Default BINPKG_COMPRESSION to zstd (bug 715108)

This includes a _compat_upgrade.binpkg_compression script that the
ebuild can call in pkg_preinst in order to maintain a backward-compatible
bzip2 default when appropriate, ensuring that binary package consumers
are not caught off guard.

Bug: https://bugs.gentoo.org/715108
Reviewed-by: Brian Dolbec <dolsen@gentoo.org>
Signed-off-by: Zac Medico <zmedico@gentoo.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/lib/portage/_compat_upgrade/binpkg_compression.py b/lib/portage/_compat_upgrade/binpkg_compression.py
new file mode 100644
index 000000000..0f5704733
--- /dev/null
+++ b/lib/portage/_compat_upgrade/binpkg_compression.py
@@ -0,0 +1,40 @@
+# Copyright 2020 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+import re
+
+import portage
+from portage import os
+from portage.const import GLOBAL_CONFIG_PATH
+
+COMPAT_BINPKG_COMPRESS = 'bzip2'
+
+
+def main():
+	"""
+	If the current installation is still configured to use the old
+	default BINPKG_COMPRESS=bzip2 setting, then patch make.globals
+	inside ${ED} to maintain backward compatibility, ensuring that
+	binary package consumers are not caught off guard. This is
+	intended to be called from the ebuild as follows:
+
+	pkg_preinst() {
+		python_setup
+		env -u BINPKG_COMPRESS
+			PYTHONPATH="${D%/}$(python_get_sitedir)${PYTHONPATH:+:${PYTHONPATH}}" \
+			"${PYTHON}" -m portage._compat_upgrade.binpkg_compression || die
+	}
+	"""
+	if portage.settings.get('BINPKG_COMPRESS', COMPAT_BINPKG_COMPRESS) == COMPAT_BINPKG_COMPRESS:
+		config_path = os.path.join(os.environ['ED'], GLOBAL_CONFIG_PATH.lstrip(os.sep), 'make.globals')
+		with open(config_path) as f:
+			content = f.read()
+			compat_setting = 'BINPKG_COMPRESS="{}"'.format(COMPAT_BINPKG_COMPRESS)
+			portage.output.EOutput().einfo('Setting make.globals default {} for backward compatibility'.format(compat_setting))
+			content = re.sub('^BINPKG_COMPRESS=.*$', compat_setting, content, flags=re.MULTILINE)
+		with open(config_path, 'wt') as f:
+			f.write(content)
+
+
+if __name__ == '__main__':
+	main()