From 0bd31039497db49d7435976c78b0494a314a1955 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 24 Nov 2020 18:19:34 -0500
Subject: [PATCH] Wires in the most common IIgs style of 2MG.

---
 Storage/Disk/DiskImage/Formats/2MG.cpp        | 11 ++++++---
 .../Disk/DiskImage/Formats/MacintoshIMG.cpp   | 24 ++++++++++++-------
 .../Disk/DiskImage/Formats/MacintoshIMG.hpp   |  8 +++++--
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/Storage/Disk/DiskImage/Formats/2MG.cpp b/Storage/Disk/DiskImage/Formats/2MG.cpp
index 7b85c9e95..a2fd936b0 100644
--- a/Storage/Disk/DiskImage/Formats/2MG.cpp
+++ b/Storage/Disk/DiskImage/Formats/2MG.cpp
@@ -8,6 +8,8 @@
 
 #include "2MG.hpp"
 
+#include "MacintoshIMG.hpp"
+
 using namespace Storage::Disk;
 
 DiskImageHolderBase *Disk2MG::open(const std::string &file_name) {
@@ -56,7 +58,12 @@ DiskImageHolderBase *Disk2MG::open(const std::string &file_name) {
 			// TODO: DOS 3.3 sector order.
 		break;
 		case 1:
-			// TODO: ProDOS sector order.
+			// ProDOS order, which could still mean Macintosh-style or Apple II-style. Try them both.
+			try {
+				return new DiskImageHolder<Storage::Disk::MacintoshIMG>(file_name, MacintoshIMG::FixedType::GCR, data_start, data_size);
+			} catch(...) {}
+
+			// TODO: Apple II-style.
 		break;
 		case 2:
 			// TODO: NIB data (yuck!).
@@ -67,8 +74,6 @@ DiskImageHolderBase *Disk2MG::open(const std::string &file_name) {
 	// a proper holder? Probably more valid than having each actual disk class do
 	// its own range logic?
 	(void)flags;
-	(void)data_start;
-	(void)data_size;
 
 	throw Error::InvalidFormat;
 	return nullptr;
diff --git a/Storage/Disk/DiskImage/Formats/MacintoshIMG.cpp b/Storage/Disk/DiskImage/Formats/MacintoshIMG.cpp
index 5fc7f5006..074ac94f5 100644
--- a/Storage/Disk/DiskImage/Formats/MacintoshIMG.cpp
+++ b/Storage/Disk/DiskImage/Formats/MacintoshIMG.cpp
@@ -23,13 +23,15 @@
 
 using namespace Storage::Disk;
 
-MacintoshIMG::MacintoshIMG(const std::string &file_name, FixedType type) :
+MacintoshIMG::MacintoshIMG(const std::string &file_name, FixedType type, size_t offset, off_t length) :
 	file_(file_name) {
 
 	switch(type) {
 		case FixedType::GCR:
-			construct_raw_gcr();
+			construct_raw_gcr(offset, length);
 		break;
+		default:
+			throw Error::InvalidFormat;
 	}
 }
 
@@ -49,7 +51,7 @@ MacintoshIMG::MacintoshIMG(const std::string &file_name) :
 		if(!((name_length == 0x4c && magic_word == 0x4b) || (name_length == 0x00 && magic_word == 0x00)))
 			throw Error::InvalidFormat;
 
-		construct_raw_gcr();
+		construct_raw_gcr(0, -1);
 	} else {
 		// DiskCopy 4.2 it is then:
 		//
@@ -120,13 +122,17 @@ MacintoshIMG::MacintoshIMG(const std::string &file_name) :
 	}
 }
 
-void MacintoshIMG::construct_raw_gcr() {
+void MacintoshIMG::construct_raw_gcr(size_t offset, off_t size) {
 	is_diskCopy_file_ = false;
-	if(file_.stats().st_size != 819200 && file_.stats().st_size != 409600)
+	if(size == -1) {
+		size = file_.stats().st_size;
+	}
+	if(size != 819200 && size != 409600)
 		throw Error::InvalidFormat;
 
-	file_.seek(0, SEEK_SET);
-	if(file_.stats().st_size == 819200) {
+	raw_offset_ = long(offset);
+	file_.seek(raw_offset_, SEEK_SET);
+	if(size == 819200) {
 		encoding_ = Encoding::GCR800;
 		format_ = 0x22;
 		data_ = file_.read(819200);
@@ -300,8 +306,8 @@ void MacintoshIMG::set_tracks(const std::map<Track::Address, std::shared_ptr<Tra
 		std::lock_guard lock_guard(file_.get_file_access_mutex());
 
 		if(!is_diskCopy_file_) {
-			// Just dump out the new sectors. Grossly lazy, possibly worth improving.
-			file_.seek(0, SEEK_SET);
+			// Just dump out the entire disk. Grossly lazy, possibly worth improving.
+			file_.seek(raw_offset_, SEEK_SET);
 			file_.write(data_);
 		} else {
 			// Write out the sectors, and possibly the tags, and update checksums.
diff --git a/Storage/Disk/DiskImage/Formats/MacintoshIMG.hpp b/Storage/Disk/DiskImage/Formats/MacintoshIMG.hpp
index 3a2a3d521..c1abb1abb 100644
--- a/Storage/Disk/DiskImage/Formats/MacintoshIMG.hpp
+++ b/Storage/Disk/DiskImage/Formats/MacintoshIMG.hpp
@@ -38,8 +38,11 @@ class MacintoshIMG: public DiskImage {
 			Constructs a @c MacintoshIMG without attempting to autodetect whether this is a raw
 			image or a Disk Copy 4.2 image; if GCR is specified and the file size checks out then
 			it is accepted as a GCR image.
+
+			If @c offset and @c length are specified and non-zero, only that portion of the file
+			will be modified.
 		*/
-		MacintoshIMG(const std::string &file_name, FixedType type);
+		MacintoshIMG(const std::string &file_name, FixedType type, size_t offset = 0, off_t length = -1);
 
 		// implemented to satisfy @c Disk
 		HeadPosition get_maximum_head_position() final;
@@ -66,7 +69,8 @@ class MacintoshIMG: public DiskImage {
 		std::mutex buffer_mutex_;
 
 		uint32_t checksum(const std::vector<uint8_t> &, size_t bytes_to_skip = 0);
-		void construct_raw_gcr();
+		void construct_raw_gcr(size_t offset, off_t length);
+		long raw_offset_ = 0;
 };
 
 }