From b3e201d123a89d9981df1713a97858660b7b4b50 Mon Sep 17 00:00:00 2001
From: JSCU-CNI <121175071+JSCU-CNI@users.noreply.github.com>
Date: Thu, 8 Feb 2024 15:39:17 +0100
Subject: [PATCH 1/7] add basic cpio loader

---
 .gitattributes                                |  2 ++
 dissect/target/helpers/fsutil.py              | 26 ++++++++++----
 dissect/target/loader.py                      |  1 +
 dissect/target/loaders/cpio.py                | 32 +++++++++++++++++
 .../loaders/cpio/initrd.img-6.1.0-15-amd64    |  3 ++
 .../loaders/cpio/initrd.img-6.1.0-17-amd64    |  3 ++
 tests/loaders/test_cpio.py                    | 36 +++++++++++++++++++
 7 files changed, 97 insertions(+), 6 deletions(-)
 create mode 100644 dissect/target/loaders/cpio.py
 create mode 100644 tests/_data/loaders/cpio/initrd.img-6.1.0-15-amd64
 create mode 100644 tests/_data/loaders/cpio/initrd.img-6.1.0-17-amd64
 create mode 100644 tests/loaders/test_cpio.py

diff --git a/.gitattributes b/.gitattributes
index 7e4edd4db..83f767082 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -13,3 +13,5 @@ tests/_data/volumes/bde/enc-volume.bin filter=lfs diff=lfs merge=lfs -text
 tests/_data/volumes/md/md-nested.bin.gz filter=lfs diff=lfs merge=lfs -text
 tests/_data/loaders/tar/test-anon-filesystems.tar filter=lfs diff=lfs merge=lfs -text
 tests/_data/plugins/apps/browser/firefox/cookies.sqlite filter=lfs diff=lfs merge=lfs -text
+tests/_data/loaders/cpio/initrd.img-6.1.0-15-amd64 filter=lfs diff=lfs merge=lfs -text
+tests/_data/loaders/cpio/initrd.img-6.1.0-17-amd64 filter=lfs diff=lfs merge=lfs -text
diff --git a/dissect/target/helpers/fsutil.py b/dissect/target/helpers/fsutil.py
index 7866eead1..2b7de8516 100644
--- a/dissect/target/helpers/fsutil.py
+++ b/dissect/target/helpers/fsutil.py
@@ -16,9 +16,16 @@
 try:
     import bz2
 
-    HAVE_BZ2 = True
+    HAS_BZ2 = True
 except ImportError:
-    HAVE_BZ2 = False
+    HAS_BZ2 = False
+
+try:
+    import zstandard
+
+    HAS_ZSTD = True
+except ImportError:
+    HAS_ZSTD = False
 
 import dissect.target.filesystem as filesystem
 from dissect.target.exceptions import FileNotFoundError, SymlinkRecursionError
@@ -451,7 +458,7 @@ def open_decompress(
     errors: Optional[str] = "backslashreplace",
     newline: Optional[str] = None,
 ) -> Union[BinaryIO, TextIO]:
-    """Open and decompress a file. Handles gz and bz2 files. Uncompressed files are opened as-is.
+    """Open and decompress a file. Handles gz, bz2 and zstd files. Uncompressed files are opened as-is.
 
     Args:
         path: The path to the file to open and decompress. It is assumed this path exists.
@@ -469,7 +476,7 @@ def open_decompress(
         for line in open_decompress(Path("/dir/file.gz"), "rt"):
             print(line)
     """
-    file = path.open()
+    file = path.open("rb")
     magic = file.read(4)
     file.seek(0)
 
@@ -480,9 +487,16 @@ def open_decompress(
 
     if magic[:2] == b"\x1f\x8b":
         return gzip.open(file, mode, encoding=encoding, errors=errors, newline=newline)
-    # In a valid bz2 header the 4th byte is in the range b'1' ... b'9'.
-    elif HAVE_BZ2 and magic[:3] == b"BZh" and 0x31 <= magic[3] <= 0x39:
+
+    elif HAS_BZ2 and magic[:3] == b"BZh" and 0x31 <= magic[3] <= 0x39:
+        # In a valid bz2 header the 4th byte is in the range b'1' ... b'9'.
         return bz2.open(file, mode, encoding=encoding, errors=errors, newline=newline)
+
+    elif HAS_ZSTD and magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
+        # stream_reader is not seekable, so we have to resort to the less
+        # efficient decompressor which returns bytes.
+        return io.BytesIO(zstandard.decompress(path.open("rb").read()))
+
     else:
         file.close()
         return path.open(mode, encoding=encoding, errors=errors, newline=newline)
diff --git a/dissect/target/loader.py b/dissect/target/loader.py
index de1c04df0..328e548ee 100644
--- a/dissect/target/loader.py
+++ b/dissect/target/loader.py
@@ -203,4 +203,5 @@ def open(item: Union[str, Path], *args, **kwargs) -> Loader:
 register("smb", "SmbLoader")
 register("cb", "CbLoader")
 register("cyber", "CyberLoader")
+register("cpio", "CpioLoader")
 register("multiraw", "MultiRawLoader")  # Should be last
diff --git a/dissect/target/loaders/cpio.py b/dissect/target/loaders/cpio.py
new file mode 100644
index 000000000..5cde3b71a
--- /dev/null
+++ b/dissect/target/loaders/cpio.py
@@ -0,0 +1,32 @@
+from pathlib import Path
+
+from dissect.util import cpio
+
+from dissect.target import Target
+from dissect.target.filesystems.tar import TarFilesystem
+from dissect.target.helpers.fsutil import open_decompress
+from dissect.target.loader import Loader
+
+
+class CpioLoader(Loader):
+    """Load (compressed) CPIO files."""
+
+    def __init__(self, path: Path, **kwargs):
+        super().__init__(path)
+
+        fh = open_decompress(path, "rb")
+        self.cpio = TarFilesystem(fh, tarinfo=cpio.CpioInfo)
+
+    @staticmethod
+    def detect(path: Path) -> bool:
+        magic = path.open("rb").read(6)
+
+        # gzip, bz2 or zstd
+        if magic[:2] == b"\x1f\x8b" or magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
+            magic = open_decompress(path, "rb").read(6)
+
+        return magic in [b"070701", b"070707", b"070702"] or magic[:2] in [b"\x71\xc7", b"\xc7\x71"]
+
+    def map(self, target: Target) -> None:
+        target.filesystems.add(self.cpio)
+        target.fs.mount("/", self.cpio)
diff --git a/tests/_data/loaders/cpio/initrd.img-6.1.0-15-amd64 b/tests/_data/loaders/cpio/initrd.img-6.1.0-15-amd64
new file mode 100644
index 000000000..5d150b16e
--- /dev/null
+++ b/tests/_data/loaders/cpio/initrd.img-6.1.0-15-amd64
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a12f63a0c0783d9f647e46d058cfd1cd973ae0fc47332741d5ada70c91838426
+size 30818636
diff --git a/tests/_data/loaders/cpio/initrd.img-6.1.0-17-amd64 b/tests/_data/loaders/cpio/initrd.img-6.1.0-17-amd64
new file mode 100644
index 000000000..fb46ce16b
--- /dev/null
+++ b/tests/_data/loaders/cpio/initrd.img-6.1.0-17-amd64
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:da629b5cf297525debef2388df1259f6c272f07a42c22162070e601dcfbe79a4
+size 38204386
diff --git a/tests/loaders/test_cpio.py b/tests/loaders/test_cpio.py
new file mode 100644
index 000000000..07eddf135
--- /dev/null
+++ b/tests/loaders/test_cpio.py
@@ -0,0 +1,36 @@
+from pathlib import Path
+
+from dissect.target import Target
+from dissect.target.loaders.cpio import CpioLoader
+from tests._utils import absolute_path
+
+
+def test_cpio_uncompressed(target_default: Target) -> None:
+    cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-17-amd64"))
+
+    loader = CpioLoader(cpio_path)
+    loader.map(target_default)
+    assert len(target_default.fs.mounts) == 1
+
+    assert [f.name for f in target_default.fs.path("/").iterdir()] == ["kernel"]
+
+
+def test_cpio_compressed_zstd(target_default: Target) -> None:
+    cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-15-amd64"))
+
+    loader = CpioLoader(cpio_path)
+    loader.map(target_default)
+    assert len(target_default.fs.mounts) == 1
+
+    assert [f.name for f in target_default.fs.path("/").iterdir()] == [
+        "bin",
+        "conf",
+        "etc",
+        "init",
+        "lib",
+        "lib64",
+        "run",
+        "sbin",
+        "scripts",
+        "usr",
+    ]

From 06cd353d54888d580b9c6ca0b34b31e226c16341 Mon Sep 17 00:00:00 2001
From: JSCU-CNI <121175071+JSCU-CNI@users.noreply.github.com>
Date: Tue, 13 Feb 2024 13:13:59 +0100
Subject: [PATCH 2/7] implement review comments

---
 dissect/target/helpers/fsutil.py | 12 ++++++------
 dissect/target/loaders/cpio.py   | 16 ++++++----------
 tests/loaders/test_cpio.py       | 14 ++++++++++++--
 3 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/dissect/target/helpers/fsutil.py b/dissect/target/helpers/fsutil.py
index 2b7de8516..f23ddc446 100644
--- a/dissect/target/helpers/fsutil.py
+++ b/dissect/target/helpers/fsutil.py
@@ -16,16 +16,16 @@
 try:
     import bz2
 
-    HAS_BZ2 = True
+    HAVE_BZ2 = True
 except ImportError:
-    HAS_BZ2 = False
+    HAVE_BZ2 = False
 
 try:
     import zstandard
 
-    HAS_ZSTD = True
+    HAVE_ZSTD = True
 except ImportError:
-    HAS_ZSTD = False
+    HAVE_ZSTD = False
 
 import dissect.target.filesystem as filesystem
 from dissect.target.exceptions import FileNotFoundError, SymlinkRecursionError
@@ -488,11 +488,11 @@ def open_decompress(
     if magic[:2] == b"\x1f\x8b":
         return gzip.open(file, mode, encoding=encoding, errors=errors, newline=newline)
 
-    elif HAS_BZ2 and magic[:3] == b"BZh" and 0x31 <= magic[3] <= 0x39:
+    elif HAVE_BZ2 and magic[:3] == b"BZh" and 0x31 <= magic[3] <= 0x39:
         # In a valid bz2 header the 4th byte is in the range b'1' ... b'9'.
         return bz2.open(file, mode, encoding=encoding, errors=errors, newline=newline)
 
-    elif HAS_ZSTD and magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
+    elif HAVE_ZSTD and magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
         # stream_reader is not seekable, so we have to resort to the less
         # efficient decompressor which returns bytes.
         return io.BytesIO(zstandard.decompress(path.open("rb").read()))
diff --git a/dissect/target/loaders/cpio.py b/dissect/target/loaders/cpio.py
index 5cde3b71a..6fd4e1a38 100644
--- a/dissect/target/loaders/cpio.py
+++ b/dissect/target/loaders/cpio.py
@@ -11,22 +11,18 @@
 class CpioLoader(Loader):
     """Load (compressed) CPIO files."""
 
-    def __init__(self, path: Path, **kwargs):
-        super().__init__(path)
-
-        fh = open_decompress(path, "rb")
-        self.cpio = TarFilesystem(fh, tarinfo=cpio.CpioInfo)
-
     @staticmethod
     def detect(path: Path) -> bool:
-        magic = path.open("rb").read(6)
+        with path.open("rb") as fh:
+            magic = fh.read(6)
 
         # gzip, bz2 or zstd
         if magic[:2] == b"\x1f\x8b" or magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
-            magic = open_decompress(path, "rb").read(6)
+            with open_decompress(path, "rb") as fh:
+                magic = fh.read(6)
 
         return magic in [b"070701", b"070707", b"070702"] or magic[:2] in [b"\x71\xc7", b"\xc7\x71"]
 
     def map(self, target: Target) -> None:
-        target.filesystems.add(self.cpio)
-        target.fs.mount("/", self.cpio)
+        tfs = TarFilesystem(open_decompress(self.path, "rb"), tarinfo=cpio.CpioInfo)
+        target.filesystems.add(tfs)
diff --git a/tests/loaders/test_cpio.py b/tests/loaders/test_cpio.py
index 07eddf135..23159a911 100644
--- a/tests/loaders/test_cpio.py
+++ b/tests/loaders/test_cpio.py
@@ -7,9 +7,14 @@
 
 def test_cpio_uncompressed(target_default: Target) -> None:
     cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-17-amd64"))
-
     loader = CpioLoader(cpio_path)
+
+    assert loader.detect(cpio_path)
+
     loader.map(target_default)
+    target_default.apply()
+
+    assert len(target_default.filesystems) == 1
     assert len(target_default.fs.mounts) == 1
 
     assert [f.name for f in target_default.fs.path("/").iterdir()] == ["kernel"]
@@ -17,9 +22,14 @@ def test_cpio_uncompressed(target_default: Target) -> None:
 
 def test_cpio_compressed_zstd(target_default: Target) -> None:
     cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-15-amd64"))
-
     loader = CpioLoader(cpio_path)
+
+    assert loader.detect(cpio_path)
+
     loader.map(target_default)
+    target_default.apply()
+
+    assert len(target_default.filesystems) == 1
     assert len(target_default.fs.mounts) == 1
 
     assert [f.name for f in target_default.fs.path("/").iterdir()] == [

From f87ad0e9a246b9d323a8b2acb02528834308451b Mon Sep 17 00:00:00 2001
From: Schamper <1254028+Schamper@users.noreply.github.com>
Date: Wed, 14 Feb 2024 21:27:12 +0100
Subject: [PATCH 3/7] Convert to filesystem

---
 dissect/target/filesystem.py       |  2 ++
 dissect/target/filesystems/cpio.py | 16 +++++++++++
 dissect/target/helpers/fsutil.py   | 23 ++++++++++++---
 dissect/target/loader.py           |  1 -
 dissect/target/loaders/cpio.py     | 28 ------------------
 tests/filesystems/test_cpio.py     | 35 +++++++++++++++++++++++
 tests/loaders/test_cpio.py         | 46 ------------------------------
 7 files changed, 72 insertions(+), 79 deletions(-)
 create mode 100644 dissect/target/filesystems/cpio.py
 delete mode 100644 dissect/target/loaders/cpio.py
 create mode 100644 tests/filesystems/test_cpio.py
 delete mode 100644 tests/loaders/test_cpio.py

diff --git a/dissect/target/filesystem.py b/dissect/target/filesystem.py
index 8d26a8c5c..3d409ad1f 100644
--- a/dissect/target/filesystem.py
+++ b/dissect/target/filesystem.py
@@ -1588,5 +1588,7 @@ def open_multi_volume(fhs: list[BinaryIO], *args, **kwargs) -> Filesystem:
 register("exfat", "ExfatFilesystem")
 register("squashfs", "SquashFSFilesystem")
 register("zip", "ZipFilesystem")
+register("tar", "TarFilesystem")
+register("cpio", "CpioFilesystem")
 register("ad1", "AD1Filesystem")
 register("jffs", "JFFSFilesystem")
diff --git a/dissect/target/filesystems/cpio.py b/dissect/target/filesystems/cpio.py
new file mode 100644
index 000000000..034a0ceea
--- /dev/null
+++ b/dissect/target/filesystems/cpio.py
@@ -0,0 +1,16 @@
+from typing import BinaryIO
+
+from dissect.util import cpio
+
+from dissect.target.filesystems.tar import TarFilesystem
+from dissect.target.helpers.fsutil import open_decompress
+
+
+class CpioFilesystem(TarFilesystem):
+    def __init__(self, fh: BinaryIO, base: str | None = None, *args, **kwargs):
+        super().__init__(open_decompress(fileobj=fh), base, tarinfo=cpio.CpioInfo, *args, **kwargs)
+
+    @staticmethod
+    def _detect(fh: BinaryIO) -> bool:
+        """Detect a cpio file on a given file-like object."""
+        return cpio.detect_header(open_decompress(fileobj=fh)) != cpio.FORMAT_CPIO_UNKNOWN
diff --git a/dissect/target/helpers/fsutil.py b/dissect/target/helpers/fsutil.py
index f23ddc446..32104c7dd 100644
--- a/dissect/target/helpers/fsutil.py
+++ b/dissect/target/helpers/fsutil.py
@@ -452,7 +452,8 @@ def resolve_link(
 
 
 def open_decompress(
-    path: TargetPath,
+    path: Optional[TargetPath] = None,
+    fileobj: Optional[BinaryIO] = None,
     mode: str = "rb",
     encoding: Optional[str] = "UTF-8",
     errors: Optional[str] = "backslashreplace",
@@ -462,6 +463,7 @@ def open_decompress(
 
     Args:
         path: The path to the file to open and decompress. It is assumed this path exists.
+        fileobj: The file-like object to open and decompress. This is mutually exclusive with path.
         mode: The mode in which to open the file.
         encoding: The decoding for text streams. By default UTF-8 encoding is used.
         errors: The error handling for text streams. By default we're more lenient and use ``backslashreplace``.
@@ -476,7 +478,17 @@ def open_decompress(
         for line in open_decompress(Path("/dir/file.gz"), "rt"):
             print(line)
     """
-    file = path.open("rb")
+    if path and fileobj:
+        raise ValueError("path and fileobj are mutually exclusive")
+
+    if not path and not fileobj:
+        raise ValueError("path or fileobj is required")
+
+    if path:
+        file = path.open("rb")
+    else:
+        file = fileobj
+
     magic = file.read(4)
     file.seek(0)
 
@@ -495,12 +507,15 @@ def open_decompress(
     elif HAVE_ZSTD and magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
         # stream_reader is not seekable, so we have to resort to the less
         # efficient decompressor which returns bytes.
-        return io.BytesIO(zstandard.decompress(path.open("rb").read()))
+        return io.BytesIO(zstandard.decompress(file.read()))
 
-    else:
+    elif path:
         file.close()
         return path.open(mode, encoding=encoding, errors=errors, newline=newline)
 
+    else:
+        return file
+
 
 def reverse_readlines(fh: TextIO, chunk_size: int = 1024 * 1024 * 8) -> Iterator[str]:
     """Like iterating over a ``TextIO`` file-like object, but starting from the end of the file.
diff --git a/dissect/target/loader.py b/dissect/target/loader.py
index 328e548ee..de1c04df0 100644
--- a/dissect/target/loader.py
+++ b/dissect/target/loader.py
@@ -203,5 +203,4 @@ def open(item: Union[str, Path], *args, **kwargs) -> Loader:
 register("smb", "SmbLoader")
 register("cb", "CbLoader")
 register("cyber", "CyberLoader")
-register("cpio", "CpioLoader")
 register("multiraw", "MultiRawLoader")  # Should be last
diff --git a/dissect/target/loaders/cpio.py b/dissect/target/loaders/cpio.py
deleted file mode 100644
index 6fd4e1a38..000000000
--- a/dissect/target/loaders/cpio.py
+++ /dev/null
@@ -1,28 +0,0 @@
-from pathlib import Path
-
-from dissect.util import cpio
-
-from dissect.target import Target
-from dissect.target.filesystems.tar import TarFilesystem
-from dissect.target.helpers.fsutil import open_decompress
-from dissect.target.loader import Loader
-
-
-class CpioLoader(Loader):
-    """Load (compressed) CPIO files."""
-
-    @staticmethod
-    def detect(path: Path) -> bool:
-        with path.open("rb") as fh:
-            magic = fh.read(6)
-
-        # gzip, bz2 or zstd
-        if magic[:2] == b"\x1f\x8b" or magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
-            with open_decompress(path, "rb") as fh:
-                magic = fh.read(6)
-
-        return magic in [b"070701", b"070707", b"070702"] or magic[:2] in [b"\x71\xc7", b"\xc7\x71"]
-
-    def map(self, target: Target) -> None:
-        tfs = TarFilesystem(open_decompress(self.path, "rb"), tarinfo=cpio.CpioInfo)
-        target.filesystems.add(tfs)
diff --git a/tests/filesystems/test_cpio.py b/tests/filesystems/test_cpio.py
new file mode 100644
index 000000000..0944d50bb
--- /dev/null
+++ b/tests/filesystems/test_cpio.py
@@ -0,0 +1,35 @@
+from pathlib import Path
+
+from dissect.target.filesystems.cpio import CpioFilesystem
+from tests._utils import absolute_path
+
+
+def test_cpio_uncompressed() -> None:
+    cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-17-amd64"))
+
+    with cpio_path.open("rb") as fh:
+        assert CpioFilesystem.detect(fh)
+
+        fs = CpioFilesystem(fh)
+        assert [f.name for f in fs.path("/").iterdir()] == ["kernel"]
+
+
+def test_cpio_compressed_zstd() -> None:
+    cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-15-amd64"))
+
+    with cpio_path.open("rb") as fh:
+        assert CpioFilesystem.detect(fh)
+
+        fs = CpioFilesystem(fh)
+        assert [f.name for f in fs.path("/").iterdir()] == [
+            "bin",
+            "conf",
+            "etc",
+            "init",
+            "lib",
+            "lib64",
+            "run",
+            "sbin",
+            "scripts",
+            "usr",
+        ]
diff --git a/tests/loaders/test_cpio.py b/tests/loaders/test_cpio.py
deleted file mode 100644
index 23159a911..000000000
--- a/tests/loaders/test_cpio.py
+++ /dev/null
@@ -1,46 +0,0 @@
-from pathlib import Path
-
-from dissect.target import Target
-from dissect.target.loaders.cpio import CpioLoader
-from tests._utils import absolute_path
-
-
-def test_cpio_uncompressed(target_default: Target) -> None:
-    cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-17-amd64"))
-    loader = CpioLoader(cpio_path)
-
-    assert loader.detect(cpio_path)
-
-    loader.map(target_default)
-    target_default.apply()
-
-    assert len(target_default.filesystems) == 1
-    assert len(target_default.fs.mounts) == 1
-
-    assert [f.name for f in target_default.fs.path("/").iterdir()] == ["kernel"]
-
-
-def test_cpio_compressed_zstd(target_default: Target) -> None:
-    cpio_path = Path(absolute_path("_data/loaders/cpio/initrd.img-6.1.0-15-amd64"))
-    loader = CpioLoader(cpio_path)
-
-    assert loader.detect(cpio_path)
-
-    loader.map(target_default)
-    target_default.apply()
-
-    assert len(target_default.filesystems) == 1
-    assert len(target_default.fs.mounts) == 1
-
-    assert [f.name for f in target_default.fs.path("/").iterdir()] == [
-        "bin",
-        "conf",
-        "etc",
-        "init",
-        "lib",
-        "lib64",
-        "run",
-        "sbin",
-        "scripts",
-        "usr",
-    ]

From 6c06e18b532474daf9a16a213bb2b85387c75fbc Mon Sep 17 00:00:00 2001
From: Schamper <1254028+Schamper@users.noreply.github.com>
Date: Wed, 14 Feb 2024 21:29:40 +0100
Subject: [PATCH 4/7] Fix type hint

---
 dissect/target/filesystems/cpio.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dissect/target/filesystems/cpio.py b/dissect/target/filesystems/cpio.py
index 034a0ceea..2f97e33ac 100644
--- a/dissect/target/filesystems/cpio.py
+++ b/dissect/target/filesystems/cpio.py
@@ -1,4 +1,4 @@
-from typing import BinaryIO
+from typing import BinaryIO, Optional
 
 from dissect.util import cpio
 
@@ -7,7 +7,7 @@
 
 
 class CpioFilesystem(TarFilesystem):
-    def __init__(self, fh: BinaryIO, base: str | None = None, *args, **kwargs):
+    def __init__(self, fh: BinaryIO, base: Optional[str] = None, *args, **kwargs):
         super().__init__(open_decompress(fileobj=fh), base, tarinfo=cpio.CpioInfo, *args, **kwargs)
 
     @staticmethod

From 23659f9e01c7892d2fe4ae81c56a1d705bea2aa0 Mon Sep 17 00:00:00 2001
From: Schamper <1254028+Schamper@users.noreply.github.com>
Date: Wed, 14 Feb 2024 21:48:00 +0100
Subject: [PATCH 5/7] Fix open_decompress arguments

---
 dissect/target/helpers/fsutil.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/dissect/target/helpers/fsutil.py b/dissect/target/helpers/fsutil.py
index 32104c7dd..a6083f8af 100644
--- a/dissect/target/helpers/fsutil.py
+++ b/dissect/target/helpers/fsutil.py
@@ -453,18 +453,21 @@ def resolve_link(
 
 def open_decompress(
     path: Optional[TargetPath] = None,
-    fileobj: Optional[BinaryIO] = None,
     mode: str = "rb",
+    *,
+    fileobj: Optional[BinaryIO] = None,
     encoding: Optional[str] = "UTF-8",
     errors: Optional[str] = "backslashreplace",
     newline: Optional[str] = None,
 ) -> Union[BinaryIO, TextIO]:
     """Open and decompress a file. Handles gz, bz2 and zstd files. Uncompressed files are opened as-is.
 
+    When passing in an already opened ``fileobj``, the mode, encoding, errors and newline arguments are ignored.
+
     Args:
         path: The path to the file to open and decompress. It is assumed this path exists.
-        fileobj: The file-like object to open and decompress. This is mutually exclusive with path.
         mode: The mode in which to open the file.
+        fileobj: The file-like object to open and decompress. This is mutually exclusive with path.
         encoding: The decoding for text streams. By default UTF-8 encoding is used.
         errors: The error handling for text streams. By default we're more lenient and use ``backslashreplace``.
         newline: How newlines are handled for text streams.

From 81f0aa102684f10856f16c86a4ebbdbe89e24548 Mon Sep 17 00:00:00 2001
From: Schamper <1254028+Schamper@users.noreply.github.com>
Date: Wed, 14 Feb 2024 22:05:28 +0100
Subject: [PATCH 6/7] Correct __type__

---
 dissect/target/filesystems/cpio.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/dissect/target/filesystems/cpio.py b/dissect/target/filesystems/cpio.py
index 2f97e33ac..5e8d2aee2 100644
--- a/dissect/target/filesystems/cpio.py
+++ b/dissect/target/filesystems/cpio.py
@@ -7,6 +7,8 @@
 
 
 class CpioFilesystem(TarFilesystem):
+    __type__ = "cpio"
+
     def __init__(self, fh: BinaryIO, base: Optional[str] = None, *args, **kwargs):
         super().__init__(open_decompress(fileobj=fh), base, tarinfo=cpio.CpioInfo, *args, **kwargs)
 

From 46d236a71955f66956c0d6890747e575c1133675 Mon Sep 17 00:00:00 2001
From: Erik Schamper <1254028+Schamper@users.noreply.github.com>
Date: Mon, 19 Feb 2024 12:32:36 +0100
Subject: [PATCH 7/7] Apply suggestions from code review

Co-authored-by: Stefan de Reuver <9864602+Horofic@users.noreply.github.com>
---
 dissect/target/helpers/fsutil.py | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/dissect/target/helpers/fsutil.py b/dissect/target/helpers/fsutil.py
index a6083f8af..cab58d1cc 100644
--- a/dissect/target/helpers/fsutil.py
+++ b/dissect/target/helpers/fsutil.py
@@ -503,21 +503,20 @@ def open_decompress(
     if magic[:2] == b"\x1f\x8b":
         return gzip.open(file, mode, encoding=encoding, errors=errors, newline=newline)
 
-    elif HAVE_BZ2 and magic[:3] == b"BZh" and 0x31 <= magic[3] <= 0x39:
+    if HAVE_BZ2 and magic[:3] == b"BZh" and 0x31 <= magic[3] <= 0x39:
         # In a valid bz2 header the 4th byte is in the range b'1' ... b'9'.
         return bz2.open(file, mode, encoding=encoding, errors=errors, newline=newline)
 
-    elif HAVE_ZSTD and magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
+    if HAVE_ZSTD and magic[:4] in [b"\xfd\x2f\xb5\x28", b"\x28\xb5\x2f\xfd"]:
         # stream_reader is not seekable, so we have to resort to the less
         # efficient decompressor which returns bytes.
         return io.BytesIO(zstandard.decompress(file.read()))
 
-    elif path:
+    if path:
         file.close()
         return path.open(mode, encoding=encoding, errors=errors, newline=newline)
 
-    else:
-        return file
+    return file
 
 
 def reverse_readlines(fh: TextIO, chunk_size: int = 1024 * 1024 * 8) -> Iterator[str]: