Fixed import of packages from requirement files with UTF-16 encoding (#…

…1387)

* Fixed import of packages from requirement files with UTF-16 encoding

* Update CHANGES.md

* Load requirement files using the pip auto_decode function

---------

Co-authored-by: Cooper Lees <[email protected]>

.flake8

@@ -4,7 +4,7 @@ max_line_length = 88
 # E722 is a duplicate of B001.
 # P207 is a duplicate of B003.
 # W503 is against PEP8
-ignore = E722, P207, W503
+ignore = E722, P207, W503, E203
 max-complexity = 20
 exclude =
     build,

CHANGES.md

@@ -7,6 +7,10 @@
 - Move Docker to build in 3.11 `PR #1341`
 - Add "--force-check" parameter to runner.py `PR #1347`
 
+## Bug Fixes
+
+- Fixed import of packages from requirement files with UTF-16 encoding `PR #1387`
+
 # 6.1.0
 
 ## New Features

src/bandersnatch/tests/plugins/test_allowlist_name.py

@@ -572,3 +572,37 @@ def test__filter__find__glob__files(self) -> None:
         # Check that the package in the last file, excluded
         # from the glob is not considered
         self.assertNotIn("baz", mirror.packages_to_sync)
+
+    def test__filter__requirements__utf16__encoding(self) -> None:
+        absolute_file_path = Path(self.tempdir.name) / "requirements.txt"
+        with open(absolute_file_path, "w", encoding="UTF-16") as fh:
+            fh.write(
+                """\
+foo==1.2.0             # via -r requirements.in
+"""
+            )
+
+        mock_config(
+            f"""\
+[mirror]
+storage-backend = filesystem
+workers = 2
+
+[plugins]
+enabled =
+    project_requirements
+[allowlist]
+requirements =
+    {absolute_file_path}
+"""
+        )
+
+        mirror = BandersnatchMirror(Path("."), Master(url="https://foo.bar.com"))
+
+        mirror.packages_to_sync = {
+            "foo": "",
+            "bar": "",
+            "baz": "",
+        }
+        mirror._filter_packages()
+        self.assertEqual({"foo": ""}, mirror.packages_to_sync)

src/bandersnatch_filter_plugins/allowlist_name.py

@@ -11,6 +11,8 @@
 
 from bandersnatch.filter import FilterProjectPlugin, FilterReleasePlugin
 
+from .encoding import auto_decode
+
 logger = logging.getLogger("bandersnatch")
 
 
@@ -153,8 +155,9 @@ def _determine_unfiltered_package_names(self) -> List[str]:
             return []
 
         for filepath in filepaths:
-            with open(filepath) as req_fh:
-                filtered_requirements |= _parse_package_lines(req_fh.readlines())
+            with open(filepath, "rb") as req_fh:
+                content = auto_decode(req_fh.read())
+                filtered_requirements |= _parse_package_lines(content.splitlines())
         return list(req.name for req in filtered_requirements)
 
 

src/bandersnatch_filter_plugins/encoding.py

@@ -0,0 +1,36 @@
+import codecs
+import locale
+import re
+import sys
+from typing import List, Tuple
+
+BOMS: List[Tuple[bytes, str]] = [
+    (codecs.BOM_UTF8, "utf-8"),
+    (codecs.BOM_UTF16, "utf-16"),
+    (codecs.BOM_UTF16_BE, "utf-16-be"),
+    (codecs.BOM_UTF16_LE, "utf-16-le"),
+    (codecs.BOM_UTF32, "utf-32"),
+    (codecs.BOM_UTF32_BE, "utf-32-be"),
+    (codecs.BOM_UTF32_LE, "utf-32-le"),
+]
+
+ENCODING_RE = re.compile(rb"coding[:=]\s*([-\w.]+)")
+
+
+def auto_decode(data: bytes) -> str:
+    """Check a bytes string for a BOM to correctly detect the encoding
+
+    Fallback to locale.getpreferredencoding(False) like open() on Python3"""
+    for bom, encoding in BOMS:
+        if data.startswith(bom):
+            return data[len(bom) :].decode(encoding)
+    # Lets check the first two lines as in PEP263
+    for line in data.split(b"\n")[:2]:
+        if line[0:1] == b"#" and ENCODING_RE.search(line):
+            result = ENCODING_RE.search(line)
+            assert result is not None
+            encoding = result.groups()[0].decode("ascii")
+            return data.decode(encoding)
+    return data.decode(
+        locale.getpreferredencoding(False) or sys.getdefaultencoding(),
+    )