Modernize python code

elftools/dwarf/callframe.py

@@ -520,7 +520,7 @@ def _decode_CFI_table(self):
             # line that serves as the base (first) line in the FDE's table.
             cie = self.cie
             cie_decoded_table = cie.get_decoded()
-            if len(cie_decoded_table.table) > 0:
+            if cie_decoded_table.table:
                 last_line_in_CIE = copy.copy(cie_decoded_table.table[-1])
                 cur_line = copy.copy(last_line_in_CIE)
             else:
@@ -725,7 +725,8 @@ def __repr__(self):
 # This dictionary is filled by automatically scanning the constants module
 # for DW_CFA_* instructions, and mapping their values to names. Since all
 # names were imported from constants with `import *`, we look in globals()
-_OPCODE_NAME_MAP = {}
-for name in list(globals().keys()):
-    if name.startswith('DW_CFA'):
-        _OPCODE_NAME_MAP[globals()[name]] = name
+_OPCODE_NAME_MAP = {
+    value: name
+    for name, value in globals().items()
+    if name.startswith('DW_CFA')
+}

elftools/dwarf/compileunit.py

@@ -86,7 +86,7 @@ def get_top_DIE(self):
 
         # Note that a top DIE always has minimal offset and is therefore
         # at the beginning of our lists, so no bisect is required.
-        if len(self._diemap) > 0:
+        if self._diemap:
             return self._dielist[0]
 
         top = DIE(
@@ -105,7 +105,7 @@ def has_top_DIE(self):
         """ Returns whether the top DIE in this CU has already been parsed and cached.
             No parsing on demand!
         """
-        return len(self._diemap) > 0        
+        return bool(self._diemap)
 
     @property
     def size(self):
@@ -205,8 +205,7 @@ def _iter_DIE_subtree(self, die):
         yield die
         if die.has_children:
             for c in die.iter_children():
-                for d in die.cu._iter_DIE_subtree(c):
-                    yield d
+                yield from die.cu._iter_DIE_subtree(c)
             yield die._terminator
 
     def _get_cached_DIE(self, offset):

elftools/dwarf/datatype_cpp.py

@@ -71,7 +71,7 @@ def parse_cpp_datatype(var_die):
             else:
                 retval_type = "void "
 
-            if len(mods) and mods[-1] == 'pointer':
+            if mods and mods[-1] == 'pointer':
                 mods.pop()
                 t.modifiers = tuple(mods)
                 t.name = "%s(%s*)(%s)" % (retval_type, ptr_prefix, params)
@@ -147,7 +147,7 @@ def __str__(self):
 
         parts = []
         # Initial const/volatile applies to the var ifself, other consts apply to the pointee
-        if len(mods) and mods[0] in ('const', 'volatile'):
+        if mods and mods[0] in ('const', 'volatile'):
             parts.append(mods[0])
             mods = mods[1:]
 
@@ -160,7 +160,7 @@ def __str__(self):
             name = '::'.join(self.scopes)+'::' + name
         parts.append(name)
 
-        if len(mods):
+        if mods:
             parts.append("".join(cpp_symbols[mod] for mod in mods))
 
         if self.dimensions:
@@ -190,7 +190,7 @@ def get_class_spec_if_member(func_spec, the_func):
         this_param = the_func.get_DIE_from_attribute('DW_AT_object_pointer')
         this_type = parse_cpp_datatype(this_param)
         class_spec = ClassDesc()
-        class_spec.scopes = this_type.scopes + (this_type.name,)
+        class_spec.scopes = (*this_type.scopes, this_type.name)
         class_spec.const_member = any(("const", "pointer") == this_type.modifiers[i:i+2]
             for i in range(len(this_type.modifiers))) # const -> pointer -> const for this arg of const
         return class_spec

elftools/dwarf/descriptions.py

@@ -603,10 +603,10 @@ def dump_expr(self, expr, cu_offset=None):
             Returns a string representing the expression.
         """
         parsed = self.expr_parser.parse_expr(expr)
-        s = []
-        for deo in parsed:
-            s.append(self._dump_to_string(deo.op, deo.op_name, deo.args, cu_offset))
-        return '; '.join(s)
+        return '; '.join(
+            self._dump_to_string(deo.op, deo.op_name, deo.args, cu_offset)
+            for deo in parsed
+        )
 
     def _init_lookups(self):
         self._ops_with_decimal_arg = set([
@@ -632,7 +632,7 @@ def _dump_to_string(self, opcode, opcode_name, args, cu_offset=None):
         if cu_offset is None:
             cu_offset = 0
 
-        if len(args) == 0:
+        if not args:
             if opcode_name.startswith('DW_OP_reg'):
                 regnum = int(opcode_name[9:])
                 return '%s (%s)' % (

elftools/dwarf/dwarf_expr.py

@@ -143,7 +143,7 @@ def parse_expr(self, expr):
             # stream, we're done.
             offset = stream.tell()
             byte = stream.read(1)
-            if len(byte) == 0:
+            if not byte:
                 break
 
             # Decode the opcode and its name.

elftools/dwarf/dwarf_util.py

@@ -67,7 +67,7 @@ def _file_crc32(file):
     """
     d = file.read(4096)
     checksum = 0
-    while len(d):
+    while d:
         checksum = binascii.crc32(d, checksum)
         d = file.read(4096)
     return checksum

elftools/dwarf/lineprogram.py

@@ -61,13 +61,17 @@ def __init__(self, default_is_stmt):
         self.discriminator = 0
 
     def __repr__(self):
-        a = ['<LineState %x:' % id(self)]
-        a.append('  address = 0x%x' % self.address)
-        for attr in ('file', 'line', 'column', 'is_stmt', 'basic_block',
-                     'end_sequence', 'prologue_end', 'epilogue_begin', 'isa',
-                     'discriminator'):
-            a.append('  %s = %s' % (attr, getattr(self, attr)))
-        return '\n'.join(a) + '>\n'
+        return '\n'.join((
+            '<LineState %x:' % id(self),
+            '  address = 0x%x' % self.address,
+            *(
+                '  %s = %s' % (attr, getattr(self, attr))
+                for attr in ('file', 'line', 'column', 'is_stmt', 'basic_block',
+                    'end_sequence', 'prologue_end', 'epilogue_begin', 'isa',
+                    'discriminator')
+            ),
+            '>',
+        ))
 
 
 class LineProgram(object):

elftools/dwarf/structs.py

@@ -375,7 +375,7 @@ def _create_lineprog_header(self):
         # past it. Therefore an If is used.
         self.Dwarf_lineprog_file_entry = Struct('file_entry',
             CString('name'),
-            If(lambda ctx: len(ctx.name) != 0,
+            If(lambda ctx: bool(ctx.name),
                 Embed(Struct('',
                     self.Dwarf_uleb128('dir_index'),
                     self.Dwarf_uleb128('mtime'),
@@ -452,7 +452,7 @@ def _parse(self, stream, context):
                     CString('include_directory'))),
             If(lambda ctx: ctx.version < 5,
                 RepeatUntilExcluding(
-                    lambda obj, ctx: len(obj.name) == 0,
+                    lambda obj, ctx: not obj.name,
                     self.Dwarf_lineprog_file_entry)) # array name is file_entry
         )
 

elftools/dwarf/typeunit.py

@@ -102,7 +102,7 @@ def get_top_DIE(self):
 
         # Note that a top DIE always has minimal offset and is therefore
         # at the beginning of our lists, so no bisect is required.
-        if len(self._diemap) > 0:
+        if self._diemap:
             return self._dielist[0]
 
         top = DIE(
@@ -121,7 +121,7 @@ def has_top_DIE(self):
         """ Returns whether the top DIE in this TU has already been parsed and cached.
             No parsing on demand!
         """
-        return len(self._diemap) > 0        
+        return bool(self._diemap)
 
     @property
     def size(self):
@@ -219,8 +219,7 @@ def _iter_DIE_subtree(self, die):
         yield die
         if die.has_children:
             for c in die.iter_children():
-                for d in die.cu._iter_DIE_subtree(c):
-                    yield d
+                yield from die.cu._iter_DIE_subtree(c)
             yield die._terminator
 
     def _get_cached_DIE(self, offset):

elftools/elf/elffile.py

@@ -398,13 +398,14 @@ def get_ehabi_infos(self):
             Object file contains many .ARM.exidx sections.
             So we must traverse every section and filter sections whose type is SHT_ARM_EXIDX.
         """
-        _ret = []
         if self['e_type'] == 'ET_REL':
             # TODO: support relocatable file
             assert False, "Current version of pyelftools doesn't support relocatable file."
-        for section in self.iter_sections(type='SHT_ARM_EXIDX'):
-            _ret.append(EHABIInfo(section, self.little_endian))
-        return _ret if len(_ret) > 0 else None
+        _ret = [
+            EHABIInfo(section, self.little_endian)
+            for section in self.iter_sections(type='SHT_ARM_EXIDX')
+        ]
+        return _ret if _ret else None
 
     def get_machine_arch(self):
         """ Return the machine architecture, as detected from the ELF header.

elftools/elf/sections.py

@@ -346,7 +346,7 @@ def num_attributes(self):
     def attributes(self):
         """ List of all attributes in the subsubsection.
         """
-        return [self.header] + list(self.iter_attributes())
+        return [self.header, *(self.iter_attributes())]
 
     def _make_attributes(self):
         """ Create all attributes for this subsubsection except the first one

elftools/elf/structs.py

@@ -273,7 +273,7 @@ def _create_rel(self):
                               self.Elf_addr('r_offset'),
                               *fields)
 
-        fields_and_addend = fields + [self.Elf_sxword('r_addend')]
+        fields_and_addend = [*fields, self.Elf_sxword('r_addend')]
         self.Elf_Rela = Struct('Elf_Rela',
                                self.Elf_addr('r_offset'),
                                *fields_and_addend

scripts/dwarfdump.py

@@ -220,10 +220,10 @@ def _desc_operationarg(s, cu):
     elif isinstance(s, int):
         return hex(s)
     elif isinstance(s, list): # Could be a blob (list of ints), could be a subexpression
-        if len(s) > 0 and isinstance(s[0], DWARFExprOp): # Subexpression
+        if s and isinstance(s[0], DWARFExprOp): # Subexpression
             return '(' + '; '.join(_desc_operation(op.op, op.op_name, op.args, cu) for op in s) + ')'
         else:
-            return " ".join((hex(len(s)),) + tuple("0x%02x" % b for b in s))
+            return " ".join((hex(len(s)), *("0x%02x" % b for b in s)))
 
 def _arch(cu):
     return cu.dwarfinfo.config.machine_arch

scripts/readelf.py

@@ -1263,7 +1263,7 @@ def _dump_debug_line_programs(self):
             ver5 = lineprogram.header.version >= 5
 
             cu_filename = bytes2str(lineprogram['file_entry'][0].name)
-            if len(lineprogram['include_directory']) > 0:
+            if lineprogram['include_directory']:
                 # GNU readelf 2.38 only outputs directory in wide mode
                 self._emitline('%s:' % cu_filename)
             else:
@@ -1394,7 +1394,7 @@ def _dump_debug_namelut(self, what):
             section = self._dwarfinfo.debug_pubtypes_sec
 
         # readelf prints nothing if the section is not present.
-        if namelut is None or len(namelut) == 0:
+        if not namelut:
             return
 
         self._emitline('Contents of the %s section:' % section.name)
@@ -1428,7 +1428,7 @@ def _dump_debug_aranges(self):
         # dumps them, so we should too.
         unordered_entries = aranges_table._get_entries(need_empty=True)
 
-        if len(unordered_entries) == 0:
+        if not unordered_entries:
             self._emitline()
             self._emitline("Section '.debug_aranges' has no debugging data.")
             return
@@ -1505,7 +1505,7 @@ def _dump_frames_interp_info(self, section, cfi_entries):
 
             # Decode the table.
             decoded_table = entry.get_decoded()
-            if len(decoded_table.table) == 0:
+            if not decoded_table.table:
                 continue
 
             # Print the heading row for the decoded table
@@ -1521,7 +1521,7 @@ def _dump_frames_interp_info(self, section, cfi_entries):
             # DWARF register number is not greater than other GPRs.)
             decoded_table = entry.get_decoded()
             reg_order = sorted(decoded_table.reg_order)
-            if len(decoded_table.reg_order):
+            if decoded_table.reg_order:
                 # Headings for the registers
                 for regnum in reg_order:
                     if regnum == ra_regnum:
@@ -1602,7 +1602,7 @@ def _dump_debug_locsection(self, di, loc_lists_sec):
         line_template = "    %%08x %%0%dx %%0%dx %%s%%s" % (addr_width, addr_width)
 
         loc_lists = list(loc_lists_sec.iter_location_lists())
-        if len(loc_lists) == 0:
+        if not loc_lists:
             # Present but empty locations section - readelf outputs a message
             self._emitline("\nSection '%s' has no debugging data." % (section_name,))
             return
@@ -1703,7 +1703,7 @@ def _dump_debug_loclists_CU_header(self, cu):
         self._emitline('  Address size:    %d' % cu.address_size)
         self._emitline('  Segment size:    %d' % cu.segment_selector_size)
         self._emitline('  Offset entries:  %d\n' % cu.offset_count)
-        if cu.offsets and len(cu.offsets):
+        if cu.offsets:
             self._emitline('  Offsets starting at 0x%x:' % cu.offset_table_offset)
             for i_offset in enumerate(cu.offsets):
                 self._emitline('    [%6d] 0x%x' % i_offset)        
@@ -1728,7 +1728,7 @@ def _dump_debug_rnglists_CU_header(self, cu):
         self._emitline('  Address size:    %d' % cu.address_size)
         self._emitline('  Segment size:    %d' % cu.segment_selector_size)
         self._emitline('  Offset entries:  %d\n' % cu.offset_count)
-        if cu.offsets and len(cu.offsets):
+        if cu.offsets:
             self._emitline('  Offsets starting at 0x%x:' % cu.offset_table_offset)
             for i_offset in enumerate(cu.offsets):
                 self._emitline('    [%6d] 0x%x' % i_offset)
@@ -1755,7 +1755,7 @@ def _dump_debug_rangesection(self, di, range_lists_sec):
         next_rcu_offset = 0
 
         range_lists = list(range_lists_sec.iter_range_lists())
-        if len(range_lists) == 0:
+        if not range_lists:
             # Present but empty ranges section - readelf outputs a message
             self._emitline("\nSection '%s' has no debugging data." % section_name)
             return

test/all_tests.py

@@ -11,7 +11,7 @@
 from utils import is_in_rootdir
 
 def run_test_script(path, *args):
-    cmd = [sys.executable, path] + list(args)
+    cmd = [sys.executable, path, *args]
     print("Running '%s'" % ' '.join(cmd))
     subprocess.check_call(cmd)
 

test/run_dwarfdump_tests.py

@@ -109,7 +109,7 @@ def compare_output(s1, s2):
     s1 = s1.replace('(0x0000000000000000 ".text")', '(0x0000000000000000)')
 
     def prepare_lines(s):
-        return [line for line in s.lower().splitlines() if line.strip() != '']
+        return [line for line in s.lower().splitlines() if line.strip()]
 
     lines1 = prepare_lines(s1)
     lines2 = prepare_lines(s2)
@@ -169,7 +169,7 @@ def main():
 
     # If file names are given as command-line arguments, only these files
     # are taken as inputs. Otherwise, autodiscovery is performed.
-    if len(args.files) > 0:
+    if args.files:
         filenames = args.files
     else:
         filenames = sorted(discover_testfiles('test/testfiles_for_dwarfdump'))

test/run_readelf_tests.py

@@ -163,7 +163,7 @@ def compare_output(s1, s2):
         to replicate. Read the documentation for more details.
     """
     def prepare_lines(s):
-        return [line for line in s.lower().splitlines() if line.strip() != '']
+        return [line for line in s.lower().splitlines() if line.strip()]
 
     lines1 = prepare_lines(s1)
     lines2 = prepare_lines(s2)
@@ -299,7 +299,7 @@ def main():
 
     # If file names are given as command-line arguments, only these files
     # are taken as inputs. Otherwise, autodiscovery is performed.
-    if len(args.files) > 0:
+    if args.files:
         filenames = args.files
     else:
         filenames = sorted(discover_testfiles('test/testfiles_for_readelf'))

test/test_dynamic.py

@@ -39,17 +39,16 @@ class TestDynamic(unittest.TestCase):
     def test_missing_sections(self):
         """Verify we can get dynamic strings w/out section headers"""
 
-        libs = []
         with open(os.path.join('test', 'testfiles_for_unittests',
                                'aarch64_super_stripped.elf'), 'rb') as f:
             elf = ELFFile(f)
-            for segment in elf.iter_segments():
-                if segment.header.p_type != 'PT_DYNAMIC':
-                    continue
-
-                for t in segment.iter_tags():
-                    if t.entry.d_tag == 'DT_NEEDED':
-                        libs.append(t.needed)
+            libs = [
+                t.needed
+                for segment in elf.iter_segments()
+                if segment.header.p_type == 'PT_DYNAMIC'
+                for t in segment.iter_tags()
+                if t.entry.d_tag == 'DT_NEEDED'
+            ]
 
         exp = ['libc.so.6']
         self.assertEqual(libs, exp)