Add Ascii85, base85, and Z85 support to binascii

Add Ascii85, base85, and Z85 encoders and decoders to `binascii`,
replacing the existing pure Python implementations in `base64`.

No API or documentation changes are necessary with respect to
`base64.a85encode()`, `b85encode()`, etc., and all existing unit
tests for those functions continue to pass without modification.

Note that attempting to decode Ascii85 or base85 data of length 1 mod 5
(after accounting for Ascii85 quirks) now produces an error, as no
encoder would emit such data. This should be the only significant
externally visible difference compared to the old implementation.

Resolves: gh-101178

Author: kangtastic

Doc/library/binascii.rst

@@ -77,6 +77,79 @@ The :mod:`binascii` module defines the following functions:
       Added the *newline* parameter.
 
 
+.. function:: a2b_ascii85(string, /, *, fold_spaces=False, wrap=False, ignore=b"")
+
+   Convert Ascii85 data back to binary and return the binary data.
+
+   Valid Ascii85 data contains characters from the Ascii85 alphabet in groups
+   of five (except for the final group, which may have from two to five
+   characters). Each group encodes 32 bits of binary data in the range from
+   ``0`` to ``2 ** 32 - 1``, inclusive. The special character ``z`` is
+   accepted as a short form of the group ``!!!!!``, which encodes four
+   consecutive null bytes.
+
+   If *fold_spaces* is true, the special character ``y`` is also accepted as a
+   short form of the group ``+<VdL``, which encodes four consecutive spaces.
+   Note that neither short form is permitted if it occurs in the middle of
+   another group.
+
+   If *wrap* is true, the input begins with ``<~`` and ends with ``~>``, as in
+   the Adobe Ascii85 format.
+
+   *ignore* is an optional bytes-like object that specifies characters to
+   ignore in the input.
+
+   Invalid Ascii85 data will raise :exc:`binascii.Error`.
+
+
+.. function:: b2a_ascii85(data, /, *, fold_spaces=False, wrap=False, width=0, pad=False)
+
+   Convert binary data to a formatted sequence of ASCII characters in Ascii85
+   coding. The return value is the converted data.
+
+   If *fold_spaces* is true, four consecutive spaces are encoded as the
+   special character ``y`` instead of the sequence ``+<VdL``.
+
+   If *wrap* is true, the output begins with ``<~`` and ends with ``~>``, as
+   in the Adobe Ascii85 format.
+
+   If *width* is provided and greater than 0, the output is split into lines
+   of no more than the specified width separated by the ASCII newline
+   character.
+
+   If *pad* is true, the input is padded to a multiple of 4 before encoding.
+
+
+.. function:: a2b_base85(string, /, *, strict_mode=False, z85=False)
+
+   Convert base85 data back to binary and return the binary data.
+   More than one line may be passed at a time.
+
+   If *strict_mode* is true, only valid base85 data will be converted.
+   Invalid base85 data will raise :exc:`binascii.Error`.
+
+   If *z85* is true, the base85 data uses the Z85 alphabet.
+   See `Z85 specification <https://rfc.zeromq.org/spec/32/>`_ for more information.
+
+   Valid base85 data contains characters from the base85 alphabet in groups
+   of five (except for the final group, which may have from two to five
+   characters). Each group encodes 32 bits of binary data in the range from
+   ``0`` to ``2 ** 32 - 1``, inclusive.
+
+
+.. function:: b2a_base85(data, /, *, pad=False, newline=True, z85=False)
+
+   Convert binary data to a line of ASCII characters in base85 coding.
+   The return value is the converted line.
+
+   If *pad* is true, the input is padded to a multiple of 4 before encoding.
+
+   If *newline* is true, a newline char is appended to the result.
+
+   If *z85* is true, the Z85 alphabet is used for conversion.
+   See `Z85 specification <https://rfc.zeromq.org/spec/32/>`_ for more information.
+
+
 .. function:: a2b_qp(data, header=False)
 
    Convert a block of quoted-printable data back to binary and return the binary

Include/internal/pycore_global_objects_fini_generated.h

@@ -454,6 +454,7 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(flags)
         STRUCT_FOR_ID(flush)
         STRUCT_FOR_ID(fold)
+        STRUCT_FOR_ID(fold_spaces)
         STRUCT_FOR_ID(follow_symlinks)
         STRUCT_FOR_ID(format)
         STRUCT_FOR_ID(format_spec)
@@ -636,6 +637,7 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(outpath)
         STRUCT_FOR_ID(overlapped)
         STRUCT_FOR_ID(owner)
+        STRUCT_FOR_ID(pad)
         STRUCT_FOR_ID(pages)
         STRUCT_FOR_ID(parent)
         STRUCT_FOR_ID(password)
@@ -792,11 +794,14 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(weekday)
         STRUCT_FOR_ID(which)
         STRUCT_FOR_ID(who)
+        STRUCT_FOR_ID(width)
         STRUCT_FOR_ID(withdata)
+        STRUCT_FOR_ID(wrap)
         STRUCT_FOR_ID(writable)
         STRUCT_FOR_ID(write)
         STRUCT_FOR_ID(write_through)
         STRUCT_FOR_ID(year)
+        STRUCT_FOR_ID(z85)
         STRUCT_FOR_ID(zdict)
     } identifiers;
     struct {