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

SyncTwoFolders 2.0.9b1 - Syncs two user-...
SyncTwoFolders simply synchronizes two folders. It supports synchronization across mounted network drives and it is a possibility to run a simulation showing in a log what will be done. Please visit... Read more
VueScan 9.5.09 - 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
Airmail 2.1 - Powerful, minimal email cl...
Airmail 2 is a new mail client designed for OS X 10.10 Yosemite with fast performance and intuitive interaction. Support for iCloud, MS Exchange, Gmail, Google Apps, IMAP, POP3, Yahoo!, AOL, Outlook.... Read more
Logitech Control Center 3.9.2 - Keyboard...
Logitech Control Center (LCC) is designed to support OS X and allows you to take full advantage of your Logitech keyboard, mouse, or trackball. With the LCC you can: Browse the Internet using... Read more
Adobe Acrobat Pro 15.007.20033 - Powerfu...
Acrobat Pro DC is available only as a part of Adobe Creative Cloud, and can only be installed and/or updated through Adobe's Creative Cloud app. Adobe Acrobat Pro DC with Adobe Document Cloud... Read more
CleanMyMac 3.0.1 - Delete files that was...
CleanMyMac makes space for the things you love. Sporting a range of ingenious new features, CleanMyMac lets you safely and intelligently scan and clean your entire system, delete large, unused files... Read more
Evernote 6.0.10 - Create searchable note...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
CleanApp 5.0.1 - Application deinstaller...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Quicken 2015 2.5.0 - Complete personal f...
Quicken 2015 helps you manage all your personal finances in one place, so you can see where you're spending and where you can save. Quicken automatically categorizes your financial transactions,... Read more
Tonality Pro 1.1.4 - Professional-grade...
Tonality Pro gives you the power to create stunning and dramatic black & white images. This is a complete monochrome image editor with more than 150 one-click style presets, totally unique... Read more

Streamline - calendar (Productivity)
Streamline - calendar 1.0 Device: iOS iPhone Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: Do you dare to break conventions? Streamline is the first real evolution from the paper diary. It is a patented and... | Read more »
The All-Consuming Snake is Back and Hung...
Taneli Armanto, the designer of Nokia 6110 Snake, is back to work. Together with Rumilus Design, he's working on a new Snake game titled Snake Rewind. [Read more] | Read more »
WAVE Personal Calendar Now Connects You...
WAVE Calendar, by e-sites, has added an interesting new feature: real life personal assistants. The e-sites webpage has been redesigned so personal assistants can apply to work directly with WAVE. [Read more] | Read more »
Find Your Vacation Home With Dwellable
Dwellable is a new travel app that helps you to find rental homes for your vacation, allowing you to swipe your way through listings from over 15,000 destinations worldwide. [Read more] | Read more »
Play Endless Golf in Flick Golf Free...
Full Fat has released a new update for Flick Golf! Free. The ‘Eliminator’ update brings a whole new way to play with its endless round. [Read more] | Read more »
The Enchanted Cave 2 (Games)
The Enchanted Cave 2 2.1 Device: iOS Universal Category: Games Price: $2.99, Version: 2.1 (iTunes) Description: Delve into a strange cave with a seemingly endless supply of treasure, strategically choosing your battles to gather as... | Read more »
Crystal Siege is on Sale With a New Univ...
Crystal Siege,  FDG Entertainment's RPG  Tower Defense game, has gone universal in its latest update. [Read more] | Read more »
Platforming Action RPG Swordigo is Curre...
Touch Foo's 2D action-platformer, Swordigo, is free for a limited time on the App Store. Now you can run, jump, and slash your way through adventure for absolutely nothing. [Read more] | Read more »
Watch This Homerun Slides into Home on t...
Eyes Wide Games has launched their one-touch baseball game, Watch This Homerun, for the Apple Watch. [Read more] | Read more »
Disney Celebrates May 4th With Galaxy Si...
For Star Wars Day, May 4, join Disney Interactive and Lucasfilm as they celebrate with a whole lot of in=-app sales for their Star Wars apps. [Read more] | Read more »

Price Scanner via MacPrices.net

Millennials’ Social Networking Habits Pose T...
Research indicates young people may be threat to corporate information-security, says tech expert Karl Volkmann, Chief Technical Officer of Chicago-based SRV Network, Inc. From Facebook to Twitter,... Read more
BuyVia Releases Apple Watch Shopping App
San Mateo, California-based BuyVia (http://www.buyvia.com), the first website and mobile app that combines in-store and online shopping across smart phones, tablets and laptops to help shoppers get... Read more
Apple Certified Refurbished iMacs available f...
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
New 2015 MacBook Airs on sale for up to $80 o...
Save up to $80 on the purchase of a new 2015 13″ or 11″ 1.6GHz MacBook Air at the following resellers. Shipping is free with each model: 11" 128GB MSRP $899 11" 256GB... Read more
Save up to $300 on a new Mac, $30 on an iPad,...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
iPad-Based iLynn Program Provides A Private U...
Lynn University of Boca Raton, Florida has announced that its innovative iPad-powered online bachelor’s degree program will be called iLynn. Beginning in fall 2015, Lynn U. says the new program will... Read more
iPad mini 4 Rumors Begin To Gel
First, I’ve been really hoping there will even be an iPad mini 4 at all. The smallest iPad has reportedly been hit pretty hard by iPhone 6 Plus cannibalization, along with getting caught in the... Read more
Mac Pros on sale for up to $260 off MSRP
B&H Photo has Mac Pros on sale for up to $260 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2799, $200 off MSRP - 3.5GHz 6-core Mac Pro: $3719.99... Read more
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... 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* 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
Senior Identity Architect - *Apple* Pay - A...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Hardware Systems Integration Engineer - *App...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Senior Identity Architect - *Apple* Pay - A...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.