TweetFollow Us on Twitter

Blessed Folder
Volume Number:5
Issue Number:9
Column Tag:HyperChat™

Related Info: File Manager (PBxxx)

The Blessed Folder

By Donald Koscheka, Arthur Young & Co., MacTutor Contributing Editor

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

A colleague related an interesting experience that occurred to him at MacHacks this year. He asked an Apple Engineer whether he could mount Appleshare volumes under program control. The engineer asked him why he’d want to and went on to explain that it’s simply not something you do. If you need to mount Appleshare volumes, use the chooser.

This struck me as odd because I’ve always believed that your programs should be able to do anything that the user can do.

Imagine some inexperienced user being told that “the server has unexpectedly shut down”. Consider the options that this error message presents to the uninitiated: Ask someone what’s going on, call Apple’s customer service department or read the manual.

Each one of these options punishes the user for a mistake that he or she did not make! Why not have a little task running somewhere that tries to reconnect the user and, failing that, alerts the poor soul that they may have to visit the chooser to regain access to the server?

Perhaps too many people at Apple are falling into that old trap of believing in everything they read. The human interface guidelines should be just that, guidelines. When you start taking guidelines as gospel, you start closing the door on creativity and intuition.

It seems to me that the good people at Apple need to spend less time saying “You can’t do that” and spend more time asking, “Why can’t you do that?”

The file manager is another area where the Macintosh tends to dump problems in the user’s lap. Consider the “Where is ...” dialog that pops up in Hypercard from time to time. Imagine how intimidating that must be to the neophyte, “If the computer can’t find it, I’m sure not going to have any luck”.

A better user interface might suggest to the user that the Mac can search the disk on the user’s behalf. It might take a while, but if the user doesn’t have a clue as to where some file is, time really doesn’t become an issue.

The problem with the file manager is that it relies too heavily on the user. Giving control to the user is a wonderful idea. Nonetheless, the user should be able to delegate tasks like searching back to the Macintosh.

Perhaps you need to store a preferences or help file somewhere. If the user moves this file on you, are you supposed to pop a dialog asking the user to find the file for you again? Of course not, you’re going to store the file in a folder that you’re guaranteed to have access to at all times. That folder is the blessed folder, so called because it contains the system file and startup application (typically the Finder). All you need is access to the blessed folder under program control and your problem is solved.

Fortunately, Apple does have a champion for developers who would like to unload some of the file management stuff from the user. Jim Friedlander has published many useful tech notes for developer technical services describing how to do things like finding that blessed folder.

Listing 1 adds an interesting spin to this blessed folder business. This XCMD, called Volumes, returns a list of all mounted volumes. The volumes XCMD uses a handy little routine called pStrToField that adds a pascal format string to the end of a zero-terminated run of text. It’s a useful way of adding names that you get from the toolbox which are almost always Pascal strings to a container that you can return to Hypercard.

If you’re building a list, terminate each item with the ‘\r’ (carriage return) character. If you are building items, then use a comma. If you don’t want any delimiters, then pass a ‘\0’.

Because pStrToField is a general purpose routine, you should add it to whatever library you use to store such routines. If you are a regular reader of this column, you know that I use a file called “HyperUtils.c” for such routines.

Retrieving the list of volumes is simple. Set some index counter to 1. Then repeatedly call PBHGetVinfo with the following fields set in the parameter block:

  ioNamePtr = pointer to a string to store the name in
  ioVRefNum  = -1, tell file manager to use the volume index.
  ioVolIndex= your index counter.  

Keep incrementing ioVolIndex until PBHGetVInfo returns an error. That’s a good indication that no more volumes were found.

Each time that pbHGetVInfo succeeds, the name of the found volume will be returned in ioNamePtr as a Pascal string. We tack the obligatory colon to the end of this name and then add the new string to the volume list that we’re building in vList.

After all is said and done, we set the last character in the container to 0 because Hypercard expects containers to be null terminated.

Knowing the names of all mounted volumes may not seem useful at first blush but given a little time, I’m sure you’ll find many interesting ways to use this XCMD.

Once we know all the volume names on line, we can find all the blessed folders. A blessed folder is one that contains the system and startup application (usually the finder). You can find the blessed folder by inspection; it’s the one whose folder contains a very small image of a Macintosh.

Knowing the blessed folder does have applicability in very many cases. Perhaps your XCMD expects to store a preferences file in the blessed folder. At any rate, knowing how to find the blessed folder should be a part of every Mac programmer’s repertoire. The XCMD in listing 2, BlessedFolder, does just that. It’s based on tech note #129 by Jim Friedlander.

Note that this time we use PBHGetvinfo with the volume reference set to 0 and the index set to -1. By passing the name of a volume, we are telling the file manager to look up information about this volume using its name rather than a reference number or index.

The information returned by PBHGetVinfo gets a little fuzzy here. One of the fields returned is ioVFndrInfo which is an array of 8 ling integers. The first entry in this array is the id of the blessed folder. I’m sure this array is documented somewhere in tech notes and if you want to further explore this information, that’s a good place to start since IM volume IV seems to gloss over this field.

Once we know the directory id of the blessed folder, we can pass it to, climbtree (published last month), to reconstruct the full pathname of this folder. Climbtree works just as well for folders as it does for files. We start climbtree off with the directory id of the blessed folder which was assigned to theCPB.dirInfo.ioDrDirID. Climbtree also needs a volume reference number which we pass via ioVRefNum.

Climbtree requires that you declare a CInfoPBRec somewhere before calling it. This is because Climbtree is recursive, and I didn’t want stack space being consumed by a declaration of the relatively large catalog info record with each activation. If you’re a purist, you might take your chances with the heap and create a nonrelocatable block in each activation. If 8K seems like too much stack space to you, go ahead and declare theCPB as an automatic of climbtree.

This month’s XCMDs fall into the category of “Now that I have them, what can I do with them”. Play around for a while and see what you discover on your own. In the meantime, I’ll be cooking up some useful applications for these XCMDs.

/************************************/
/* File: Volumes.c */
/* */
/* Return a list of all on-line  */
/* Takes no input and returns */
/* a carrieage return delimited  */
/* list of all volumes currently */
/* on line*/
/* */
/* --------------------------------*/
/* ©1989, Donald Koscheka */
/* All Rights Reserved    */
/************************************/

#include<MacTypes.h>
#include<OSUtil.h>
#include<MemoryMgr.h>
#include<FileMgr.h>
#include<ResourceMgr.h>
#include<pascal.h>
#include<hfs.h>
#include<string.h>
#include  “HyperXCmd.h”
#include“HyperUtils.h”

#define nil 0L

char    colon[2] = “\p:”;

short pStrToField( str, delim, list )
 char *str; 
 char delim;
 Handle list;
/*********************************
* Given a pascal string, append it to
* the end of the handle passed in list
* which is assumed to be a valid handle
* of length >= 0.
*
* delim is some character to stick on the
* end of the string to delimit it.
* if you want to build a list for presentation
* in a field, pass ‘\r’ as the delimiter
*
* If you are building items pass a comma
* 
* A value of 0 for delim is ignored.  Pass
* 0 when you don’t want a delimiter.
*********************************/
{
 long   strlen;/* length of input string*/
 long   oldHSize;/* size of input handle*/
 char   *end;  /* pointer to end of data     */
 
 strlen = str[0];/* length of string is in first byte*/
 oldHSize = GetHandleSize( list );
 
 SetHandleSize( list, oldHSize + strlen );
 end = *list + oldHSize;

 BlockMove( (char *)&str[1] , end, strlen );
 
 if( delim ){
 oldHSize = GetHandleSize( list );
 SetHandleSize( list, oldHSize + 1 );
 end = *list + oldHSize;
 *end = delim;
 } 
}

pascal void main( paramPtr )
 XCmdBlockPtr  paramPtr;
{
 short  index;
 long   len; 
 char   *end;
 HParamBlockRec  theHPB;
 Handle vlist;
 char   vol_Name[256];
 OSErr  err;

 colon[0] = 1;
 colon[1] = ‘:’;
 
 /*** empty is the default answer ***/
 vlist = NewHandle( 0L );

 /*** Search for every volume that is on-line***/
 index = 1;
 do{  /*** Appeal to the volume manager      ***/
 /*** for the name of each volume  ***/
 /*** that is known to it ***/

 vol_Name[0] = ‘\0’;
 theHPB.volumeParam.ioNamePtr = (StringPtr)vol_Name;     
 theHPB.volumeParam.ioVRefNum = (short)-1;         
 theHPB.volumeParam.ioVolIndex   = index;                      
 err = PBHGetVInfo( &theHPB, 0);
 
 if ( !err ){/** Add each Volume to List **/
 Concat( vol_Name, colon );
 pStrToField( (char *)&vol_Name, ‘\r’, vlist );
 index += 1;
 }
 }while (err == noErr);

 /*** once done, tack a 0 onto the end of vlist ***/
 len = GetHandleSize( vlist );
 SetHandleSize( vlist, len+1 );
 end = *vlist + len;
 *end = ‘\0’;
 
 paramPtr->returnValue = vlist;
}

Listing 1. Volumes.c


/************************************/
/* File: Blessed Folder.c */
/* */
/* Given the name of a volume */
/* in params[0]  */
/* returns the id of the  */
/* blessed folder. */
/* --------------------------------*/
/* Based on tech note #129*/
/* by Jim Friedlander*/
/************************************/

#include<MacTypes.h>
#include<OSUtil.h>
#include<MemoryMgr.h>
#include<FileMgr.h>
#include<ResourceMgr.h>
#include<pascal.h>
#include<hfs.h>
#include<string.h>
#include  “HyperXCmd.h”
#include“HyperUtils.h”

#define nil 0L

char    colon[2] = “\p:”;
pascal void main( paramPtr )
 XCmdBlockPtr  paramPtr;
{
long    sid;/*** id of  blessed folder ***/
HParamBlockRec theHPB;  
CInfoPBRectheCPB;/**to reconstruct path name**/
char    vName[256];/*** volume we’re checking      ***/
char    fullPath[256];
OSErr   err;

 HLock( paramPtr->params[0] );
 ZeroToPas( paramPtr, *(paramPtr->params[0]), &vName );
 HUnlock( paramPtr->params[0] );
 /*** Given the name of a volume,  ***/
 /*** try to get the volume reference***/
 /*** number     ***/
 theHPB.volumeParam.ioNamePtr = (StringPtr)vName;  
 theHPB.volumeParam.ioVRefNum = (short)0;          
 theHPB.volumeParam.ioVolIndex = -1; 
 err = PBHGetVInfo( &theHPB, 0);

  fullPath[0] = ‘\0’;
 if ( !err ){
 theCPB.dirInfo.ioFDirIndex = -1;
 theCPB.dirInfo.ioDrDirID =theHPB.volumeParam.ioVFndrInfo[0]; 
 theCPB.dirInfo.ioVRefNum   = theHPB.volumeParam.ioVRefNum;    
 fullPath[0] = ‘\0’; 
 ClimbTree(theCPB.dirInfo.ioDrDirID,
 (CInfoPBPtr)&theCPB, (char *)fullPath );
 }
 paramPtr->returnValue = PasToZero( paramPtr, fullPath );
}

Listing 2. BlessedFolder.c

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Airfoil 5.1.2 - Send audio from any app...
Airfoil allows you to send any audio to AirPort Express units, Apple TVs, and even other Macs and PCs, all in sync! It's your audio - everywhere. With Airfoil you can take audio from any... Read more
Firefox 49.0.1 - Fast, safe Web browser.
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more
Default Folder X 5.0.7 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click on... Read more
Safari Technology Preview 10.1 - The new...
Safari Technology Preview contains the most recent additions and improvements to WebKit and the latest advances in Safari web technologies. And once installed, you will receive notifications of... Read more
Pinegrow Web Designer 2.94 - 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
ExpanDrive 5.4.1 - 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
MacUpdate Desktop 6.1.3 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click app 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... Read more
VOX 2.8.6 - Music player that supports m...
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
Espionage 3.6.6 - Simple, state-of-the-a...
Espionage offers state-of-the-art encryption and plausible deniability for your confidential data. Sometimes, encrypting your data isn't enough to protect it. That's why Espionage 3 goes beyond data... Read more
VOX 2.8.6 - Music player that supports m...
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

3 tips for catching the gnarliest waves...
Like a wave breaking on the shore, Tidal Rider swept its way onto the App Store charts this week settling firmly in the top 10. It’s a one-touch high score-chaser in which you pull surfing stunts while dodging seagulls and collecting coins. The... | Read more »
The beginner's guide to destroying...
Age of Heroes: Conquest is 5th Planet Games’ all new turn-based multiplayer RPG, full of fantasy exploration, guild building, and treasure hunting. It’s pretty user-friendly as far as these games go, but when you really get down to it, you’ll find... | Read more »
Infinite Tanks (Games)
Infinite Tanks 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: | Read more »
Agatha Christie - The ABC Murders (FULL)...
Agatha Christie - The ABC Murders (FULL) 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Agatha Christie: The ABC Murders Your weapon is your knowledge. Your wits will be put to the ultimate... | Read more »
HeadlessD (Games)
HeadlessD 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: HeadlessD is hand-painted dungeon crawler with intuitive touch controls and NO in-app purchases. | Read more »
Leaf for Twitter (Social Networking)
Leaf for Twitter 1.0.1 Device: iOS iPhone Category: Social Networking Price: $4.99, Version: 1.0.1 (iTunes) Description: | Read more »
Banner Saga 2 (Games)
Banner Saga 2 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: The epic award winning story-based role-playing game continues its emotional journey across a breaking world. Lead your Viking... | Read more »
Concrete Jungle (Games)
Concrete Jungle 1.16 Device: iOS Universal Category: Games Price: $4.99, Version: 1.16 (iTunes) Description: A follow up to the puzzle hit 'MegaCity'! Concrete Jungle is a new take on the city building genre that swaps micro-... | Read more »
5 great apps for the budget traveller
Travelling abroad, or even within your home country, has never been easier thanks to our handy smartphone companions. There are hundreds of apps on the market that promise to make your world journeys hassle-free, but we've selected five of the... | Read more »
Zip—Zap (Games)
Zip—Zap 1.01 Device: iOS Universal Category: Games Price: $1.99, Version: 1.01 (iTunes) Description: Touch to contract.Release to let go.Bring the clumsy mechanical beings home. · · · over 100 levelsno adsno in-app-purchases Zip—... | Read more »

Price Scanner via MacPrices.net

12-inch 32GB WiFi iPad Pros on sale for $50 o...
B&H Photo has 12″ 32GB WiFi Apple iPad Pros on sale for $50 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
Recent price drops on refurbished iPad minis...
Apple recently dropped prices on several Certified Refurbished iPad mini 4s and 2s as well as iPad Air 2s. An Apple one-year warranty is included with each model, and shipping is free: - 16GB iPad... Read more
Apple refurbished Mac minis available startin...
Apple has Certified Refurbished Mac minis available 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
13-inch 2.5GHz MacBook Pro available for $928...
Overstock has the 13″ 2.5GHz MacBook Pro available for $927.99 including free shipping. Their price is $171 off MSRP. Read more
Buying McLaren Would Give Apple Instant Car C...
Apple “iCar” rumors have waxed and waned over the years, piquing interest and speculation as to whether Apple is seriously interested in getting into the automotobile business, either in a joint... Read more
Aetna to Transform Members’ Consumer Health E...
Health care benefits company Aetna, which has an estimated 46.3 million clients, today announced a new initiative to revolutionize members consumer health experience by combining the power of iOS... Read more
USB-IF Announces USB Audio Device Class 3.0 S...
USB Implementers Forum (USB-IF), the support organization for the advancement and adoption of USB technology, today announced the USB Audio Device Class 3.0 specification to establish USB Audio over... Read more
Clearance 12-inch 1.2GHz Retina MacBooks, App...
Apple has Certified Refurbished 2015 12″ 1.2GHz Retina MacBooks available for $1189, or $410 off original MSRP. Apple will include a standard one-year warranty with each MacBook, and shipping is free... Read more
Logitech SmartDock and Skype For Business Com...
Logitech has announced Logitech SmartDock, an AV meeting room solution designed in collaboration with Microsoft. Logitech SmartDock works with Skype for Business and qualified devices, including... Read more
27-inch iMacs on sale for up to $220 off MSRP
B&H Photo has 27″ Apple iMacs on sale for up to $200 off MSRP including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2099 $200 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $1899.99 $... Read more

Jobs Board

*Apple* Retail - Multiple Positions- Chicago...
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* Retail - Multiple Positions- Raleigh...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
User Support Specialist *Apple* Product Spe...
…Description:Ciber, Inc. is seeking a User Support Specialist - Apple Product Support in Nashville, TN!Responsibilities:Support, implementation, and upgrade of Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.