ROB: Capture UnicodeDecodeError at PdfReader.pdf_header

pypdf/_reader.py

@@ -360,7 +360,10 @@ def pdf_header(self) -> str:
         #       but that needs a deprecation
         loc = self.stream.tell()
         self.stream.seek(0, 0)
-        pdf_file_version = self.stream.read(8).decode("utf-8")
+        try:
+            pdf_file_version = self.stream.read(8).decode("utf-8")
+        except UnicodeDecodeError:
+            return "unknown"
         self.stream.seek(loc, 0)  # return to where it was
         return pdf_file_version
 

tests/test_reader.py

@@ -1352,3 +1352,38 @@ def test_iss1710():
     name = "irbookonlinereading.pdf"
     in_pdf = PdfReader(BytesIO(get_pdf_from_url(url, name=name)))
     in_pdf.outline
+
+
+def test_broken_file_header():
+    pdf_data = (
+        b"%%PDF-\xa0sd\n"
+        b"1 0 obj << /Count 1 /Kids [4 0 R] /Type /Pages >> endobj\n"
+        b"2 0 obj << >> endobj\n"
+        b"3 0 obj << >> endobj\n"
+        b"4 0 obj << /Contents 3 0 R /CropBox [0.0 0.0 2550.0 3508.0]"
+        b" /MediaBox [0.0 0.0 2550.0 3508.0] /Parent 1 0 R"
+        b" /Resources << /Font << >> >>"
+        b" /Rotate 0 /Type /Page >> endobj\n"
+        b"5 0 obj << /Pages 1 0 R /Type /Catalog >> endobj\n"
+        b"xref 1 5\n"
+        b"%010d 00000 n\n"
+        b"%010d 00000 n\n"
+        b"%010d 00000 n\n"
+        b"%010d 00000 n\n"
+        b"%010d 00000 n\n"
+        b"trailer << %s/Root 5 0 R /Size 6 >>\n"
+        b"startxref %d\n"
+        b"%%%%EOF"
+    )
+    with_prev_0 = True
+    pdf_data = pdf_data % (
+        pdf_data.find(b"1 0 obj"),
+        pdf_data.find(b"2 0 obj"),
+        pdf_data.find(b"3 0 obj"),
+        pdf_data.find(b"4 0 obj"),
+        pdf_data.find(b"5 0 obj"),
+        b"/Prev 0 " if with_prev_0 else b"",
+        pdf_data.find(b"xref") - 1,
+    )
+    reader = PdfReader(io.BytesIO(pdf_data))
+    assert reader.pdf_header == "unknown"