basic: add new variable $SYSTEMD_OS_RELEASE to override location of os-release

The test for the variable is added in test-systemctl-enable because there we
can do it almost for free, and the variable is most likely to be used with
'systemctl enable --root' anyway.

1 files changed, 11 insertions, 5 deletions

diff --git a/src/basic/os-util.c b/src/basic/os-util.c
index bf86f64348..acfff24319 100644
--- a/src/basic/os-util.c
+++ b/src/basic/os-util.c
@@ -170,13 +170,19 @@ int open_extension_release(const char *root, const char *extension, char **ret_p
                         }
                 }
         } else {
-                FOREACH_STRING(p, "/etc/os-release", "/usr/lib/os-release") {
-                        r = chase_symlinks(p, root, CHASE_PREFIX_ROOT,
+                const char *var = secure_getenv("SYSTEMD_OS_RELEASE");
+                if (var)
+                        r = chase_symlinks(var, root, 0,
                                            ret_path ? &q : NULL,
                                            ret_fd ? &fd : NULL);
-                        if (r != -ENOENT)
-                                break;
-                }
+                else
+                        FOREACH_STRING(path, "/etc/os-release", "/usr/lib/os-release") {
+                                r = chase_symlinks(path, root, CHASE_PREFIX_ROOT,
+                                                   ret_path ? &q : NULL,
+                                                   ret_fd ? &fd : NULL);
+                                if (r != -ENOENT)
+                                        break;
+                        }
         }
         if (r < 0)
                 return r;