From 73065f814aceb9734a5c6be3370db87182dbf3fc Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Mon, 18 Aug 2025 16:24:22 -0600
Subject: [PATCH] modify API of Evoral::SMF::append_event_beats() to add
 meta-event legality

If the (new) final argument is true, we allow writing SMF meta events to the
underlying libsmf object (which doesn't care one way or another).
---
 libs/evoral/SMF.cc       | 27 +++++++++++++++++++--------
 libs/evoral/evoral/SMF.h |  2 +-
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/libs/evoral/SMF.cc b/libs/evoral/SMF.cc
index 3d9dbd08db..483744a136 100644
--- a/libs/evoral/SMF.cc
+++ b/libs/evoral/SMF.cc
@@ -411,8 +411,6 @@ SMF::read_event(uint32_t* delta_t, uint32_t* bufsize, uint8_t** buf, event_id_t*
 	}
 }
 
-void
-SMF::append_event_delta(uint32_t delta_t, uint32_t size, const uint8_t* buf, event_id_t note_id)
 bool
 SMF::is_meta (uint8_t const* buf, uint32_t size)
 {
@@ -442,11 +440,13 @@ SMF::is_meta (uint8_t const* buf, uint32_t size)
 	return false;
 }
 
+int
+SMF::append_event_delta (uint32_t delta_t, uint32_t size, const uint8_t* buf, event_id_t note_id, bool allow_meta)
 {
 	Glib::Threads::Mutex::Lock lm (_smf_lock);
 
 	if (size == 0) {
-		return;
+		return 0;
 	}
 
 	/* printf("SMF::append_event_delta @ %u:", delta_t);
@@ -468,15 +468,24 @@ SMF::is_meta (uint8_t const* buf, uint32_t size)
 	case 0xfc:
 	case 0xfd:
 	case 0xfe:
-	case 0xff:
 		/* System Real Time or System Common event: not valid in SMF
 		 */
-		return;
+		return 0;
 	}
 
-	if (!midi_event_is_valid(buf, size)) {
-		cerr << "WARNING: SMF ignoring illegal MIDI event" << endl;
-		return;
+	if (buf[0] == 0xff) { /* meta event */
+
+		if (!is_meta (buf, size) || !allow_meta) {
+			return 0;
+		}
+
+	} else {
+
+		if (!midi_event_is_valid(buf, size)) {
+			cerr << "WARNING: SMF ignoring illegal MIDI event" << endl;
+			return 0;
+		}
+
 	}
 
 	smf_event_t* event;
@@ -534,6 +543,8 @@ SMF::is_meta (uint8_t const* buf, uint32_t size)
 	assert(_smf_track);
 	smf_track_add_event_delta_pulses(_smf_track, event, delta_t);
 	_empty = false;
+
+	return size;
 }
 
 void
diff --git a/libs/evoral/evoral/SMF.h b/libs/evoral/evoral/SMF.h
index 67ba0074b2..9914d54684 100644
--- a/libs/evoral/evoral/SMF.h
+++ b/libs/evoral/evoral/SMF.h
@@ -91,7 +91,7 @@ public:
 	static bool is_meta (uint8_t const * buf, uint32_t size);
 
 	void begin_write();
-	void append_event_delta(uint32_t delta_t, uint32_t size, const uint8_t* buf, event_id_t note_id);
+	int append_event_delta (uint32_t delta_t, uint32_t size, const uint8_t* buf, event_id_t note_id, bool allow_meta = false);
 	void end_write(std::string const &);
 
 	void flush() {};