From: eliben Date: Thu, 8 Sep 2011 13:24:49 +0000 (+0300) Subject: Some code reorg: X-Git-Tag: v0.10~136 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=75b5fde294e320f239f9df85728ee4e6f2935098;p=pyelftools.git Some code reorg: * created common/ dir and moved exceptions there (along with utils) * moved struct_parse from elffile to utils * moved string table functionality to its own section class --- diff --git a/elftools/common/__init__.py b/elftools/common/__init__.py new file mode 100644 index 0000000..e69de29 diff --git a/elftools/common/exceptions.py b/elftools/common/exceptions.py new file mode 100644 index 0000000..05fa602 --- /dev/null +++ b/elftools/common/exceptions.py @@ -0,0 +1,15 @@ +#------------------------------------------------------------------------------- +# elftools: common/exceptions.py +# +# Exception classes for elftools +# +# Eli Bendersky (eliben@gmail.com) +# This code is in the public domain +#------------------------------------------------------------------------------- + +class ELFError(Exception): + pass + +class ELFParseError(ELFError): + pass + diff --git a/elftools/common/utils.py b/elftools/common/utils.py new file mode 100644 index 0000000..716bebd --- /dev/null +++ b/elftools/common/utils.py @@ -0,0 +1,25 @@ +#------------------------------------------------------------------------------- +# elftools: common/utils.py +# +# Miscellaneous utilities for elftools +# +# Eli Bendersky (eliben@gmail.com) +# This code is in the public domain +#------------------------------------------------------------------------------- +from .exceptions import ELFParseError + + +def struct_parse(struct, stream, stream_pos=None): + """ Convenience function for using the given struct to parse a stream (at + its current location). + If stream_pos is provided, the stream is seeked to this position before + the parsing is done. + Wraps the error thrown by construct with our own error. + """ + try: + if stream_pos is not None: + stream.seek(stream_pos) + return struct.parse_stream(stream) + except ConstructError as e: + raise ELFParseError(e.message) + diff --git a/elftools/elf/elffile.py b/elftools/elf/elffile.py index 01be519..7d134b9 100644 --- a/elftools/elf/elffile.py +++ b/elftools/elf/elffile.py @@ -6,13 +6,11 @@ # Eli Bendersky (eliben@gmail.com) # This code is in the public domain #------------------------------------------------------------------------------- - -from cStringIO import StringIO - -from ..exceptions import ELFError, ELFParseError -from ..construct import ConstructError, CString +from ..common.exceptions import ELFError +from ..common.utils import struct_parse +from ..construct import ConstructError from .structs import ELFStructs -from .sections import Section +from .sections import Section, StringTableSection from .segments import Segment @@ -35,7 +33,8 @@ class ELFFile(object): little_endian=self.little_endian, elfclass=self.elfclass) self.header = self._parse_elf_header() - self._stringtable = self._get_stringtable() + + self._file_stringtable_section = self._get_file_stringtable() def num_sections(self): """ Number of sections in the file @@ -119,51 +118,40 @@ class ELFFile(object): def _get_section_header(self, n): """ Find the header of section #n, parse it and return the struct """ - self.stream.seek(self._section_offset(n)) - return self._struct_parse(self.structs.Elf_Shdr) + 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 _get_segment_header(self, n): """ Find the header of segment #n, parse it and return the struct """ - self.stream.seek(self._segment_offset(n)) - return self._struct_parse(self.structs.Elf_Phdr) + return struct_parse( + self.structs.Elf_Phdr, + self.stream, + stream_pos=self._segment_offset(n)) - def _get_section_name(self, section_header): - """ Given a section header, find this section's name in the file's - string table, and return it as a normal Python string. - """ - offset = section_header['sh_name'] - self._stringtable.seek(offset) - return CString('').parse_stream(self._stringtable) - - def _get_stringtable(self): - """ Find the file's string table section, read it and return the string - table as a StringIO object pointing to the section's contents. + def _get_file_stringtable(self): + """ Find the file's string table section """ - # Find the section header for the stringtable header, and read the - # section's contents from it - # stringtable_section_num = self['e_shstrndx'] - stringtable_header = self._get_section_header(stringtable_section_num) - self.stream.seek(stringtable_header['sh_offset']) - return StringIO(self.stream.read(stringtable_header['sh_size'])) + 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. """ - self.stream.seek(0) - return self._struct_parse(self.structs.Elf_Ehdr) - - def _struct_parse(self, struct): - """ Convenience method for parsing at the current stream location with - the given struct. Also wraps the error thrown by construct with our - own error. - """ - try: - return struct.parse_stream(self.stream) - except ConstructError as e: - raise ELFParseError(e.message) + return struct_parse(self.structs.Elf_Ehdr, self.stream, stream_pos=0) def _assert(self, cond, msg=''): """ Assert that cond is True, otherwise raise ELFError(msg) diff --git a/elftools/elf/sections.py b/elftools/elf/sections.py index 4fb4249..502b69f 100644 --- a/elftools/elf/sections.py +++ b/elftools/elf/sections.py @@ -6,6 +6,8 @@ # Eli Bendersky (eliben@gmail.com) # This code is in the public domain #------------------------------------------------------------------------------- +from ..construct import CString + class Section(object): def __init__(self, header, name, stream): @@ -24,3 +26,18 @@ class Section(object): """ return self.header[name] + +class StringTableSection(Section): + def __init__(self, header, name, stream): + super(StringTableSection, self).__init__(header, name, stream) + + def get_string(self, offset): + """ Get the string stored at the given offset in this string table. + """ + table_offset = self['sh_offset'] + self.stream.seek(table_offset + offset) + return CString('').parse_stream(self.stream) + + + + diff --git a/elftools/exceptions.py b/elftools/exceptions.py deleted file mode 100644 index b61b463..0000000 --- a/elftools/exceptions.py +++ /dev/null @@ -1,15 +0,0 @@ -#------------------------------------------------------------------------------- -# elftools: exceptions.py -# -# Exception classes for elftools -# -# Eli Bendersky (eliben@gmail.com) -# This code is in the public domain -#------------------------------------------------------------------------------- - -class ELFError(Exception): - pass - -class ELFParseError(ELFError): - pass - diff --git a/z.py b/z.py index 9f208d3..adcfd6c 100644 --- a/z.py +++ b/z.py @@ -9,6 +9,9 @@ stream = open('binfiles/z.elf', 'rb') efile = ELFFile(stream) +print '===> %s sections!' % efile.num_sections() +print '===> %s segments!' % efile.num_segments() + for sec in efile.iter_sections(): print sec.name