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

Apple Safari 11.0 - Apple's Web bro...
Note: The direct download link is currently unavailable. It is available in the OS X 10.12.6 release, as well as in the Apple Security Updates. Apple Safari is Apple's web browser that comes with... Read more
Xcode 9.0 - Integrated development envir...
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
BetterTouchTool 2.302 - Customize Multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Apple iOS 11 - The latest version of App...
iOS 11 sets a new standard for what is already the world’s most advanced mobile operating system. It makes iPhone better than before. It makes iPad more capable than ever. And now it opens up both to... Read more
NTFS 15.0.911 - $19.95
NTFS breaks down the barriers between Windows and macOS. Paragon NTFS effectively solves the communication problems between the Mac system and NTFS. Write, edit, copy, move, delete files on NTFS... Read more
Airfoil 5.6.3 - Send audio from any app...
Airfoil allows you to send any audio to AirPort Express units, Apple TVs, and even other Macs and PCs, all in sync! It's your audio - everywhere. With Airfoil you can take audio from any... Read more
ExpanDrive 6.0.16 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Smultron 9.4.2 - Easy-to-use, powerful t...
Smultron 9 is an elegant and powerful text editor that is easy to use. Use it to create or edit any text document. Everything from a web page, a note or a script to any single piece of text or code.... Read more
Typinator 7.3 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
coconutBattery 3.6.4 - Displays info abo...
With coconutBattery you're always aware of your current battery health. It shows you live information about your battery such as how often it was charged and how is the current maximum capacity in... Read more

The best games to play while you wait fo...
SteamWorld Dig 2 is out this week on PC and Switch, and people are understandably excited. This clever series by Image and Form combines our favorite metroidvania mechanics with an esquisite universe, excellent storytelling, and true wit. While... | Read more »
Drag'n'Boom beginner's gu...
Have you ever wanted to burn and pillage a village as a bloodthirsty dragon? If you answered yes to that question, Drag'n'Boom offers you the perfect chance to do so, casting you as an adorable little dragon that wants to set humankind aflame. It... | Read more »
Thimbleweed Park (Games)
Thimbleweed Park 1.0.0 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.0 (iTunes) Description: A brand new adventure game from Ron Gilbert and Gary Winnick, creators of the classics Monkey Island and Maniac Mansion!... | Read more »
The best simulation games on mobile
There's nothing like a good sim -- from the seemingly ridiculous to the incredibly mundane, you can be there's a simulation game out there for your every whim. [Read more] | Read more »
INKS guide - how to create works of pinb...
INKS puts a clever new spin on everyone's favorite classic arcade game, pinball. The core mechanics are the same -- keep a little ball pinging around the board for as long as possible without letting it fall into the precarious holes in the board.... | Read more »
Warbands: Bushido (Games)
Warbands: Bushido 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: Warbands:Bushido is a miniatures board game with cards, miniatures, dice and beautiful terrains to fight on, with both... | Read more »
The best mobile games like Divinity: Ori...
Divinity: Original Sin 2 launched this week to the excitement of RPG fans everywhere. The game, which derives a lot of of its story and mechanics from old-school isometric RPGs and Dungeons & Dragons, has unseated PlayerUnknown's... | Read more »
Iron Marines guide - beginner tips and t...
Iron Marines is a brilliant RTS title that feels a bit like Starcraft. It's got a sci-fi setting and some of the most spectacular strategy mechanics we've seen in mobile games to date. With that said, the RTS genre can be a bit tricky to break... | Read more »
The best new games we played this week -...
The work week can be tough, but on the bright side, it's almost overandthere are bunches of brand new games to try out this weekend. This week definitely makes up for last week's sleepiness ten-fold. We've got one of the finest RTS game on mobile... | Read more »
Through the Ages (Games)
Through the Ages 1.0.60 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.60 (iTunes) Description: The offical adaptation of Vlaada Chvátil’s strategy classic, the second best board game ever by Board Game Geek website... | Read more »

Price Scanner via MacPrices.net

Apple Refurbished 3TB Time Capsule for $279,...
Apple has Certified Refurbished 3TB Time Capsules available for $279 including free shipping plus Apple’s standard one-year warranty. Their price is $120 off MSRP. Read more
19% off Smart Battery Cases for iPhone 7
Amazon has both Black and White Smart Battery Cases for iPhone 7s available for $80.41 including free shipping. Their price is $18.59, or 19%, off MSRP. Read more
Back on sale: 10.5-inch 64GB iPad Pros for $5...
MacMall has 10.5″ 64GB Apple iPad Pros on sale again for $599 including free shipping. That’s $50 off MSRP and the lowest price available for this model from any reseller. Read more
Verizon offers Certified Preowned 16GB iPhone...
Verizon has the 16GB iPhone 6, Certified Preowned, available for $259.99 or $10.83 per month for 24 months. Service plan required. According to Verizon, “All CPO devices have been reconditioned to... Read more
Preorder new iPhone 8 at US Cellular, and tak...
Preorder the new iPhone 8 or iPhone 8 Plus at US Cellular, and take $50 off the prepaid price: – 64GB iPhone 8: $649.99 – 128GB iPhone 8: $799.99 – 64GB iPhone 8 Plus: $749.99 – 128GB iPhone 8 Plus... Read more
12-inch and 9-inch Apple iPad Pros, Certified...
Apple has Certified Refurbished 2016 12″ WiFi iPad Pros available starting at $589. An Apple one-year warranty is included with each model, and shipping is free: – 32GB 12″ iPad Pro WiFi: $589... Read more
QuickerTek Announces Solar PV Chargers for US...
Wichita, Kansas based QuickerTek has announced its new 30 Watt and 60 Watt USB Type-C Solar Juicz Chargers. These solar panels are the only products of their kind, featuring the USB 3.1 adapter cable... Read more
Apple refurbished 128GB iPhone 6s and 6s Plus...
Apple has Certified Refurbished 128GB iPhone 6s and 6s Plus’ available for up to $100 off the price of new models. Space Gray, Silver, Gold, and Rose Gold models are available. Each phone comes... Read more
13-inch 2.3GHz Silver MacBook Pros on sale fo...
B&H Photo has 2017 13″ 2.3GHz Silver MacBook Pros in stock today and on sale for $100 off MSRP, each including free shipping plus NY & NJ sales tax only: – 13-inch 2.3GHz/128GB Silver... Read more
12-inch 64GB iPad Pros available for $749, $5...
MacMall has 12″ 64GB iPad Pros on sale for $749 including free shipping. Their price is $50 off MSRP. Read more

Jobs Board

*Apple* Solutions Consultant - Apple Inc. (U...
…about helping others on a team while also delighting customers? As an Apple Solutions Consultant (ASC), you will discover customers needs and help connect them Read more
Software/Data Engineer, *Apple* Media Produ...
Job Summary Apple Media Products is the team behind the App Store, Apple Music, iTunes, and many other high profile products on iPhone, Mac and AppleTV. Our Data Read more
SW Engineer , *Apple* Media - Apple Inc. (U...
Job Summary Our team is responsible for exposing Apple Media content and services to the world, and building the infrastructure for next generation internal and Read more
*Apple* Data Center Site Selection and Strat...
Job Summary As Apple 's products and services scale the globe, the Data Center Affairs team works behind the scenes to secure infrastructure for Apple 's data Read more
*Apple* Professional Learning Specialist - A...
Job Summary The Apple Professional Learning Specialist is a full-time position for one year with Apple in the Yuma, AZ area. This position requires a high Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.