From 46a9ee5d9b913716205505f84d60d544b76878e7 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 26 May 2021 17:17:11 +0200
Subject: [PATCH] core: support specifier expansion in DefaultEnvironment= and
 ManagerEnvironment=

Strictly speaking adding this is a compatibility break, given that
previously % weren't special. But I'd argue that was simply a bug, as
for the much more prominent Environment= service setting we always
resolved specifiers, and DEfaultEnvironment= is explicitly listed as
being the default for that. Hence, let's fix that.

Replaces: #16787
---
 man/systemd-system.conf.xml | 48 ++++++++++++++++++++++++++++++++++++-
 src/core/load-fragment.c    | 17 ++++++-------
 2 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/man/systemd-system.conf.xml b/man/systemd-system.conf.xml
index 3f229908c92..2851bae31e7 100644
--- a/man/systemd-system.conf.xml
+++ b/man/systemd-system.conf.xml
@@ -328,6 +328,9 @@
         project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
         details about environment variables.</para>
 
+        <para>Simple <literal>%</literal>-specifier expansion is supported, see below for a list of supported
+        specifiers.</para>
+
         <para>Example:
 
         <programlisting>DefaultEnvironment="VAR1=word1 word2" VAR2=word3 "VAR3=word 5 6"</programlisting>
@@ -349,7 +352,11 @@
 
         <para>Setting environment variables for the manager process may be useful to modify its behaviour.
         See <ulink url="https://systemd.io/ENVIRONMENT">ENVIRONMENT</ulink> for a descriptions of some
-        variables understood by <command>systemd</command>.</para></listitem>
+        variables understood by <command>systemd</command>.</para>
+
+        <para>Simple <literal>%</literal>-specifier expansion is supported, see below for a list of supported
+        specifiers.</para>
+        </listitem>
       </varlistentry>
 
       <varlistentry>
@@ -440,6 +447,45 @@
     </variablelist>
   </refsect1>
 
+  <refsect1>
+    <title>Specifiers</title>
+
+    <para>Specifiers may be used in the <varname>DefaultEnvironment=</varname> and
+    <varname>ManagerEnvironment=</varname> settings. The following expansions are understood:</para>
+      <table class='specifiers'>
+        <title>Specifiers available</title>
+        <tgroup cols='3' align='left' colsep='1' rowsep='1'>
+          <colspec colname="spec" />
+          <colspec colname="mean" />
+          <colspec colname="detail" />
+          <thead>
+            <row>
+              <entry>Specifier</entry>
+              <entry>Meaning</entry>
+              <entry>Details</entry>
+            </row>
+          </thead>
+          <tbody>
+            <xi:include href="standard-specifiers.xml" xpointer="a"/>
+            <xi:include href="standard-specifiers.xml" xpointer="A"/>
+            <xi:include href="standard-specifiers.xml" xpointer="b"/>
+            <xi:include href="standard-specifiers.xml" xpointer="B"/>
+            <xi:include href="standard-specifiers.xml" xpointer="H"/>
+            <xi:include href="standard-specifiers.xml" xpointer="l"/>
+            <xi:include href="standard-specifiers.xml" xpointer="m"/>
+            <xi:include href="standard-specifiers.xml" xpointer="M"/>
+            <xi:include href="standard-specifiers.xml" xpointer="o"/>
+            <xi:include href="standard-specifiers.xml" xpointer="v"/>
+            <xi:include href="standard-specifiers.xml" xpointer="w"/>
+            <xi:include href="standard-specifiers.xml" xpointer="W"/>
+            <xi:include href="standard-specifiers.xml" xpointer="T"/>
+            <xi:include href="standard-specifiers.xml" xpointer="V"/>
+            <xi:include href="standard-specifiers.xml" xpointer="percent"/>
+          </tbody>
+        </tgroup>
+      </table>
+  </refsect1>
+
   <refsect1>
       <title>See Also</title>
       <para>
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index ff6eaf32ef6..d31d6420170 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -57,6 +57,7 @@
 #include "signal-util.h"
 #include "socket-bind.h"
 #include "socket-netlink.h"
+#include "specifier.h"
 #include "stat-util.h"
 #include "string-util.h"
 #include "strv.h"
@@ -2656,15 +2657,15 @@ int config_parse_environ(
                 if (r == 0)
                         return 0;
 
-                if (u) {
+                if (u)
                         r = unit_env_printf(u, word, &resolved);
-                        if (r < 0) {
-                                log_syntax(unit, LOG_WARNING, filename, line, r,
-                                           "Failed to resolve unit specifiers in %s, ignoring: %m", word);
-                                continue;
-                        }
-                } else
-                        resolved = TAKE_PTR(word);
+                else
+                        r = specifier_printf(word, sc_arg_max(), system_and_tmp_specifier_table, NULL, &resolved);
+                if (r < 0) {
+                        log_syntax(unit, LOG_WARNING, filename, line, r,
+                                   "Failed to resolve specifiers in %s, ignoring: %m", word);
+                        continue;
+                }
 
                 if (!env_assignment_is_valid(resolved)) {
                         log_syntax(unit, LOG_WARNING, filename, line, 0,
-- 
2.47.3