1 #-------------------------------------------------------------------------------
2 # elftools: dwarf/dwarfinfo.py
4 # DWARFInfo - Main class for accessing DWARF debug information
6 # Eli Bendersky (eliben@gmail.com)
7 # This code is in the public domain
8 #-------------------------------------------------------------------------------
10 from collections
import namedtuple
11 from bisect
import bisect_right
13 from ..construct
.lib
.container
import Container
14 from ..common
.exceptions
import DWARFError
15 from ..common
.utils
import (struct_parse
, dwarf_assert
,
16 parse_cstring_from_stream
)
17 from .structs
import DWARFStructs
18 from .compileunit
import CompileUnit
19 from .abbrevtable
import AbbrevTable
20 from .lineprogram
import LineProgram
21 from .callframe
import CallFrameInfo
22 from .locationlists
import LocationLists
, LocationListsPair
23 from .ranges
import RangeLists
, RangeListsPair
24 from .aranges
import ARanges
25 from .namelut
import NameLUT
28 # Describes a debug section
30 # stream: a stream object containing the data of this section
31 # name: section name in the container file
32 # global_offset: the global offset of the section in its container file
33 # size: the size of the section's data, in bytes
34 # address: the virtual address for the section's data
36 # 'name' and 'global_offset' are for descriptional purposes only and
37 # aren't strictly required for the DWARF parsing to work. 'address' is required
38 # to properly decode the special '.eh_frame' format.
40 DebugSectionDescriptor
= namedtuple('DebugSectionDescriptor',
41 'stream name global_offset size address')
44 # Some configuration parameters for the DWARF reader. This exists to allow
45 # DWARFInfo to be independent from any specific file format/container.
48 # boolean flag specifying whether the data in the file is little endian
51 # Machine architecture as a string. For example 'x86' or 'x64'
53 # default_address_size:
54 # The default address size for the container file (sizeof pointer, in bytes)
56 DwarfConfig
= namedtuple('DwarfConfig',
57 'little_endian machine_arch default_address_size')
60 class DWARFInfo(object):
61 """ Acts also as a "context" to other major objects, bridging between
62 various parts of the debug infromation.
78 debug_str_offsets_sec
,
81 debug_rnglists_sec
): # Not parsed for now
86 DebugSectionDescriptor for a section. Pass None for sections
87 that don't exist. These arguments are best given with
91 self
.debug_info_sec
= debug_info_sec
92 self
.debug_aranges_sec
= debug_aranges_sec
93 self
.debug_abbrev_sec
= debug_abbrev_sec
94 self
.debug_frame_sec
= debug_frame_sec
95 self
.eh_frame_sec
= eh_frame_sec
96 self
.debug_str_sec
= debug_str_sec
97 self
.debug_loc_sec
= debug_loc_sec
98 self
.debug_ranges_sec
= debug_ranges_sec
99 self
.debug_line_sec
= debug_line_sec
100 self
.debug_addr_sec
= debug_addr_sec
101 self
.debug_line_str_sec
= debug_line_str_sec
102 self
.debug_pubtypes_sec
= debug_pubtypes_sec
103 self
.debug_pubnames_sec
= debug_pubnames_sec
104 self
.debug_loclists_sec
= debug_loclists_sec
105 self
.debug_rnglists_sec
= debug_rnglists_sec
107 # This is the DWARFStructs the context uses, so it doesn't depend on
108 # DWARF format and address_size (these are determined per CU) - set them
110 self
.structs
= DWARFStructs(
111 little_endian
=self
.config
.little_endian
,
113 address_size
=self
.config
.default_address_size
)
115 # Cache for abbrev tables: a dict keyed by offset
116 self
._abbrevtable
_cache
= {}
118 # Cache of compile units and map of their offsets for bisect lookup.
119 # Access with .iter_CUs(), .get_CU_containing(), and/or .get_CU_at().
121 self
._cu
_offsets
_map
= []
124 def has_debug_info(self
):
125 """ Return whether this contains debug information.
127 It can be not the case when the ELF only contains .eh_frame, which is
128 encoded DWARF but not actually for debugging.
130 return bool(self
.debug_info_sec
)
132 def get_DIE_from_lut_entry(self
, lut_entry
):
133 """ Get the DIE from the pubnames or putbtypes lookup table entry.
136 A NameLUTEntry object from a NameLUT instance (see
137 .get_pubmames and .get_pubtypes methods).
139 cu
= self
.get_CU_at(lut_entry
.cu_ofs
)
140 return self
.get_DIE_from_refaddr(lut_entry
.die_ofs
, cu
)
142 def get_DIE_from_refaddr(self
, refaddr
, cu
=None):
143 """ Given a .debug_info section offset of a DIE, return the DIE.
146 The refaddr may come from a DW_FORM_ref_addr attribute.
149 The compile unit object, if known. If None a search
150 from the closest offset less than refaddr will be performed.
153 cu
= self
.get_CU_containing(refaddr
)
154 return cu
.get_DIE_from_refaddr(refaddr
)
156 def get_CU_containing(self
, refaddr
):
157 """ Find the CU that includes the given reference address in the
161 Either a refaddr of a DIE (possibly from a DW_FORM_ref_addr
162 attribute) or the section offset of a CU (possibly from an
165 This function will parse and cache CUs until the search criteria
166 is met, starting from the closest known offset lessthan or equal
167 to the given address.
171 'CU lookup but no debug info section')
173 0 <= refaddr
< self
.debug_info_sec
.size
,
174 "refaddr %s beyond .debug_info size" % refaddr
)
176 # The CU containing the DIE we desire will be to the right of the
177 # DIE insert point. If we have a CU address, then it will be a
178 # match but the right insert minus one will still be the item.
179 # The first CU starts at offset 0, so start there if cache is empty.
180 i
= bisect_right(self
._cu
_offsets
_map
, refaddr
)
181 start
= self
._cu
_offsets
_map
[i
- 1] if i
> 0 else 0
183 # parse CUs until we find one containing the desired address
184 for cu
in self
._parse
_CUs
_iter
(start
):
185 if cu
.cu_offset
<= refaddr
< cu
.cu_offset
+ cu
.size
:
188 raise ValueError("CU for reference address %s not found" % refaddr
)
190 def get_CU_at(self
, offset
):
191 """ Given a CU header offset, return the parsed CU.
194 The offset may be from an accelerated access table such as
195 the public names, public types, address range table, or
198 This function will directly parse the CU doing no validation of
199 the offset beyond checking the size of the .debug_info section.
203 'CU lookup but no debug info section')
205 0 <= offset
< self
.debug_info_sec
.size
,
206 "offset %s beyond .debug_info size" % offset
)
208 return self
._cached
_CU
_at
_offset
(offset
)
211 """ Yield all the compile units (CompileUnit objects) in the debug info
213 return self
._parse
_CUs
_iter
()
215 def get_abbrev_table(self
, offset
):
216 """ Get an AbbrevTable from the given offset in the debug_abbrev
219 The only verification done on the offset is that it's within the
220 bounds of the section (if not, an exception is raised).
221 It is the caller's responsibility to make sure the offset actually
222 points to a valid abbreviation table.
224 AbbrevTable objects are cached internally (two calls for the same
225 offset will return the same object).
228 offset
< self
.debug_abbrev_sec
.size
,
229 "Offset '0x%x' to abbrev table out of section bounds" % offset
)
230 if offset
not in self
._abbrevtable
_cache
:
231 self
._abbrevtable
_cache
[offset
] = AbbrevTable(
232 structs
=self
.structs
,
233 stream
=self
.debug_abbrev_sec
.stream
,
235 return self
._abbrevtable
_cache
[offset
]
237 def get_string_from_table(self
, offset
):
238 """ Obtain a string from the string table section, given an offset
239 relative to the section.
241 return parse_cstring_from_stream(self
.debug_str_sec
.stream
, offset
)
243 def get_string_from_linetable(self
, offset
):
244 """ Obtain a string from the string table section, given an offset
245 relative to the section.
247 return parse_cstring_from_stream(self
.debug_line_str_sec
.stream
, offset
)
249 def line_program_for_CU(self
, CU
):
250 """ Given a CU object, fetch the line program it points to from the
252 If the CU doesn't point to a line program, return None.
254 Note about directory and file names. They are returned as two collections
255 in the lineprogram object's header - include_directory and file_entry.
257 In DWARFv5, they have introduced a different, extensible format for those
258 collections. So in a lineprogram v5+, there are two more collections in
259 the header - directories and file_names. Those might contain extra DWARFv5
260 information that is not exposed in include_directory and file_entry.
262 # The line program is pointed to by the DW_AT_stmt_list attribute of
263 # the top DIE of a CU.
264 top_DIE
= CU
.get_top_DIE()
265 if 'DW_AT_stmt_list' in top_DIE
.attributes
:
266 return self
._parse
_line
_program
_at
_offset
(
267 top_DIE
.attributes
['DW_AT_stmt_list'].value
, CU
.structs
)
272 """ Does this dwarf info have a dwarf_frame CFI section?
274 return self
.debug_frame_sec
is not None
276 def CFI_entries(self
):
277 """ Get a list of dwarf_frame CFI entries from the .debug_frame section.
280 stream
=self
.debug_frame_sec
.stream
,
281 size
=self
.debug_frame_sec
.size
,
282 address
=self
.debug_frame_sec
.address
,
283 base_structs
=self
.structs
)
284 return cfi
.get_entries()
286 def has_EH_CFI(self
):
287 """ Does this dwarf info have a eh_frame CFI section?
289 return self
.eh_frame_sec
is not None
291 def EH_CFI_entries(self
):
292 """ Get a list of eh_frame CFI entries from the .eh_frame section.
295 stream
=self
.eh_frame_sec
.stream
,
296 size
=self
.eh_frame_sec
.size
,
297 address
=self
.eh_frame_sec
.address
,
298 base_structs
=self
.structs
,
300 return cfi
.get_entries()
302 def get_pubtypes(self
):
304 Returns a NameLUT object that contains information read from the
305 .debug_pubtypes section in the ELF file.
307 NameLUT is essentially a dictionary containing the CU/DIE offsets of
308 each symbol. See the NameLUT doc string for more details.
311 if self
.debug_pubtypes_sec
:
312 return NameLUT(self
.debug_pubtypes_sec
.stream
,
313 self
.debug_pubtypes_sec
.size
,
318 def get_pubnames(self
):
320 Returns a NameLUT object that contains information read from the
321 .debug_pubnames section in the ELF file.
323 NameLUT is essentially a dictionary containing the CU/DIE offsets of
324 each symbol. See the NameLUT doc string for more details.
327 if self
.debug_pubnames_sec
:
328 return NameLUT(self
.debug_pubnames_sec
.stream
,
329 self
.debug_pubnames_sec
.size
,
334 def get_aranges(self
):
335 """ Get an ARanges object representing the .debug_aranges section of
336 the DWARF data, or None if the section doesn't exist
338 if self
.debug_aranges_sec
:
339 return ARanges(self
.debug_aranges_sec
.stream
,
340 self
.debug_aranges_sec
.size
,
345 def location_lists(self
):
346 """ Get a LocationLists object representing the .debug_loc/debug_loclists section of
347 the DWARF data, or None if this section doesn't exist.
349 If both sections exist, it returns a LocationListsPair.
351 if self
.debug_loclists_sec
and self
.debug_loc_sec
is None:
352 return LocationLists(self
.debug_loclists_sec
.stream
, self
.structs
, 5, self
)
353 elif self
.debug_loc_sec
and self
.debug_loclists_sec
is None:
354 return LocationLists(self
.debug_loc_sec
.stream
, self
.structs
, 4, self
)
355 elif self
.debug_loc_sec
and self
.debug_loclists_sec
:
356 return LocationListsPair(self
.debug_loclists_sec
.stream
, self
.debug_loclists_sec
.stream
, self
.structs
, self
)
360 def range_lists(self
):
361 """ Get a RangeLists object representing the .debug_ranges/.debug_rnglists section of
362 the DWARF data, or None if this section doesn't exist.
364 If both sections exist, it returns a RangeListsPair.
366 if self
.debug_rnglists_sec
and self
.debug_ranges_sec
is None:
367 return RangeLists(self
.debug_rnglists_sec
.stream
, self
.structs
, 5, self
)
368 elif self
.debug_ranges_sec
and self
.debug_rnglists_sec
is None:
369 return RangeLists(self
.debug_ranges_sec
.stream
, self
.structs
, 4, self
)
370 elif self
.debug_ranges_sec
and self
.debug_rnglists_sec
:
371 return RangeListsPair(self
.debug_ranges_sec
.stream
, self
.debug_rnglists_sec
.stream
, self
.structs
, self
)
375 #------ PRIVATE ------#
377 def _parse_CUs_iter(self
, offset
=0):
378 """ Iterate CU objects in order of appearance in the debug_info section.
381 The offset of the first CU to yield. Additional iterations
382 will return the sequential unit objects.
384 See .iter_CUs(), .get_CU_containing(), and .get_CU_at().
386 if self
.debug_info_sec
is None:
389 while offset
< self
.debug_info_sec
.size
:
390 cu
= self
._cached
_CU
_at
_offset
(offset
)
391 # Compute the offset of the next CU in the section. The unit_length
392 # field of the CU header contains its size not including the length
396 cu
.structs
.initial_length_field_size())
399 def _cached_CU_at_offset(self
, offset
):
400 """ Return the CU with unit header at the given offset into the
401 debug_info section from the cache. If not present, the unit is
402 header is parsed and the object is installed in the cache.
405 The offset of the unit header in the .debug_info section
406 to of the unit to fetch from the cache.
410 # Find the insert point for the requested offset. With bisect_right,
411 # if this entry is present in the cache it will be the prior entry.
412 i
= bisect_right(self
._cu
_offsets
_map
, offset
)
413 if i
>= 1 and offset
== self
._cu
_offsets
_map
[i
- 1]:
414 return self
._cu
_cache
[i
- 1]
416 # Parse the CU and insert the offset and object into the cache.
417 # The ._cu_offsets_map[] contains just the numeric offsets for the
418 # bisect_right search while the parallel indexed ._cu_cache[] holds
419 # the object references.
420 cu
= self
._parse
_CU
_at
_offset
(offset
)
421 self
._cu
_offsets
_map
.insert(i
, offset
)
422 self
._cu
_cache
.insert(i
, cu
)
425 def _parse_CU_at_offset(self
, offset
):
426 """ Parse and return a CU at the given offset in the debug_info stream.
428 # Section 7.4 (32-bit and 64-bit DWARF Formats) of the DWARF spec v3
429 # states that the first 32-bit word of the CU header determines
430 # whether the CU is represented with 32-bit or 64-bit DWARF format.
432 # So we peek at the first word in the CU header to determine its
433 # dwarf format. Based on it, we then create a new DWARFStructs
434 # instance suitable for this CU and use it to parse the rest.
436 initial_length
= struct_parse(
437 self
.structs
.Dwarf_uint32(''), self
.debug_info_sec
.stream
, offset
)
438 dwarf_format
= 64 if initial_length
== 0xFFFFFFFF else 32
441 # Temporary structs for parsing the header
442 # The structs for the rest of the CU depend on the header data.
444 cu_structs
= DWARFStructs(
445 little_endian
=self
.config
.little_endian
,
446 dwarf_format
=dwarf_format
,
450 cu_header
= struct_parse(
451 cu_structs
.Dwarf_CU_header
, self
.debug_info_sec
.stream
, offset
)
453 # structs for the rest of the CU, taking into account bitness and DWARF version
454 cu_structs
= DWARFStructs(
455 little_endian
=self
.config
.little_endian
,
456 dwarf_format
=dwarf_format
,
457 address_size
=cu_header
['address_size'],
458 dwarf_version
=cu_header
['version'])
460 cu_die_offset
= self
.debug_info_sec
.stream
.tell()
462 self
._is
_supported
_version
(cu_header
['version']),
463 "Expected supported DWARF version. Got '%s'" % cu_header
['version'])
469 cu_die_offset
=cu_die_offset
)
471 def _is_supported_version(self
, version
):
472 """ DWARF version supported by this parser
474 return 2 <= version
<= 5
476 def _parse_line_program_at_offset(self
, debug_line_offset
, structs
):
477 """ Given an offset to the .debug_line section, parse the line program
478 starting at this offset in the section and return it.
479 structs is the DWARFStructs object used to do this parsing.
481 lineprog_header
= struct_parse(
482 structs
.Dwarf_lineprog_header
,
483 self
.debug_line_sec
.stream
,
486 # DWARF5: resolve names
487 def resolve_strings(self
, lineprog_header
, format_field
, data_field
):
488 if lineprog_header
.get(format_field
, False):
489 data
= lineprog_header
[data_field
]
490 for field
in lineprog_header
[format_field
]:
491 def replace_value(data
, content_type
, replacer
):
493 entry
[content_type
] = replacer(entry
[content_type
])
495 if field
.form
== 'DW_FORM_line_strp':
496 replace_value(data
, field
.content_type
, self
.get_string_from_linetable
)
497 elif field
.form
== 'DW_FORM_strp':
498 replace_value(data
, field
.content_type
, self
.get_string_from_table
)
499 elif field
.form
in ('DW_FORM_strp_sup', 'DW_FORM_strx', 'DW_FORM_strx1', 'DW_FORM_strx2', 'DW_FORM_strx3', 'DW_FORM_strx4'):
500 raise NotImplementedError()
502 resolve_strings(self
, lineprog_header
, 'directory_entry_format', 'directories')
503 resolve_strings(self
, lineprog_header
, 'file_name_entry_format', 'file_names')
505 # DWARF5: provide compatible file/directory name arrays for legacy lineprogram consumers
506 if lineprog_header
.get('directories', False):
507 lineprog_header
.include_directory
= tuple(d
.DW_LNCT_path
for d
in lineprog_header
.directories
)
508 if lineprog_header
.get('file_names', False):
509 lineprog_header
.file_entry
= tuple(
511 'name':e
.get('DW_LNCT_path'),
512 'dir_index': e
.get('DW_LNCT_directory_index'),
513 'mtime': e
.get('DW_LNCT_timestamp'),
514 'length': e
.get('DW_LNCT_size')})
515 for e
in lineprog_header
.file_names
)
517 # Calculate the offset to the next line program (see DWARF 6.2.4)
518 end_offset
= ( debug_line_offset
+ lineprog_header
['unit_length'] +
519 structs
.initial_length_field_size())
522 header
=lineprog_header
,
523 stream
=self
.debug_line_sec
.stream
,
525 program_start_offset
=self
.debug_line_sec
.stream
.tell(),
526 program_end_offset
=end_offset
)