From faf149d08eb4af322a8bbaa8ce83324d691a7737 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Fri, 31 Jan 2020 19:32:38 +0100
Subject: [PATCH] lib/xiph/OggVisitor: add method ReadGranulepos()

---
 src/lib/xiph/OggVisitor.cxx | 11 +++++++++++
 src/lib/xiph/OggVisitor.hxx | 16 ++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/lib/xiph/OggVisitor.cxx b/src/lib/xiph/OggVisitor.cxx
index 153d20b7d..9f6d91dc5 100644
--- a/src/lib/xiph/OggVisitor.cxx
+++ b/src/lib/xiph/OggVisitor.cxx
@@ -108,3 +108,14 @@ OggVisitor::PostSeek(uint64_t offset)
 
 	post_seek = true;
 }
+
+ogg_int64_t
+OggVisitor::ReadGranulepos() noexcept
+{
+	ogg_packet packet;
+	while (stream.PacketOut(packet) == 1)
+		if (packet.granulepos >= 0)
+			return packet.granulepos;
+
+	return -1;
+}
diff --git a/src/lib/xiph/OggVisitor.hxx b/src/lib/xiph/OggVisitor.hxx
index fd21313a6..20f7dcf2e 100644
--- a/src/lib/xiph/OggVisitor.hxx
+++ b/src/lib/xiph/OggVisitor.hxx
@@ -66,6 +66,22 @@ public:
 	 */
 	void PostSeek(uint64_t offset);
 
+	/**
+	 * Skip packets (#ogg_packet) from the #OggStreamState until a
+	 * packet with a valid granulepos is found or until the stream
+	 * has run dry.
+	 *
+	 * Since this will discard pending packets and will disturb
+	 * this object, this should only be used while seeking.
+	 *
+	 * This method must not be called from within one of the
+	 * virtual methods.
+	 *
+	 * @return the granulepos or -1 if no valid granulepos was
+	 * found
+	 */
+	ogg_int64_t ReadGranulepos() noexcept;
+
 private:
 	void EndStream();
 	bool ReadNextPage();