macos: build and link against libedit

libreadline is GPL v3. Python supports linking against libedit, which has
a more permissive license. So, this commit teaches the build system to
build libedit and to link the readline extension against it.

Doing this with our custom-built ncurses resulted in a failure to find
the terminfo database. The workaround is to build/link against the
system ncurses. I'm not sure if this is ideal, as it leaves a dependency
on libraries in /usr/lib. But it is the easiest way to make the "readline"
module work. I'll have to research how all this stuff works and see if
we can ship ncurses safely on macOS.

Author: indygreg

Diff for: README.rst

@@ -134,9 +134,31 @@ the output of this project into derived works.**
 Dependency Notes
 ================
 
+DBM
+---
+
 Python has the option of building its ``_dbm`` extension against
 NDBM, GDBM, and Berkeley DB. Both NDBM and GDBM are GNU GPL Version 3.
 Modern versions of Berkeley DB are GNU AGPL v3. Versions 6.0.19 and
 older are licensed under the Sleepycat License. The Sleepycat License
 is more permissive. So we build the ``_dbm`` extension against BDB
 6.0.19.
+
+readline / libedit / ncurses
+----------------------------
+
+Python has the option of building its ``readline`` extension against
+either ``libreadline`` or ``libedit``. ``libreadline`` is licensed GNU
+GPL Version 3 and ``libedit`` has a more permissive license. We choose
+to link against ``libedit`` because of the more permissive license.
+
+``libedit``/``libreadline`` link against a curses library, most likely
+``ncurses``. And ``ncurses`` has tie-ins with a terminal database. This
+is a thorny situation, as terminal databases can be difficult to
+distribute because end-users often want software to respect their
+terminal databases. But for that to work, ``ncurses`` needs to be compiled
+in a way that respects the user's environment.
+
+On macOS, we statically link a ``libedit`` we compile ourselves. We
+dynamically link against ``libncurses``, which is provided by the
+system, typically in ``/usr/lib``.

Diff for: cpython-macos/Makefile

@@ -15,6 +15,9 @@ $(OUTDIR)/bdb-macos.tar: $(HERE)/build-bdb.sh
 $(OUTDIR)/bzip2-macos.tar: $(HERE)/build-bzip2.sh
 	$(BUILD) bzip2
 
+$(OUTDIR)/libedit-macos.tar: $(HERE)/build-libedit.sh
+	$(BUILD) libedit
+
 $(OUTDIR)/libffi-macos.tar: $(HERE)/build-libffi.sh
 	$(BUILD) libffi
 
@@ -41,6 +44,7 @@ PYTHON_DEPENDS := \
 	$(HERE)/build-cpython.sh \
 	$(OUTDIR)/bdb-macos.tar \
     $(OUTDIR)/bzip2-macos.tar \
+    $(OUTDIR)/libedit-macos.tar \
     $(OUTDIR)/libffi-macos.tar \
     $(OUTDIR)/ncurses-macos.tar \
     $(OUTDIR)/openssl-macos.tar \

Diff for: cpython-macos/build-libedit.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+set -ex
+
+ROOT=`pwd`
+
+export CC=clang
+export CXX=clang++
+
+tar -xf libedit-${LIBEDIT_VERSION}.tar.gz
+pushd libedit-${LIBEDIT_VERSION}
+
+./configure --prefix /
+
+make -j ${NUM_CPUS}
+make -j ${NUM_CPUIS} install DESTDIR=${ROOT}/out

Diff for: cpython-macos/build.py

@@ -37,8 +37,6 @@
     b'nis',
     # Not available on macOS.
     b'ossaudiodev',
-    # Not yet supported.
-    b'readline',
     # Not available on macOS.
     b'spwd',
 }
@@ -124,8 +122,10 @@ def build_cpython():
 
         extract_tar_to_directory(BUILD / 'bdb-macos.tar', deps_dir)
         extract_tar_to_directory(BUILD / 'bzip2-macos.tar', deps_dir)
+        extract_tar_to_directory(BUILD / 'libedit-macos.tar', deps_dir)
         extract_tar_to_directory(BUILD / 'libffi-macos.tar', deps_dir)
-        extract_tar_to_directory(BUILD / 'ncurses-macos.tar', deps_dir)
+        # We use the system ncurses and statically link (for now).
+        #extract_tar_to_directory(BUILD / 'ncurses-macos.tar', deps_dir)
         extract_tar_to_directory(BUILD / 'openssl-macos.tar', deps_dir)
         extract_tar_to_directory(BUILD / 'sqlite-macos.tar', deps_dir)
         extract_tar_to_directory(BUILD / 'uuid-macos.tar', deps_dir)
@@ -180,7 +180,7 @@ def main():
     with log_path.open('wb') as log_fh:
         LOG_FH[0] = log_fh
 
-        if action in ('bdb', 'bzip2', 'libffi', 'openssl', 'ncurses', 'sqlite', 'uuid', 'xz', 'zlib'):
+        if action in ('bdb', 'bzip2', 'libedit', 'libffi', 'openssl', 'ncurses', 'sqlite', 'uuid', 'xz', 'zlib'):
             simple_build(action)
 
         elif action == 'cpython':

Diff for: cpython-macos/static-modules

@@ -30,5 +30,5 @@ _testmultiphase _testmultiphase.c
 _uuid _uuidmodule.c -luuid
 _xxtestfuzz _xxtestfuzz/_xxtestfuzz.c _xxtestfuzz/fuzzer.c
 pyexpat pyexpat.c expat/xmlparse.c expat/xmlrole.c expat/xmltok.c -DHAVE_EXPAT_CONFIG_H=1 -DXML_POOR_ENTROPY=1 -DUSE_PYEXPAT_CAPI -IModules/expat
-#readline readline.c -I/tools/deps/include -I/tools/deps/include/ncurses -L/tools/deps/lib -lreadline -lncurses
+readline readline.c -ledit -lncurses
 xxlimited xxlimited.c -DPy_LIMITED_API=0x03050000

Diff for: python-licenses.rst

@@ -1112,6 +1112,39 @@ the library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.  But first, please read
 <http://www.gnu.org/philosophy/why-not-lgpl.html>.
 
+libedit
+=======
+
+Copyright (c) 1992, 1993
+ The Regents of the University of California.  All rights reserved.
+
+This code is derived from software contributed to Berkeley by
+Christos Zoulas of Cornell University.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. Neither the name of the University nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
+
 libffi
 ======
 

Diff for: pythonbuild/downloads.py

@@ -82,6 +82,12 @@
         'sha256': '9b45c759ff397512eae4d938ff82827b1bd7ccba49920777e5b5e460baeb245f',
         'version': '7.0.0',
     },
+    'libedit': {
+        'url': 'https://www.thrysoee.dk/editline/libedit-20181209-3.1.tar.gz',
+        'size': 521931,
+        'sha256': '2811d70c0b000f2ca91b7cb1a37203134441743c4fcc9c37b0b687f328611064',
+        'version': '20181209-3.1',
+    },
     'libffi': {
         'url': 'ftp://sourceware.org/pub/libffi/libffi-3.2.1.tar.gz',
         'size': 940837,