--- a/src/lib-storage/list/mailbox-list-delete.h	Wed Jun 28 23:37:22 2017 +0300
+++ b/src/lib-storage/list/mailbox-list-delete.h	Tue Jun 27 15:57:10 2017 +0300
@@ -3,20 +3,69 @@
 
 #include "mailbox-list.h"
 
+/* Delete the mailbox atomically by rename()ing it to trash_dir and afterwards
+   recursively deleting the trash_dir. If the rename() fails because trash_dir
+   already exists, the trash_dir is first deleted and rename() is retried.
+
+   Returns 1 if the rename() succeeded. Returns 0 if rename() fails with EXDEV,
+   which means the source and destination are on different filesystems and
+   the rename can never succeeed.
+
+   If the path didn't exist, returns -1 and sets the list error to
+   MAIL_ERROR_NOTFOUND.
+
+   Attempting to delete INBOX or the namespace root returns -1 and sets the
+   list error to MAIL_ERROR_NOTPOSSIBLE.
+
+   Returns -1 and sets the list error on other errors. */
 int mailbox_list_delete_maildir_via_trash(struct mailbox_list *list,
 					  const char *name,
 					  const char *trash_dir);
+/* Try to unlink() the path. Returns 0 on success. If the path didn't exist,
+   returns -1 and sets the list error to MAIL_ERROR_NOTFOUND.
+   Returns -1 and sets the list error on other errors. */
 int mailbox_list_delete_mailbox_file(struct mailbox_list *list,
 				     const char *name, const char *path);
+/* Delete all files from the given path. Also all internal directories
+   (as returned by is_internal_name() check) are recursively deleted.
+   Otherwise directories are left undeleted.
+
+   Returns 0 if anything was unlink()ed and no unexpected errors happened.
+   Also returns 0 if there were no files and the path was successfully
+   rmdir()ed.
+
+   If the path didn't exist, returns -1 and sets the list error to
+   MAIL_ERROR_NOTFOUND.
+
+   If the path exists and has subdirectories, but no files were unlink()ed,
+   returns -1 and sets the list error to MAIL_ERROR_NOTPOSSIBLE.
+
+   Attempting to delete INBOX or the namespace root returns -1 and sets the
+   list error to MAIL_ERROR_NOTPOSSIBLE.
+
+   Returns -1 and sets the list error on other errors. */
 int mailbox_list_delete_mailbox_nonrecursive(struct mailbox_list *list,
 					     const char *name, const char *path,
 					     bool rmdir_path);
+/* Lookup INDEX, CONTROL and ALT directories for the mailbox and delete them. */
 void mailbox_list_delete_finish(struct mailbox_list *list, const char *name);
 
+/* rmdir() path and its parent directories until the root directory is reached.
+   The root isn't rmdir()ed. */
 void mailbox_list_delete_until_root(struct mailbox_list *list, const char *path,
 				    enum mailbox_list_path_type type);
+/* Wrapper to unlink_directory(UNLINK_DIRECTORY_FLAG_RMDIR). If it fails due
+   to ELOOP, try to unlink() the path instead. */
 int mailbox_list_delete_trash(const char *path);
+/* Try to unlink() the path to the mailbox. Returns 0 on success.
 
+   If the path didn't exist, returns -1 and sets the list error to
+   MAIL_ERROR_NOTFOUND.
+
+   If the path is a directory, returns -1 and sets the list error to
+   MAIL_ERROR_NOTPOSSIBLE.
+
+   Returns -1 and sets the list error on other errors. */
 int mailbox_list_delete_symlink_default(struct mailbox_list *list,
 					const char *name);