[PATCH v5] env-update: create systemd user-session environment definition

Portage's env-update currently transforms the environment information
from /etc/env.d into /etc/profile.env, which is typically sourced by
every user session, setting up its environment.

However, /etc/profile.env is not sourced by systemd user
services. Instead, for the definition of a systemd user session
environment, the 'environment.d' machinery exists. Unfortunately, up
to now, env-update does not produce a profile.env equivalent for this
machinery, causing issues for systemd user services. For example, an
emacs daemon run as user systemd service does not have a complete
PATH (bug #704412 [1]), because some PATH components are injected by
packages via /etc/env.d. For example, an LLVM ebuild may set
PATH="/usr/lib/llvm/9/bin".

This commit changes env-update so that a systemd user session
environment configuration file named

/etc/environment.d/10-gentoo-env.conf

is created.

Thanks to Michael 'veremitz' Everitt, Arfrever Frehtes Taifersar
Arahesis, Ulrich Müller, Joakim Tjernlund, and Zac Medico for the
useful feedback.

1: https://bugs.gentoo.org/704412

Closes: https://bugs.gentoo.org/704416
Signed-off-by: Florian Schmaus <[email protected]>
---

Notes:
    - Shorten created filename to 10-gentoo-env.conf
    - Minor fixes in the commit message
    - Use atomic_ofstream()
    - Use os.makedirs() (Thanks Zac)

 lib/portage/util/env_update.py | 42 +++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/lib/portage/util/env_update.py b/lib/portage/util/env_update.py
index f130b6f6b..ab3caee47 100644
--- a/lib/portage/util/env_update.py
+++ b/lib/portage/util/env_update.py
@@ -333,14 +333,16 @@ def _env_update(makelinks, target_root, prev_mtimes, contents, env,
 
 	del specials["LDPATH"]
 
-	penvnotice  = "# THIS FILE IS AUTOMATICALLY GENERATED BY env-update.\n"
-	penvnotice += "# DO NOT EDIT THIS FILE. CHANGES TO STARTUP PROFILES\n"
+	notice      = "# THIS FILE IS AUTOMATICALLY GENERATED BY env-update.\n"
+	notice     += "# DO NOT EDIT THIS FILE."
+	penvnotice  = notice + " CHANGES TO STARTUP PROFILES\n"
 	cenvnotice  = penvnotice[:]
 	penvnotice += "# GO INTO /etc/profile NOT /etc/profile.env\n\n"
 	cenvnotice += "# GO INTO /etc/csh.cshrc NOT /etc/csh.env\n\n"
 
 	#create /etc/profile.env for bash support
-	outfile = atomic_ofstream(os.path.join(eroot, "etc", "profile.env"))
+	profile_env_path = os.path.join(eroot, "etc", "profile.env")
+	outfile = atomic_ofstream(profile_env_path)
 	outfile.write(penvnotice)
 
 	env_keys = [x for x in env if x != "LDPATH"]
@@ -353,6 +355,40 @@ def _env_update(makelinks, target_root, prev_mtimes, contents, env,
 			outfile.write("export %s='%s'\n" % (k, v))
 	outfile.close()
 
+	# Create the systemd user environment configuration file
+	# /etc/environment.d/10-gentoo-env.conf with the
+	# environment configuration from /etc/env.d.
+	systemd_environment_dir = os.path.join(eroot, "etc", "environment.d")
+	os.makedirs(systemd_environment_dir, exist_ok=True)
+
+	systemd_gentoo_env_path = os.path.join(systemd_environment_dir,
+					     "10-gentoo-env.conf")
+	systemd_gentoo_env = atomic_ofstream(systemd_gentoo_env_path)
+	try:
+		senvnotice = notice + "\n\n"
+		systemd_gentoo_env.write(senvnotice)
+
+		for env_key in env_keys:
+			env_key_value = env[env_key]
+
+			# Skip variables with the empty string
+			# as value. Those sometimes appear in
+			# profile.env (e.g. "export GCC_SPECS=''"),
+			# but are invalid in systemd's syntax.
+			if not env_key_value:
+				continue
+
+			# Transform into systemd environment.d
+			# conf syntax, basically shell variable
+			# assignment (without "export ").
+			line = f"{env_key}={env_key_value}\n"
+
+			systemd_gentoo_env.write(line)
+	except:
+		systemd_gentoo_env.abort()
+		raise
+	systemd_gentoo_env.close()
+
 	#create /etc/csh.env for (t)csh support
 	outfile = atomic_ofstream(os.path.join(eroot, "etc", "csh.env"))
 	outfile.write(cenvnotice)
-- 
2.26.2