systemd-analyze: make dump work for large # of units

If there is a large number of units, the size of the generated dump
string can overstep DBus message size limit. So let's pass that string
via a fd.

1 files changed, 24 insertions, 1 deletions

diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index ced5d06bd4..8a784747bb 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -1321,7 +1321,7 @@ static int method_unsubscribe(sd_bus_message *message, void *userdata, sd_bus_er
         return sd_bus_reply_method_return(message, NULL);
 }
 
-static int method_dump(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+static int dump_impl(sd_bus_message *message, void *userdata, sd_bus_error *error, int (*reply)(sd_bus_message *, char *)) {
         _cleanup_free_ char *dump = NULL;
         Manager *m = userdata;
         int r;
@@ -1339,9 +1339,31 @@ static int method_dump(sd_bus_message *message, void *userdata, sd_bus_error *er
         if (r < 0)
                 return r;
 
+        return reply(message, dump);
+}
+
+static int reply_dump(sd_bus_message *message, char *dump) {
         return sd_bus_reply_method_return(message, "s", dump);
 }
 
+static int method_dump(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        return dump_impl(message, userdata, error, reply_dump);
+}
+
+static int reply_dump_by_fd(sd_bus_message *message, char *dump) {
+        _cleanup_close_ int fd = -1;
+
+        fd = acquire_data_fd(dump, strlen(dump), 0);
+        if (fd < 0)
+                return fd;
+
+        return sd_bus_reply_method_return(message, "h", fd);
+}
+
+static int method_dump_by_fd(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        return dump_impl(message, userdata, error, reply_dump_by_fd);
+}
+
 static int method_refuse_snapshot(sd_bus_message *message, void *userdata, sd_bus_error *error) {
         return sd_bus_error_setf(error, SD_BUS_ERROR_NOT_SUPPORTED, "Support for snapshots has been removed.");
 }
@@ -2598,6 +2620,7 @@ const sd_bus_vtable bus_manager_vtable[] = {
         SD_BUS_METHOD("Subscribe", NULL, NULL, method_subscribe, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Unsubscribe", NULL, NULL, method_unsubscribe, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("Dump", NULL, "s", method_dump, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("DumpByFileDescriptor", NULL, "h", method_dump_by_fd, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("CreateSnapshot", "sb", "o", method_refuse_snapshot, SD_BUS_VTABLE_UNPRIVILEGED|SD_BUS_VTABLE_HIDDEN),
         SD_BUS_METHOD("RemoveSnapshot", "s", NULL, method_refuse_snapshot, SD_BUS_VTABLE_UNPRIVILEGED|SD_BUS_VTABLE_HIDDEN),
         SD_BUS_METHOD("Reload", NULL, NULL, method_reload, SD_BUS_VTABLE_UNPRIVILEGED),