[systemd-devel] [PATCH 2/3] Allow $SYSTEMD_PRETEND_INITRD to override initramfs detection

[Zbigniew Jędrzejewski-Szmek]

When testing generators and other utilities, it is extremely useful
to be able to trigger initramfs behaviour.

We already allow $SYSTEMD_UNIT_PATH to modify systemd behaviour, this
follows the same principle.
---
 src/shared/util.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/shared/util.c b/src/shared/util.c
index 2c7254eeda..b110909e30 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -3734,23 +3734,29 @@ bool documentation_url_is_valid(const char *url) {
 bool in_initrd(void) {
         static int saved = -1;
         struct statfs s;
+        const char *e;
 
         if (saved >= 0)
                 return saved;
 
-        /* We make two checks here:
+        /* We make three checks here:
          *
-         * 1. the flag file /etc/initrd-release must exist
-         * 2. the root file system must be a memory file system
+         * 0. First check for SYSTEMD_PRETEND_INITRD.
+         * 1. The flag file /etc/initrd-release must exist
+         * 2. The root file system must be a memory file system
          *
          * The second check is extra paranoia, since misdetecting an
          * initrd can have bad bad consequences due the initrd
          * emptying when transititioning to the main systemd.
          */
 
-        saved = access("/etc/initrd-release", F_OK) >= 0 &&
-                statfs("/", &s) >= 0 &&
-                is_temporary_fs(&s);
+        e = getenv("SYSTEMD_PRETEND_INITRD");
+        if (e && parse_boolean(e) > 0)
+                saved = true;
+        else
+                saved = access("/etc/initrd-release", F_OK) >= 0 &&
+                        statfs("/", &s) >= 0 &&
+                        is_temporary_fs(&s);
 
         return saved;
 }
-- 
2.3.5