diff options
Diffstat (limited to 'dev-python/pyelftools/files/pyelftools-0.21-dyntable.patch')
-rw-r--r-- | dev-python/pyelftools/files/pyelftools-0.21-dyntable.patch | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/dev-python/pyelftools/files/pyelftools-0.21-dyntable.patch b/dev-python/pyelftools/files/pyelftools-0.21-dyntable.patch new file mode 100644 index 00000000000..e43e6cb0a4d --- /dev/null +++ b/dev-python/pyelftools/files/pyelftools-0.21-dyntable.patch @@ -0,0 +1,143 @@ +changeset: 207:92736c403d53 +tag: tip +user: Mike Frysinger <vapier@gentoo.org> +date: Mon Apr 22 19:02:21 2013 -0400 +summary: support parsing of dynamic ELFs w/out section headers + +At runtime, ELFs do not use the section headers at all. Instead, only +the program segments and dynamic tags get used. This means you can +strip the section table completely from an ELF and have it still work. + +In practice, people rarely do this, but it's not unheard of. Make the +Dynamic tags work even in these cases by loading the strings table the +same way the runtime loader does: +- parse the symtab address from DT_STRTAB +- locate the file offset via the program segments + +In order to avoid circular deps (parsing a dyntag requires walking parsed +dyntags), add a set of internal funcs for returning the raw values. + +diff --git a/elftools/elf/dynamic.py b/elftools/elf/dynamic.py +--- a/elftools/elf/dynamic.py ++++ b/elftools/elf/dynamic.py +@@ -10,11 +10,26 @@ + + from .sections import Section + from .segments import Segment +-from ..common.utils import struct_parse ++from ..common.utils import struct_parse, parse_cstring_from_stream + + from .enums import ENUM_D_TAG + + ++class _DynamicStringTable(object): ++ """ Bare string table based on values found via ELF dynamic tags and ++ loadable segments only. Good enough for get_string() only. ++ """ ++ def __init__(self, stream, table_offset): ++ self._stream = stream ++ self._table_offset = table_offset ++ ++ def get_string(self, offset): ++ """ Get the string stored at the given offset in this string table. ++ """ ++ return parse_cstring_from_stream(self._stream, ++ self._table_offset + offset) ++ ++ + class DynamicTag(object): + """ Dynamic Tag object - representing a single dynamic tag entry from a + dynamic section. +@@ -27,10 +42,9 @@ + _HANDLED_TAGS = frozenset( + ['DT_NEEDED', 'DT_RPATH', 'DT_RUNPATH', 'DT_SONAME']) + +- def __init__(self, entry, elffile): ++ def __init__(self, entry, dynstr): + self.entry = entry +- if entry.d_tag in self._HANDLED_TAGS: +- dynstr = elffile.get_section_by_name(b'.dynstr') ++ if entry.d_tag in self._HANDLED_TAGS and dynstr: + setattr(self, entry.d_tag[3:].lower(), + dynstr.get_string(self.entry.d_val)) + +@@ -60,26 +74,66 @@ + self._num_tags = -1 + self._offset = position + self._tagsize = self._elfstructs.Elf_Dyn.sizeof() ++ self.__string_table = None ++ ++ @property ++ def _string_table(self): ++ if self.__string_table: ++ return self.__string_table ++ ++ # If the ELF has stripped its section table (which is unusual, but ++ # perfectly valid), we need to use the dynamic tags to locate the ++ # dynamic string table. ++ strtab = None ++ for tag in self._iter_tags(type='DT_STRTAB'): ++ strtab = tag['d_val'] ++ break ++ # If we found a dynamic string table, locate the offset in the file ++ # by using the program headers. ++ if strtab: ++ for segment in self._elffile.iter_segments(): ++ if (strtab >= segment['p_vaddr'] and ++ strtab < segment['p_vaddr'] + segment['p_filesz']): ++ self.__string_table = _DynamicStringTable( ++ self._stream, ++ segment['p_offset'] + (strtab - segment['p_vaddr'])) ++ return self.__string_table ++ ++ # That didn't work for some reason. Let's use the section header ++ # even though this ELF is super weird. ++ self.__string_table = self._elffile.get_section_by_name(b'.dynstr') ++ ++ return self.__string_table ++ ++ def _iter_tags(self, type=None): ++ """ Yield all raw tags (limit to |type| if specified) ++ """ ++ for n in itertools.count(): ++ tag = self._get_tag(n) ++ if type is None or tag['d_tag'] == type: ++ yield tag ++ if tag['d_tag'] == 'DT_NULL': ++ break + + def iter_tags(self, type=None): + """ Yield all tags (limit to |type| if specified) + """ +- for n in itertools.count(): +- tag = self.get_tag(n) +- if type is None or tag.entry.d_tag == type: +- yield tag +- if tag.entry.d_tag == 'DT_NULL': +- break ++ for tag in self._iter_tags(type=type): ++ yield DynamicTag(tag, self._string_table) ++ ++ def _get_tag(self, n): ++ """ Get the raw tag at index #n from the file ++ """ ++ offset = self._offset + n * self._tagsize ++ return struct_parse( ++ self._elfstructs.Elf_Dyn, ++ self._stream, ++ stream_pos=offset) + + def get_tag(self, n): + """ Get the tag at index #n from the file (DynamicTag object) + """ +- offset = self._offset + n * self._tagsize +- entry = struct_parse( +- self._elfstructs.Elf_Dyn, +- self._stream, +- stream_pos=offset) +- return DynamicTag(entry, self._elffile) ++ return DynamicTag(self._get_tag(n), self._string_table) + + def num_tags(self): + """ Number of dynamic tags in the file + |