TweetFollow Us on Twitter

July 90 - Macintosh Q & A

July 90 - Macintosh Q & A

MACINTOSH DEVELOPER TECHNICAL SUPPORT

Q How can I keep track of a file the next time my application is launched?

A Technical Note #238, Getting a Full Pathname, documents the recommended method for "remembering" a file's location.

. . . you should remember the DirID of the directory the file is in along with its name. This way, you will still be able to find your file even if the directory has been moved. Under System 7.0 or later, save the file's unique 32-bit ID number as well, so that you can also find the file even if its name has changed.

To remember a file's location, keep the volume name, DirID, and filename. This information is all you need to locate any file. Standard File returns the DirID of the file in CurDirStore or the wdRefNum in the vRefNum field of the reply.record. Note that Technical Note #238 mentions how to get a file's DirID while in Standard File. Given the working directory, you can find its vRefNum and DirID by calling _GetWDInfo. Refer to Inside Macintosh, volume IV. Volume references and working directories are dynamic; they change every time the system is booted, so you cannot use the vRefNum or wdRefNum. Typically, the volume name and filename are not changed. The DirID will not change unless the user deletes the folder. Renaming the folder does not change its DirID.

First ask the user to locate the file by calling SFGetFile. Keep the volume name, DirID, and filename for this file. The next time you want to locate the file, use this same information. If you do not find the file, then again call SFGetFile asking the user to locate it.

DTS has an example application, SC.018.StdFile, which you may find helpful. You can find this in the Sample Code folder on the enclosed Developer Essentials disc.

Q How can I determine the size of my application's MultiFinder partition?

A It's really difficult to find the exact size of the memory partition that the application is running under. If it can be determined, I doubt that the effort would be worth the trouble. I think the real concern you have is the size of the available stack and heap, but not the entire partition. Since there is little that an application can do to change its partition size (except to change the 'SIZE' resource and then force a relaunch), the real concern would be to find the size of the available stack and heap. Included in the application's partition are the application parameters, jump table, application globals, and QuickDraw globals. The size of the partition is not easily determined. The only portions of an application's memory use that are adjustable at run time are the stack and the heap.The stack and heap sizes are fixed within the boundaries of the entire application partition. Increasing one decreases the other. There are Memory Manager calls to change the size of the heap. To increase the stack size, you decrease the heap's size.

Q In earlier versions of the Chooser, there was a limit of 16 volumes per server for AppleShare servers. Has this limit changed in System 6.0.4?

A The limit of 16 volumes per server in the Chooser has not changed with System 6.0.4. We hope to have a new version of the Chooser for System 7.0.

Q How do I force the Finder to update its windows after my application has changed a file's FndrInfo?

A There is no direct way to tell the Finder to update the desktop. The Finder will synchronize the desktop file's appearance after it detects that the volume's modification date has changed. Whenever you create or delete a file, or move it to another folder, the hierarchical file system (HFS) will change the modification date of the volume and that folder. When the Finder has noticed the volume's modification date has changed, it begins scanning about once every 10 seconds for changes in all of the open folders. Changing the file's FndrInfo or renaming it is not going to change the modification date. As a suggestion for an installer program, you can initially create a temporary file. Once all the files are installed you can delete the temporary file. Deleting this temporary file as a last step will cause the Finder's window to be updated.

Q My little application has two handles in memory that have been allocated. I want to lock one handle high in memory and the other one low in memory. I noticed that the Mac toolbox has the functionality to lock a handle high (MoveHHi); however, I did not notice any routine that would move the block low in memory, before a lock. I'm looking for a MoveHLow routine. Does one exist? If not, how would I go about doing this?

A There is no similar functionality for locking a handle low. The best way to go about doing this is to use NewPtr, which automatically allocates the block as low as possible. Of course, it's not a handle, but it's still a locked block as low in the heap as possible.

Another way to do this is to use ResrvMem which, as Inside Macintosh, volume 2, page 39 says, "will try every available means to place the block as close as possible to the bottom of the zone, including moving other blocks upward, expanding the zone, or purging blocks from it." Then make your call to NewHandle with the same size as requested in ResrvMem. That'll allocate the handle as low as possible.

Q How can I support multiple HFS partitions on a SCSI device?

A If at all possible, avoid trying to support partitions. We'll warn you up front that an ejectable drive that contains multiple HFS partitions is not going to be anything less than difficult. You'll be betteroff not attempting to support multiple HFS partitions. It greatly complicates the code, and there are user interface problems too. What if the user ejects one of the partitions? What should happen? This is technically difficult for the driver to handle.

If the user ejects a partition, then the driver might eject the media and mark all of its remaining partitions as off-line. If the user drags a partition to the trash, this should unmount only that partition (but then how would the user unmount the entire media?). The remaining partitions should be marked off-line and the user will see them as gray icons on the desktop. If users want to access one of these partitions, they'll get the Disk Switch alert. They need to insert the proper cartridge and the device will then post a disk insert event for every partition (because it cannot determine exactly which partition is really needed). This will again bring all partitions back. The trap _Offline should take care of all this for you, but it cannot be called at interrupt time. Therefore, the driver will need to use accRun calls to use _OffLine.

Again, the system doesn't support multiple HFS partitioned drives. It only expects to find one HFS partition on a volume. The system will attempt to read from the first HFS partition and then stop. If the first one is not bootable, then that device cannot be a startup device. If you attempt to put more than one partition on a device, then you have to perform additional hacks to mount them. Be warned that hacking this feature into your drive involves a compatibility risk.

All the work will be up to the driver. It will have to find the extra partitions and mount them. Each partition will have a drive queue entry having each element reference the same driver. When your driver's open routine is called, you call _AddDrive for each partition. This calls _Enqueue and installs each element into the drive queue. Once the driver is closed, you should remove each of the queue elements with _Dequeue.

Q I would like to write James Brown in jail, but now that he is on work release, where do I write?

A You can write the Godfather of Soul at
Lower Savannah Work Center
Route 4, Box 50
Aiken, SC 29801

Brown is serving concurrent six-year and six-year-and-three month terms for his involvement in a wild, two-state car chase in September of 1988. He won't be eligible for parole until 1992.

These questions and answers are compiled by the Macintosh Developer Technical Support group. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

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
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
iShowU Instant 1.2.0 - Full-featured scr...
iShowU Instant gives you real-time screen recording like you've never seen before! It is the fastest, most feature-filled real-time screen capture tool from shinywhitebox yet. All of the features you... Read more
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
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
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
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
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
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
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

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

Development Operations and Site Reliability E...
Development Operations and Site Reliability Engineer, Apple Payment Gateway Job Number: 57572631 Santa Clara Valley, California, United States Posted: Jul. 27, 2017 Read more
*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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.