From cae8edd93ca2ef90c41cb9b6322b6908d12947b5 Mon Sep 17 00:00:00 2001
From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Tue, 17 May 2022 14:57:54 +0200
Subject: [PATCH] journal: Add new _INITRD field

The _INITRD field is a boolean field (0 or 1) that specifies whether
a message was processed by systemd-journald in the initrd or not.
---
 man/systemd.journal-fields.xml | 8 ++++++++
 src/journal/journald-server.c  | 5 +++++
 src/journal/journald-server.h  | 2 +-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/man/systemd.journal-fields.xml b/man/systemd.journal-fields.xml
index d50e89f0bb9..320b7829923 100644
--- a/man/systemd.journal-fields.xml
+++ b/man/systemd.journal-fields.xml
@@ -398,6 +398,14 @@
         for details about journal namespaces.</para>
         </listitem>
       </varlistentry>
+      <varlistentry>
+        <term><varname>_SYSTEM_CONTEXT=</varname></term>
+
+        <listitem><para>A string field that specifies the context in which the message was logged. If
+        <literal>initrd</literal>, the log message was processed while systemd-journald
+        was running inside the initrd. If <literal>main</literal>, the log message was generated after
+        journald switched root to the root filesystem.</para></listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
 
diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c
index 15b6844d5d4..0061abadff5 100644
--- a/src/journal/journald-server.c
+++ b/src/journal/journald-server.c
@@ -1035,6 +1035,11 @@ static void dispatch_message_real(
         if (!isempty(s->namespace_field))
                 iovec[n++] = IOVEC_MAKE_STRING(s->namespace_field);
 
+        if (in_initrd())
+                iovec[n++] = IOVEC_MAKE_STRING("_SYSTEM_CONTEXT=initrd");
+        else
+                iovec[n++] = IOVEC_MAKE_STRING("_SYSTEM_CONTEXT=main");
+
         assert(n <= m);
 
         if (s->split_mode == SPLIT_UID && c && uid_is_valid(c->uid))
diff --git a/src/journal/journald-server.h b/src/journal/journald-server.h
index 01244e1ce10..ee8f3741908 100644
--- a/src/journal/journald-server.h
+++ b/src/journal/journald-server.h
@@ -179,7 +179,7 @@ struct Server {
 #define SERVER_MACHINE_ID(s) ((s)->machine_id_field + STRLEN("_MACHINE_ID="))
 
 /* Extra fields for any log messages */
-#define N_IOVEC_META_FIELDS 23
+#define N_IOVEC_META_FIELDS 24
 
 /* Extra fields for log messages that contain OBJECT_PID= (i.e. log about another process) */
 #define N_IOVEC_OBJECT_FIELDS 18