From 0e37d6309077cb016ea52e462757755ce1cccc90 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Victor?= <bjorn@victor.se>
Date: Mon, 10 Jun 2024 13:02:12 +0200
Subject: [PATCH] Read saveset name from the right place

Support DUMPER format 6, which has saveset name at different offset. Also check dumper tape format and reject too old or invalid format codes.
---
 dumper.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/dumper.c b/dumper.c
index bd6df1b..d680bfa 100644
--- a/dumper.c
+++ b/dumper.c
@@ -437,9 +437,22 @@ read_tape_header (FILE *f, word_t word)
 
   word = read_record (f, word);
 
-  //fprintf (stderr, "006: %012llo format\n", data[0]);
-
-  read_asciz (name, &data[3]);
+  // Check tape format! Otherwise breaks e.g. on Install tapes (which aren't in dumper format).
+  if ((data[0] < 4) || (data[0] > 6)) {
+    // Formats older than 4 not supported, and 6 was the highest (TOPS-20 v6-7).
+    // If you want to support older fmts, write the code. :-)
+    fprintf (stderr, "Bad dumper tape format %012llo\n", data[0]);
+    return -1;
+  }
+
+  // Get the saveset name from the right place.
+  // In TOPS-20 v4-5, see DUMPER.MAC, label SETHDR.
+  // In TOPS-20 v6-7, see DUMPER.MAC, label NOSPCL.
+  if (data[1] == 0) {		 // v6-7: if no pointer,
+    read_asciz(name, &data[data[0] > 4 ? 020 : 03]); // use standard offset (SV.MSG vs BFMSG)
+  } else {
+    read_asciz(name, &data[data[1]]); // else get the ss name via pointer
+  }
   fprintf (stderr, "DUMPER tape #%d, %s, ", right (block[2]), name);
   print_timestamp (stderr, data[2]);
   fputc ('\n', stderr);
@@ -543,7 +556,7 @@ read_tape (FILE *f)
 	case FILL:
 	  break;
 	default:
-	  fprintf (stderr, "Uknown record type.\n");
+	  fprintf (stderr, "Unknown record type %#llo.\n", word);
 	  exit (1);
 	  break;
 	}