From 89b67d3871441955ef3a379dd340b8b940cd3551 Mon Sep 17 00:00:00 2001
From: AllSeeingEyeTolledEweSew <allseeingeyetolledewesew@protonmail.com>
Date: Tue, 22 Sep 2020 06:59:57 +0000
Subject: [PATCH] post save_resume_data_failed_alert if torrent was removed.
 Closes #5174

---
 src/torrent.cpp      |  7 +++++++
 test/test_resume.cpp | 27 +++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/src/torrent.cpp b/src/torrent.cpp
index 4e3e84f46f6..4ef76fa39d6 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -8574,6 +8574,13 @@ bool is_downloading_state(int const st)
 		TORRENT_ASSERT(is_single_thread());
 		INVARIANT_CHECK;
 
+		if (m_abort)
+		{
+			alerts().emplace_alert<save_resume_data_failed_alert>(get_handle()
+				, errors::torrent_removed);
+			return;
+		}
+
 		if ((flags & torrent_handle::only_if_modified) && !m_need_save_resume_data)
 		{
 			alerts().emplace_alert<save_resume_data_failed_alert>(get_handle()
diff --git a/test/test_resume.cpp b/test/test_resume.cpp
index 8efb9a3124c..15ea612fc9c 100644
--- a/test/test_resume.cpp
+++ b/test/test_resume.cpp
@@ -1729,3 +1729,30 @@ TORRENT_TEST(resume_data_have_pieces)
 	TEST_EQUAL(rs->params.unfinished_pieces.size(), 1);
 }
 
+// See https://github.com/arvidn/libtorrent/issues/5174
+TORRENT_TEST(removed)
+{
+	lt::session ses(settings());
+	std::shared_ptr<torrent_info> ti = generate_torrent();
+	add_torrent_params p;
+	p.ti = ti;
+	p.save_path = ".";
+	// we're _likely_ to trigger the condition, but not guaranteed. loop
+	// until we do.
+	bool triggered = false;
+	for (int i = 0; i < 10; i++) {
+		torrent_handle h = ses.add_torrent(p);
+		// this is asynchronous
+		ses.remove_torrent(h);
+		try {
+			h.save_resume_data();
+			triggered = true;
+		} catch (std::exception const&) {
+			std::printf("failed to trigger condition, retrying\n");
+		}
+	}
+	TEST_CHECK(triggered);
+	if (!triggered) return;
+	alert const* a = wait_for_alert(ses, save_resume_data_failed_alert::alert_type);
+	TEST_CHECK(a != nullptr);
+}