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

ExpanDrive 4.3.2 - 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
RapidWeaver 6.0.8 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
Artlantis Studio 5.1.2.7 - 3D rendering...
Artlantis Studio is a unique and ideal tool for performing very high resolution rendering easily and in real time. The new FastRadiosity engine now lets you compute images in radiosity-even in... Read more
MacUpdate Desktop 6.0.5 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
BitTorrent Sync 2.0.82 - Sync files secu...
BitTorrent Sync allows you to sync unlimited files between your own devices, or share a folder with friends and family to automatically sync anything. File transfers are encrypted. Your information... Read more
Google Drive 1.20 - File backup and shar...
Google Drive is a place where you can create, share, collaborate, and keep all of your stuff. Whether you're working with a friend on a joint research project, planning a wedding with your fiancé, or... Read more
Simon 4.0.3 - Monitor changes and crashe...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
Vitamin-R 2.23 - Personal productivity t...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
iDefrag 5.0.0 - 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
PCalc 4.2 - Full-featured scientific cal...
PCalc is a full-featured, scriptable scientific calculator with support for hexadecimal, octal, and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit... Read more

Warner Bros. Interactive Entertainment A...
Warner Bros. has some exciting games coming down the pipe! | Read more »
GDC 2015 – Star Trek Timelines will Prob...
GDC 2015 – Star Trek Timelines will Probably Make Your Inner Trekkie Squeal With Glee Posted by Rob Rich on March 4th, 2015 [ permalink ] Any popular fictional universe has its fair share of fan fiction – where belo | Read more »
Protect Yourself from an Onslaught of Ca...
Surprise Attack Games has announced a Cat-astrophic new physics puzzler called Fort Meow! In the game, a young girl named Nia finds her grandfather’s journal which triggers an all mighty feline attack! Why do the cats want the journal? Who knows,... | Read more »
GDC 2015 – Jelly Reef will be Game Oven’...
GDC 2015 – Jelly Reef will be Game Oven’s Last Hurrah, and it Seems like a Good Note to Go Out on Posted by Rob Rich on March 4th, 2015 [ permalink ] It’s sad knowing that Game Oven ( | Read more »
daWindci Deluxe Review
daWindci Deluxe Review By Campbell Bird on March 4th, 2015 Our Rating: :: BLUSTERY PUZZLESUniversal App - Designed for iPhone and iPad This updated puzzle game offers some creative gameplay and new mechanics, but still suffers from... | Read more »
Dungeon Hunter 5 Coming on March 12
Gameloft has excitedly announced that Dungeon Hunter 5 is on its way! Once again, you will adventure across the land of Valenthia exploring dungeons and fighting monsters. The game will have a new asynchronous multiplayer mode called Strongholds... | Read more »
GDC 2015 – The Sandbox 2 is Coming, and...
GDC 2015 – The Sandbox 2 is Coming, and Now it has Textures! | Read more »
Warner Bros. Interactive Announces Mort...
Mortal Kombat X, by Warner Bros. and NetherRealm Studios, will be a a free-to-play fighting/card-battle Mortal Kombat game. The game promises card collecting, multiplayer team combat, classic characters such as Scorpion, Sub-Zero and Raiden, and the... | Read more »
GDC 2015 – Piloteer is Whitaker Trebella...
GDC 2015 – Piloteer is Whitaker Trebella’s Latest Project, and it’s Definitely Something DIfferent Posted by Rob Rich on March 3rd, 2015 [ permalink ] You know | Read more »
PangoLand Review
PangoLand Review By Amy Solomon on March 3rd, 2015 Our Rating: :: COME VISIT PANGO AND FRIENDSUniversal App - Designed for iPhone and iPad PangoLand is an open-ended world full of familiar characters, bright colors and interactive... | Read more »

Price Scanner via MacPrices.net

Roundup of MacBook Air sale prices, models up...
B&H Photo has MacBook Airs on sale for up to $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 11″ 128GB MacBook Air: $799 100 off MSRP - 11″ 256GB MacBook Air: $999 $100... Read more
New Firstrade Mobile App Enables On-The-Go Tr...
Firstrade Securities Inc. has announced its new mobile app, which gives investors immediate access to the company’s trading platform on all mobile devices. The app was developed in-house and was... Read more
Sonnet Introduces USB 3.0 + eSATA Thunderbolt...
Sonnet has announced the launch of its new USB 3.0 + eSATA Thunderbolt Adapter for easy connectivity to USB 3.0 devices and eSATA storage, and USB 3.0 + Gigabit Ethernet Thunderbolt Adapter for easy... Read more
Apple restocks refurbished 27-inch 5K iMacs f...
The Apple Store has restocked Apple Certified Refurbished 27″ 3.5GHz 5K iMacs for $2119 including free shipping. Their price is $380 off the cost of new models, and it’s the lowest price available... Read more
Free Clean Reader Mobile App Hides Swear Word...
The new Clean Reader app, now available in the Apple App Store and Google Play, delivers the opportunity of reading any book without being exposed to profanity. By selecting how clean they want their... Read more
Kinsa Launches “Groups” App to Monitor Illnes...
Kinsa, makers of the first FDA approved app-enabled smartphone thermometer thst won the 2013 Cleveland Clinic Medical Innovation Grand Prize and recently appeared in Apple’s “Parenthood” TV... Read more
iPad: A More Positive Outlook – The ‘Book Mys...
It’s good to hear someone saying positive things about the iPad. I’ve been trying to bend my mind around how Apple’s tablet could have gone from zero to bestselling personal computing device on the... Read more
Mac Pros on sale for up to $279 off MSRP
Amazon has Mac Pros in stock and on sale for up to $279 off MSRP. Shipping is free: - 4-Core Mac Pro: $2725.87, $273 off MSRP (9%) - 6-Core Mac Pro: $3719.99, $279 off MSRP (7%) Read more
Sale! 13-inch Retina MacBook Pros for up to $...
B&H Photo has 13″ Retina MacBook Pros on sale for up to $205 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.6GHz/128GB Retina MacBook Pro: $1219.99 save $80 - 13″ 2.... Read more
Another Tranche Of IBM MobileFirst For iOS Ap...
IBM has announced the next expansion phase for  its IBM MobileFirst for iOS portfolio, with a troika of new apps to address key priorities for the Banking and Financial Services, Airline and Retail... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
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
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
Position Opening at *Apple* - Apple (United...
…Summary** As a Specialist, you help create the energy and excitement around Apple products, providing the right solutions and getting products into customers' hands. You Read more
Position Opening at *Apple* - Apple (United...
**Job Summary** The Apple Store is a retail environment like no other - uniquely focused on delivering amazing customer experiences. As an Expert, you introduce people Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.