factor out function to dump crl

OpenSSL/crypto.py

@@ -1998,23 +1998,7 @@ def export(self, cert, key, type=FILETYPE_PEM, days=100,
         if not sign_result:
             _raise_current_error()
 
-        if type == FILETYPE_PEM:
-            ret = _lib.PEM_write_bio_X509_CRL(bio, self._crl)
-        elif type == FILETYPE_ASN1:
-            ret = _lib.i2d_X509_CRL_bio(bio, self._crl)
-        elif type == FILETYPE_TEXT:
-            ret = _lib.X509_CRL_print(bio, self._crl)
-        else:
-            raise ValueError(
-                "type argument must be FILETYPE_PEM, FILETYPE_ASN1, or "
-                "FILETYPE_TEXT"
-            )
-
-        if not ret:
-            # TODO: This is untested.
-            _raise_current_error()
-
-        return _bio_to_string(bio)
+        return dump_crl(type, self)
 CRLType = CRL
 
 
@@ -2576,6 +2560,30 @@ def verify(cert, signature, data, digest):
     if verify_result != 1:
         _raise_current_error()
 
+def dump_crl(type, crl):
+    """
+    Dump a certificate revocation list to a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1, or
+        FILETYPE_TEXT)
+    :param crl: The certificate revocation list to dump
+    :return: The buffer with the dumped certificate revocation list
+    """
+    bio = _new_mem_buf()
+
+    if type == FILETYPE_PEM:
+        ret = _lib.PEM_write_bio_X509_CRL(bio, crl._crl)
+    elif type == FILETYPE_ASN1:
+        ret = _lib.i2d_X509_CRL_bio(bio, crl._crl)
+    elif type == FILETYPE_TEXT:
+        ret = _lib.X509_CRL_print(bio, crl._crl)
+    else:
+        raise ValueError(
+            "type argument must be FILETYPE_PEM, FILETYPE_ASN1, or "
+            "FILETYPE_TEXT")
+
+    assert ret == 1
+    return _bio_to_string(bio)
 
 def load_crl(type, buffer):
     """

OpenSSL/test/test_crypto.py

@@ -31,7 +31,7 @@
 from OpenSSL.crypto import dump_certificate_request, dump_privatekey
 from OpenSSL.crypto import PKCS7Type, load_pkcs7_data
 from OpenSSL.crypto import PKCS12, PKCS12Type, load_pkcs12
-from OpenSSL.crypto import CRL, Revoked, load_crl
+from OpenSSL.crypto import CRL, Revoked, dump_crl, load_crl
 from OpenSSL.crypto import NetscapeSPKI, NetscapeSPKIType
 from OpenSSL.crypto import (
     sign, verify, get_elliptic_curve, get_elliptic_curves)
@@ -3205,6 +3205,14 @@ def test_load_crl_bad_data(self):
         """
         self.assertRaises(Error, load_crl, FILETYPE_PEM, b"hello, world")
 
+    def test_dump_crl(self):
+        """
+        Dump a known CRL and ensure it is output correctly.
+        """
+        crl = load_crl(FILETYPE_PEM, crlData)
+        buf = dump_crl(FILETYPE_PEM, crl)
+        self.assertEqual(crlData, buf)
+
 
 class X509StoreContextTests(TestCase):
     """