BUG: encoding_errors=None with read_csv c-engine (#45180)

Author: twoertwein

doc/source/whatsnew/v1.4.0.rst

@@ -881,6 +881,7 @@ I/O
 - Bug in :func:`read_csv` silently ignoring errors when failing to create a memory-mapped file (:issue:`44766`)
 - Bug in :func:`read_csv` when passing a ``tempfile.SpooledTemporaryFile`` opened in binary mode (:issue:`44748`)
 - Bug in :func:`read_json` raising ``ValueError`` when attempting to parse json strings containing "://" (:issue:`36271`)
+- Bug in :func:`read_csv` when ``engine="c"`` and ``encoding_errors=None`` which caused a segfault (:issue:`45180`)
 -
 
 Period

pandas/_libs/parsers.pyx

@@ -375,6 +375,8 @@ cdef class TextReader:
         # set encoding for native Python and C library
         if isinstance(encoding_errors, str):
             encoding_errors = encoding_errors.encode("utf-8")
+        elif encoding_errors is None:
+            encoding_errors = b"strict"
         Py_INCREF(encoding_errors)
         self.encoding_errors = PyBytes_AsString(encoding_errors)
 

pandas/tests/io/test_common.py

@@ -555,9 +555,8 @@ def test_encoding_errors(encoding_errors, format):
     bad_encoding = b"\xe4"
 
     if format == "csv":
-        return
-        content = bad_encoding + b"\n" + bad_encoding
-        reader = pd.read_csv
+        content = b"," + bad_encoding + b"\n" + bad_encoding * 2 + b"," + bad_encoding
+        reader = partial(pd.read_csv, index_col=0)
     else:
         content = (
             b'{"'