added bneg unpacker

fact_extractor/plugins/unpacking/bneg/code/bneg.py

@@ -0,0 +1,44 @@
+import os
+import struct
+from pathlib import Path
+
+NAME = 'Instar BNEG'
+MIME_PATTERNS = ['firmware/bneg']
+VERSION = '0.1.0'
+HEADER_SIZE = 20
+
+
+class BnegHeader:
+    def __init__(self, data: bytes):
+        (
+            self.magic,
+            self.major_version,
+            self.minor_version,
+            *self.partitions,
+        ) = struct.unpack('<4sIIII', data)
+
+    def to_dict(self):
+        return self.__dict__
+
+
+def unpack_function(file_path: str, tmp_dir: str) -> dict:
+    input_file = Path(file_path)
+    output_dir = Path(tmp_dir)
+    with input_file.open('rb') as fp:
+        header = BnegHeader(fp.read(HEADER_SIZE))
+        output = [f'Found BNEG v{header.major_version}.{header.minor_version}']
+        offset = HEADER_SIZE
+        for idx, partition in enumerate(header.partitions, start=1):
+            if partition:
+                with (output_dir / f'partition_{idx}.bin').open('wb') as fp_out:
+                    os.sendfile(fp_out.fileno(), fp.fileno(), offset, partition)
+                output.append(f'Unpacked partition {idx} at offset {offset} to partition_{idx}.bin (size {partition})')
+                offset += partition
+
+    return {'output': '\n'.join(output)}
+
+
+# ----> Do not edit below this line <----
+def setup(unpack_tool):
+    for item in MIME_PATTERNS:
+        unpack_tool.register_plugin(item, (unpack_function, NAME, VERSION))

fact_extractor/plugins/unpacking/bneg/test/test_bneg.py

@@ -0,0 +1,27 @@
+from pathlib import Path
+
+from test.unit.unpacker.test_unpacker import TestUnpackerBase
+
+TEST_DATA_DIR = Path(__file__).parent / 'data'
+
+
+class TestInstarBnegUnpacker(TestUnpackerBase):
+
+    def test_unpacker_selection_generic(self):
+        self.check_unpacker_selection('firmware/bneg', 'Instar BNEG')
+
+    def test_extraction_bneg(self):
+        in_file = TEST_DATA_DIR / 'test.bneg'
+        assert in_file.is_file(), 'test file is missing'
+        files, meta = self.unpacker.extract_files_from_file(str(in_file), self.tmp_dir.name)
+        assert len(files) == 2  # noqa: PLR2004
+        assert 'output' in meta
+        assert 'size 7' in meta['output']
+        assert 'size 8' in meta['output']
+
+        file1 = Path(self.tmp_dir.name) / 'partition_1.bin'
+        assert file1.is_file()
+        assert file1.read_bytes() == b'foobar\n'
+        file2 = Path(self.tmp_dir.name) / 'partition_2.bin'
+        assert file2.is_file()
+        assert file2.read_bytes() == b'test123\n'