TweetFollow Us on Twitter

AShare UserName
Volume Number:7
Issue Number:6
Column Tag:Programmer's Forum

AppleShare Username to Chooser Name INIT

By Mark Gavin, Darby, PA

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

[ Mark Gavin is a consultant in the Philadelphia area who specializes in Macintosh software development using MacApp, Object Pascal and 68000 Assembly. He can be reached via AppleLink GAVIN.MARK. ]

INIT’s in General

It used to be that an INIT had to be loaded into the system file using ResEdit or some other resource installer. Only 32 INIT’s were allowed in the system file and you had to be aware of possible resource ID conflicts during the installation process. A while back Apple enhanced the INIT system by placing INIT 31 within the system file. The job of INIT 31 is to look in the system folder for any files of type ‘INIT’ who happen to have one or more ‘INIT’ resources. The search is in alphabetical order by filename. When INIT 31 locates an INIT resource it is called and executed as if it were a procedure (Inside Macintosh Volume IV, pp. 255-257) . INIT 31 can also allocate memory in the system heap for the INIT if you use the ‘sysz’ resource (Inside Macintosh Volume V, pg. 352). As is, INIT 31 gives you at least a 16K block within the system heap.

An INIT in it’s basic form is a stand alone code module which normally has no access to global data or anything that uses A5 relative addressing like QuickDraw. This minor inconvenience can be easily circumvented by creating your own A5 world. There is a very good explanation, and examples, of setting up your own A5 world in Apple’s Macintosh Technical Note #256, Stand-Alone Code, ad nauseam.

Network Administration and Responder

One of my clients has implemented a wide area EtherNet network which covers 15 sites with 76 zones and 56 networks throughout the United States. Network support is via Timbuktu which uses the Chooser name to identify each Mac. They also use Inter•Poll and NetMinder for network diagnostics. These, also, use the Chooser name, broadcast by the Responder.

Responder is an INIT supplied by Apple on the Macintosh System software disks. Its function is to register the Macintosh Chooser name on the AppleShare network. The Responder and the other utilities described above, play an important role in network administration by allowing us to easily locate an individual Macintosh and it’s owner on the network. The Chooser name, however, can be easily modified or deleted by the user. For example, the network administrator, located in Pennsylvania, would have trouble determining who owns a Macintosh named ‘Wizard’ located in California or Connecticut. In addition, there is no guarantee the Macintosh will have the same name tomorrow or the next day.

Placing the AppleShare username into the Chooser name appears to be the most straight forward solution to the problem of system identification and offers us several advantages:

1. Avoid burdening the user with yet one more administrative task.

2. Automatic update of Chooser name with new user.

3. The Chooser name can not be permanently modified by the user.

The AShareNameINIT

The function of the AShareNameINIT is to extract the AppleShare username from the ‘AppleShare Prep’ file and place the username in the Chooser. I have chosen not to display an ICON at startup because this INIT is a network administration tool that should not be disabled by the user. Therefore, the less obtrusive the better.

The AppleShare Prep File

Apple hasn’t released any information on the AppleShare Prep file, so this is what I have figured out thus far.

The AppleShare Prep file is created by selecting the AppleShare device within the Chooser. When the file is created it contains 4 bytes, all nil, within a single resource ‘BMLS’ 2447. The AppleShare logon name is only placed into the BMLS resource if the user chooses to have an AppleShare volume auto-logon at startup. As a side note; If you elect to have AppleShare automatically logon to a server with your name and password, the password is also placed in the AppleShare Prep file but it is not encrypted in any way. By looking at the resource with ResEdit you can read any stored password.

The AppleShare Prep file saves a username and server history when the server name changes. There does not appear to be any way of deleting information that is no longer being used by AppleShare. This history is stored in a linked list of entries. The number of entries in the file is stored in the first word of the BMLS resource. The second word of the resource contains the size of the block to follow. It is also used as an offset to the next entry in the list. Logical block size within the resource is variable according to how many server disks are mounted. The username is a 32 byte Pascal string located 20 bytes after the blocksize. Currently, the INIT uses the last name in the list of AppleShare usernames located within the BMLS resource.

The Chooser Name

The Chooser Name is located in a ‘STR ‘ resource within the System file whose ID is -16096. This is a Pascal string which is exactly 32 bytes. Any more or less may cause problems because all of the applications that use the Chooser name expect 32 bytes. Even-thought it is technically a STR resource, it would not be wise to try to fill it with a Str255.

The Code

The TYPE intPtr is used to coerce the Mac into returning a word instead of a byte as it would normally.

There is bug in the 128K and later versions of the ROM which will cause _OpenRFPerm not to pass trap discipline under TMON. When you hard code a string into the code resource, like I am doing with the ‘AppleShare Prep’ filename, _OpenRFPerm calls _RecoverHandle with a bad Master Pointer. This is the reason for calling StripAddress on the address of the filename. For a more complete explanation please refer to Technical Note #232 Strip with _OpenResFile and _OpenRFPerm.

The ENTRYPOINT Procedure and the forward declaration of the AShareNameINIT procedure are needed because of the CloseAndExit nested procedure. If the forward declaration is not used the CloseAndExit procedure will be the first procedure executed within the INIT code segment and cause all kinds of nasty things to happen; i.e., trample on the stack.

The CloseAndExit procedure could have been avoided just by using a GOTO to jump to the CloseResFile statement at the end of the procedure. However, I think the nested procedure results in cleaner looking code even-though using a GOTO is a more efficient solution in this particular case.

I like to place the About information and the compilation date directly into the executable code. MPW Pascal, however, is an optimizing compiler which will strip out all string constants or code that are not referenced. The IF statement containing the deadStrip boolean is a quick and dirty way of bypassing the MPW Pascal compiler optimization and forcing an About string and the compilation date into the executable code segment. The deadStrip boolean is needed because simply setting the IF statement to false will cause the entire IF statement to be striped from the code.

When the user sets AppleShare to autologon to a server as a Guest, the AppleShare Prep file contains a null string. If this is the case, we do not want to copy a null string into the Chooser because Responder will ask the user to name the Macintosh after each restart. This would be rather annoying to the user.

Program Flow

1. Get the vRefNum of the startup volume.

2. Open the resource fork of the AppleShare Prep file.

3. Get a handle to BMLS 2447.

4. Get a handle to STR -16096.

5. Check for data in BMLS 2447.

6. How many entries are in the linked list.

7. Offset to the last entry in the linked list.

8. Check for a nil name.

9. Copy the name to STR -16096.

10. Cleanup.

That’s all there is to it. INIT’s, in general, are relatively straight forward to write. Just be careful and test using heap scramble, purge and trap discipline.

Bibliography

Macintosh Technical Notes:

#129 _SysEnvirons: System 6.0 and Beyond.

#232 Strip with _OpenResFile and _OpenRFPerm.

#247 Giving the (Desk)Hook to INIT’s.

#256 Stand-Alone Code, ad nauseam.

Listing: ASharINIT.p

{ --------------------------
  AShareNameINIT
  
 Type   INIT
 ID16056
 Version1.5
 Wednesday, December 5, 1990 9:53:37 AM
 ©1990 by Mark Gavin
 All Rights Reserved
-------------------------- }
{$Z+} { Identify all routines to the Linker as
 external.  If this is not used then
 ENTRYPOINT must be placed in the
 INTERFACE section }
    
  UNIT _AShareNameINIT;

INTERFACE
 USES
 Types, Memory, ToolUtils,
 OSUtils, Resources, PaslibIntf, Packages;

 TYPE
 intPtr = ^integer;
 {used to retrieve an integer from the resource}
 

{$R-}   { Turn Off Range Checking }
{$OV-}  { Ignore Arithmetic Overflows }

IMPLEMENTATION

 PROCEDURE AShareNameINIT;FORWARD;


 PROCEDURE ENTRYPOINT;

 BEGIN
 AShareNameINIT;
 END;

{ ---------------------------------- }
  PROCEDURE AShareNameINIT;
 
    VAR
 str    : Str255;
 
 volNamePtr : StringPtr;
 
 theStringPtr,
 theNamePtr : Ptr;
 
 { AppleShare Prep resHdl }
 ASPResHandle,
 chooserStringHdl: Handle;
 
 ASPHandleSize   : longint;
 
 index,
 blocksize,
 resOffset,
 offsetMultiplier,
 stringLength,
 refNum,
 vRefNum,
 oldResFileRef   : integer;
 
 anError: OSErr;
 
 deadStrip: Boolean;

 { ------------------------------------ }
 PROCEDURE CloseAndExit;
 
 BEGIN  
 CloseResFile(refNum);
 UseResFile(oldResFileRef);
 EXIT(AShareNameINIT);    
 END;
 
 { ------------------------------------ }
 BEGIN  
 oldResFileRef := CurResFile;
 
 deadStrip := False;
 IF deadStrip THEN BEGIN
 str := ‘AShareNameINIT 1.5 by Mark Gavin’;
 str := compdate;
 END;

 { GetVol returns the name of the
 default volume in volNamePtr and
 its volume reference number in vRefNum. }
 
 volNamePtr := StringPtr(NewPtr(256));
 IF MemError <> noErr THEN
 EXIT(AShareNameINIT);

 anError := GetVol(volNamePtr, vRefNum);
 IF anError <> noErr THEN
 EXIT(AShareNameINIT);

 DisposPtr(Ptr(volNamePtr));
 { Ptr only needed for GetVol }

 str := ‘AppleShare Prep’;
 { StripAddress used per Tech Note 232
 - bug in OpenRFPerm }
 refNum := OpenRFPerm(StringPtr(StripAddress(@str))^, vRefNum, fsRdPerm);
 IF ResError <> noErr THEN
 EXIT(AShareNameINIT);  
 
 ASPResHandle := GetResource(‘BMLS’, 2447);
 IF ResError <> noErr THEN
 CloseAndExit; 
 HNoPurge(ASPResHandle);
 
 chooserStringHdl := GetResource(‘STR ‘, -16096);
 IF ResError <> noErr THEN
 CloseAndExit; 
 HNoPurge(chooserStringHdl);
 
 ASPHandleSize := GetHandleSize(ASPResHandle);
 IF MemError <> noErr THEN
 CloseAndExit;
 
 { Make sure there is data in the handle }
 IF ASPHandleSize < 55 THEN
 CloseAndExit; 
 
 offsetMultiplier := intPtr(ASPResHandle^)^;
 IF offsetMultiplier < 1 THEN
 CloseAndExit; 

 blockSize := intPtr(ORD4(ASPResHandle^) + 2)^;
 IF blockSize < 1 THEN
 CloseAndExit; 
 
 resOffset := 2;
 
 FOR index := 1 TO (offsetMultiplier - 1) DO
 BEGIN
 resOffset := resOffset + blockSize;
 blockSize := intPtr(ORD4(ASPResHandle^) + resOffset)^;
 IF blockSize < 1 THEN
 CloseAndExit;
 END;

 resOffset :=  resOffset + 20;
 { offset to string within block }

 theNamePtr := Ptr(ORD4(ASPResHandle^) + resOffset);
 
 IF theNamePtr^ = 0 THEN
 CloseAndExit;{ exit on nil name }
 
 theStringPtr := chooserStringHdl^;

 BlockMove(theNamePtr, theStringPtr, 32);
 
 ChangedResource(chooserStringHdl);
 WriteResource(chooserStringHdl);

 HPurge(chooserStringHdl);
 HPurge(ASPResHandle);
 
 CloseResFile(refNum);
 
 UseResFile(oldResFileRef);

   END;
 END.
Listing:  AShareINIT.make

{ -------------------------- }
#   File:       AShareNameINIT.make
#   Target:     AShareNameINIT
#   Sources:    AShareNameINIT.p
#   Created:    Monday, November 26, 1990 4:39:50 PM
#©1990 by Mark Gavin

AShareNameINIT.p.o ƒ AShareNameINIT.make AShareNameINIT.p
  Pascal  AShareNameINIT.p

SOURCES = AShareNameINIT.p
OBJECTS = AShareNameINIT.p.o

AShareNameINIT ƒƒ AShareNameINIT.make AShareNameINIT.p.o
 Link -t INIT -c ‘ASN?’ -rt INIT=16056 -ra =resLocked -sg AShareNameINIT 
-m ENTRYPOINT 
 {OBJECTS} 
 “{Libraries}”Interface.o 
 -o AShareNameINIT

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Sketch 47.1 - Design app for UX/UI for i...
Sketch is an innovative and fresh look at vector drawing. Its intentionally minimalist design is based upon a drawing space of unlimited size and layers, free of palettes, panels, menus, windows, and... Read more
Cocktail 11.0.1 - General maintenance an...
Cocktail is a general purpose utility for macOS that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Path Finder 7.6.1 - Powerful, award-winn...
Path Finder makes you a master of file management. Take full control over your file system. Save your time: compare and synchronize folders, view hidden files, use Dual Pane and full keyboard... Read more
Slack 2.8.2 - Collaborative communicatio...
Slack is a collaborative communication app that simplifies real-time messaging, archiving, and search for modern working teams. Version 2.8.2: A small release containing nothing but another Electron... Read more
Smultron 10.0.2 - Easy-to-use, powerful...
Smultron 10 is an elegant and powerful text editor that is easy to use. You can use Smultron 10 to create or edit any text document. Everything from a web page, a note or a script to any single piece... Read more
Capto 1.2.5 - $29.99
Capto (was Voila) is an easy-to-use app that takes capturing, recording, video and image editing to the next level. With an intelligent file manager and quick sharing options, Capto is perfect for... Read more
ScreenFlow 7.1.1 - Create screen recordi...
ScreenFlow is powerful, easy-to-use screencasting software for the Mac. With ScreenFlow you can record the contents of your entire monitor while also capturing your video camera, microphone and your... Read more
Xcode 9.0.1 - Integrated development env...
Xcode includes everything developers need to create great applications for Mac, iPhone, iPad, and Apple Watch. Xcode provides developers a unified workflow for user interface design, coding, testing... Read more
TotalFinder 1.10.2 - Adds tabs, hotkeys,...
TotalFinder is a universally acclaimed navigational companion for your Mac. Enhance your Mac's Finder with features so smart and convenient, you won't believe you ever lived without them. Features... Read more
Adobe Flash Player 27.0.0.170 - Plug-in...
Adobe Flash Player is a cross-platform, browser-based application runtime that provides uncompromised viewing of expressive applications, content, and videos across browsers and operating systems.... Read more

The best deals on the App Store this wee...
Happy Tuesday, dear readers. Your favorite part of the week as officially arrived. It's time to take a look at the best deals in games. Things are admittedly a bit sparse, but there are a few diamonds in the rough to see you through if you're... | Read more »
Be the last person standing in Legacy of...
Yoozoo Games’ popular action MMO Legacy of Discord is getting a huge new update to celebrate its first anniversary. Perhaps the biggest change is the addition of an exciting survival mode titled Last Guardian. This new survival mode will pit you... | Read more »
Home Street guide - how to make friends...
From the creators of Food Street comes Home Street, a new simulation game that tasks you with building a social network and designing a beautiful home. It's a bit like The Sims, but you won't have to worry about the daily chores involved (feeding,... | Read more »
Color Ballz guide - how to bounce to the...
Color Ballz is an addictive new arcade title from Ketchapp Studios. It takes old school mechanics from games like Brickles and puts a fun twist on it. Your job? To catch balls with a paddle and send them back into a chute to be carried back to... | Read more »
Q&A: A-33 Studio explains why Combat...
When it comes to mobile FPS, it’s often tricky to get the fundamentals right on a platform lacking a physical controller, large display and hefty RAM. With Combat Squad: Project Wednesday, A-33 Studio bravely took on the challenge of making a... | Read more »
Taichi Panda 3: Dragon Hunter guide - ti...
Taichi Panda 3: Dragon Hunter launched this week to players all over the world. It's a beautiful mobile MMORPG that blends elements of Eastern and Western fantasy. It reminds us of a mix between World of Warcraft and Jade Empire. MMO's can have a... | Read more »
The best new games we played this week -...
Phew. It has been a week, but now it's time to relax, put your feet up, and enjoy some brand new mobile games. It was a bit of slow week, but there's still plenty of new titles to add to your collection. Here are four of our favorites. [Read... | Read more »
Yoink - Improved Drag and Drop (Product...
Yoink - Improved Drag and Drop 1.0 Device: iOS Universal Category: Productivity Price: $2.99, Version: 1.0 (iTunes) Description: Yoink for iPad and iPhone lets you easily and quickly store items you drag, copy or share, for later use... | Read more »
Cottage Garden (Games)
Cottage Garden 1.11 Device: iOS Universal Category: Games Price: $4.99, Version: 1.11 (iTunes) Description: | Read more »
Into the Dead 2 guide - how to survive t...
Into the Dead 2 is an endless gunner, of sorts, with a lot of grit and satisfying gunplay behind it. The game looks amazing, and tells an effective story to boot. Plus, it has some quality voice acting behind it to really bring the story to life... | Read more »

Price Scanner via MacPrices.net

13″ MacBook Pros on sale for up to $120 off M...
B&H Photo has 2017 13″ MacBook Pros in stock today and on sale for up to $120 off MSRP, each including free shipping plus NY & NJ sales tax only: – 13-inch 2.3GHz/128GB Space Gray MacBook... Read more
15″ MacBook Pros on sale for up to $200 off M...
B&H Photo has 15″ MacBook Pros on sale for up to $200 off MSRP. Shipping is free, and B&H charges sales tax in NY & NJ only: – 15″ 2.8GHz MacBook Pro Space Gray (MPTR2LL/A): $2249, $150... Read more
Roundup of Apple Certified Refurbished iMacs,...
Apple has a full line of Certified Refurbished 2017 21″ and 27″ iMacs available starting at $1019 and ranging up to $350 off original MSRP. Apple’s one-year warranty is standard, and shipping is free... Read more
Sale! 27″ 3.8GHz 5K iMac for $2098, save $201...
Amazon has the 27″ 3.8GHz 5K iMac (MNED2LL/A) on sale today for $2098 including free shipping. Their price is $201 off MSRP, and it’s the lowest price available for this model (Apple’s $1949... Read more
Sale! 10″ Apple WiFi iPad Pros for up to $100...
B&H Photo has 10.5″ WiFi iPad Pros in stock today and on sale for $50-$100 off MSRP. Each iPad includes free shipping, and B&H charges sales tax in NY & NJ only: – 10.5″ 64GB iPad Pro: $... Read more
Apple iMacs on sale for up to $130 off MSRP w...
B&H Photo has 21-inch and 27-inch iMacs in stock and on sale for up to $130 off MSRP including free shipping. B&H charges sales tax in NY & NJ only: – 27″ 3.8GHz iMac (MNED2LL/A): $2179 $... Read more
2017 3.5GHz 6-Core Mac Pro on sale for $2799,...
B&H Photo has the 2017 3.5GHz 6-Core Mac Pro (MD878LL/A) on sale today for $2799 including free shipping plus NY & NJ sales tax only . Their price is $200 off MSRP. Read more
12″ 1.2GHz Space Gray MacBook on sale for $11...
Amazon has the 2017 12″ 1.2GHz Space Gray Retina MacBook on sale for $100 off MSRP. Shipping is free: 12″ 1.2GHz Space Gray MacBook: $1199.99 $100 off MSRP Read more
Bare Bones Software Releases macOS High Sierr...
Bare Bones Software has announced the release and immediate availability of BBEdit 12.0, a significant upgrade to its professional strength text and code editor. BBEdit 12 introduces a new foundation... Read more
Yale Announces Availability of Apple HomeKit-...
Yale Locks & Hardware has announced that Apple HomeKit support for its Assure Lock family is available this month. The new Yale iM1 Network Module, which provides support for the Apple Home app... Read more

Jobs Board

Lead *Apple* Solution Consultant - Apple In...
…develop a team of diverse partner employees focusing on excellence to deliver the Apple story. Even when you're not present, you will maintain a consistent influence Read more
watchOS Frameworks Engineering Manager, *App...
Job Summary Join the team that is shaping the future of software development for Apple Watch! Apple is looking for an exceptional software engineering leader to Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions - Farmin...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.