Pack and unpack LEB128 values on demand.

1 files changed, 108 insertions, 0 deletions

diff --git a/tests/common/leb128.py b/tests/common/leb128.py
new file mode 100644
index 0000000..db3013e
--- /dev/null
+++ b/tests/common/leb128.py
@@ -0,0 +1,108 @@
+
+from chrysacase import ChrysalideTestCase
+from pychrysalide.common import pack_uleb128, unpack_uleb128, pack_leb128, unpack_leb128
+from pychrysalide.common import PackedBuffer
+
+
+class TestLEB128Values(ChrysalideTestCase):
+    """TestCase for common LEB128 features*"""
+
+    def testUnsignedLeb128Encoding(self):
+        """Pack and unpack unsigned LEB128 values."""
+
+        cases = {
+            624485: b'\xe5\x8e\x26',
+            127: b'\x7f',
+            128: b'\x80\x01',
+        }
+
+        for value, encoding in cases.items():
+
+            pbuf = PackedBuffer()
+
+            status = pack_uleb128(value, pbuf)
+            self.assertTrue(status)
+
+            self.assertEqual(pbuf.payload_length, len(encoding))
+
+            pbuf.rewind()
+
+            got = pbuf.extract(len(encoding))
+
+            self.assertEqual(got, encoding)
+
+            self.assertFalse(pbuf.more_data)
+
+        for value, encoding in cases.items():
+
+            pbuf = PackedBuffer()
+            pbuf.extend(encoding, False)
+
+            pbuf.rewind()
+
+            got = unpack_uleb128(pbuf)
+            self.assertIsNotNone(got)
+
+            self.assertEqual(got, value)
+
+
+    def testSignedLeb128Encoding(self):
+        """Pack and unpack signed LEB128 values."""
+
+        cases = {
+            -123456: b'\xc0\xbb\x78',
+            -42: b'\x56',
+            -9001: b'\xd7\xb9\x7f',
+        }
+
+        for value, encoding in cases.items():
+
+            pbuf = PackedBuffer()
+
+            status = pack_leb128(value, pbuf)
+            self.assertTrue(status)
+
+            self.assertEqual(pbuf.payload_length, len(encoding))
+
+            pbuf.rewind()
+
+            got = pbuf.extract(len(encoding))
+
+            self.assertEqual(got, encoding)
+
+            self.assertFalse(pbuf.more_data)
+
+        for value, encoding in cases.items():
+
+            pbuf = PackedBuffer()
+            pbuf.extend(encoding, False)
+
+            pbuf.rewind()
+
+            got = unpack_leb128(pbuf)
+            self.assertIsNotNone(got)
+
+            self.assertEqual(got, value)
+
+
+    def testTooBigLeb128Encodings(self):
+        """Prevent overflow for LEB128 values."""
+
+        pbuf = PackedBuffer()
+        pbuf.extend(b'\x80' * 10 + b'\x7f', False)
+
+        pbuf.rewind()
+
+        got = unpack_uleb128(pbuf)
+
+        self.assertIsNone(got)
+
+        pbuf = PackedBuffer()
+        pbuf.extend(b'\x80' * 10 + b'\x7f', False)
+
+        pbuf.rewind()
+
+        got = unpack_leb128(pbuf)
+
+        self.assertIsNone(got)
+