fix(rtmp): avoid segfault on connection-refused teardown

Track libavformat RTMP session initialization state so teardown only writes a trailer after the muxer header succeeds. This avoids calling av_write_trailer() on partially initialized sessions when avio_open2() fails with Connection refused.

Add a fault-suite regression for libavformat RTMP connection refusal and update the summary helper to compute all_pass from the actual manifest size instead of a hardcoded seven-row expectation.

Verified by rebuilding cvmmap_streamer and rtmp_output_tester, reproducing the refused-connection path without a crash, and running ./scripts/fault_suite.sh successfully (8/8).

scripts/fault_suite.sh

@@ -238,6 +238,18 @@ EOF
 		--frame-interval-ms 1 \
 		--linger-ms 0
 
+	run_expected_failure 8 "libavformat_connection_refused" "libavformat connection refusal surfaces without crashing" \
+		"failed to open RTMP output 'rtmp://127.0.0.1:1/live/test': Connection refused" \
+		"${RTMP_OUTPUT_TESTER}" \
+		--rtmp-url rtmp://127.0.0.1:1/live/test \
+		--transport libavformat \
+		--codec h264 \
+		--frames 1 \
+		--width 320 \
+		--height 240 \
+		--frame-interval-ms 1 \
+		--linger-ms 0
+
 	local finished_at_utc
 	finished_at_utc="$(date -u +"%Y-%m-%dT%H:%M:%SZ")"
 
@@ -294,7 +306,7 @@ PY
 		echo "counts_pass=${pass_count}"
 		echo "counts_fail=${fail_count}"
 		echo "all_pass=${all_pass}"
-		echo "scenarios=removed_encoder_backend,removed_rtmp_transport,removed_rtmp_mode_cli,removed_rtmp_mode_toml,missing_rtmp_url,invalid_rtp_endpoint,ffmpeg_process_bad_binary"
+		echo "scenarios=removed_encoder_backend,removed_rtmp_transport,removed_rtmp_mode_cli,removed_rtmp_mode_toml,missing_rtmp_url,invalid_rtp_endpoint,ffmpeg_process_bad_binary,libavformat_connection_refused"
 	} > "${EVIDENCE_TEXT}"
 
 	if [[ "${all_pass}" == "true" ]]; then

scripts/fault_summary_helper.py

@@ -86,7 +86,7 @@ def build_summary(args: CliArgs) -> dict[str, object]:
     pass_count = sum(1 for row in rows if row["status"] == "PASS")
     fail_count = sum(1 for row in rows if row["status"] == "FAIL")
     skip_count = sum(1 for row in rows if row["status"] == "SKIP")
-    all_pass = len(rows) == 7 and pass_count == 7 and fail_count == 0 and skip_count == 0
+    all_pass = len(rows) > 0 and pass_count == len(rows) and fail_count == 0 and skip_count == 0
 
     return {
         "run_id": args.run_id,

src/protocol/rtmp_output.cpp

@@ -230,6 +230,8 @@ public:
 		std::string url{};
 		AVFormatContext *format_context{nullptr};
 		AVStream *video_stream{nullptr};
+		bool io_opened{false};
+		bool header_written{false};
 	};
 
 	LibavformatRtmpOutput() = default;
@@ -368,6 +370,7 @@ private:
 					ERR_NETWORK,
 					"failed to open RTMP output '" + url + "': " + av_error_string(open_result));
 			}
+			session.io_opened = true;
 		}
 
 		// RTMP sockets are non-seekable, so the FLV muxer must not try to backfill
@@ -388,6 +391,7 @@ private:
 				ERR_PROTOCOL,
 				"failed to write RTMP header for '" + url + "': " + av_error_string(header_result));
 		}
+		session.header_written = true;
 
 		spdlog::info(
 			"RTMP_OUTPUT_READY backend=libavformat codec={} url={}",
@@ -401,9 +405,15 @@ private:
 			return;
 		}
 
-		av_write_trailer(session.format_context);
-		if (!(session.format_context->oformat->flags & AVFMT_NOFILE) && session.format_context->pb != nullptr) {
+		if (session.header_written) {
+			av_write_trailer(session.format_context);
+			session.header_written = false;
+		}
+		if (session.io_opened &&
+			!(session.format_context->oformat->flags & AVFMT_NOFILE) &&
+			session.format_context->pb != nullptr) {
 			avio_closep(&session.format_context->pb);
+			session.io_opened = false;
 		}
 		avformat_free_context(session.format_context);
 		session.format_context = nullptr;