From 41944a04bd2597acab10f8a47ea1c5ba50d1cd08 Mon Sep 17 00:00:00 2001
From: barberd <46797210+barberd@users.noreply.github.com>
Date: Sun, 28 Mar 2021 23:02:31 -0400
Subject: [PATCH] Add files via upload

---
 mfsextract.py | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 mfsextract.py

diff --git a/mfsextract.py b/mfsextract.py
new file mode 100644
index 0000000..48216a5
--- /dev/null
+++ b/mfsextract.py
@@ -0,0 +1,134 @@
+#!/usr/bin/env python3
+
+#Created by Don Barber, don@dgb3.net
+#Pass the raw disk image on the command line as argument 1
+#add verbose as argument 2 if you want some extra details
+
+#MFS implementation details from https://www.macgui.com/news/article.php?t=482
+
+#If the image is a diskcopy 4.2 image, extract the raw MFS image first via:
+# dd if=INPUTFILE of=OUTPUTFILE bs=84 skip=1
+
+#Idea for improvement: extract files as macbinary format instead of
+#individual data and resource forks
+
+import sys
+import os
+import math
+
+filename=sys.argv[1]
+
+file_size = os.path.getsize(filename)
+fh=open(filename,"r+b")
+
+fh.seek(1026)
+
+drCrDate = int.from_bytes(fh.read(4),'big')
+drLsBkUp = int.from_bytes(fh.read(4),'big')
+drAtrb=int.from_bytes(fh.read(2),'big')
+drNmFls=int.from_bytes(fh.read(2),'big')
+drDirSt=int.from_bytes(fh.read(2),'big')
+drBlLen=int.from_bytes(fh.read(2),'big')
+drNmAlBlks=int.from_bytes(fh.read(2),'big')
+drAlBlkSiz=int.from_bytes(fh.read(4),'big')
+drClpSiz=int.from_bytes(fh.read(4),'big')
+drAlBlSt=int.from_bytes(fh.read(2),'big')
+drNxtFNum=int.from_bytes(fh.read(4),'big')
+drFreeBks=int.from_bytes(fh.read(2),'big')
+drVNl=int.from_bytes(fh.read(1),'big')
+drVN=fh.read(drVNl)
+print("Volume Name:",drVN)
+if 'verbose' in sys.argv:
+    print("Volume Create Datestamp:",drCrDate)
+    print("Volume Modify Datestamp:",drLsBkUp)
+
+maplocation=0x440
+
+def getmapentry(blocknum):
+    location=((blocknum-2)*12/8)
+    if location==math.ceil(location):
+        fh.seek(maplocation+int(location))
+        entry=(int.from_bytes(fh.read(2),'big') >> 4)
+    else:
+        fh.seek(maplocation+math.floor(location))
+        entry=(int.from_bytes(fh.read(2),'big') & 0xFFF )
+    return entry
+
+def getfilecontents(block,length):
+    blocklist=[block]
+    while True:
+        block=getmapentry(block)
+        #print(block)
+        if block==1:
+            break
+        blocklist.append(block)
+        if block==0:
+            raise Exception("Unused Block")
+    if 'verbose' in sys.argv:
+        print("Blocklist:",blocklist)
+    contents=b''
+    for block in blocklist:
+        if 'verbose' in sys.argv:
+            print("Seeking to:",hex(drAlBlSt*512+(block-2)*drAlBlkSiz),"for block",block)
+        fh.seek(drAlBlSt*512+(block-2)*drAlBlkSiz)
+        data=fh.read(drAlBlkSiz)
+        contents+=data
+    return contents[:length]
+
+fh.seek(drDirSt*512)
+i=0
+while True:
+    flFlgs=fh.read(1)
+    if flFlgs==b'\x00':
+        fh.read(50)
+        i+=50
+    else:
+        flType=int.from_bytes(fh.read(1),'big')
+        flUsrWds=fh.read(16)
+        flFlNum=int.from_bytes(fh.read(4),'big')
+        flStBlk=int.from_bytes(fh.read(2),'big')
+        flLgLen=int.from_bytes(fh.read(4),'big')
+        flPyLen=int.from_bytes(fh.read(4),'big')
+        flRStBlk=int.from_bytes(fh.read(2),'big')
+        flRLgLen=int.from_bytes(fh.read(4),'big')
+        flRPyLen=int.from_bytes(fh.read(4),'big')
+        flCrDat=int.from_bytes(fh.read(4),'big')
+        flMdDat=int.from_bytes(fh.read(4),'big')
+        flNaml=int.from_bytes(fh.read(1),'big')
+        flNam=fh.read(flNaml)
+        i+=51+flNaml
+        if flFlNum!=0:
+            print(hex(fh.tell()),flFlNum,flNaml,flNam)
+            if 'verbose' in sys.argv:
+                print("Create Datestamp:",flCrDat)
+                print("Modify Datestamp:",flMdDat)
+            location=fh.tell()
+            oh=open(flNam+b".info","wb")
+            oh.write(flUsrWds)
+            oh.close()
+
+            if(flStBlk==0 and flRStBlk==0):
+                print("Error:",flNam,"has neither data nor resource fork")
+            if flStBlk!=0:
+                content=getfilecontents(flStBlk,flLgLen)
+                oh=open(flNam+b".data","wb")
+                oh.write(content)
+                oh.close()
+            if flRStBlk!=0:
+                content=getfilecontents(flRStBlk,flRLgLen)
+                oh=open(flNam+b".rsrc","wb")
+                oh.write(content)
+                oh.close()
+            fh.seek(location)
+    if (fh.tell()%2==1):
+        fh.read(1)
+        i+=1
+    if i>512:
+        fh.seek(math.floor(fh.tell()/512)*512)
+        i=0
+    if fh.tell()>=((drDirSt+drBlLen-1)*512):
+        break
+
+fh.close()
+
+