Change /usr/portage council approved locations (bug 378603)

This includes a _compat_upgrade.default_locations script that the
ebuild can call in pkg_preinst in order to maintain backward-compatible
defaults when appropriate. The new defaults are specified in the
summary of the 20180729 council meeting:

Vote: Default locations for the Gentoo repository, distfiles, and
binary packages will be, respectively:
   /var/db/repos/gentoo
   /var/cache/distfiles
   /var/cache/binpkgs
Accepted with 6 yes votes and 1 no vote.

See: https://projects.gentoo.org/council/meeting-logs/20180729-summary.txt
Bug: https://bugs.gentoo.org/378603
Signed-off-by: Zac Medico <zmedico@gentoo.org>

2 files changed, 82 insertions, 0 deletions

diff --git a/lib/portage/_compat_upgrade/__init__.py b/lib/portage/_compat_upgrade/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/lib/portage/_compat_upgrade/__init__.py
diff --git a/lib/portage/_compat_upgrade/default_locations.py b/lib/portage/_compat_upgrade/default_locations.py
new file mode 100644
index 000000000..91f300637
--- /dev/null
+++ b/lib/portage/_compat_upgrade/default_locations.py
@@ -0,0 +1,82 @@
+# Copyright 2018-2019 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_DISTDIR = 'usr/portage/distfiles'
+COMPAT_PKGDIR = 'usr/portage/packages'
+COMPAT_MAIN_REPO = 'usr/portage'
+
+
+def main():
+	"""
+	If the current installation is still configured to use any of the
+	legacy default /usr/portage locations, then patch make.globals and
+	repos.conf inside ${ED} to maintain compatible defaults. This is
+	intended to be called from the ebuild as follows:
+
+	pkg_preinst() {
+		python_setup
+		python_export PYTHON_SITEDIR
+		env -u DISTDIR \
+			-u PORTAGE_OVERRIDE_EPREFIX \
+			-u PORTAGE_REPOSITORIES \
+			-u PORTDIR \
+			-u PORTDIR_OVERLAY \
+			PYTHONPATH="${ED%/}${PYTHON_SITEDIR}${PYTHONPATH:+:${PYTHONPATH}}" \
+			"${PYTHON}" -m portage._compat_upgrade.default_locations || die
+	}
+	"""
+	out = portage.output.EOutput()
+	config = portage.settings
+
+	compat_distdir = os.path.join(portage.const.EPREFIX or '/', COMPAT_DISTDIR)
+	try:
+		do_distdir = os.path.samefile(config['DISTDIR'], compat_distdir)
+	except OSError:
+		do_distdir = False
+
+	compat_pkgdir = os.path.join(portage.const.EPREFIX or '/', COMPAT_PKGDIR)
+	try:
+		do_pkgdir = os.path.samefile(config['PKGDIR'], compat_pkgdir)
+	except OSError:
+		do_pkgdir = False
+
+	compat_main_repo = os.path.join(portage.const.EPREFIX or '/', COMPAT_MAIN_REPO)
+	try:
+		do_main_repo = os.path.samefile(config.repositories.mainRepoLocation(), compat_main_repo)
+	except OSError:
+		do_main_repo = False
+
+	if do_distdir or do_pkgdir:
+		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()
+			if do_distdir:
+				compat_setting = 'DISTDIR="{}"'.format(compat_distdir)
+				out.einfo('Setting make.globals default {} for backward compatibility'.format(compat_setting))
+				content = re.sub('^DISTDIR=.*$', compat_setting, content, flags=re.MULTILINE)
+			if do_pkgdir:
+				compat_setting = 'PKGDIR="{}"'.format(compat_pkgdir)
+				out.einfo('Setting make.globals default {} for backward compatibility'.format(compat_setting))
+				content = re.sub('^PKGDIR=.*$', compat_setting, content, flags=re.MULTILINE)
+		with open(config_path, 'wt') as f:
+			f.write(content)
+
+	if do_main_repo:
+		config_path = os.path.join(os.environ['ED'], GLOBAL_CONFIG_PATH.lstrip(os.sep), 'repos.conf')
+		with open(config_path) as f:
+			content = f.read()
+			compat_setting = 'location = {}'.format(compat_main_repo)
+			out.einfo('Setting repos.conf default {} for backward compatibility'.format(compat_setting))
+			content = re.sub('^location =.*$', compat_setting, content, flags=re.MULTILINE)
+		with open(config_path, 'wt') as f:
+			f.write(content)
+
+
+if __name__ == '__main__':
+	main()