1 files changed, 104 insertions, 0 deletions
diff --git a/src/lib-storage/index/index-pop3-uidl.c b/src/lib-storage/index/index-pop3-uidl.c
new file mode 100644
index 0000000..e537e9f
--- /dev/null
+++ b/src/lib-storage/index/index-pop3-uidl.c
@@ -0,0 +1,104 @@
+/* Copyright (c) 2016-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "index-storage.h"
+#include "index-mail.h"
+#include "index-pop3-uidl.h"
+
+void index_pop3_uidl_set_max_uid(struct mailbox *box,
+				 struct mail_index_transaction *trans,
+				 uint32_t uid)
+{
+	struct mailbox_index_pop3_uidl uidl;
+
+	i_zero(&uidl);
+	uidl.max_uid_with_pop3_uidl = uid;
+
+	mail_index_update_header_ext(trans, box->pop3_uidl_hdr_ext_id,
+				     0, &uidl, sizeof(uidl));
+}
+
+bool index_pop3_uidl_can_exist(struct mail *mail)
+{
+	struct mailbox_index_pop3_uidl uidl;
+	const void *data;
+	size_t size;
+
+	/* We'll assume that if the header exists, it's up-to-date. normally
+	   UIDLs are set only during migration, so this value never changes.
+	   Also even if it does, it becomes out-of-date only when the mailbox
+	   is modified with old Dovecot versions. To fix that we'd have to
+	   add and keep updating "max tracked uid" in this header for every
+	   saved mail, which isn't worth it. */
+	mail_index_get_header_ext(mail->transaction->view,
+				  mail->box->pop3_uidl_hdr_ext_id,
+				  &data, &size);
+	if (size < sizeof(uidl)) {
+		/* this header isn't set yet */
+		return TRUE;
+	}
+	memcpy(&uidl, data, sizeof(uidl));
+	return mail->uid <= uidl.max_uid_with_pop3_uidl;
+}
+
+void index_pop3_uidl_update_exists(struct mail *mail, bool exists)
+{
+	struct mailbox_transaction_context *trans = mail->transaction;
+
+	if (exists) {
+		if (trans->highest_pop3_uidl_uid < mail->uid) {
+			trans->highest_pop3_uidl_uid = mail->uid;
+			trans->prev_pop3_uidl_tracking_seq = mail->seq;
+		}
+	} else if (mail->seq == trans->prev_pop3_uidl_tracking_seq+1) {
+		trans->prev_pop3_uidl_tracking_seq++;
+	} else {
+		/* skipping mails. we don't know the state. */
+	}
+}
+
+void index_pop3_uidl_update_exists_finish(struct mailbox_transaction_context *trans)
+{
+	struct mail_index_view *view;
+	struct mailbox_index_pop3_uidl uidl;
+	const void *data;
+	size_t size;
+	bool seen_all_msgs;
+
+	mail_index_get_header_ext(trans->view, trans->box->pop3_uidl_hdr_ext_id,
+				  &data, &size);
+
+	if (trans->highest_pop3_uidl_uid == 0 && size >= sizeof(uidl)) {
+		/* header already set and nothing to change */
+		return;
+	}
+
+	/* First check that we actually looked at UIDL for all messages.
+	   Otherwise we can't say for sure if the newest messages had UIDLs. */
+	if (trans->prev_pop3_uidl_tracking_seq !=
+	    mail_index_view_get_messages_count(trans->view))
+		return;
+
+	/* Just to be sure: Refresh the index and check again. POP3 keeps
+	   transactions open for duration of the entire session. Maybe another
+	   process already added new mails (and already updated this header).
+	   This check is racy, but normally UIDLs aren't added after migration
+	   so it's a bit questionable if it's even worth having this check in
+	   there. */
+	view = mail_index_view_open(trans->box->index);
+	seen_all_msgs = mail_index_refresh(trans->box->index) == 0 &&
+		trans->prev_pop3_uidl_tracking_seq ==
+		mail_index_view_get_messages_count(view);
+	mail_index_view_close(&view);
+	if (!seen_all_msgs)
+		return;
+
+	/* check if we have already the same header */
+	if (size >= sizeof(uidl)) {
+		memcpy(&uidl, data, sizeof(uidl));
+		if (trans->highest_pop3_uidl_uid == uidl.max_uid_with_pop3_uidl)
+			return;
+	}
+	index_pop3_uidl_set_max_uid(trans->box, trans->itrans,
+				    trans->highest_pop3_uidl_uid);
+}