build: Initialize Python virtual environment and install project dependencies.

.venv/lib/python3.11/site-packages/elftools/common/construct_utils.py

@@ -0,0 +1,134 @@
+#-------------------------------------------------------------------------------
+# elftools: common/construct_utils.py
+#
+# Some complementary construct utilities
+#
+# Eli Bendersky (eliben@gmail.com)
+# This code is in the public domain
+#-------------------------------------------------------------------------------
+from struct import Struct
+from ..construct import (
+    Subconstruct, ConstructError, ArrayError, Adapter, Field, RepeatUntil,
+    Rename, SizeofError, Construct, StaticField, FieldError
+    )
+
+
+class RepeatUntilExcluding(Subconstruct):
+    """ A version of construct's RepeatUntil that doesn't include the last
+        element (which casued the repeat to exit) in the return value.
+
+        Only parsing is currently implemented.
+
+        P.S. removed some code duplication
+    """
+    __slots__ = ["predicate"]
+    def __init__(self, predicate, subcon):
+        Subconstruct.__init__(self, subcon)
+        self.predicate = predicate
+        self._clear_flag(self.FLAG_COPY_CONTEXT)
+        self._set_flag(self.FLAG_DYNAMIC)
+    def _parse(self, stream, context):
+        obj = []
+        try:
+            context_for_subcon = context
+            if self.subcon.conflags & self.FLAG_COPY_CONTEXT:
+                context_for_subcon = context.__copy__()
+
+            while True:
+                subobj = self.subcon._parse(stream, context_for_subcon)
+                if self.predicate(subobj, context):
+                    break
+                obj.append(subobj)
+        except ConstructError as ex:
+            raise ArrayError("missing terminator", ex)
+        return obj
+    def _build(self, obj, stream, context):
+        raise NotImplementedError('no building')
+    def _sizeof(self, context):
+        raise SizeofError("can't calculate size")
+
+class ULEB128(Construct):
+    """A construct based parser for ULEB128 encoding.
+
+       Incompatible with Python 2 - assumes that the return of read()
+       is an indexed collection of numbers.
+    """
+    def _parse(self, stream, context):
+        value = 0
+        shift = 0
+        while True:
+            data = stream.read(1)
+            if len(data) != 1:
+                raise FieldError("unexpected end of stream while parsing a ULEB128 encoded value")
+            b = data[0]
+            value |= (b & 0x7F) << shift
+            shift += 7
+            if b & 0x80 == 0:
+                return value
+
+class SLEB128(Construct):
+    """A construct based parser for SLEB128 encoding.
+
+       Incompatible with Python 2 - assumes that the return of read()
+       is an indexed collection of numbers.
+    """
+    def _parse(self, stream, context):
+        value = 0
+        shift = 0
+        while True:
+            data = stream.read(1)
+            if len(data) != 1:
+                raise FieldError("unexpected end of stream while parsing a SLEB128 encoded value")
+            b = data[0]
+            value |= (b & 0x7F) << shift
+            shift += 7
+            if b & 0x80 == 0:
+                return value | (~0 << shift) if b & 0x40 else value
+
+class StreamOffset(Construct):
+    """
+    Captures the current stream offset
+
+    Parameters:
+    * name - the name of the value
+
+    Example:
+    StreamOffset("item_offset")
+    """
+    __slots__ = []
+    def __init__(self, name):
+        Construct.__init__(self, name)
+        self._set_flag(self.FLAG_DYNAMIC)
+    def _parse(self, stream, context):
+        return stream.tell()
+    def _build(self, obj, stream, context):
+        context[self.name] = stream.tell()
+    def _sizeof(self, context):
+        return 0
+
+_UBInt24_packer = Struct(">BH")
+_ULInt24_packer = Struct("<HB")
+
+class UBInt24(StaticField):
+    """unsigned, big endian 24-bit integer"""
+    def __init__(self, name):
+        StaticField.__init__(self, name, 3)
+
+    def _parse(self, stream, context):
+        (h, l) = _UBInt24_packer.unpack(StaticField._parse(self, stream, context))
+        return l | (h << 16)
+    
+    def _build(self, obj, stream, context):
+        StaticField._build(self, _UBInt24_packer.pack(obj >> 16, obj & 0xFFFF), stream, context)
+
+class ULInt24(StaticField):
+    """unsigned, little endian 24-bit integer"""
+    def __init__(self, name):
+        StaticField.__init__(self, name, 3)
+
+    def _parse(self, stream, context):
+        (l, h) = _ULInt24_packer.unpack(StaticField._parse(self, stream, context))
+        return l | (h << 16)
+    
+    def _build(self, obj, stream, context):
+        StaticField._build(self, _ULInt24_packer.pack(obj & 0xFFFF, obj >> 16), stream, context)