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

MacFamilyTree 8.1.3 - Create and explore...
MacFamilyTree gives genealogy a facelift: modern, interactive, convenient and fast. Explore your family tree and your family history in a way generations of chroniclers before you would have loved.... Read more
WhiteCap 6.6 - Visual plug-in for iTunes...
WhiteCap is a sleek and sophisticated music visualizer and screensaver that features futuristic, wireframe mesh visuals with dynamic backgrounds and colors. WhiteCap contains thousands of visual... Read more
VOX 2.8.14 - Music player that supports...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
Paparazzi! 1.0b2 - Make user-defined siz...
Paparazzi! is a small utility for OS X that makes screenshots of webpages. This very simple tool takes screenshots of websites which do not fit on one screen. You specify the desired width, minimal... Read more
Carbon Copy Cloner 4.1.13 - Easy-to-use...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
TrailRunner 3.8.832 - Route planning for...
TrailRunner is the perfect companion for runners, bikers, hikers, and all people wandering under the sky. Plan routes on a geographical map. Import GPS or workout recordings and journalize your... Read more
VueScan 9.5.65 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Adobe Illustrator CC 2017 21.0.2 - Profe...
Illustrator CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Illustrator customer). Adobe Illustrator CC 2017 is the industry... Read more
iDefrag 5.1.7 - Disk defragmentation and...
iDefrag helps defragment and optimize your disk for improved performance. Features include: Supports HFS and HFS+ (Mac OS Extended). Supports case sensitive and journaled filesystems. Supports... Read more
Quicken 4.4.2 - Complete personal financ...
Quicken makes managing your money easier than ever. Whether paying bills, upgrading from Windows, enjoying more reliable downloads, or getting expert product help, Quicken's new and improved features... Read more

5 dastardly difficult roguelikes like th...
Edmund McMillen's popular roguelike creation The Binding of Isaac: Rebirth has finally crawled onto mobile devices. It's a grotesque dual-stick shooter that tosses you into an endless, procedurally generated basement as you, the pitiable Isaac,... | Read more »
Last week on PocketGamer
Welcome to a weekly feature looking back on the past seven days of coverage on our sister website, PocketGamer. It’s taken a while for 2017 to really get going, at least when it comes to the world of portable gaming. Thank goodness, then, for... | Read more »
ROME: Total War - Barbarian Invasion set...
To the delight of mobile strategy fans, Feral Interactive released ROME: Total War just a few months ago. Now the game's expansion, Barbarian Invasion is marching onto iPads as a standalone release. [Read more] | Read more »
Yuri (Games)
Yuri 1.0 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: It's night. Yuri opens his eyes. He wakes up in a strange forest.The small, courageous explorer rides on his bed on casters in this... | Read more »
Space schmup Xenoraid launches on the Ap...
10Tons Xenoraid is out today on the App Store, bringing some high-speed space action to your mobile gadgets just in time for the weekend. The company's last premium title, another sci-fi game titled Neon Chrome, did quite well for itself, so... | Read more »
Star Wars: Force Arena Beginner's G...
Star Wars: Force Arena joined the populous ranks of Star Wars games on mobile today. It's a two-lane MOBA starring many familiar faces from George Lucas's famed sci-fi franchise. As with most games of this nature, Force Arena can be a little obtuse... | Read more »
Mysterium: The Board Game (Games)
Mysterium: The Board Game 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: The official adaptation of the famous board game Mysterium! | Read more »
Sonny (Games)
Sonny 1.0.4 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.4 (iTunes) Description: Reimagined for iOS, cult-hit RPG Sonny brings challenging turn-based combat that requires strategy and mastery of each new skill to... | Read more »
Towaga (Games)
Towaga 1.0 Device: iOS iPhone Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: "It has been foretold that a masked being would stand atop the legendary Towaga Temple, dwelling among shadows to fulfil The Black Moon... | Read more »
Bubble Witch 3 Saga Guide: How to get th...
King's bringing its fairytale bubble-popping puzzler back for its 3rd outing in Bubble Witch 3 Saga. If you're familiar with the series, not much has changed here on the surface level, though you'll likely be pleased with the improvements. If you'... | Read more »

Price Scanner via MacPrices.net

New 2016 13-inch MacBook Pros on sale for up...
B&H Photo has the new 2016 13″ MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.9GHz/512GB Touch Bar MacBook Pro... Read more
New 15-inch Touch Bar MacBook Pros in stock a...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
Opera Announces Neon Concept Browser For Mac
Opera is inviting users to get a glimpse of what Opera for computers could become with its Opera Neon browser concept. Each Opera Neon feature is described as “an alternate reality” for the Opera... Read more
Tellini Releases TabView 3.0 Missing Tool fo...
Tellini has announced the release of TabView 3.0. TabView has been the first macOS viewer for PowerTab tablatures. PowerTab is a well-known and widely adopted tablature editor for Windows systems and... Read more
13-inch 1.6GHz/128GB MacBook Air on sale for...
Overstock.com has the 1.6GHz/128GB 13″ MacBook Air on sale for $130 off MSRP including free shipping: - 13″ 1.6GHz/128GB MacBook Air (MMGF2LL/A): $869.99 $130 off MSRP Their price is the lowest... Read more
12-inch 32GB Space Gray iPad Pro on sale for...
B&H Photo has 12″ Space Gray 32GB WiFi Apple iPad Pros on sale for $55 off MSRP including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $744.44 $55 off... Read more
9-inch 32GB Space Gray iPad Pro on sale for $...
B&H Photo has the 9.7″ 32GB Space Gray Apple iPad Pro on sale for $549 for a limited time. Shipping is free, and B&H charges NY sales tax only. Read more
Apple iMacs on sale for up to $120 off MSRP,...
B&H Photo has 21″ and 27″ Apple iMacs on sale for up to $120 off MSRP, each including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2199 $100 off MSRP - 27″ 3.2GHz/1TB Fusion iMac... Read more
Apple refurbished Apple TVs available for up...
Apple has Certified Refurbished 32GB and 64GB Apple TVs available for up to $30 off the cost of new models. Apple’s standard one-year warranty is included with each model, and shipping is free: -... Read more
1.4GHz Mac mini, refurbished, available for $...
The Apple Store has Apple Certified Refurbished 1.4GHz Mac minis available for $419. Apple’s one-year warranty is included, and shipping is free. Their price is $80 off MSRP, and it’s the lowest... Read more

Jobs Board

*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Stamford, CT We have immediate job openings for several Desktop Support Technicians with one of our most well-known Read more
*Apple* macOS Systems Integration Administra...
…most exceptional support available in the industry. SCI is seeking an Junior Apple macOS systems integration administrator that will be responsible for providing Read more
*Apple* Premier Retailer - Service Technicia...
DescriptionSimply Mac is the largest premier retailer for Apple products and solutions. At Simply Mac we are all Apple , all the time. Same products. Same prices. Read more
*Apple* Premier Retailer - Service Technicia...
DescriptionSimply Mac is the largest premier retailer for Apple products and solutions. At Simply Mac we are all Apple , all the time. Same products. Same prices. Read more
*Apple* Premier Retailer - Service Manager -...
DescriptionSimply Mac is the largest premier retailer for Apple products and solutions. At Simply Mac we are all Apple , all the time. Same products. Same prices. Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.