From 8d45eecd456c81f7b334bfd72610f17164ac7a03 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sun, 27 Dec 2015 03:40:48 +0100
Subject: [PATCH] somewhat better solution to prev commit.

parse up to 32bit VLQs, match smf_format_vlq()
---
 libs/evoral/src/Event.cpp         | 15 ++++-----------
 libs/evoral/src/libsmf/smf_load.c | 10 ++++++++--
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/libs/evoral/src/Event.cpp b/libs/evoral/src/Event.cpp
index 3c1cc000bd..64caba3952 100644
--- a/libs/evoral/src/Event.cpp
+++ b/libs/evoral/src/Event.cpp
@@ -38,23 +38,16 @@ init_event_id_counter(event_id_t n)
 event_id_t
 next_event_id ()
 {
-	/* libsmf supports reading variable-length data up to 4 bytes only.
-	 * so we wrap around at 2^(4 * 7) - 1
-	 *
-	 * interestingly enough libsmf happily writes data longer than that, but then
-	 * fails to load it in ./libs/evoral/src/libsmf/smf_load.c:237
-	 * g_critical("SMF error: Variable Length Quantities longer than four bytes are not supported yet.");
+	/* TODO: handle 31bit overflow , event_id_t is an int32_t,
+	 * and libsmf only supports loading uint32_t vlq's, see smf_extract_vlq()
 	 *
 	 * event-IDs only have to be unique per .mid file.
 	 * Previously (Ardour 4.2ish) Ardour re-generated those IDs when loading the
 	 * file but that lead to .mid files being modified on every load/save.
 	 *
-	 * For now just assume that by the time 2^28 is reached, files with low ids have vanished.
-	 * There is only one user who managed to get to 268 million events so far.
-	 * quite a feat: id-counter="6483089" event-counter="276390506"
-	 * Eventually a proper solution will have to be implemented.
+	 * current user-record: is event-counter="276390506" (just abov 2^28)
 	 */
-	return g_atomic_int_add (&_event_id_counter, 1) & 268435455;
+	return g_atomic_int_add (&_event_id_counter, 1);
 }
 
 #ifdef EVORAL_EVENT_ALLOC
diff --git a/libs/evoral/src/libsmf/smf_load.c b/libs/evoral/src/libsmf/smf_load.c
index a23a88fa49..001774cd14 100644
--- a/libs/evoral/src/libsmf/smf_load.c
+++ b/libs/evoral/src/libsmf/smf_load.c
@@ -214,13 +214,19 @@ smf_extract_vlq(const unsigned char *buf, const size_t buffer_length, uint32_t *
 {
 	uint32_t val = 0;
 	const unsigned char *c = buf;
+	int i = 0;
 
-	for (;;) {
+	for (;; ++i) {
 		if (c >= buf + buffer_length) {
 			g_critical("End of buffer in extract_vlq().");
 			return (-1);
 		}
 
+		if (i == 4 && (val & 0xfe000000)) {
+			g_critical("SMF error: Variable Length Quantities longer than four bytes are not supported yet.");
+			return (-2);
+		}
+
 		val = (val << 7) + (*c & 0x7F);
 
 		if (*c & 0x80)
@@ -233,7 +239,7 @@ smf_extract_vlq(const unsigned char *buf, const size_t buffer_length, uint32_t *
 	*value = val;
 	*len = c - buf + 1;
 
-	if (*len > 4) {
+	if (*len > 5) {
 		g_critical("SMF error: Variable Length Quantities longer than four bytes are not supported yet.");
 		return (-2);
 	}