From c74e3aa5b7fd656aad903a6064c8b01b7801498c Mon Sep 17 00:00:00 2001
From: Daan De Meyer <daan@amutable.com>
Date: Fri, 7 Aug 2026 10:57:22 +0200
Subject: [PATCH] install: preset in the scope the caller asked for

unit_file_preset() and unit_file_preset_all() zero-initialized their
install contexts, so their scope was always RUNTIME_SCOPE_SYSTEM. In
the global scope, specifiers in [Install] were then resolved as if for
the system: %U became 0 and a unit got enabled into
target-0.target.wants/. Set the scope the caller asked for, so that
this fails with -EUNATCH instead.

Covered by a new test that presets a unit using %U in the global
scope, with both functions.

(cherry picked from commit 0a4491ef3fce30d31a35c95031c8026a0235e0a2)
---
 src/shared/install.c         |  4 ++--
 src/test/test-install-root.c | 43 ++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/src/shared/install.c b/src/shared/install.c
index f8f05c624f..23397f7990 100644
--- a/src/shared/install.c
+++ b/src/shared/install.c
@@ -3688,7 +3688,7 @@ int unit_file_preset(
                 InstallChange **changes,
                 size_t *n_changes) {
 
-        _cleanup_(install_context_done) InstallContext plus = {}, minus = {};
+        _cleanup_(install_context_done) InstallContext plus = { .scope = scope }, minus = { .scope = scope };
         _cleanup_(lookup_paths_done) LookupPaths lp = {};
         _cleanup_(unit_file_presets_done) UnitFilePresets presets = {};
         const char *config_path;
@@ -3727,7 +3727,7 @@ int unit_file_preset_all(
                 InstallChange **changes,
                 size_t *n_changes) {
 
-        _cleanup_(install_context_done) InstallContext plus = {}, minus = {};
+        _cleanup_(install_context_done) InstallContext plus = { .scope = scope }, minus = { .scope = scope };
         _cleanup_(lookup_paths_done) LookupPaths lp = {};
         _cleanup_(unit_file_presets_done) UnitFilePresets presets = {};
         const char *config_path = NULL;
diff --git a/src/test/test-install-root.c b/src/test/test-install-root.c
index 2545b1fd04..9786675b4c 100644
--- a/src/test/test-install-root.c
+++ b/src/test/test-install-root.c
@@ -10,6 +10,7 @@
 #include "path-util.h"
 #include "rm-rf.h"
 #include "special.h"
+#include "stat-util.h"
 #include "string-util.h"
 #include "tests.h"
 #include "tmpfile-util.h"
@@ -1131,6 +1132,48 @@ TEST(preset_multiple_instances) {
         install_changes_free(changes, n_changes);
 }
 
+TEST(preset_scope) {
+        const char *unit, *preset, *link;
+        InstallChange *changes = NULL;
+        size_t n_changes = 0;
+
+        /* %U can't be resolved in the global scope, since there's no user to resolve it to. Make sure
+         * presetting in the global scope fails because of that, instead of resolving specifiers in the
+         * system scope (where %U is 0) and creating a target-0.target.wants/ symlink. Check both
+         * unit_file_preset() and unit_file_preset_all(), they set up their install contexts separately. */
+
+        unit = strjoina(root, "/usr/lib/systemd/user/scoped.service");
+        ASSERT_OK(mkdir_parents(unit, 0755));
+        ASSERT_OK(write_string_file(unit,
+                                    "[Install]\n"
+                                    "WantedBy=target-%U.target\n", WRITE_STRING_FILE_CREATE));
+
+        preset = strjoina(root, "/usr/lib/systemd/user-preset/50-scoped.preset");
+        ASSERT_OK(mkdir_parents(preset, 0755));
+        ASSERT_OK(write_string_file(preset, "enable scoped.service\n", WRITE_STRING_FILE_CREATE));
+
+        ASSERT_ERROR(unit_file_preset(RUNTIME_SCOPE_GLOBAL, 0, root, STRV_MAKE("scoped.service"),
+                                      UNIT_FILE_PRESET_FULL, &changes, &n_changes), EUNATCH);
+        ASSERT_EQ(n_changes, 1u);
+        ASSERT_EQ(changes[0].type, -EUNATCH);
+        ASSERT_STREQ(changes[0].path, "target-%U.target");
+        install_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        link = strjoina(root, USER_CONFIG_UNIT_DIR"/target-0.target.wants/scoped.service");
+        ASSERT_ERROR(is_symlink(link), ENOENT);
+
+        ASSERT_ERROR(unit_file_preset_all(RUNTIME_SCOPE_GLOBAL, 0, root, UNIT_FILE_PRESET_FULL,
+                                          &changes, &n_changes), EUNATCH);
+        ASSERT_EQ(n_changes, 1u);
+        ASSERT_EQ(changes[0].type, -EUNATCH);
+        ASSERT_STREQ(changes[0].path, "target-%U.target");
+        install_changes_free(changes, n_changes);
+        changes = NULL; n_changes = 0;
+
+        ASSERT_ERROR(is_symlink(link), ENOENT);
+}
+
 static void verify_one(
                 const InstallInfo *i,
                 const char *alias,