libmakepkg: reproducibilty for python packages

Arch Linux has been setting PYTHONHASHSEED=0 to create deterministic
.pyc files.  After a thorough review by the Arch Security Team, setting
this variable was determined not to generated vulnerable .pyc files, as
when the loader loads the .pyc file and unmarshalls it, the internal
runtime will just populate the unordered data structures and use a new
runtime hash for them.
Signed-off-by: Allan McRae <allan@archlinux.org>

scripts/libmakepkg/meson.build

@@ -5,6 +5,7 @@ libmakepkg_modules = [
   { 'name' : 'lint_config',   'has_subdir' : true },
   { 'name' : 'lint_package',  'has_subdir' : true },
   { 'name' : 'lint_pkgbuild', 'has_subdir' : true },
+  { 'name' : 'reproducible',  'has_subdir' : true },
   { 'name' : 'source',        'has_subdir' : true },
   { 'name' : 'srcinfo',                           },
   { 'name' : 'tidy',          'has_subdir' : true },

scripts/libmakepkg/reproducible.sh.in

+#!/bin/bash
+#
+#   reproducible.sh - utilities for improving package reproducibility
+#
+#   Copyright (c) 2021 Pacman Development Team <pacman-dev@archlinux.org>
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; either version 2 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+[[ -n "$LIBMAKEPKG_REPRODUCIBLE_SH" ]] && return
+LIBMAKEPKG_REPRODUCIBLE_SH=1
+
+LIBRARY=${LIBRARY:-'@libmakepkgdir@'}
+
+
+for lib in "$LIBRARY/reproducible/"*.sh; do
+	source "$lib"
+done

scripts/libmakepkg/reproducible/meson.build

+libmakepkg_module = 'reproducible'
+
+sources = [
+  'python.sh.in',
+]
+
+foreach src : sources
+  output_dir = join_paths(get_option('datadir'), 'makepkg', libmakepkg_module)
+
+  custom_target(
+    libmakepkg_module + '_' + src.underscorify(),
+    command : [ SCRIPT_EDITOR, '@INPUT@', '@OUTPUT@' ],
+    input : src,
+    output : '@BASENAME@',
+    install : true,
+    install_dir : output_dir)
+endforeach

scripts/libmakepkg/reproducible/python.sh.in

+#!/bin/bash
+#
+#   python.sh - creating reproducible python packages
+#
+#   Copyright (c) 2021 Pacman Development Team <pacman-dev@archlinux.org>
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; either version 2 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+[[ -n "$LIBMAKEPKG_REPRODUCIBLE_PYTHON_SH" ]] && return
+LIBMAKEPKG_REPRODUCIBLE_PYTHON_SH=1
+
+
+LIBRARY=${LIBRARY:-'@libmakepkgdir@'}
+
+
+# disable hash randomization when creating .pyc files
+export PYTHONHASHSEED=0