core: add WorkingDirectory to Unit.StartTransient

This commit adds setting the WorkingDirectory to the `io.systemd.Unit.StartTransient` varlink call. This is a first step towards more complete StartTransient in varlink. The goal is to be as close as possible to the D-Bus parameters. The exception is WorkingDirectory which is an object here so that we avoid the `-` prefixes and use a more type-safe approach by making it an explicit `missingOK` parameter. The key names stay the same as the D-Bus properties (PascalCase). If there are no equivalent D-Bus properties the native varlink convention of camelCase is used.
2026-05-13 19:28:35 +02:00
parent 6e8e0ba26d
commit a2aa3a7450
3 changed files with 159 additions and 12 deletions
@@ -702,6 +702,18 @@ static void transient_exec_command_item_done(TransientExecCommandItem *i) {
 static JSON_DISPATCH_ENUM_DEFINE(dispatch_service_type, ServiceType, service_type_from_string);
 static JSON_DISPATCH_ENUM_DEFINE(dispatch_job_mode, JobMode, job_mode_from_string);

+typedef struct TransientWorkingDirectory {
+        const char *path;
+        bool home;
+        bool missing_ok;
+} TransientWorkingDirectory;
+
+typedef struct TransientExecContextParameters {
+        bool present;
+        bool working_directory_set;
+        TransientWorkingDirectory working_directory;
+} TransientExecContextParameters;
+
 typedef struct TransientServiceParameters {
        bool present;
        ServiceType type;
@@ -753,7 +765,9 @@ static int dispatch_transient_exec_command(const char *name, sd_json_variant *va
 typedef struct StartTransientContextParameters {
        const char *id;
        const char *description;
+        TransientExecContextParameters exec;
        TransientServiceParameters service;
+        const char *bad_exec_field; /* Set by inner Exec dispatcher to the unknown sub-property name */
 } StartTransientContextParameters;

 static void start_transient_context_parameters_done(StartTransientContextParameters *p) {
@@ -766,12 +780,49 @@ typedef struct StartTransientParameters {
        JobMode mode;
        int notify_job_changes;
        int notify_unit_changes;
-        const char *unsupported_property; /* For error reporting on unknown context fields */
+        char *unsupported_property; /* For error reporting on unknown context fields */
 } StartTransientParameters;

 static void start_transient_parameters_done(StartTransientParameters *p) {
        assert(p);
        start_transient_context_parameters_done(&p->context);
+        free(p->unsupported_property);
+}
+
+static int dispatch_const_string_empty_as_null(const char *name, sd_json_variant *variant, sd_json_dispatch_flags_t flags, void *userdata) {
+        const char **s = ASSERT_PTR(userdata);
+        int r;
+
+        r = sd_json_dispatch_const_string(name, variant, flags, s);
+        if (r >= 0 && isempty(*s))
+                *s = NULL;
+        return r;
+}
+
+static int dispatch_transient_working_directory(const char *name, sd_json_variant *variant, sd_json_dispatch_flags_t flags, void *userdata) {
+        /* No equivalent D-Bus properties, so use varlink camelCase */
+        static const sd_json_dispatch_field dispatch[] = {
+                { "path",      SD_JSON_VARIANT_STRING,  dispatch_const_string_empty_as_null, offsetof(TransientWorkingDirectory, path),       0 },
+                { "home",      SD_JSON_VARIANT_BOOLEAN, sd_json_dispatch_stdbool,            offsetof(TransientWorkingDirectory, home),       0 },
+                { "missingOK", SD_JSON_VARIANT_BOOLEAN, sd_json_dispatch_stdbool,            offsetof(TransientWorkingDirectory, missing_ok), 0 },
+                {}
+        };
+
+        TransientExecContextParameters *p = ASSERT_PTR(userdata);
+        p->working_directory_set = true;
+        return sd_json_dispatch(variant, dispatch, flags, &p->working_directory);
+}
+
+static int dispatch_transient_exec_context(const char *name, sd_json_variant *variant, sd_json_dispatch_flags_t flags, void *userdata) {
+        /* Key names compatible with D-Bus property names */
+        static const sd_json_dispatch_field exec_dispatch[] = {
+                { "WorkingDirectory", SD_JSON_VARIANT_OBJECT, dispatch_transient_working_directory, 0, 0 },
+                {}
+        };
+
+        StartTransientContextParameters *p = ASSERT_PTR(userdata);
+        p->exec.present = true;
+        return sd_json_dispatch_full(variant, exec_dispatch, /* bad= */ NULL, /* flags= */ 0, &p->exec, &p->bad_exec_field);
 }

 static int dispatch_transient_service(const char *name, sd_json_variant *variant, sd_json_dispatch_flags_t flags, void *userdata) {
@@ -789,9 +840,10 @@ static int dispatch_transient_service(const char *name, sd_json_variant *variant

 static int dispatch_transient_context(const char *name, sd_json_variant *variant, sd_json_dispatch_flags_t flags, void *userdata) {
        static const sd_json_dispatch_field context_dispatch[] = {
-                { "ID",          SD_JSON_VARIANT_STRING, json_dispatch_const_unit_name, offsetof(StartTransientContextParameters, id),          SD_JSON_MANDATORY },
-                { "Description", SD_JSON_VARIANT_STRING, sd_json_dispatch_const_string, offsetof(StartTransientContextParameters, description), 0                 },
-                { "Service",     SD_JSON_VARIANT_OBJECT, dispatch_transient_service,    0,                                                      0                 },
+                { "ID",          SD_JSON_VARIANT_STRING, json_dispatch_const_unit_name,   offsetof(StartTransientContextParameters, id),          SD_JSON_MANDATORY },
+                { "Description", SD_JSON_VARIANT_STRING, sd_json_dispatch_const_string,   offsetof(StartTransientContextParameters, description), 0                 },
+                { "Exec",        SD_JSON_VARIANT_OBJECT, dispatch_transient_exec_context, 0,                                                      0                 },
+                { "Service",     SD_JSON_VARIANT_OBJECT, dispatch_transient_service,      0,                                                      0                 },
                {}
        };

@@ -802,10 +854,18 @@ static int dispatch_transient_context(const char *name, sd_json_variant *variant
        /* Don't propagate the caller's flags (in particular SD_JSON_MANDATORY from the outer 'context'
         * field) into the nested dispatch, otherwise every inner field becomes mandatory. */
        r = sd_json_dispatch_full(variant, context_dispatch, /* bad= */ NULL, /* flags= */ 0, &p->context, &bad_field);
-        if (r == -EADDRNOTAVAIL && !isempty(bad_field))
+        if (r == -EADDRNOTAVAIL && !isempty(bad_field)) {
                /* A UnitContext field that exists in the schema but is not settable at creation time: stash
-                 * the name so the caller can map this to io.systemd.Unit.PropertyNotSupported. */
-                p->unsupported_property = bad_field;
+                 * the name so the caller can map this to io.systemd.Unit.PropertyNotSupported. If the
+                 * unknown field lives inside the nested Exec object, compose a dotted name to identify the
+                 * actual sub-property. */
+                if (streq(bad_field, "Exec") && !isempty(p->context.bad_exec_field))
+                        p->unsupported_property = strjoin("Exec.", p->context.bad_exec_field);
+                else
+                        p->unsupported_property = strdup(bad_field);
+                if (!p->unsupported_property)
+                        return -ENOMEM;
+        }
        return r;
 }

@@ -825,6 +885,49 @@ static int transient_unit_apply_properties(Unit *u, StartTransientContextParamet
        return 0;
 }

+static int transient_exec_context_apply_properties(Unit *u, ExecContext *c, TransientExecContextParameters *p) {
+        int r;
+
+        assert(u);
+        assert(c);
+        assert(p);
+
+        if (p->working_directory_set) {
+                TransientWorkingDirectory *wd = &p->working_directory;
+                _cleanup_free_ char *simplified = NULL;
+
+                if (wd->home && wd->path)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "WorkingDirectory: 'home' and 'path' are mutually exclusive");
+                if (!wd->home && !wd->path)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "WorkingDirectory: must specify either 'home' or 'path'");
+
+                if (!wd->home) {
+                        if (!path_is_absolute(wd->path))
+                                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "WorkingDirectory: expects an absolute path");
+                        r = path_simplify_alloc(wd->path, &simplified);
+                        if (r < 0)
+                                return r;
+                        if (!path_is_normalized(simplified))
+                                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                                       "WorkingDirectory: expects a normalized path");
+                }
+
+                free_and_replace(c->working_directory, simplified);
+                c->working_directory_home = wd->home;
+                c->working_directory_missing_ok = wd->missing_ok;
+
+                unit_write_settingf(u, UNIT_RUNTIME|UNIT_PRIVATE|UNIT_ESCAPE_SPECIFIERS, "WorkingDirectory",
+                                    "WorkingDirectory=%s%s",
+                                    c->working_directory_missing_ok ? "-" : "",
+                                    c->working_directory_home ? "~" : strempty(c->working_directory));
+        }
+
+        return 0;
+}
+
 static int transient_service_apply_properties(Service *s, TransientServiceParameters *sp) {
        Unit *u = UNIT(ASSERT_PTR(s));
        int r;
@@ -978,6 +1081,15 @@ int vl_method_start_transient_unit(sd_varlink *link, sd_json_variant *parameters
        if (r < 0)
                return sd_varlink_error(link, VARLINK_ERROR_UNIT_BAD_SETTING, NULL);

+        /* Apply exec-specific properties from context.Exec */
+        ExecContext *c = unit_get_exec_context(u);
+        if (c) {
+                r = transient_exec_context_apply_properties(u, c, &p.context.exec);
+                if (r < 0)
+                        return sd_varlink_error(link, VARLINK_ERROR_UNIT_BAD_SETTING, NULL);
+        } else if (p.context.exec.present)
+                return sd_varlink_error(link, VARLINK_ERROR_UNIT_TYPE_NOT_SUPPORTED, NULL);
+
        /* Apply service-specific properties from context.Service */
        Service *s = SERVICE(u);
        if (s) {
@@ -421,10 +421,12 @@ static SD_VARLINK_DEFINE_STRUCT_TYPE(
 /* ExecContext */
 static SD_VARLINK_DEFINE_STRUCT_TYPE(
                WorkingDirectory,
-                SD_VARLINK_FIELD_COMMENT("The path to the working directory"),
-                SD_VARLINK_DEFINE_FIELD(path, SD_VARLINK_STRING, 0),
+                SD_VARLINK_FIELD_COMMENT("The path to the working directory. Mutually exclusive with 'home'"),
+                SD_VARLINK_DEFINE_FIELD(path, SD_VARLINK_STRING, SD_VARLINK_NULLABLE),
+                SD_VARLINK_FIELD_COMMENT("If true, use the configured user's home directory as the working directory. Mutually exclusive with 'path'"),
+                SD_VARLINK_DEFINE_FIELD(home, SD_VARLINK_BOOL, SD_VARLINK_NULLABLE),
                SD_VARLINK_FIELD_COMMENT("Whether the path to the working directory is allowed to not exist"),
-                SD_VARLINK_DEFINE_FIELD(missingOK, SD_VARLINK_BOOL, 0));
+                SD_VARLINK_DEFINE_FIELD(missingOK, SD_VARLINK_BOOL, SD_VARLINK_NULLABLE));

 static SD_VARLINK_DEFINE_STRUCT_TYPE(
                PartitionMountOptions,
@@ -1182,8 +1184,9 @@ static SD_VARLINK_DEFINE_STRUCT_TYPE(
                SD_VARLINK_DEFINE_FIELD(parameter, SD_VARLINK_STRING, SD_VARLINK_NULLABLE));

 /* UnitContext is used both as input to StartTransient (subset settable at creation time: ID,
- * Description, Service) and as output from List/StartTransient (full unit configuration). Fields that
- * are not settable at creation time are rejected with PropertyNotSupported when supplied as input. */
+ * Description, Service, and the Exec subset {WorkingDirectory}) and as output from
+ * List/StartTransient (full unit configuration). Fields that are not settable at creation time are
+ * rejected with PropertyNotSupported when supplied as input. */
 static SD_VARLINK_DEFINE_STRUCT_TYPE(
                UnitContext,
                SD_VARLINK_FIELD_COMMENT("The unit type"),
@@ -621,6 +621,27 @@ result=$(varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
 echo "$result" | jq -e '.context.Service.ExecStart[0].arguments == ["/bin/true"]'
 timeout 30 bash -c 'until systemctl is-active varlink-transient-noargs.service; do sleep 0.5; done'

+# Exec.WorkingDirectory
+defer_transient_cleanup varlink-transient-exec.service
+result=$(varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
+    '{"context":{"ID":"varlink-transient-exec.service","Exec":{"WorkingDirectory":{"path":"/tmp","missingOK":false}},"Service":{"Type":"oneshot","RemainAfterExit":true,"ExecStart":[{"path":"/bin/true"}]}}}')
+echo "$result" | jq -e '.context.Exec.WorkingDirectory.path == "/tmp"'
+timeout 30 bash -c 'until systemctl is-active varlink-transient-exec.service; do sleep 0.5; done'
+systemctl show -P WorkingDirectory varlink-transient-exec.service | grep '^/tmp$' >/dev/null
+
+# WorkingDirectory with missingOK=true (path does not exist but unit still starts)
+defer_transient_cleanup varlink-transient-wd-missing.service
+varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
+    '{"context":{"ID":"varlink-transient-wd-missing.service","Exec":{"WorkingDirectory":{"path":"/nonexistent/path","missingOK":true}},"Service":{"Type":"oneshot","RemainAfterExit":true,"ExecStart":[{"path":"/bin/true"}]}}}'
+timeout 30 bash -c 'until systemctl is-active varlink-transient-wd-missing.service; do sleep 0.5; done'
+
+# WorkingDirectory with home=true, missingOK omitted (defaults to false)
+defer_transient_cleanup varlink-transient-wd-home.service
+varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
+    '{"context":{"ID":"varlink-transient-wd-home.service","Exec":{"WorkingDirectory":{"home":true}},"Service":{"Type":"oneshot","RemainAfterExit":true,"ExecStart":[{"path":"/bin/true"}]}}}'
+timeout 30 bash -c 'until systemctl is-active varlink-transient-wd-home.service; do sleep 0.5; done'
+systemctl show -P WorkingDirectory varlink-transient-wd-home.service | grep '^~$' >/dev/null
+
 # Error cases: verify specific varlink error types
 set +o pipefail
 varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
@@ -634,6 +655,17 @@ varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
 defer_transient_cleanup varlink-transient-badpath.service
 varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
    '{"context":{"ID":"varlink-transient-badpath.service","Service":{"Type":"simple","ExecStart":[{"path":""}]}}}' |& grep "io.systemd.Unit.BadUnitSetting"
+# Relative WorkingDirectory path is rejected
+defer_transient_cleanup varlink-transient-bad-wd.service
+varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
+    '{"context":{"ID":"varlink-transient-bad-wd.service","Exec":{"WorkingDirectory":{"path":"relative/path","missingOK":false}},"Service":{"Type":"oneshot","ExecStart":[{"path":"/bin/true"}]}}}' |& grep "io.systemd.Unit.BadUnitSetting"
+# Exec on a unit type without an exec context (.target) is rejected
+varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
+    '{"context":{"ID":"varlink-transient-exec.slice","Exec":{"WorkingDirectory":{"path":"/tmp","missingOK":false}}}}' |& grep "io.systemd.Unit.UnitTypeNotSupported"
+# Unknown field in Exec is rejected as PropertyNotSupported
+defer_transient_cleanup varlink-transient-unknown-exec.service
+varlinkctl call "$MANAGER_SOCKET" io.systemd.Unit.StartTransient \
+    '{"context":{"ID":"varlink-transient-unknown-exec.service","Exec":{"RootDirectory":"/tmp"},"Service":{"Type":"oneshot","ExecStart":[{"path":"/bin/true"}]}}}' |& grep "io.systemd.Unit.PropertyNotSupported"
 set -o pipefail

 transient_cleanup