Encode a whole number of bytes per line.

Author: serhiy-storchaka

Lib/test/test_base64.py

@@ -214,9 +214,9 @@ def test_b64encode_wrapcol(self):
         b = b'www.python.org'
         eq(base64.b64encode(b, wrapcol=0), b'd3d3LnB5dGhvbi5vcmc=')
         eq(base64.b64encode(b, wrapcol=8), b'd3d3LnB5\ndGhvbi5v\ncmc=')
+        eq(base64.b64encode(b, wrapcol=11), b'd3d3LnB5\ndGhvbi5v\ncmc=')
         eq(base64.b64encode(b, wrapcol=76), b'd3d3LnB5dGhvbi5vcmc=')
-        eq(base64.b64encode(b, wrapcol=1),
-           b'd\n3\nd\n3\nL\nn\nB\n5\nd\nG\nh\nv\nb\ni\n5\nv\nc\nm\nc\n=')
+        eq(base64.b64encode(b, wrapcol=1), b'd3d3\nLnB5\ndGhv\nbi5v\ncmc=')
         eq(base64.b64encode(b, wrapcol=sys.maxsize), b'd3d3LnB5dGhvbi5vcmc=')
         if check_impl_detail():
             eq(base64.b64encode(b, wrapcol=sys.maxsize*2),

Lib/test/test_binascii.py

@@ -493,12 +493,14 @@ def test_b2a_base64_wrapcol(self):
                          b'd3d3LnB5dGhvbi5vcmc=\n')
         self.assertEqual(binascii.b2a_base64(b, wrapcol=8),
                          b'd3d3LnB5\ndGhvbi5v\ncmc=\n')
+        self.assertEqual(binascii.b2a_base64(b, wrapcol=11),
+                         b'd3d3LnB5\ndGhvbi5v\ncmc=\n')
         self.assertEqual(binascii.b2a_base64(b, wrapcol=76),
                          b'd3d3LnB5dGhvbi5vcmc=\n')
         self.assertEqual(binascii.b2a_base64(b, wrapcol=8, newline=False),
                          b'd3d3LnB5\ndGhvbi5v\ncmc=')
         self.assertEqual(binascii.b2a_base64(b, wrapcol=1),
-            b'd\n3\nd\n3\nL\nn\nB\n5\nd\nG\nh\nv\nb\ni\n5\nv\nc\nm\nc\n=\n')
+                         b'd3d3\nLnB5\ndGhv\nbi5v\ncmc=\n')
         self.assertEqual(binascii.b2a_base64(b, wrapcol=sys.maxsize),
                          b'd3d3LnB5dGhvbi5vcmc=\n')
         if check_impl_detail():

Modules/binascii.c

@@ -565,7 +565,6 @@ binascii_b2a_base64_impl(PyObject *module, Py_buffer *data, size_t wrapcol,
 
     const unsigned char *bin_data = data->buf;
     Py_ssize_t bin_len = data->len;
-
     assert(bin_len >= 0);
 
     /* Each group of 3 bytes (rounded up) gets encoded as 4 characters,
@@ -579,6 +578,8 @@ binascii_b2a_base64_impl(PyObject *module, Py_buffer *data, size_t wrapcol,
         goto toolong;
     }
     if (wrapcol && out_len) {
+        /* Each line should encode a whole number of bytes. */
+        wrapcol = wrapcol < 4 ? 4 : wrapcol / 4 * 4;
         out_len += (out_len - 1u) / wrapcol;
         if (out_len > PY_SSIZE_T_MAX) {
             goto toolong;