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

TunnelBear 3.5.1 - Subscription-based pr...
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
Typinator 7.4 - 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
Monosnap 3.4.9 - Versatile screenshot ut...
Monosnap lets you capture screenshots, share files, and record video and .gifs! Features Capture Capture full screen, just part of the screen, or a selected window Make your crop area pixel... Read more
Fantastical 2.4.5 - Create calendar even...
Fantastical 2 is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event... Read more
TunnelBear 3.5.1 - Subscription-based pr...
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
Typinator 7.4 - 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
Fantastical 2.4.5 - Create calendar even...
Fantastical 2 is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event... Read more
Monosnap 3.4.9 - Versatile screenshot ut...
Monosnap lets you capture screenshots, share files, and record video and .gifs! Features Capture Capture full screen, just part of the screen, or a selected window Make your crop area pixel... Read more
Skim 1.4.32 - PDF reader and note-taker...
Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file. Skim includes many features and has a... Read more
ForkLift 3.1.1 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more

Latest Forum Discussions

See All

What mobile gaming can learn from the Ni...
While Nintendo might not have had things all its own way since it began developing for mobile, one thing it has got right is the release of the Switch. After the disappointment of the WiiU, which I still can't really explain, the Switch felt a... | Read more »
Programmer of Sonic The Hedgehog launche...
Japanese programmer Yuji Naka is best known for leading the team that created the original Sonic The Hedgehog. He’s moved on from the speedy blue hero since then, launching his own company based in Tokyo – Prope Games. Legend of Coin is the... | Read more »
Why doesn't mobile gaming have its...
The Overwatch League is a pretty big deal. It's an attempt to really push eSports into the mainstream, by turning them into, well, regular sports. But slightly less sweaty. It's a lavish affair with teams from all around the world, and more... | Read more »
Give Webzen’s new billiard game PoolTime...
Best known for producing hugely popular MMO titles, South Korean publisher Webzen is now taking aim at a different genre altogether. PoolTime is a realistic eight ball pool simulator, allowing you to compete in real-time matches against players... | Read more »
Let Them Come Guide - How to survive aga...
Let Them Come is all about making it as far as possible against overwhelming odds. Check out some of these tips to help you last a little longer in your unwinnable fight: [Read more] | Read more »
All the best games on sale for iPhone an...
Happy last day of the week. I hope you've been having a good one. I have. I saw ten doggos today. So because I'm in a good mood, I thought I'd round up all of the best games that are currently on sale on the App Store. [Read more] | Read more »
The very best games that came out for iP...
We're getting to the end of the first real, full, proper week of 2018. And in that time we've seen some pretty awesome games landing on the App Store. Of course, we've seen some absolute duffers as well. The sort of games that you look at and... | Read more »
Rusty Lake Paradise (Games)
Rusty Lake Paradise 1.4 Device: iOS Universal Category: Games Price: $2.99, Version: 1.4 (iTunes) Description: Jakob, the oldest son of the Eilander family, is returning to Paradise island after his mother passed away. Since her... | Read more »
Antihero Guide - Sneaky tricks to get ah...
Games of Antihero start out small and streamlined, but they quickly turn into long strategic conquests as you fight for control of the Victorian-era streets. If you find yourself struggling in the skullduggery department, here are a few things you... | Read more »
Here's why Niantic pulling Pokemon...
If there's one thing that Pokemon GO did well, it was bringing people together. I still remember seeing groups of people around the marina near where I live in the weeks after the game came out, all of them trying to grab some water Pokemon. There... | Read more »

Price Scanner via MacPrices.net

10″ iPad Pros on sale for $50-$75 off MSRP, n...
B&H Photo has 10″ and #Apple #iPad Pros on sale for up to $75 off MSRP. Shipping is free, and B&H charges sales tax in NY & NJ only. Note that some sale prices are restricted to certain... Read more
Apple refurbished Mac minis available startin...
Apple has restocked Certified Refurbished Mac minis starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: – 1.4GHz Mac mini: $419 $80 off MSRP – 2.6GHz Mac... Read more
Amazon offers Silver 13″ Apple MacBook Pros f...
Amazon has new Silver 2017 13″ #Apple #MacBook Pros on sale today for up to $150 off MSRP, each including free shipping: – 13″ 2.3GHz/128GB Silver MacBook Pro (MPXR2LL/A): $1199.99 $100 off MSRP – 13... Read more
Sale: 12″ 1.3GHz MacBooks on sale for $1499,...
B&H Photo has Space Gray and Rose Gold 12″ 1.3GHz #Apple MacBooks on sale for $100 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 12″ 1.3GHz Space... Read more
Apple offers Certified Refurbished 2017 iMacs...
Apple has a full line of Certified Refurbished iMacs available for up to $350 off original MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available: – 27... Read more
13″ MacBook Airs on sale for $120-$100 off MS...
B&H Photo has 2017 13″ 128GB MacBook Airs on sale for $120 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 1.8GHz/128GB MacBook Air (MQD32LL/A): $... Read more
15″ Touch Bar MacBook Pros on sale for up to...
Adorama has Space Gray 15″ MacBook Pros on sale for $200 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 15″ 2.8GHz MacBook Pro Space Gray (MPTR2LL/A): $2199, $200 off... Read more
21″ 3.4GHz 4K iMac on sale for $1399, $100 of...
Adorama has the 21″ 3.4GHz 4K #Apple #iMac on sale today for $1399. Their price is $100 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: – 21″ 3.4GHz 4K iMac (MNE02LL/A... Read more
B&H offering 13″ Apple MacBook Pros for u...
B&H Photo has 13″ MacBook Pros on sale for up to $75-$120 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz/128GB Space Gray MacBook Pro (... Read more
B&H continues to offer clearance 2016 15″...
B&H Photo has clearance 2016 15″ #MacBook Pros available for up to $800 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: – 15″ 2.7GHz Touch Bar MacBook Pro... Read more

Jobs Board

Commerce Engineer, *Apple* Media Products -...
# Commerce Engineer, Apple Media Products Job Number: 113161479 Santa Clara Valley, California, United States Posted: 01-Nov-2017 Weekly Hours: 40.00 **Job Summary** 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
Site Reliability Engineer, *Apple* Pay - Ap...
# Site Reliability Engineer, Apple Pay Job Number: 113356036 Santa Clara Valley, California, United States Posted: 12-Jan-2018 Weekly Hours: 40.00 **Job Summary** Read more
UI Tools and Automation Engineer, *Apple* M...
# UI Tools and Automation Engineer, Apple Media Products Job Number: 86351939 Santa Clara Valley, California, United States Posted: 11-Jan-2018 Weekly Hours: 40.00 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.