From 3d1ee7a43eb8c7a0f2ecb285d156f57675faa245 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Fri, 10 Dec 2021 19:56:00 +0000
Subject: [PATCH] Don't spin in an infinite loop if the decoder tries to find a
 data record and the matcher fails to find anything, leaving the seek point
 unchanged.

---
 arch/ibm/decoder.cc      | 2 ++
 lib/decoders/decoders.cc | 1 +
 lib/decoders/decoders.h  | 3 +++
 lib/fluxmap.h            | 5 +++++
 4 files changed, 11 insertions(+)

diff --git a/arch/ibm/decoder.cc b/arch/ibm/decoder.cc
index 331357c7..ec2f2af7 100644
--- a/arch/ibm/decoder.cc
+++ b/arch/ibm/decoder.cc
@@ -114,6 +114,8 @@ public:
 		auto idbits = readRawBits(16);
 		const Bytes idbytes = decodeFmMfm(idbits);
 		uint8_t id = idbytes.slice(0, 1)[0];
+		if (eof())
+			return RecordType::UNKNOWN_RECORD;
 		seek(here);
 		
 		switch (id)
diff --git a/lib/decoders/decoders.cc b/lib/decoders/decoders.cc
index e2119751..0dee46e4 100644
--- a/lib/decoders/decoders.cc
+++ b/lib/decoders/decoders.cc
@@ -107,6 +107,7 @@ std::unique_ptr<TrackDataFlux> AbstractDecoder::decodeToSectors(
 					break;
 				if (fmr.eof())
                     break;
+				fmr.skipToEvent(F_BIT_PULSE);
 			}
             recordStart = fmr.tell();
             if (r == DATA_RECORD)
diff --git a/lib/decoders/decoders.h b/lib/decoders/decoders.h
index 44ff3e54..f6414cad 100644
--- a/lib/decoders/decoders.h
+++ b/lib/decoders/decoders.h
@@ -57,6 +57,9 @@ public:
     void seek(const Fluxmap::Position& pos)
     { return _fmr->seek(pos); } 
 
+    bool eof() const
+    { return _fmr->eof(); }
+
 	virtual std::set<unsigned> requiredSectors(unsigned cylinder, unsigned head) const;
 
 protected:
diff --git a/lib/fluxmap.h b/lib/fluxmap.h
index 94a6646c..4c7ebf7f 100644
--- a/lib/fluxmap.h
+++ b/lib/fluxmap.h
@@ -3,6 +3,7 @@
 
 #include "bytes.h"
 #include "protocol.h"
+#include "fmt/format.h"
 
 class RawBits;
 
@@ -17,6 +18,10 @@ public:
 
         nanoseconds_t ns() const
         { return ticks * NS_PER_TICK; }
+
+        operator std::string () {
+            return fmt::format("[b:{}, t:{}, z:{}]", bytes, ticks, zeroes);
+        }
     };
 
 public: