)
elif segtype == 'PT_NOTE':
return NoteSegment(segment_header, self.stream, self)
else:
return Segment(segment_header, self.stream)
def _get_section_header(self, n):
""" Find the header of section #n, parse it and return the struct
"""
return struct_parse(
self.structs.Elf_Shdr,
self.stream,
stream_pos=self._section_offset(n))
def _get_section_name(self, section_header):
""" Given a section header, find this section's name in the file's
string table
"""
name_offset = section_header['sh_name']
return self._file_stringtable_section.get_string(name_offset)
def _make_section(self, section_header):
""" Create a section object of the appropriate type
"""
name = self._get_section_name(section_header)
sectype = section_header['sh_type']
if sectype == 'SHT_STRTAB':
return StringTableSection(section_header, name, self.stream)
elif sectype == 'SHT_NULL':
return NullSection(section_header, name, self.stream)
elif sectype in ('SHT_SYMTAB', 'SHT_DYNSYM', 'SHT_SUNW_LDYNSYM'):
return self._make_symbol_table_section(section_header, name)
elif sectype == 'SHT_SUNW_syminfo':
return self._make_sunwsyminfo_table_section(section_header, name)
elif sectype == 'SHT_GNU_verneed':
return self._make_gnu_verneed_section(section_header, name)
elif sectype == 'SHT_GNU_verdef':
return self._make_gnu_verdef_section(section_header, name)
elif sectype == 'SHT_GNU_versym':
return self._make_gnu_versym_section(section_header, name)
elif sectype in ('SHT_REL', 'SHT_RELA'):
return RelocationSection(
section_header, name, self.stream, self)
elif sectype == 'SHT_DYNAMIC':
return DynamicSection(section_header, name, self.stream, self)
elif sectype == 'SHT_NOTE':
return NoteSection(section_header, name, self.stream, self)
else:
return Section(section_header, name, self.stream)
def _make_symbol_table_section(self, section_header, name):
""" Create a SymbolTableSection
"""
linked_strtab_index = section_header['sh_link']
strtab_section = self.get_section(linked_strtab_index)
return SymbolTableSection(
section_header, name, self.stream,
elffile=self,
stringtable=strtab_section)
def _make_sunwsyminfo_table_section(self, section_header, name):
""" Create a SUNWSyminfoTableSection
"""
linked_strtab_index = section_header['sh_link']
strtab_section = self.get_section(linked_strtab_index)
return SUNWSyminfoTableSection(
section_header, name, self.stream,
elffile=self,
symboltable=strtab_section)
def _make_gnu_verneed_section(self, section_header, name):
""" Create a GNUVerNeedSection
"""
linked_strtab_index = section_header['sh_link']
strtab_section = self.get_section(linked_strtab_index)
return GNUVerNeedSection(
section_header, name, self.stream,
elffile=self,
stringtable=strtab_section)
def _make_gnu_verdef_section(self, section_header, name):
""" Create a GNUVerDefSection
"""
linked_strtab_index = section_header['sh_link']
strtab_section = self.get_section(linked_strtab_index)
return GNUVerDefSection(
section_header, name, self.stream,
elffile=self,
stringtable=strtab_section)
def _make_gnu_versym_section(self, section_header, name):
""" Create a GNUVerSymSection
"""
linked_strtab_index = section_header['sh_link']
strtab_section = self.get_section(linked_strtab_index)
return GNUVerSymSection(
section_header, name, self.stream,
elffile=self,
symboltable=strtab_section)
def _get_segment_header(self, n):
""" Find the header of segment #n, parse it and return the struct
"""
return struct_parse(
self.structs.Elf_Phdr,
self.stream,
stream_pos=self._segment_offset(n))
def _get_file_stringtable(self):
""" Find the file's string table section
"""
stringtable_section_num = self['e_shstrndx']
return StringTableSection(
header=self._get_section_header(stringtable_section_num),
name='',
stream=self.stream)
def _parse_elf_header(self):
""" Parses the ELF file header and assigns the result to attributes
of this object.
"""
return struct_parse(self.structs.Elf_Ehdr, self.stream, stream_pos=0)
def _read_dwarf_section(self, section, relocate_dwarf_sections):
""" Read the contents of a DWARF section from the stream and return a
DebugSectionDescriptor. Apply relocations if asked to.
"""
self.stream.seek(section['sh_offset'])
# The section data is read into a new stream, for processing
section_stream = BytesIO()
section_stream.write(self.stream.read(section['sh_size']))
if relocate_dwarf_sections:
reloc_handler = RelocationHandler(self)
reloc_section = reloc_handler.find_relocations_for_section(section)
if reloc_section is not None:
reloc_handler.apply_section_relocations(
section_stream, reloc_section)
return DebugSectionDescriptor(
stream=section_stream,
name=section.name,
global_offset=section['sh_offset'],
size=section['sh_size'])
@staticmethod
def _decompress_dwarf_section(section):
""" Returns the uncompressed contents of the provided DWARF section.
"""
# TODO: support other compression formats from readelf.c
assert section.size > 12, 'Unsupported compression format.'
section.stream.seek(0)
# According to readelf.c the content should contain "ZLIB"
# followed by the uncompressed section size - 8 bytes in
# big-endian order
compression_type = section.stream.read(4)
assert compression_type == b'ZLIB', \
'Invalid compression type: %r' % (compression_type)
uncompressed_size = struct.unpack('>Q', section.stream.read(8))[0]
decompressor = zlib.decompressobj()
uncompressed_stream = BytesIO()
while True:
chunk = section.stream.read(PAGESIZE)
if not chunk:
break
uncompressed_stream.write(decompressor.decompress(chunk))
uncompressed_stream.write(decompressor.flush())
uncompressed_stream.seek(0, io.SEEK_END)
size = uncompressed_stream.tell()
assert uncompressed_size == size, \
'Wrong uncompressed size: expected %r, but got %r' % (
uncompressed_size, size,
)
return section._replace(stream=uncompressed_stream, size=size)
|