TweetFollow Us on Twitter

December 96 - KON & BAL'S PUZZLE PAGE: Folder Fun


Konstantin Othmer and Bruce Leak

See if you can solve this programming puzzle, presented in the form of a dialog between Konstantin Othmer (KON) and Bruce Leak (BAL). The dialog gives clues to help you. Keep guessing until you're done; your score is the number to the left of the clue that gave you the correct answer. Even if you never run into the particular problems being solved here, you'll learn some valuable debugging techniques that will help you solve your own programming conundrums. And you'll also learn interesting Macintosh trivia.

KON It's you again.
BAL It seems our bid for drumming up Puzzle Page authors hasn't gone well.
KON I guess everyone's waiting for the Mac OS 8 release. From what I hear, they'll be waiting quite a while.
BAL I've got a lot of work to do. Can we get on with this?
KON OK. Have you ever heard of Retrospect Remote?
BAL Yeah, we run it. It's that backup program. It slows your machine to a crawl when it's doing its thing, but we've never had a problem with it. Our engineers don't allow it on their machines, though.
KON Apparently someone went around one morning and installed it while we were all sleeping. It's been running great for the last year, but suddenly one of the machines started showing an execution error.
BAL Easy enough. Go check out the logs and see what it's complaining about.

100KON It says folders are nested too deep on that machine. Sure enough, the machine has a folder called "<unknown name>," and inside that folder is another called "<unknown name>," and so on. It was mixed in with our project files.
BAL What system are you running?
KON A Power Mac 7100/66 with 32 MB of RAM and an 800 MB hard disk, running system version 7.1.2 -- the "last trusted system," according to Chris Derossi.
BAL What happens when you use the Finder to get info on the folder?
90 KON It says there are 99 items inside this one for zero K of disk space.
BAL Go in a level and try the same thing. Still 99 items?
KON Yep.
BAL Go in a few more levels and rename one of the folders. Come back out and go back in. Anything unusual?
KON Nope. The renamed folder kept its new name. The Finder tells you there are 99 items inside it.
BAL Just keep opening folders. How deep does it go?
80 KON After opening folders for a few minutes, you get too bored to continue.
BAL Rename every tenth folder or so, to create some landmarks. Dig down doing this. Can you Command-click on the window title and see the whole hierarchy?
KON Yes. You're doing one heck of a test on the pop-up menu manager.
BAL So, what happens?
70 KON After you do this about 150 times, the Finder displays the familiar "out of memory" message. It says you might try closing some windows to make more memory available. I have the feeling this might be one case where that advice actually works!
BAL Do a Get Info on the hard drive. How many items does it have?
KON 16,774 items on disk.
BAL Somehow I was expecting a larger number! Try copying the folder.
KON We crash.
BAL Where? Any clues?
KON In CopyDoubler.
BAL That sounds like a subject for another column. Hold down the Control key when copying the folder to tell CopyDoubler to stay out of it.
60 KON The Finder puts up the copy dialog, waits about two minutes, advances the thermometer the entire way in about three seconds, and then waits another two minutes before finishing. The copy dialog says there are 100 items to be copied. You now have two folder hierarchies.
BAL That's interesting. I've seen the Finder copy way more than 100 items at one time, but somehow its knowledge of folder nesting is limited to 99 or 100. Do a Get Info on the drive again and see how many new items were created.
KON Now there are 18,679 items on disk -- 1,905 new ones.
BAL Copy it to a file server.
55 KON OK. Now the Finder does the copy the same as before, except after the thermometer is finished, the dialog stays up, waiting for a long time.
BAL How long?
KON Suppose we go to a long dinner at the Peppermill Lounge. When we come back it still won't be done.
BAL Look at the folder hierarchy on the network from another Mac.
KON While it's still copying?
BAL Sure.
50 KON You see a bunch of folders, as you'd expect, except the network is really slow. Apparently the Finder is generating a lot of network traffic trying to create all those directories.
BAL Stop that file copy.
45 KON The Stop button in the copy dialog is highlighted (indicating that you pressed it), and the network is back to normal, but the copy dialog doesn't go away.
BAL Reboot and look at the folders in Standard File.
KON No new clues. How deep do you want do go?
BAL Hmm. Try running Norton Utilities on the disk.
KON There were a few bundle bits that are wrong. But once those are fixed, Norton says the disk is fine.
BAL Try DropStuffing the folder.
KON DropStuff crashes.
BAL Try Disk First Aid.
40 KON It tells you that the folder nesting exceeds the Finder-recommended nesting of 100. But other than that, it says the disk is fine.
BAL I guess those folders are really there. The system is running into a bunch of boundary conditions trying to deal with them. The question is how they got there, and I'm not sure how we figure that out given that all we have is a smoking gun.
KON Wait a second...the column isn't supposed to end this way!
BAL OK. I've got an idea. I'll try looking at these folders from MPW with a files -r -c command.
35 KON MPW prints out a bunch of folders and then crashes. The interesting thing is that it crashed right after printing out the 100th level down, which we know from the "rename every tenth folder" exercise we did earlier.
BAL Well, there are some mysteries that we should be able to solve. Clearly, some software on this machine created the folder called "<unknown name>," probably when a directory with a null name or some other exception condition was encountered.
BAL It's probably the Finder, the File Manager, or one of the applications that's commonly used on the machine. Let's ask Paul Mercer if he knows anything about it.
30 Paul First of all, the Finder isn't going to rename a folder on you. And second, even if it did, no one on the Finder team would give the folder a name that contains an angle bracket -- that's just too unpleasant aesthetically. Maybe the File Manager would do such a thing, though.
KON We could try Dave Feldman. I'm not sure he'd have the same issues with angle brackets that Paul has.
25 Dave No issue with angle brackets here! But the File Manager doesn't ever attempt to detect or fix damaged catalog info. It will rebuild the volume bitmap (that long pause when remounting a disk after a system crash), but it leaves everything else alone. No matter how much it's abused by the Finder, the File Manager will never surreptitiously set a folder to "<unknown name>." Tell Paul I said what does he know, he's been gone from Apple long enough to have forgotten what little he once knew about the File Manager. Furthermore, the File Manager doesn't care how deep you nest folders; that's a Finder problem.
BAL Well, the system hasn't changed much since either of those guys left Apple, so it's probably something else. Maybe you can get someone at Apple to search all the system sources and see if they can come up with a hit on "unknown name."
20 KON I talked to Jim Luther about it and he said it shows up in only one place -- the Alias Manager. Apparently the Alias Manager will store the name of the user who created the alias as part of the alias record. If a user who logs on as a guest creates an alias, the name of the alias creator is set to "unknown name," but there are no angle brackets.
BAL Let's grep the hard disk and see if we can find any hits on "<unknown name>."
KON How do you propose we do that?
BAL Have you seen AltaVista?
KON You mean the search engine on the Internet? Totally awesome. When you do a query they can instantly give you a list of the top hits from any Web site. But what does that have to do with this puzzle?
BAL Well, I figure they can search huge amounts of data way faster than we could ever do it on our local machine. So we dump the entire contents of the hard disk to a Web page, register it with AltaVista, and perform the search.
KON A little unrealistic, but not a bad idea.
BAL Ron Avitzur thought it up.
KON For those keeping score, you're approaching 15.
BAL OK, OK. I'll use Norton Disk Editor and search the whole volume for the string "<unknown name>."
15 KON The first hit is in the catalog. I get the feeling you're going to find at least 1905 of these on this disk, probably more since you duplicated the folders so many times.
BAL OK. Try it on one of your other development machines.
10 KON The string is found in a bunch of places but the sectors aren't owned by a file. But then the needle in the haystack pokes your probing finger -- you find the string in the MPW Shell application.
BAL Open up MPW Shell with ResEdit and find out which resource it's in.
KON Duh! Wrong tool for the job! ResEdit can't search the entire resource fork.
BAL OK. Use Resorcerer.
KON You find the string in CODE resource 27, called %A5Init.
BAL So, it sounds like we should contact someone in MPW land and see if they know what's going on. Here's Alex McKale; maybe he can help us.
5 Alex Sure enough, Projector will create folders with the name "<unknown name>." CheckOutDir creates a folder hierarchy that matches the project hierarchy.
BAL The project hierarchy on this machine is only three or four levels deep, not 1905! Any explanation for that?
Alex Did the machine ever crash while checking out? Maybe some script got in an infinite loop, and you hit the reset button or crashed after some time. This would mean the depth of the hierarchy is based on how long the machine was running in the loop, rather than on some magic number, such as everyone's favorite year plus 1.
KON It happened on Richard's machine. He says his Mac crashes all the time, and he'd be hard pressed to tell you what it was doing during any particular crash.
BAL Hmm. I guess we just need a plausible explanation. Any ideas, Alex?
Alex Your guess is as good as mine. CheckOutDir does very little error checking, so if the project tree got munged -- for example, if there was no terminator in the project folder hierarchy -- it would keep creating folders called "<unknown name>" until it hit a terminator. Give me a reproducible case, and this thing is dead meat.
KON No can do. I guess the exact cause will remain a mystery, along with the true nature of consciousness, the details of Jimmy Hoffa's demise, and the location of my other red sock. Well, at least we managed to narrow it down to Projector, so we can point both our accusatory fingers in the same direction. If nothing else, maybe this will get the Projector folks to add a little more error checking to CheckOutDir.
BAL Nasty.
KON Yeah.


70-100Congratulations! You win free lifetime upgrades to MPW.
45-60You win a free copy of Mac OS 8.
25-40You win a lifetime subscription to eWorld.
5-20You win a dinner with Paul and Dave.

KONSTANTIN OTHMER AND BRUCE LEAK are cashing in on the enormous popularity of the Puzzle Page by starting their own online magazine. After rejecting titles like MacsBug Life and Dead Mackerel, they've settled on Mired as the name for their daily diary of debugging. The first issue will include hard-hitting articles like "MacsBug: The Best Command-Line Interface for the Mac?" and "Celebrity dcmds." Watch for it soon in your local cybernews shop!*

Thanks to Chris Derossi, Dave Feldman, Jim Luther, Alex McKale, and Paul Mercer for reviewing this column.*


Community Search:
MacTech Search:

Software Updates via MacUpdate

Duet - Use your iPad as an exter...
Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable. Note: This app requires a $14.99 iOS companion app. Version Read more
Apple iTunes 12.5.2 - Play Apple Music a...
Apple iTunes lets you organize and stream Apple Music, download and watch video and listen to Podcasts. It can automatically download new music, app, and book purchases across all your devices and... Read more
Pinegrow Web Designer 2.95 - Mockup and...
Pinegrow Web Designer is desktop app that lets you mockup and design webpages faster with multi-page editing, CSS and LESS styling, and smart components for Bootstrap, Foundation, Angular JS, and... Read more
jAlbum Pro 13.6 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more
jAlbum 13.6 - Create custom photo galler...
With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly, with pro results - Simply drag and drop photos into groups, choose a design... Read more
TextMate 2.0-beta.12.26 - Code/markup ed...
TextMate is a versatile plain text editor with a unique and innovative feature set which caused it to win an Apple Design Award for Best Mac OS X Developer Tool in August 2006. A rapidly growing... Read more
VMware Fusion 8.5.1 - Run Windows apps a...
VMware Fusion 8 and Fusion 8 Pro--the latest versions of its virtualization software for running Windows on a Mac without rebooting--include full support for Windows 10, OS X El Capitan, and the... Read more
Apple Final Cut Pro X 10.3 - Professiona...
Apple Final Cut Pro X is a professional video editing solution.Completely redesigned from the ground up, Final Cut Pro adds extraordinary speed, quality, and flexibility to every part of the post-... Read more
Civilization VI 1.0.0 - Next iteration o...
Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
Paperless 2.3.7 - $49.95
Paperless is a digital documents manager. Remember when everyone talked about how we would soon be a paperless society? Now it seems like we use paper more than ever. Let's face it - we need and we... Read more

Latest Forum Discussions

See All

Roofbot: Puzzler On The Roof (Games)
Roofbot: Puzzler On The Roof 1.0.2 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.2 (iTunes) Description: Guide Roofie through gorgeous, meditative rooftops and try to get the right color energy balls into the... | Read more »
The 4 best food delivery apps
As the temperatures continue to drop, so does the motivation to venture outside. Sometimes you still want to eat a nice meal from that sushi place down the road though. Thankfully in these trying times, there are a number of fine food delivery... | Read more »
Toca Life: Farm (Education)
Toca Life: Farm 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: Work and play the farmer's way! Milk your cow, gather eggs from your hens and raise your crops. Have a picnic, play the... | Read more »
The Lost Shield (Games)
The Lost Shield 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: The Lost shield is a brick break/adventure game. You play as a hero who must return a powerful but dangerous magic shield... | Read more »
The Forgotten Room (Games)
The Forgotten Room 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: Play as paranormal investigator John “Buster of Ghosts” Murr as he explores yet another mysteriously creepy house. This... | Read more »
5 Halloween mobile games for wimps
If you're anything like me, horror games are a great way to have nightly nightmares for the next decade or three. They're off limits, but perhaps you want to get in on the Halloween celebrations in some way. Fortunately not all Halloween themed... | Read more »
The 5 scariest mobile games
It's the most wonderful time of the year for people who enjoy scaring themselves silly with haunted houses, movies, video games, and what have you. Mobile might not be the first platform you'd turn to for quality scares, but rest assured there are... | Read more »
Lifeline: Flatline (Games)
Lifeline: Flatline 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: The Lifeline series takes a terrifying turn in this interactive horror experience. Every decision you make could help... | Read more »
Game of Dice is now available on Faceboo...
After celebrating its anniversary in style with a brand new update, there’s even more excitement in store for Game of Dice has after just being launched on Facebook Gameroom. A relatively new platform, Facebook Gameroom has been designed for PC... | Read more »
4 addictive clicker games like Best Fien...
Clickers are passive games that take advantage of basic human psychology to suck you in, and they're totally unashamed of that. As long as you're aware that this game has been created to take hold of your brain and leave you perfectly content to... | Read more »

Price Scanner via

Apple Unveils Redesigned MacBook Pro With Tou...
October 27, 2016 – Apple today introduced the thinnest and lightest MacBook Pro yet, along with a new interface innovation that replaces the traditional row of function keys with a Retina-quality... Read more
Apple Unveils New TV App for Apple TV, iPhone...
October 27, 2016 – Apple today introduced a new TV app, offering a unified experience for discovering and accessing TV shows and movies from multiple apps on Apple TV, iPhone and iPad. The TV app... Read more
Price drops on select refurbished 2015 13″ Re...
Apple dropped prices on select Certified Refurbished 2015 13″ Retina MacBook Pros by as much as $90. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz/256GB... Read more
Apple reveals new next-generation 15″ and 13″...
Apple today revealed their next-generation 15″ and 13″ MacBook Pros. The new models are thinner and lighter than before with a new aluminum design featuring an enhanced keyboard with retina, multi-... Read more
Worldwide Smartphone Shipments Up 1.0% Year o...
According to preliminary results from the International Data Corporation (IDC) Worldwide Quarterly Mobile Phone Tracker, vendors shipped a total of 362.9 million smartphones worldwide in the third... Read more
TuneBand Arm Band For iPhone 7 and 7 Plus Rel...
Grantwood Technology has added the TuneBand for iPhone 7 and 7 Plus to its smartphone armband series. The TuneBand provides a lightweight and comfortable way to wear the iPhone while running,... Read more
1.4GHz Mac mini on sale for $449, save $50
Adorama has the 1.4GHz Mac mini on sale for $50 off MSRP including free shipping plus NY & NJ sales tax only: - 1.4GHz Mac mini (Apple sku# MGEM2LL/A): $449 $50 off MSRP To purchase a mini at... Read more
21-inch 1.6GHz iMac on sale for $999, save $1...
B&H has the 21″ 1.6GHz Apple iMac on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more
Macs’ Superior Enterprise Deployment Cost Eco...
IBM’s debunking of conventional wisdom and popular mythology about the relative cost of using Apple Mac computers as opposed to PCs running Microsoft Windows at the sixth annual Jamf Nation User... Read more
12-inch WiFi Apple iPad Pros on sale for $50-...
B&H Photo has 12″ WiFi Apple iPad Pros on sale for $50-$70 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off MSRP -... Read more

Jobs Board

*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
Software Engineering Intern: UI Applications...
Job Summary Apple is currently seeking enthusiastic interns who can work full-time for a minimum of 12-weeks between Fall 2015 and Summer 2016. Our software Read more
Security Data Analyst - *Apple* Information...
…data sources need to be collected to allow Information Security to better protect Apple employees and customers from a wide range of threats.Act as the subject 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
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 52812872 Houston, Texas, United States Posted: Oct. 18, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Solutions Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.