TweetFollow Us on Twitter

HFS Tree Climb
Volume Number:5
Issue Number:8
Column Tag:HyperChat™

Related Info: File Manager Standard File

XCMD Corner: HFS Tree Climbing

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.

Hyper Lite

In keeping with the spirit of the summer season, this month’s XCMD is light and easy. Not too long ago, I promised to provide an XCMD that, given the name and directory id of a file, returned that file’s full pathname. Such a utility is eminently useful in the current incantation of Hypercard.

Hypercard is fully capable of opening a file, reading and writing its contents and then closing the file. Unfortunately, unless you know the full path name of the file, you are limited to accessing files in Hypercard’s working directory.

One of the first published XCMDs was a little gem from Steve Maller of Apple Computer Inc. that eliminates this MSDOS-compatible feature of Hypercard. Steve’s FileName.p presents the user with the standard file package and returns the full pathname of the file specified.

If you are a regular reader of this column, you’ll recall that I translated Steve’s XCMD from pascal to “C”. You also know that my version lost something in the translation. Rather than return a full pathname, GetFileName.c returns the file’s name and working directory id. I felt this was more useful because the file’s name and wdid open up access to most of the file manager calls for the XCMD programmer. Still, if you want to continue to use Hypercard’s built-in file I/O, getfileName won’t be of much use since it doesn’t return the full pathname required by hypercard.

Listing 1 (FullPathName.c) is a simple XCMD that accepts the filename and working directory id as input and returns the fullpathname of the file as output.

As is often the case, this XCMD first converts the input data from c-string format to pascal strings and numbers as needed. Note that the default return value will be the name of the file that was passed in param[0].

A Review of HFS

As a rule, we don’t come into contact with full pathnames very often on the Macintosh so the format may require a little explaining. If you want to explore the Hierarchical File System in greater detail, take the time to read Chapter 19 of volume IV of Inside Macintosh. If you don’t have volume IV handy, the following discussion will get help you understand the code.

Devices that can store and retrieve data on the Macintosh are called “volumes”. Files are organized on volumes in folders. Folders can contain other folders yielding a hierarchical or “Tree structure”. The order in which folders are stored in this tree structure specify a path to any file that is contained in that folder.

The root of this tree is the volume name. If we stick a “:” onto the end of the volume name, we have the beginning of a full pathname. In other words full pathnames always start with the volume name. Each path in the pathname is delineated by the “:”. Thus, Hd:folder:file specifies a valid pathname. The last item in the pathname is the name of the file itself. The folder that holds this file is referred to by a unique directory id. When the user selects a file using SFGetFile or SFPutFile, the file manager returns the file’s name as well as the directory id. For historical purposes, the directory id is stored in the vRefNum field of the reply record. This little tweak is how Apple was able to make HFS backward compatible with the flat-file system.

Tree Climbing

The folder that contains the file represents the deepest node on the tree. The next folder up the hierarchy is called the parent. Knowing the parent’s id, we can call PBGetCatInfo to get its name as well as the directory id of its parent folder. We climb the tree by continuously feeding a parent directory id into PBGetCatInfo until we detect an error (no more folders on this path).

Tree climbing suggests recursion. The routine ClimbTree in Listing 1 calls PBGetCatInfo to get information about the directory whose id was passed in. We kick it off by first getting information about the folder that holds the file. This is the directory whose id was returned in the reply record.

Each activation of climbTree uses the same catalog parameter block (cpb) which was allocated in the stack frame of FullPathName. This is legal because the only information that is unique to each activation is the directory id (passed as a parameter in child) as well as a pointer to the string the PBGetCatInfo uses to store the folder’s name. Each activation allocates memory for the name string and sets cpb’s ioNamePtr field to point to its own copy of the string.

I allocate the string, folder_name, in the heap and point to it on the stack because successful recursion dictates that one be mindful of the stack at all times. Even if there is no danger of overflowing the stack, a little defensive programming goes a long way.

A nice feature of the recursion is that we can build the string in forward order. Although we walked the tree backwards, we don’t actually put the full pathname together until we reach the root which is detected by discovering that it has no parent folder. Once we reach the root, the stack unwinds in the order of root->parent->child->filename.

The following script, working with GetFileName.c (See Mactutor Vol. 5 No. 6) returns the full pathname of a file selected via standard dialog:

--1

on mouseup
 put getfilenametoOpen() into it
 if item 1 of it is not empty then
 put Fullpathname(item 1 of it, item 2 of it) into it
  end if
end mouseup

Because Hierarchical File System can’t handle pathnames longer than 256 characters, I limit the string returned by Fullpathname to 256 characters. If you want to return the full path regardless of length, you can modify the concat routine in “HyperUtils.c” to “grow” the output string on demand.

Listing:  FullPathName.c
/********************************/
/* File: FullPathName.c   */
/* Given the name and working */
/* directory of a file, walk the*/
/* directory tree to determine*/
/* what the full pathname of the*/
/* directory is... */
/* Paramters:    */
/* param0 = file namenum  */
/* param1 = directory id  */
/* Out: */
/* full pathname of the working  */
/* directory   */
/* Once again, I am indepbted to*/
/* Steve Maller of Apple  */
/* Computer Inc for illuminating*/
/* this oft too dark realm of */
/* the toolbox.  */
/********************************/
#include<MacTypes.h>
#include<OSUtil.h>
#include<MemoryMgr.h>
#include<FileMgr.h>
#include<ResourceMgr.h>
#include<pascal.h>
#include<strings.h>
#include<hfs.h>
#include  “HyperXCmd.h”
#include“HyperUtils.h”
#define nil 0L

char    colon[2] = “\p:”;

void ClimbTree( child, cpb, fullName )
 long   child;
 CInfoPBPtr cpb;
 char   *fullName;
/*************************
* Climb the directory tree
* until we reach the root
* Allocate the records in the
* heap to keep the stack frame
* as small as necessary.  Too
* large a stack frame can 
* lead to a case of terminal
* terminal.
* child is the working directory
* id of the “current folder”, vol
* is the volume reference number and
* fullName points to the 
* output string
*************************/
{
 StringPtrfolder_name= (StringPtr)NewPtr( 256 );
/*** setting the file directory index to -1***/
/*** lets us get information about the ***/
/*** directory whose id is specified inthe***/
/*** ioDrDIrID field of the parameter block***/
 folder_name[0] = ‘\0’; 
 cpb->dirInfo.ioNamePtr   = (StringPtr)folder_name;
 cpb->dirInfo.ioDrDirID   = child; 

 if( PBGetCatInfo( cpb, 0) == noErr ){
 ClimbTree(cpb->dirInfo.ioDrParID,cpb,fullName);

 Concat( (char *)fullName, (char *)folder_name );
 Concat( (char *)fullName, (char *)&colon );
 }
 DisposPtr( folder_name   );
 
}

pascal void main( paramPtr )
 XCmdBlockPtr  paramPtr;
{
 Str31  str,fName;
 short  wdid;
 WDPBRectheWDPB;
 CInfoPBRec theCPB;
 HParamBlockRec  theHPB;
 char   fullPath[256];
 char   part_Name[256]; /*** used in HPB     ***/
 char   vol_Name[256];
 OSErr  err;

 colon[0] = 1;
 colon[1] = ‘:’;
 
 vol_Name[0] = ‘\0’;
 part_Name[0]= ‘\0’;
 /*** empty is the default answer ***/
 paramPtr->returnValue = 0L;

 HLock( paramPtr->params[0] );
 ZeroToPas( paramPtr, *(paramPtr->params[0]), &fName );
 HUnlock( paramPtr->params[0] );
 
 /*** convert the wdid to a usable form ***/
 HLock( paramPtr->params[1] );
 ZeroToPas( paramPtr, *(paramPtr->params[1]), &str );
 HUnlock( paramPtr->params[1] );
 wdid = StrToNum( paramPtr, &str );
 
 /*** First, we appeal to GetVInfo to get    ***/
 /*** volume name that the file lives on     ***/
 part_Name[0]    = ‘\0’;  
 theHPB.volumeParam.ioNamePtr = (StringPtr)vol_Name;     
 theHPB.volumeParam.ioVRefNum = (short)wdid;             
 theHPB.volumeParam.ioVolIndex   = 0;  
 if(PBHGetVInfo( &theHPB, 0) != noErr )
 return;  

 /*** Next, use the working directory info   ***/
 /*** to walk the directory tree backwards   ***/
 /*** to the root directory ***/
 theWDPB.ioNamePtr = (StringPtr)part_Name;
 theWDPB.ioVRefNum = wdid;  
 theWDPB.ioWDProcID= 0;   
 theWDPB.ioWDIndex = 0;   
 if( PBGetWDInfo( &theWDPB, 0) != noErr )    
 return;
 
 fullPath[0] = ‘\0’; 
 theCPB.dirInfo.ioFDirIndex = -1; 
 theCPB.dirInfo.ioVRefNum = theHPB.volumeParam.ioVRefNum;      
 
 ClimbTree( theWDPB.ioWDDirID, 
 (CInfoPBPtr)&theCPB, 
 (StringPtr)fullPath );
 
 /*** Climbing the tree yields the names of  ***/
 /*** all the folders which we still need to ***/
 /*** add the file’s name to. ***/
 Concat( (char *)fullPath, (char *)&fName );
 paramPtr->returnValue = PasToZero( paramPtr, fullPath );
}
Listing:  HyperUtils.H
/********************************/
/* HyperUtils.H  */
/* Header file for HyperUtils.c  */
/* routines...   */
/********************************/
#define NIL 0L
#define UPFRONT  -1L
void  CenterWindow( WindowPtr wptr );
void  Concat( char * str1, char * str2 );
void  CopyPStr( char * pStr1, char * pStr2 );
short GetFileNameToOpen(SFTypeList typs,short typcnt, char *theName, 
short *theWDID);
Listing:  HyperUtils.c
/****************************/
/* HyperUtils.c  */
/* A collection of useful */
/* routines...   */
/****************************/
#include<MacTypes.h>
#include<OSUtil.h>
#include<MemoryMgr.h>
#include<FileMgr.h>
#include<ResourceMgr.h>
#include<StdFilePkg.h>
#include  “HyperXCmd.h”
#include  “HyperUtils.h”

void  CenterWindow( wptr )
 WindowPtrwptr;
/***************************
* Center a window in the current
* screen port.  Note: Does not
* attempt to work with multi-screen
* systems.
* This code is inspired by a
* similar routine written by Steve
* Maller in MPW Pascal.  Thanks Steve.
***************************/
{
 short  hWindSize = wptr->portRect.right - wptr->portRect.left;
 short  vWindSize = wptr->portRect.bottom - wptr->portRect.top;
 short  hSize = wptr->portBits.bounds.right - wptr->portBits.bounds.left;
 short  vSize = wptr->portBits.bounds.bottom - wptr->portBits.bounds.top;
 
 MoveWindow( wptr, ( hSize - hWindSize ) / 2, 
 ( vSize - vWindSize + 20) / 2, false);
}

void Concat( str1, str2 )
 char *str1;
 char *str2;
/*****************************
* Append string 2 to the end of
* string 1.  Both strings are 
* pascal-format strings.
* str1 must be large enough to hold
* the new string and is assumed to 
* be of Type Str255 (a pascal string)
*****************************/
{
 short len1 = *str1;/***number of chars in string 1***/
 short len2 = *str2++;/*** number of chars in string 2***/
 char  *temp;    /*** string pointer ***/
 
 if( len1 +len2  > 255 )
 len2 = 255 - len1;
 *str1++ += len2 ; /***add sizes together to get new size***/
 temp = str1 + len1;/*** move to end of string 1***/
 while( len2 ){
 *temp++ = *str2++;/*** add char to temp and move along***/
 --len2;/*** until all characters are added***/
 }
}

void  CopyPStr( pStr1, pStr2 )
 char *pStr1;
 char *pStr2;
/****************************
* Copy the contents of pstr1 into
* pstr2.  The strings are assumed 
* to be of type STR255 (length byte
* precedes data 
****************************/
{short  i;
 char *tstr;
 
 tstr = pStr2; 
 for( i = 0; i <= *pStr1; i++ )
 *tstr++ = *pStr1++;
}

short GetFileNameToOpen( typs, typCnt,theName, theWDID )
 SFTypeList typs; short   typCnt;
 char   *theName; short   *theWDID;
/*****************************
* Invokes SFOpenFile to query the 
* user for the name of a file to open.  
* In:   List of types of files to
*filter for (up to 4)
* Out:  fileName if picked in theName
*working directory in theWDID
*nil otherwise
*the file’s volum ref num.
* ( Note that the space for the 
* string must be allocated by the
* caller).
*****************************/
{
 Point  where;
 char   prompt[1];
 SFReplyreply;
 GrafPort *oldPort;
 WindowPtrdlogID;
 prompt[0]  = ‘\0’;
 /*** Get and put up the standard file ***/
 /*** dialog.  You will only see the file***/
 /*** types that you filtered for.  If ***/
 /*** you filtered for no files, then  ***/
 /*** all files will display***/
 GetPort( &oldPort );
 dlogID = GetNewDialog( (short)getDlgID, (Ptr)NIL, (Ptr)UPFRONT );
 SetPort( dlogID );
 CenterWindow( dlogID );
 where.h = dlogID->portRect.left;
 where.v = dlogID->portRect.top;
 LocalToGlobal( &where );
 SFGetFile( where, prompt, (Ptr)NIL, typCnt, typs, (Ptr)NIL, &reply );
 DisposDialog( dlogID );
 SetPort( oldPort );
 /*** If the user selected a file, let’s ***/
 /*** get the information about it ***/
 if (reply.good){
 *theWDID = reply.vRefNum;
 PtoCstr( (char *)&reply.fName );
 strcpy( theName, &reply.fName  );
 }
 return( reply.good );
}

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Dropbox 193.4.5594 - Cloud backup and sy...
Dropbox is a file hosting service that provides cloud storage, file synchronization, personal cloud, and client software. It is a modern workspace that allows you to get to all of your files, manage... Read more
Google Chrome 122.0.6261.57 - Modern and...
Google Chrome is a Web browser by Google, created to be a modern platform for Web pages and applications. It utilizes very fast loading of Web pages and has a V8 engine, which is a custom built... Read more
Skype 8.113.0.210 - Voice-over-internet...
Skype is a telecommunications app that provides HD video calls, instant messaging, calling to any phone number or landline, and Skype for Business for productive cooperation on the projects. This... Read more
Tor Browser 13.0.10 - Anonymize Web brow...
Using Tor Browser you can protect yourself against tracking, surveillance, and censorship. Tor was originally designed, implemented, and deployed as a third-generation onion-routing project of the U.... Read more
Deeper 3.0.4 - Enable hidden features in...
Deeper is a personalization utility for macOS which allows you to enable and disable the hidden functions of the Finder, Dock, QuickTime, Safari, iTunes, login window, Spotlight, and many of Apple's... Read more
OnyX 4.5.5 - Maintenance and optimizatio...
OnyX is a multifunction utility that you can use to verify the startup disk and the structure of its system files, to run miscellaneous maintenance and cleaning tasks, to configure parameters in the... Read more
Hopper Disassembler 5.14.1 - Binary disa...
Hopper Disassembler is a binary disassembler, decompiler, and debugger for 32- and 64-bit executables. It will let you disassemble any binary you want, and provide you all the information about its... Read more
WhatsApp 24.3.78 - Desktop client for Wh...
WhatsApp is the desktop client for WhatsApp Messenger, a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for... Read more
War Thunder 2.33.0.135 - Multiplayer war...
In War Thunder, aircraft, attack helicopters, ground forces and naval ships collaborate in realistic competitive battles. You can choose from over 1,500 vehicles and an extensive variety of combat... Read more
Iridient Developer 4.2 - Powerful image-...
Iridient Developer (was RAW Developer) is a powerful image-conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more

Latest Forum Discussions

See All

A Legitimate Massage Parlor, I Swear – T...
In this week’s Episode of The TouchArcade Show we talk about some of the major new releases on mobile this week including Warframe, we go over all the major news that came out from the Nintendo Direct Partner Showcase on Wednesday, we read our one... | Read more »
TouchArcade Game of the Week: ‘Rainbow S...
I feel like I am in a fever dream right now. What is this game that I’m playing? It’s a Rainbow Six game? But it’s all cutesy, and cartoony, and also kind of psychedelic? How is this a real thing? Well, it’s no fever dream, it is indeed a real thing... | Read more »
SwitchArcade Round-Up: ‘Promenade’, ‘Cho...
Hello gentle readers, and welcome to the SwitchArcade Round-Up for February 23rd, 2024. It’s Friday, so we have to check out the remaining releases of the week. Not so many big ones today, but a healthy crop nonetheless. After summarizing all the... | Read more »
Steam Deck Weekly: Gundam Breaker 4 and...
Welcome to this week’s slightly shorter edition of the Steam Deck Weekly. I was a bit unwell this week so no reviews in this edition, but there is a lot of news and new Steam Deck Verified and Playable games to catch up on. I have something special... | Read more »
The 10 Best Run-And-Gun Games for Ninten...
The year 2024 is a rare one, because it is a year with a brand-new Contra game. Contra: Operation Galuga might be the freshest face on the block when it comes to Nintendo Switch run-and-gun action games, but it’s hardly fighting that war alone.... | Read more »
Version 1.4 of Reverse: 1999 will be lan...
Free up your diary for February 29th, as Bluepoch has announced the impending release of the award-winning Reverse: 1999s Version 1.4 update. The Prisoner in the Cave is an Ancient Greece-themed update with new recruits, gameplay modes, and plenty... | Read more »
Premium Mobile RPG ‘Ex Astris’ From ‘Ark...
Arknights developer Hypergryph’s premium RPG Ex Astris () recently had its release date confirmed, and we finally have an extended gameplay showcase. | Read more »
Apple Arcade Weekly Round-Up: Updates fo...
Following yesterday’s big Hello Kitty Island Adventure update, a few more notable game updates and events have gone live on Apple Arcade. Cypher 007 () has gotten its first content update in a few months taking you to Egypt for five new levels... | Read more »
‘Thunder Ray’ and ‘Hime’s Quest’ Are Now...
Crunchyroll has pushed two new games into the Crunchyroll Game Vault including Purple Tree Studio’s Thunder Ray which was already on iOS before as a premium release. Shaun even reviewed it last year. Read his review here. The second game is Poppy... | Read more »
Adorable Kitty-Collector Sequel ‘Neko At...
Ya’ll. This October will mark the ten-year anniversary of Hit Point launching Neko Atsume, the adorable kitty collecting sim that has become a runaway success and essentially created a sub-genre of cozy pet-collecting life sim games. Sure, the... | Read more »

Price Scanner via MacPrices.net

16-inch M3 Max MacBook Pro on sale for $300 o...
Amazon is offering a $300 instant discount on one of Apple’s 16″ M3 Max MacBook Pros today. Shipping is free: – 16″ M3 Max MacBook Pros (36GB/1TB/Space Black): $3199, $300 off MSRP Their price is the... Read more
Apple M2 Mac minis on sale for $100 off MSRP...
B&H Photo has Apple’s M2-powered Mac minis in stock and on sale for $100 off MSRP this weekend with prices available starting at $499. Free 1-2 day shipping is available to most US addresses: –... Read more
Apple Watch SE on sale for $50 off MSRP this...
Best Buy has all Apple Watch SE models on sale this weekend for $50 off MSRP on their online store. Sale prices available for online orders only, in-store prices may vary. Order online, and choose... Read more
Deal Alert! Apple 15-inch M2 MacBook Airs on...
Looking for the lowest sale price on a new 15″ M2 MacBook Air? Best Buy has Apple 15″ MacBook Airs with M2 CPUs in stock and on sale today for $300 off MSRP on their online store. Prices valid for... Read more
Amazon discounts iPad mini 6 models up to $12...
Amazon is offering Apple’s 8.3″ WiFi iPad minis for $100-$120 off MSRP, including free shipping, for a limited time. Prices start at $399. Amazon’s prices are among the lowest currently available for... Read more
Apple AirPods Pro with USB-C discounted to $1...
Walmart has Apple’s 2023 AirPods Pro with USB-C in stock and on sale for $199.99 on their online store. Their price is $50 off MSRP, and it’s currently one the lowest prices available for new AirPods... Read more
Apple has 14-inch M3 MacBook Pro with 16GB of...
Apple has 14″ M3 MacBook Pros with 16GB of RAM, Certified Refurbished, available for $270-$300 off MSRP. Each model features a new outer case, shipping is free, and an Apple 1-year warranty is... Read more
Save $318-$432 on 16-inch M3 Max MacBook Pros...
Apple retailer Expercom has 16″ M3 Max MacBook Pros on sale for $318-$432 off MSRP when bundled with a 3-year AppleCare+ Protection Plan. Discounts are available for Silver models as well a Space... Read more
New today at Apple: 16-inch M3 Pro/M3 Max Mac...
Apple is now offering 16″ M3 Pro and M3 Max MacBook Pros, Certified Refurbished, starting at $2119 and ranging up to $530 off MSRP. Each model features a new outer case, shipping is free, and an... Read more
Apple is now offering $300-$480 discounts on...
Apple is now offering 14″ M3 Pro and M3 Max MacBook Pros, Certified Refurbished, starting at $1699 and ranging up to $480 off MSRP. Each model features a new outer case, shipping is free, and an... Read more

Jobs Board

Part-time *Apple* and Peach Research Assist...
…and minimum qualifications: + Assist with planting, pruning, and harvesting of apple and peach trees + Conduct regular maintenance tasks to ensure optimal Read more
Housekeeper, *Apple* Valley Villa - Cassia...
Apple Valley Villa, part of a senior living community, is hiring entry-level Full-Time Housekeepers to join our team! We will train you for this position and offer a Read more
Sublease Associate Optometrist- *Apple* Val...
Sublease Associate Optometrist- Apple Valley, CA- Target Optical Date: Feb 22, 2024 Brand: Target Optical Location: Apple Valley, CA, US, 92307 **Requisition Read more
Sublease Associate Optometrist- *Apple* Val...
Sublease Associate Optometrist- Apple Valley, CA- Target Optical Date: Jan 24, 2024 Brand: Target Optical Location: Apple Valley, CA, US, 92307 **Requisition Read more
Housekeeper, *Apple* Valley Village - Cassi...
Apple Valley Village Health Care Center, a senior care campus, is hiring a Part-Time Housekeeper to join our team! We will train you for this position! In this role, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.