diff options
| author | David Lamparter <equinox@opensourcerouting.org> | 2022-10-28 10:59:41 +0100 |
|---|---|---|
| committer | David Lamparter <equinox@opensourcerouting.org> | 2022-10-28 11:01:22 +0100 |
| commit | 00f0c39903653772d72c9c0adce661508138c0b0 (patch) | |
| tree | a5d3c0536c2edf4bb8ae314b7ae07bfc223597d8 /python/clippy/elf.py | |
| parent | 3727be24a032e0577d19ccf5ad995059f7cf6d68 (diff) | |
python: apply black formatting
The python/ directory hasn't been shoved into black yet (unlike
topotests, where most FRR python code is.) Run black over it.
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
Diffstat (limited to 'python/clippy/elf.py')
| -rw-r--r-- | python/clippy/elf.py | 199 |
1 files changed, 117 insertions, 82 deletions
diff --git a/python/clippy/elf.py b/python/clippy/elf.py index 02cb2e38b3..5aaba832a9 100644 --- a/python/clippy/elf.py +++ b/python/clippy/elf.py @@ -16,7 +16,7 @@ # with this program; see the file COPYING; if not, write to the Free Software # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA -''' +""" Wrapping layer and additional utility around _clippy.ELFFile. Essentially, the C bits have the low-level ELF access bits that should be @@ -28,7 +28,7 @@ across architecture, word size and even endianness boundaries. Both the C module (through GElf_*) and this code (cf. struct.unpack format mangling in ELFDissectStruct) will take appropriate measures to flip and resize fields as needed. -''' +""" import struct from collections import OrderedDict @@ -40,16 +40,18 @@ from _clippy import ELFFile, ELFAccessError # data access # + class ELFNull(object): - ''' + """ NULL pointer, returned instead of ELFData - ''' + """ + def __init__(self): self.symname = None self._dstsect = None def __repr__(self): - return '<ptr: NULL>' + return "<ptr: NULL>" def __hash__(self): return hash(None) @@ -57,33 +59,37 @@ class ELFNull(object): def get_string(self): return None + class ELFUnresolved(object): - ''' + """ Reference to an unresolved external symbol, returned instead of ELFData :param symname: name of the referenced symbol :param addend: offset added to the symbol, normally zero - ''' + """ + def __init__(self, symname, addend): self.addend = addend self.symname = symname self._dstsect = None def __repr__(self): - return '<unresolved: %s+%d>' % (self.symname, self.addend) + return "<unresolved: %s+%d>" % (self.symname, self.addend) def __hash__(self): return hash((self.symname, self.addend)) + class ELFData(object): - ''' + """ Actual data somewhere in the ELF file. :type dstsect: ELFSubset :param dstsect: container data area (section or entire file) :param dstoffs: byte offset into dstsect :param dstlen: byte size of object, or None if unknown, open-ended or string - ''' + """ + def __init__(self, dstsect, dstoffs, dstlen): self._dstsect = dstsect self._dstoffs = dstoffs @@ -91,62 +97,74 @@ class ELFData(object): self.symname = None def __repr__(self): - return '<ptr: %s+0x%05x/%d>' % (self._dstsect.name, self._dstoffs, self._dstlen or -1) + return "<ptr: %s+0x%05x/%d>" % ( + self._dstsect.name, + self._dstoffs, + self._dstlen or -1, + ) def __hash__(self): return hash((self._dstsect, self._dstoffs)) def get_string(self): - ''' + """ Interpret as C string / null terminated UTF-8 and get the actual text. - ''' + """ try: - return self._dstsect[self._dstoffs:str].decode('UTF-8') + return self._dstsect[self._dstoffs : str].decode("UTF-8") except: - import pdb; pdb.set_trace() + import pdb + + pdb.set_trace() def get_data(self, reflen): - ''' + """ Interpret as some structure (and check vs. expected length) :param reflen: expected size of the object, compared against actual size (which is only known in rare cases, mostly when directly accessing a symbol since symbols have their destination object size recorded) - ''' + """ if self._dstlen is not None and self._dstlen != reflen: - raise ValueError('symbol size mismatch (got %d, expected %d)' % (self._dstlen, reflen)) - return self._dstsect[self._dstoffs:self._dstoffs+reflen] + raise ValueError( + "symbol size mismatch (got %d, expected %d)" % (self._dstlen, reflen) + ) + return self._dstsect[self._dstoffs : self._dstoffs + reflen] def offset(self, offs, within_symbol=False): - ''' + """ Get another ELFData at an offset :param offs: byte offset, can be negative (e.g. in container_of) :param within_symbol: retain length information - ''' + """ if self._dstlen is None or not within_symbol: return ELFData(self._dstsect, self._dstoffs + offs, None) else: return ELFData(self._dstsect, self._dstoffs + offs, self._dstlen - offs) + # # dissection data items # + class ELFDissectData(object): - ''' + """ Common bits for ELFDissectStruct and ELFDissectUnion - ''' + """ def __len__(self): - ''' + """ Used for boolean evaluation, e.g. "if struct: ..." - ''' - return not (isinstance(self._data, ELFNull) or isinstance(self._data, ELFUnresolved)) + """ + return not ( + isinstance(self._data, ELFNull) or isinstance(self._data, ELFUnresolved) + ) def container_of(self, parent, fieldname): - ''' + """ Assume this struct is embedded in a larger struct and get at the larger Python ``self.container_of(a, b)`` = C ``container_of(self, a, b)`` @@ -154,25 +172,26 @@ class ELFDissectData(object): :param parent: class (not instance) of the larger struct :param fieldname: fieldname that refers back to this :returns: instance of parent, with fieldname set to this object - ''' + """ offset = 0 - if not hasattr(parent, '_efields'): + if not hasattr(parent, "_efields"): parent._setup_efields() for field in parent._efields[self.elfclass]: if field[0] == fieldname: break spec = field[1] - if spec == 'P': - spec = 'I' if self.elfclass == 32 else 'Q' + if spec == "P": + spec = "I" if self.elfclass == 32 else "Q" offset += struct.calcsize(spec) else: - raise AttributeError('%r not found in %r.fields' % (fieldname, parent)) + raise AttributeError("%r not found in %r.fields" % (fieldname, parent)) + + return parent(self._data.offset(-offset), replace={fieldname: self}) - return parent(self._data.offset(-offset), replace = {fieldname: self}) class ELFDissectStruct(ELFDissectData): - ''' + """ Decode and provide access to a struct somewhere in the ELF file Handles pointers and strings somewhat nicely. Create a subclass for each @@ -205,30 +224,31 @@ class ELFDissectStruct(ELFDissectData): .. attribute:: fieldrename Dictionary to rename fields, useful if fields comes from tiabwarfo.py. - ''' + """ class Pointer(object): - ''' + """ Quick wrapper for pointers to further structs This is just here to avoid going into infinite loops when loading structs that have pointers to each other (e.g. struct xref <--> struct xrefdata.) The pointer destination is only instantiated when actually accessed. - ''' + """ + def __init__(self, cls, ptr): self.cls = cls self.ptr = ptr def __repr__(self): - return '<Pointer:%s %r>' % (self.cls.__name__, self.ptr) + return "<Pointer:%s %r>" % (self.cls.__name__, self.ptr) def __call__(self): if isinstance(self.ptr, ELFNull): return None return self.cls(self.ptr) - def __new__(cls, dataptr, parent = None, replace = None): + def __new__(cls, dataptr, parent=None, replace=None): if dataptr._dstsect is None: return super().__new__(cls) @@ -239,19 +259,19 @@ class ELFDissectStruct(ELFDissectData): dataptr._dstsect._pointers[(cls, dataptr)] = obj return obj - replacements = 'lLnN' + replacements = "lLnN" @classmethod def _preproc_structspec(cls, elfclass, spec): elfbits = elfclass - if hasattr(spec, 'calcsize'): - spec = '%ds' % (spec.calcsize(elfclass),) + if hasattr(spec, "calcsize"): + spec = "%ds" % (spec.calcsize(elfclass),) if elfbits == 32: - repl = ['i', 'I'] + repl = ["i", "I"] else: - repl = ['q', 'Q'] + repl = ["q", "Q"] for c in cls.replacements: spec = spec.replace(c, repl[int(c.isupper())]) return spec @@ -269,8 +289,8 @@ class ELFDissectStruct(ELFDissectData): size += struct.calcsize(newf[1]) cls._esize[elfclass] = size - def __init__(self, dataptr, parent = None, replace = None): - if not hasattr(self.__class__, '_efields'): + def __init__(self, dataptr, parent=None, replace=None): + if not hasattr(self.__class__, "_efields"): self._setup_efields() self._fdata = None @@ -290,12 +310,12 @@ class ELFDissectStruct(ELFDissectData): # need to correlate output from struct.unpack with extra metadata # about the particular fields, so note down byte offsets (in locs) # and tuple indices of pointers (in ptrs) - pspec = '' + pspec = "" locs = {} ptrs = set() for idx, spec in enumerate(pspecl): - if spec == 'P': + if spec == "P": ptrs.add(idx) spec = self._elfsect.ptrtype @@ -326,7 +346,9 @@ class ELFDissectStruct(ELFDissectData): self._fdata[name] = replace[name] continue - if isinstance(self.fields[i][1], type) and issubclass(self.fields[i][1], ELFDissectData): + if isinstance(self.fields[i][1], type) and issubclass( + self.fields[i][1], ELFDissectData + ): dataobj = self.fields[i][1](dataptr.offset(locs[i]), self) self._fdata[name] = dataobj continue @@ -353,35 +375,39 @@ class ELFDissectStruct(ELFDissectData): def __repr__(self): if not isinstance(self._data, ELFData): - return '<%s: %r>' % (self.__class__.__name__, self._data) - return '<%s: %s>' % (self.__class__.__name__, - ', '.join(['%s=%r' % t for t in self._fdata.items()])) + return "<%s: %r>" % (self.__class__.__name__, self._data) + return "<%s: %s>" % ( + self.__class__.__name__, + ", ".join(["%s=%r" % t for t in self._fdata.items()]), + ) @classmethod def calcsize(cls, elfclass): - ''' + """ Sum up byte size of this struct Wraps struct.calcsize with some extra features. - ''' - if not hasattr(cls, '_efields'): + """ + if not hasattr(cls, "_efields"): cls._setup_efields() - pspec = ''.join([f[1] for f in cls._efields[elfclass]]) + pspec = "".join([f[1] for f in cls._efields[elfclass]]) - ptrtype = 'I' if elfclass == 32 else 'Q' - pspec = pspec.replace('P', ptrtype) + ptrtype = "I" if elfclass == 32 else "Q" + pspec = pspec.replace("P", ptrtype) return struct.calcsize(pspec) + class ELFDissectUnion(ELFDissectData): - ''' + """ Decode multiple structs in the same place. Not currently used (and hence not tested.) Worked at some point but not needed anymore and may be borked now. Remove this comment when using. - ''' - def __init__(self, dataptr, parent = None): + """ + + def __init__(self, dataptr, parent=None): self._dataptr = dataptr self._parent = parent self.members = [] @@ -391,20 +417,25 @@ class ELFDissectUnion(ELFDissectData): setattr(self, name, item) def __repr__(self): - return '<%s: %s>' % (self.__class__.__name__, ', '.join([repr(i) for i in self.members])) + return "<%s: %s>" % ( + self.__class__.__name__, + ", ".join([repr(i) for i in self.members]), + ) @classmethod def calcsize(cls, elfclass): return max([member.calcsize(elfclass) for name, member in cls.members]) + # # wrappers for spans of ELF data # + class ELFSubset(object): - ''' + """ Common abstract base for section-level and file-level access. - ''' + """ def __init__(self): super().__init__() @@ -415,7 +446,7 @@ class ELFSubset(object): return hash(self.name) def __getitem__(self, k): - ''' + """ Read data from slice Subscript **must** be a slice; a simple index will not return a byte @@ -425,22 +456,22 @@ class ELFSubset(object): - `this[123:456]` - extract specific range - `this[123:str]` - extract until null byte. The slice stop value is the `str` type (or, technically, `unicode`.) - ''' + """ return self._obj[k] def getreloc(self, offset): - ''' + """ Check for a relocation record at the specified offset. - ''' + """ return self._obj.getreloc(offset) - def iter_data(self, scls, slice_ = slice(None)): - ''' + def iter_data(self, scls, slice_=slice(None)): + """ Assume an array of structs present at a particular slice and decode :param scls: ELFDissectData subclass for the struct :param slice_: optional range specification - ''' + """ size = scls.calcsize(self._elffile.elfclass) offset = slice_.start or 0 @@ -453,7 +484,7 @@ class ELFSubset(object): offset += size def pointer(self, offset): - ''' + """ Try to dereference a pointer value This checks whether there's a relocation at the given offset and @@ -463,10 +494,12 @@ class ELFSubset(object): :param offset: byte offset from beginning of section, or virtual address in file :returns: ELFData wrapping pointed-to object - ''' + """ ptrsize = struct.calcsize(self.ptrtype) - data = struct.unpack(self.endian + self.ptrtype, self[offset:offset + ptrsize])[0] + data = struct.unpack( + self.endian + self.ptrtype, self[offset : offset + ptrsize] + )[0] reloc = self.getreloc(offset) dstsect = None @@ -497,14 +530,15 @@ class ELFSubset(object): # wrap_data is different between file & section return self._wrap_data(data, dstsect) + class ELFDissectSection(ELFSubset): - ''' + """ Access the contents of an ELF section like ``.text`` or ``.data`` :param elfwrap: ELFDissectFile wrapper for the file :param idx: section index in section header table :param section: section object from C module - ''' + """ def __init__(self, elfwrap, idx, section): super().__init__() @@ -524,8 +558,9 @@ class ELFDissectSection(ELFSubset): dstsect = self._elfwrap.get_section(dstsect.idx) return ELFData(dstsect, offs, None) + class ELFDissectFile(ELFSubset): - ''' + """ Access the contents of an ELF file. Note that offsets for array subscript and relocation/pointer access are @@ -537,7 +572,7 @@ class ELFDissectFile(ELFSubset): address like 0x400000 on x86. :param filename: ELF file to open - ''' + """ def __init__(self, filename): super().__init__() @@ -546,8 +581,8 @@ class ELFDissectFile(ELFSubset): self._elffile = self._obj = ELFFile(filename) self._sections = {} - self.ptrtype = 'I' if self._elffile.elfclass == 32 else 'Q' - self.endian = '>' if self._elffile.bigendian else '<' + self.ptrtype = "I" if self._elffile.elfclass == 32 else "Q" + self.endian = ">" if self._elffile.bigendian else "<" @property def _elfwrap(self): @@ -557,9 +592,9 @@ class ELFDissectFile(ELFSubset): return ELFData(self, data, None) def get_section(self, secname): - ''' + """ Look up section by name or index - ''' + """ if isinstance(secname, int): sh_idx = secname section = self._elffile.get_section_idx(secname) |
