Strip embedded Project-Id-Version content from GNU message catalog type

src/typecode/magic2.py

@@ -31,6 +31,7 @@
 import ctypes.util
 import glob
 import os
+import re
 import sys
 import warnings
 
@@ -301,6 +302,18 @@ def encoding(location):
     return _detect(location, DETECT_ENC)
 
 
+#  For GNU message catalog (.mo) files, some libmagic versions append the
+#  gettext PO header's "Project-Id-Version" field verbatim to the detected
+#  type string. That field is free-form content taken from inside the
+#  scanned file (translators can put arbitrary, including non-ASCII escaped,
+#  text there) rather than structural information about the file type, so we
+#  strip it and keep only libmagic's own description.
+MO_FILE_TYPE_RE = re.compile(
+    r"^(GNU message catalog \([^)]*\), revision [\d.]+, \d+ messages),"
+    r" Project-Id-Version:.*$"
+)
+
+
 def _detect(location, flags):
     """ "
     Return the detected type using `flags` of file at `location` or an empty
@@ -314,7 +327,11 @@ def _detect(location, flags):
     val = detector.get(location)
     val = val or ""
     val = val.decode("ascii", "ignore").strip()
-    return " ".join(val.split())
+    val = " ".join(val.split())
+    mo_match = MO_FILE_TYPE_RE.match(val)
+    if mo_match:
+        val = mo_match.group(1)
+    return val
 
 
 class MagicException(Exception):

tests/test_magic2.py

@@ -7,8 +7,49 @@
 # See https://aboutcode.org for more information about nexB OSS projects.
 #
 
+from typecode.magic2 import MO_FILE_TYPE_RE
 from typecode.magic2 import libmagic_version
 
 
 def test_load_lib():
     assert float(libmagic_version()) > 5
+
+
+def _clean_mo_type(val):
+    match = MO_FILE_TYPE_RE.match(val)
+    return match.group(1) if match else val
+
+
+def test_mo_file_type_strips_embedded_project_id_version_ascii():
+    val = (
+        "GNU message catalog (little endian), revision 0.0, 349 messages, "
+        "Project-Id-Version: django '%(datetime)s non se puido interpretar na "
+        "zona hora horaria %(current_timezone)s; pode ser ambiguo ou non "
+        "existir.'"
+    )
+    assert _clean_mo_type(val) == (
+        "GNU message catalog (little endian), revision 0.0, 349 messages"
+    )
+
+
+def test_mo_file_type_strips_embedded_project_id_version_escaped_bytes():
+    val = (
+        "GNU message catalog (little endian), revision 0.0, 349 messages, "
+        "Project-Id-Version: django '%(datetime)s \\343\\201\\257 "
+        "%(current_timezone)s \\343\\201\\256\\343\\202\\277\\343\\202\\244"
+        "\\343\\203\\240\\343\\202\\276\\343\\203\\274\\343\\203\\263"
+        "\\343\\201\\247\\343\\201\\257\\350\\247\\243\\351\\207\\210"
+        "\\343\\201\\247\\343\\201\\215\\343\\201\\276\\343\\201\\233"
+        "\\343\\202\\223\\343\\201\\247\\343\\201\\227\\343\\201\\237"
+        "\\343\\200\\202\\343\\201\\235\\343\\202\\214\\343\\201\\257"
+        "\\346\\233\\226\\346\\230\\247\\343\\201\\247\\343\\201\\202"
+        "\\343\\202\\213\\343\\201\\213\\343\\200'"
+    )
+    assert _clean_mo_type(val) == (
+        "GNU message catalog (little endian), revision 0.0, 349 messages"
+    )
+
+
+def test_mo_file_type_leaves_unrelated_types_unchanged():
+    assert _clean_mo_type("ASCII text") == "ASCII text"
+    assert _clean_mo_type("ELF 64-bit LSB executable") == "ELF 64-bit LSB executable"