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

TextSoap 8.4.1 - Automate tedious text d...
TextSoap can automatically remove unwanted characters, fix up messed up carriage returns, and do pretty much anything else that we can think of to text. Save time and effort. Be more productive. Stop... Read more
Backblaze 4.3.0.44 - Online backup servi...
Backblaze is an online backup service designed from the ground-up for the Mac. With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Numi 3.15 - Menu-bar calculator supports...
Numi is a calculator that magically combines calculations with text, and allows you to freely share your computations. Numi combines text editor and calculator Support plain English. For example, '5... Read more
EtreCheck 3.3.3 - For troubleshooting yo...
EtreCheck is an app that displays the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to... Read more
BusyContacts 1.1.8 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
TunnelBear 3.0.14 - Subscription-based p...
TunnelBear is a subscription-based virtual private network (VPN) service and companion app, enabling you to browse the internet privately and securely. Features Browse privately - Secure your data... Read more
Apple Final Cut Pro X 10.3.4 - Professio...
Apple Final Cut Pro X is a professional video editing solution.Completely redesigned from the ground up, Final Cut Pro adds extraordinary speed, quality, and flexibility to every part of the post-... Read more
Hopper Disassembler 4.2.1- - Binary disa...
Hopper Disassembler is a binary disassembler, decompiler, and debugger for 32-bit and 64-bit executables. It will let you disassemble any binary you want, and provide you all the information about... Read more
Slack 2.6.2 - Collaborative communicatio...
Slack is a collaborative communication app that simplifies real-time messaging, archiving, and search for modern working teams. Version 2.6.2: Fixed Inexplicably, context menus and spell-check... Read more
Arq 5.8.5 - Online backup to Google Driv...
Arq is super-easy online backup for Mac and Windows computers. Back up to your own cloud account (Amazon Cloud Drive, Google Drive, Dropbox, OneDrive, Google Cloud Storage, any S3-compatible server... Read more

Latest Forum Discussions

See All

The best new games we played this week
We were quite busy this week. A bunch of big mobile games launched over the past few days, alongside a few teeny surprises. There're lots of quality games to load your phone with. We've gone and picked out five of our favorites for the week. [... | Read more »
Magikarp Jump beginner's guide
Magikarp Jump is a mystifying little game. Part Tamagotchi, part idle clicker, there's not a whole lot of video game there, per se, but for some reason we can't help coming back to it again and again. Your goal is to train up a little Magikarp to... | Read more »
Goat Simulator PAYDAY (Games)
Goat Simulator PAYDAY 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: ** IMPORTANT - SUPPORTED DEVICES **iPhone 4S, iPad 2, iPod Touch 5 or better Goat Simulator: Payday is the most... | Read more »
GRID Autosport delayed until autumn
Sorry mobile racing fans -- GRID Autosport has been delayed a few months. The game is now expected to launch this fall on iOS. Feral Interactive announced that they wanted more time to work on the game's UI and overall performance before launching... | Read more »
Zombie Gunship Survival Beginner's...
The much anticipated Zombie Gunship Survival is here. In this latest entry in the Zombie Gunship franchise, you're tasked with supporting ground troops and protecting your base from the zombie horde. There's a lot of rich base building fun, and... | Read more »
Mordheim: Warband Skirmish (Games)
Mordheim: Warband Skirmish 1.2.2 Device: iOS Universal Category: Games Price: $3.99, Version: 1.2.2 (iTunes) Description: Explore the ruins of the City of Mordheim, clash with other scavenging warbands and collect Wyrdstone -... | Read more »
Mordheim: Warband Skirmish brings tablet...
Legendary Games has just launched Mordheim: Warband Skirmish, a new turn-based action game for iOS and Android. | Read more »
Magikarp Jump splashes onto Android worl...
If you're tired ofPokémon GObut still want something to satisfy your mobilePokémon fix,Magikarp Jumpmay just do the trick. It's out now on Android devices the world over. While it looks like a simple arcade jumper, there's quite a bit more to it... | Read more »
Purrfectly charming open-world RPG Cat Q...
Cat Quest, an expansive open-world RPG from former Koei-Tecmo developers, got a new gameplay trailer today. The video showcases the combat and exploration features of this feline-themed RPG. Cat puns abound as you travel across a large map in a... | Read more »
Jaipur: A Card Game of Duels (Games)
Jaipur: A Card Game of Duels 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: ** WARNING: iPad 2, iPad Mini 1 & iPhone 4S are NOT compatible. ** *** Special Launch Price for a limited... | Read more »

Price Scanner via MacPrices.net

Memorial Day savings: 13-inch Touch Bar MacBo...
B&H Photo has the 2016 Apple 13″ Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: - 13″ 2.9GHz/512GB... Read more
Apple refurbished 13-inch MacBook Airs availa...
Apple has Certified Refurbished 2016 13″ MacBook Airs available starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: - 13″ 1.6GHz/8GB/128GB MacBook Air: $... Read more
Apple restocks refurbished 11-inch MacBook Ai...
Apple has Certified Refurbished 11″ MacBook Airs (the latest models recently discontinued by Apple), available for up to $170 off original MSRP. An Apple one-year warranty is included with each... Read more
12-inch 1.2GHz Retina MacBooks on sale for up...
B&H has 12″ 1.2GHz Retina MacBooks on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: - 12″ 1.2GHz Space Gray Retina MacBook: $1449.99 $150 off... Read more
15-inch 2.7GHz Silver Touch Bar MacBook Pro o...
MacMall has the 15-inch 2.7GHz Silver Touch Bar MacBook Pro (MLW82LL/A) on sale for $2569 as part of their Memorial Day sale. Shipping is free. Their price is $230 off MSRP. Read more
Free Tread Wisely Mobile App Endorsed By Fath...
Just in time for the summer driving season, Cooper Tire & Rubber Company has announced the launch of a new Tread Wisely mobile app. Designed to promote tire and vehicle safety among teens and... Read more
Commercial Notebooks And Detachable Tablets W...
Worldwide shipments of personal computing devices (PCDs), comprised of traditional PCs (a combination of desktop, notebook, and workstations) and tablets (slates and detachables), are forecast to... Read more
Best value this Memorial Day weekend: Touch B...
Apple has Certified Refurbished 2016 15″ and 13″ MacBook Pros available for $230 to $420 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2.6GHz... Read more
13-inch MacBook Airs on sale for up to $130 o...
Overstock.com has 13″ MacBook Airs on sale for up to $130 off MSRP including free shipping: - 13″ 1.6GHz/128GB MacBook Air (sku MMGF2LL/A): $869.99 $130 off MSRP - 13″ 1.6GHz/256GB MacBook Air (sku... Read more
2.8GHz Mac mini available for $973 with free...
Adorama has the 2.8GHz Mac mini available for $973, $16 off MSRP, including a free copy of Apple’s 3-Year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax in NY & NJ... Read more

Jobs Board

*Apple* Media Products - Commerce Engineerin...
Apple Media Products - Commerce Engineering Manager Job Number: 57037480 Santa Clara Valley, California, United States Posted: Apr. 18, 2017 Weekly Hours: 40.00 Job Read more
Best Buy *Apple* Computing Master - Best Bu...
**509643BR** **Job Title:** Best Buy Apple Computing Master **Location Number:** 001482- Apple Valley-Store **Job Description:** **What does a Best Buy Apple Read more
*Apple* Media Products - Commerce Engineerin...
Apple Media Products - Commerce Engineering Manager Job Number: 57037480 Santa Clara Valley, California, United States Posted: Apr. 18, 2017 Weekly Hours: 40.00 Job Read more
*Apple* Mac and Mobility Engineer - Infogrou...
Title: Apple Mac and Mobility Engineer Location: Portland, OR Area Type: 12 month contract Job: 17412 Here's a chance to take your skills to the limit, learn new Read more
*Apple* Retail - Multiple Positions, White P...
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.