lib-storage: LAYOUT=index now first creates the backend mailbox and only then adds...

This avoids any race conditions with mailbox creation and opening it.

diff --git a/src/lib-storage/list/mailbox-list-index-backend.c b/src/lib-storage/list/mailbox-list-index-backend.c
index b0eb36e32108ae3b0da4575ccfc4dc9bba0cd84d..d0ef630398fa1af93e2e07283714cb49b88b8519 100644 (file)
--- a/src/lib-storage/list/mailbox-list-index-backend.c
+++ b/src/lib-storage/list/mailbox-list-index-backend.c
@@ -16,6 +16,9 @@
 struct index_mailbox_list {
        struct mailbox_list list;
        const char *temp_prefix;
+
+       const char *create_mailbox_name;
+       guid_128_t create_mailbox_guid;
 };
 
 extern struct mailbox_list index_mailbox_list;
@@ -136,6 +139,13 @@ index_list_get_path(struct mailbox_list *_list, const char *name,
        if (!mailbox_list_set_get_root_path(&_list->set, type, &root_dir))
                return 0;
 
+       if (list->create_mailbox_name != NULL &&
+           strcmp(list->create_mailbox_name, name) == 0) {
+               *path_r = index_get_guid_path(_list, root_dir,
+                                             list->create_mailbox_guid);
+               return 1;
+       }
+
        if (ilist->sync_ctx != NULL) {
                /* we could get here during sync from
                   index_list_mailbox_create_selectable() */
@@ -338,19 +348,39 @@ index_list_mailbox_create(struct mailbox *box,
                        new_update = *update;
                if (guid_128_is_empty(new_update.mailbox_guid))
                        guid_128_generate(new_update.mailbox_guid);
-               ret = index_list_mailbox_create_selectable(box, new_update.mailbox_guid);
-               if (ret < 0) {
-                       mail_storage_copy_list_error(box->storage, box->list);
-                       return -1;
-               }
-               if (ret > 0) {
-                       /* mailbox entry was created. create the mailbox
-                          itself now after the mailbox list index is already
-                          unlocked (to avoid deadlocks in case the create_box()
-                          goes back to updating mailbox list index). */
-                       if (ibox->module_ctx.super.create_box(box, update, FALSE) < 0)
-                               return -1;
+
+               /* create the backend mailbox first before it exists in the
+                  list. the mailbox creation wants to use get_path() though,
+                  so use a bit kludgy create_mailbox_* variables during the
+                  creation to return the path. we'll also support recursively
+                  creating more mailboxes in here. */
+               const char *old_name;
+               guid_128_t old_guid;
+
+               old_name = list->create_mailbox_name;
+               guid_128_copy(old_guid, list->create_mailbox_guid);
+
+               list->create_mailbox_name = box->name;
+               guid_128_copy(list->create_mailbox_guid, new_update.mailbox_guid);
+
+               ret = ibox->module_ctx.super.create_box(box, &new_update, FALSE);
+
+               if (ret == 0) {
+                       /* backend mailbox was successfully created. now add it
+                          to the list. */
+                       ret = index_list_mailbox_create_selectable(box, new_update.mailbox_guid);
+                       if (ret < 0)
+                               mail_storage_copy_list_error(box->storage, box->list);
+                       if (ret <= 0) {
+                               /* failed to add to list. rollback the backend
+                                  mailbox creation */
+                               (void)mailbox_delete(box);
+                       }
                }
+               list->create_mailbox_name = old_name;
+               guid_128_copy(list->create_mailbox_guid, old_guid);
+               if (ret < 0)
+                       return ret;
        } else {
                ret = 0;
        }
@@ -460,13 +490,20 @@ index_list_delete_finish(struct mailbox_list *list, const char *name)
 }
 
 static int
-index_list_delete_entry(struct mailbox_list *list, const char *name,
+index_list_delete_entry(struct index_mailbox_list *list, const char *name,
                        bool delete_selectable)
 {
        struct mailbox_list_index_sync_context *sync_ctx;
        int ret;
 
-       if (mailbox_list_index_sync_begin(list, &sync_ctx) < 0)
+       if (strcmp(name, list->create_mailbox_name) == 0) {
+               /* we're rollbacking a failed create. if the name exists in the
+                  list, it was done by somebody else so we don't want to
+                  remove it. */
+               return 0;
+       }
+
+       if (mailbox_list_index_sync_begin(&list->list, &sync_ctx) < 0)
                return -1;
        ret = mailbox_list_index_sync_delete(sync_ctx, name, delete_selectable);
        if (mailbox_list_index_sync_end(&sync_ctx, TRUE) < 0)
@@ -477,6 +514,7 @@ index_list_delete_entry(struct mailbox_list *list, const char *name,
 static int
 index_list_delete_mailbox(struct mailbox_list *_list, const char *name)
 {
+       struct index_mailbox_list *list = (struct index_mailbox_list *)_list;
        const char *path;
        int ret;
 
@@ -498,7 +536,7 @@ index_list_delete_mailbox(struct mailbox_list *_list, const char *name)
        if (ret == 0 || (_list->props & MAILBOX_LIST_PROP_AUTOCREATE_DIRS) != 0)
                index_list_delete_finish(_list, name);
        if (ret == 0) {
-               if (index_list_delete_entry(_list, name, TRUE) < 0)
+               if (index_list_delete_entry(list, name, TRUE) < 0)
                        return -1;
        }
        return ret;
@@ -507,9 +545,10 @@ index_list_delete_mailbox(struct mailbox_list *_list, const char *name)
 static int
 index_list_delete_dir(struct mailbox_list *_list, const char *name)
 {
+       struct index_mailbox_list *list = (struct index_mailbox_list *)_list;
        int ret;
 
-       if ((ret = index_list_delete_entry(_list, name, FALSE)) < 0)
+       if ((ret = index_list_delete_entry(list, name, FALSE)) < 0)
                return -1;
        if (ret == 0) {
                mailbox_list_set_error(_list, MAIL_ERROR_EXISTS,