bpo-30103: Allow Uuencode in Python using backtick as zero instead of space (#1326)

10 files changed, 137 insertions, 67 deletions

diff --git a/Doc/library/binascii.rst b/Doc/library/binascii.rst
index 0476f50..4d3d0e0 100644
--- a/Doc/library/binascii.rst
+++ b/Doc/library/binascii.rst
@@ -40,11 +40,14 @@ The :mod:`binascii` module defines the following functions:
    data may be followed by whitespace.
 
 
-.. function:: b2a_uu(data)
+.. function:: b2a_uu(data, *, backtick=False)
 
    Convert binary data to a line of ASCII characters, the return value is the
    converted line, including a newline char. The length of *data* should be at most
-   45.
+   45. If *backtick* is true, zeros are represented by ``'`'`` instead of spaces.
+
+   .. versionchanged:: 3.7
+      Added the *backtick* parameter.
 
 
 .. function:: a2b_base64(string)
@@ -53,7 +56,7 @@ The :mod:`binascii` module defines the following functions:
    than one line may be passed at a time.
 
 
-.. function:: b2a_base64(data, \*, newline=True)
+.. function:: b2a_base64(data, *, newline=True)
 
    Convert binary data to a line of ASCII characters in base64 coding. The return
    value is the converted line, including a newline char if *newline* is
diff --git a/Doc/library/uu.rst b/Doc/library/uu.rst
index 33fb36d..0bc8021 100644
--- a/Doc/library/uu.rst
+++ b/Doc/library/uu.rst
@@ -28,12 +28,16 @@ This code was contributed by Lance Ellinghouse, and modified by Jack Jansen.
 The :mod:`uu` module defines the following functions:
 
 
-.. function:: encode(in_file, out_file, name=None, mode=None)
+.. function:: encode(in_file, out_file, name=None, mode=None, *, backtick=False)
 
    Uuencode file *in_file* into file *out_file*.  The uuencoded file will have
    the header specifying *name* and *mode* as the defaults for the results of
    decoding the file. The default defaults are taken from *in_file*, or ``'-'``
-   and ``0o666`` respectively.
+   and ``0o666`` respectively.  If *backtick* is true, zeros are represented by
+   ``'`'`` instead of spaces.
+
+   .. versionchanged:: 3.7
+      Added the *backtick* parameter.
 
 
 .. function:: decode(in_file, out_file=None, mode=None, quiet=False)
diff --git a/Doc/tools/susp-ignored.csv b/Doc/tools/susp-ignored.csv
index 01b1d98..ef11b68 100644
--- a/Doc/tools/susp-ignored.csv
+++ b/Doc/tools/susp-ignored.csv
@@ -328,3 +328,7 @@ whatsnew/3.5,,:exception,ERROR:root:exception
 whatsnew/changelog,,:version,import sys; I = version[:version.index(' ')]
 whatsnew/changelog,,`,"for readability (was ""`"")."
 whatsnew/changelog,,:end,str[start:end]
+library/binascii,,`,'`'
+library/uu,,`,'`'
+whatsnew/3.7,,`,'`'
+whatsnew/changelog,,`,'`'
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index cb0086c..7edf4fc 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -95,6 +95,13 @@ New Modules
 Improved Modules
 ================
 
+binascii
+--------
+
+The :func:`~binascii.b2a_uu` function now accepts an optional *backtick*
+keyword argument.  When it's true, zeros are represented by ``'`'``
+instead of spaces.  (Contributed by Xiang Zhang in :issue:`30103`.)
+
 contextlib
 ----------
 
@@ -159,6 +166,13 @@ urllib.parse
 adding `~` to the set of characters that is never quoted by default.
 (Contributed by Christian Theune and Ratnadeep Debnath in :issue:`16285`.)
 
+uu
+--
+
+Function :func:`~uu.encode` now accepts an optional *backtick*
+keyword argument.  When it's true, zeros are represented by ``'`'``
+instead of spaces.  (Contributed by Xiang Zhang in :issue:`30103`.)
+
 
 Optimizations
 =============
diff --git a/Lib/test/test_binascii.py b/Lib/test/test_binascii.py
index 6b3e437..8fa57cd 100644
--- a/Lib/test/test_binascii.py
+++ b/Lib/test/test_binascii.py
@@ -112,29 +112,41 @@ class BinASCIITest(unittest.TestCase):
 
     def test_uu(self):
         MAX_UU = 45
-        lines = []
-        for i in range(0, len(self.data), MAX_UU):
-            b = self.type2test(self.rawdata[i:i+MAX_UU])
-            a = binascii.b2a_uu(b)
-            lines.append(a)
-        res = bytes()
-        for line in lines:
-            a = self.type2test(line)
-            b = binascii.a2b_uu(a)
-            res += b
-        self.assertEqual(res, self.rawdata)
+        for backtick in (True, False):
+            lines = []
+            for i in range(0, len(self.data), MAX_UU):
+                b = self.type2test(self.rawdata[i:i+MAX_UU])
+                a = binascii.b2a_uu(b, backtick=backtick)
+                lines.append(a)
+            res = bytes()
+            for line in lines:
+                a = self.type2test(line)
+                b = binascii.a2b_uu(a)
+                res += b
+            self.assertEqual(res, self.rawdata)
 
         self.assertEqual(binascii.a2b_uu(b"\x7f"), b"\x00"*31)
         self.assertEqual(binascii.a2b_uu(b"\x80"), b"\x00"*32)
         self.assertEqual(binascii.a2b_uu(b"\xff"), b"\x00"*31)
         self.assertRaises(binascii.Error, binascii.a2b_uu, b"\xff\x00")
         self.assertRaises(binascii.Error, binascii.a2b_uu, b"!!!!")
-
         self.assertRaises(binascii.Error, binascii.b2a_uu, 46*b"!")
 
         # Issue #7701 (crash on a pydebug build)
         self.assertEqual(binascii.b2a_uu(b'x'), b'!>   \n')
 
+        self.assertEqual(binascii.b2a_uu(b''), b' \n')
+        self.assertEqual(binascii.b2a_uu(b'', backtick=True), b'`\n')
+        self.assertEqual(binascii.a2b_uu(b' \n'), b'')
+        self.assertEqual(binascii.a2b_uu(b'`\n'), b'')
+        self.assertEqual(binascii.b2a_uu(b'\x00Cat'), b'$ $-A=   \n')
+        self.assertEqual(binascii.b2a_uu(b'\x00Cat', backtick=True),
+                         b'$`$-A=```\n')
+        self.assertEqual(binascii.a2b_uu(b'$`$-A=```\n'),
+                         binascii.a2b_uu(b'$ $-A=   \n'))
+        with self.assertRaises(TypeError):
+            binascii.b2a_uu(b"", True)
+
     def test_crc_hqx(self):
         crc = binascii.crc_hqx(self.type2test(b"Test the CRC-32 of"), 0)
         crc = binascii.crc_hqx(self.type2test(b" this string."), crc)
diff --git a/Lib/test/test_uu.py b/Lib/test/test_uu.py
index ad2f2c5..11bd08c 100644
--- a/Lib/test/test_uu.py
+++ b/Lib/test/test_uu.py
@@ -10,11 +10,11 @@ import sys, os
 import uu
 import io
 
-plaintext = b"The smooth-scaled python crept over the sleeping dog\n"
+plaintext = b"The symbols on top of your keyboard are !@#$%^&*()_+|~\n"
 
 encodedtext = b"""\
-M5&AE('-M;V]T:\"US8V%L960@<'ET:&]N(&-R97!T(&]V97(@=&AE('-L965P
-(:6YG(&1O9PH """
+M5&AE('-Y;6)O;',@;VX@=&]P(&]F('EO=7(@:V5Y8F]A<F0@87)E("% (R0E
+*7B8J*"E?*WQ^"@  """
 
 # Stolen from io.py
 class FakeIO(io.TextIOWrapper):
@@ -44,9 +44,14 @@ class FakeIO(io.TextIOWrapper):
         return self.buffer.getvalue().decode(self._encoding, self._errors)
 
 
-def encodedtextwrapped(mode, filename):
-    return (bytes("begin %03o %s\n" % (mode, filename), "ascii") +
-            encodedtext + b"\n \nend\n")
+def encodedtextwrapped(mode, filename, backtick=False):
+    if backtick:
+        res = (bytes("begin %03o %s\n" % (mode, filename), "ascii") +
+               encodedtext.replace(b' ', b'`') + b"\n`\nend\n")
+    else:
+        res = (bytes("begin %03o %s\n" % (mode, filename), "ascii") +
+               encodedtext + b"\n \nend\n")
+    return res
 
 class UUTest(unittest.TestCase):
 
@@ -59,20 +64,27 @@ class UUTest(unittest.TestCase):
         out = io.BytesIO()
         uu.encode(inp, out, "t1", 0o644)
         self.assertEqual(out.getvalue(), encodedtextwrapped(0o644, "t1"))
+        inp = io.BytesIO(plaintext)
+        out = io.BytesIO()
+        uu.encode(inp, out, "t1", backtick=True)
+        self.assertEqual(out.getvalue(), encodedtextwrapped(0o666, "t1", True))
+        with self.assertRaises(TypeError):
+            uu.encode(inp, out, "t1", 0o644, True)
 
     def test_decode(self):
-        inp = io.BytesIO(encodedtextwrapped(0o666, "t1"))
-        out = io.BytesIO()
-        uu.decode(inp, out)
-        self.assertEqual(out.getvalue(), plaintext)
-        inp = io.BytesIO(
-            b"UUencoded files may contain many lines,\n" +
-            b"even some that have 'begin' in them.\n" +
-            encodedtextwrapped(0o666, "t1")
-        )
-        out = io.BytesIO()
-        uu.decode(inp, out)
-        self.assertEqual(out.getvalue(), plaintext)
+        for backtick in True, False:
+            inp = io.BytesIO(encodedtextwrapped(0o666, "t1", backtick=backtick))
+            out = io.BytesIO()
+            uu.decode(inp, out)
+            self.assertEqual(out.getvalue(), plaintext)
+            inp = io.BytesIO(
+                b"UUencoded files may contain many lines,\n" +
+                b"even some that have 'begin' in them.\n" +
+                encodedtextwrapped(0o666, "t1", backtick=backtick)
+            )
+            out = io.BytesIO()
+            uu.decode(inp, out)
+            self.assertEqual(out.getvalue(), plaintext)
 
     def test_truncatedinput(self):
         inp = io.BytesIO(b"begin 644 t1\n" + encodedtext)
@@ -94,25 +106,33 @@ class UUTest(unittest.TestCase):
 
     def test_garbage_padding(self):
         # Issue #22406
-        encodedtext = (
+        encodedtext1 = (
             b"begin 644 file\n"
             # length 1; bits 001100 111111 111111 111111
             b"\x21\x2C\x5F\x5F\x5F\n"
             b"\x20\n"
             b"end\n"
         )
+        encodedtext2 = (
+            b"begin 644 file\n"
+            # length 1; bits 001100 111111 111111 111111
+            b"\x21\x2C\x5F\x5F\x5F\n"
+            b"\x60\n"
+            b"end\n"
+        )
         plaintext = b"\x33"  # 00110011
 
-        with self.subTest("uu.decode()"):
-            inp = io.BytesIO(encodedtext)
-            out = io.BytesIO()
-            uu.decode(inp, out, quiet=True)
-            self.assertEqual(out.getvalue(), plaintext)
+        for encodedtext in encodedtext1, encodedtext2:
+            with self.subTest("uu.decode()"):
+                inp = io.BytesIO(encodedtext)
+                out = io.BytesIO()
+                uu.decode(inp, out, quiet=True)
+                self.assertEqual(out.getvalue(), plaintext)
 
-        with self.subTest("uu_codec"):
-            import codecs
-            decoded = codecs.decode(encodedtext, "uu_codec")
-            self.assertEqual(decoded, plaintext)
+            with self.subTest("uu_codec"):
+                import codecs
+                decoded = codecs.decode(encodedtext, "uu_codec")
+                self.assertEqual(decoded, plaintext)
 
 class UUStdIOTest(unittest.TestCase):
 
@@ -250,11 +270,6 @@ class UUFileTest(unittest.TestCase):
         finally:
             self._kill(f)
 
-def test_main():
-    support.run_unittest(UUTest,
-                              UUStdIOTest,
-                              UUFileTest,
-                              )
 
 if __name__=="__main__":
-    test_main()
+    unittest.main()
diff --git a/Lib/uu.py b/Lib/uu.py
index d68d293..8333e86 100755
--- a/Lib/uu.py
+++ b/Lib/uu.py
@@ -26,8 +26,8 @@
 
 """Implementation of the UUencode and UUdecode functions.
 
-encode(in_file, out_file [,name, mode])
-decode(in_file [, out_file, mode])
+encode(in_file, out_file [,name, mode], *, backtick=False)
+decode(in_file [, out_file, mode, quiet])
 """
 
 import binascii
@@ -39,7 +39,7 @@ __all__ = ["Error", "encode", "decode"]
 class Error(Exception):
     pass
 
-def encode(in_file, out_file, name=None, mode=None):
+def encode(in_file, out_file, name=None, mode=None, *, backtick=False):
     """Uuencode file"""
     #
     # If in_file is a pathname open it and change defaults
@@ -79,9 +79,12 @@ def encode(in_file, out_file, name=None, mode=None):
         out_file.write(('begin %o %s\n' % ((mode & 0o777), name)).encode("ascii"))
         data = in_file.read(45)
         while len(data) > 0:
-            out_file.write(binascii.b2a_uu(data))
+            out_file.write(binascii.b2a_uu(data, backtick=backtick))
             data = in_file.read(45)
-        out_file.write(b' \nend\n')
+        if backtick:
+            out_file.write(b'`\nend\n')
+        else:
+            out_file.write(b' \nend\n')
     finally:
         for f in opened_files:
             f.close()
diff --git a/Misc/NEWS b/Misc/NEWS
index c041d61..d458f11 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -317,6 +317,9 @@ Extension Modules
 Library
 -------
 
+- bpo-30103: binascii.b2a_uu() and uu.encode() now support using ``'`'``
+  as zero instead of space.
+
 - bpo-28556: Various updates to typing module: add typing.NoReturn type, use
   WrapperDescriptorType, minor bug-fixes.  Original PRs by
   Jim Fasarakis-Hilliard and Ivan Levkivskyi.
diff --git a/Modules/binascii.c b/Modules/binascii.c
index fbd2320..1f9ff5a 100644
--- a/Modules/binascii.c
+++ b/Modules/binascii.c
@@ -335,13 +335,15 @@ binascii.b2a_uu
 
     data: Py_buffer
     /
+    *
+    backtick: bool(accept={int}) = False
 
 Uuencode line of data.
 [clinic start generated code]*/
 
 static PyObject *
-binascii_b2a_uu_impl(PyObject *module, Py_buffer *data)
-/*[clinic end generated code: output=0070670e52e4aa6b input=00fdf458ce8b465b]*/
+binascii_b2a_uu_impl(PyObject *module, Py_buffer *data, int backtick)
+/*[clinic end generated code: output=b1b99de62d9bbeb8 input=b26bc8d32b6ed2f6]*/
 {
     unsigned char *ascii_data;
     const unsigned char *bin_data;
@@ -367,7 +369,10 @@ binascii_b2a_uu_impl(PyObject *module, Py_buffer *data)
         return NULL;
 
     /* Store the length */
-    *ascii_data++ = ' ' + (bin_len & 077);
+    if (backtick && !bin_len)
+        *ascii_data++ = '`';
+    else
+        *ascii_data++ = ' ' + bin_len;
 
     for( ; bin_len > 0 || leftbits != 0 ; bin_len--, bin_data++ ) {
         /* Shift the data (or padding) into our buffer */
@@ -381,7 +386,10 @@ binascii_b2a_uu_impl(PyObject *module, Py_buffer *data)
         while ( leftbits >= 6 ) {
             this_ch = (leftchar >> (leftbits-6)) & 0x3f;
             leftbits -= 6;
-            *ascii_data++ = this_ch + ' ';
+            if (backtick && !this_ch)
+                *ascii_data++ = '`';
+            else
+                *ascii_data++ = this_ch + ' ';
         }
     }
     *ascii_data++ = '\n';       /* Append a courtesy newline */
diff --git a/Modules/clinic/binascii.c.h b/Modules/clinic/binascii.c.h
index ca5d4c5..130e249 100644
--- a/Modules/clinic/binascii.c.h
+++ b/Modules/clinic/binascii.c.h
@@ -34,27 +34,31 @@ exit:
 }
 
 PyDoc_STRVAR(binascii_b2a_uu__doc__,
-"b2a_uu($module, data, /)\n"
+"b2a_uu($module, data, /, *, backtick=False)\n"
 "--\n"
 "\n"
 "Uuencode line of data.");
 
 #define BINASCII_B2A_UU_METHODDEF    \
-    {"b2a_uu", (PyCFunction)binascii_b2a_uu, METH_O, binascii_b2a_uu__doc__},
+    {"b2a_uu", (PyCFunction)binascii_b2a_uu, METH_FASTCALL, binascii_b2a_uu__doc__},
 
 static PyObject *
-binascii_b2a_uu_impl(PyObject *module, Py_buffer *data);
+binascii_b2a_uu_impl(PyObject *module, Py_buffer *data, int backtick);
 
 static PyObject *
-binascii_b2a_uu(PyObject *module, PyObject *arg)
+binascii_b2a_uu(PyObject *module, PyObject **args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"", "backtick", NULL};
+    static _PyArg_Parser _parser = {"y*|$i:b2a_uu", _keywords, 0};
     Py_buffer data = {NULL, NULL};
+    int backtick = 0;
 
-    if (!PyArg_Parse(arg, "y*:b2a_uu", &data)) {
+    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
+        &data, &backtick)) {
         goto exit;
     }
-    return_value = binascii_b2a_uu_impl(module, &data);
+    return_value = binascii_b2a_uu_impl(module, &data, backtick);
 
 exit:
     /* Cleanup for data */
@@ -558,4 +562,4 @@ exit:
 
     return return_value;
 }
-/*[clinic end generated code: output=35821bce7e0e4714 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=9db57e86dbe7b2fa input=a9049054013a1b77]*/