From b9511ec83f0bafd9c492f769ce1cf3de4ec37bfd Mon Sep 17 00:00:00 2001
From: Olivier Galibert <galibert@pobox.com>
Date: Fri, 19 Feb 2021 17:55:21 +0100
Subject: [PATCH] mfi: Don't crash on a fully unformatted disk

---
 src/lib/formats/mfi_dsk.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/lib/formats/mfi_dsk.cpp b/src/lib/formats/mfi_dsk.cpp
index df60e5aeec0..049660272a3 100644
--- a/src/lib/formats/mfi_dsk.cpp
+++ b/src/lib/formats/mfi_dsk.cpp
@@ -115,10 +115,14 @@ bool mfi_format::load(io_generic *io, uint32_t form_factor, const std::vector<ui
 	io_generic_read(io, &h, 0, sizeof(header));
 	int resolution = h.cyl_count >> RESOLUTION_SHIFT;
 	h.cyl_count &= CYLINDER_MASK;
+
 	io_generic_read(io, &entries, sizeof(header), (h.cyl_count << resolution)*h.head_count*sizeof(entry));
 
 	image->set_form_variant(h.form_factor, h.variant);
 
+	if(!h.cyl_count)
+		return true;
+
 	std::vector<uint8_t> compressed;
 
 	entry *ent = entries;