TweetFollow Us on Twitter

Boot Disk Icon
Volume Number:5
Issue Number:5
Column Tag:Programmer's Forum

Related Info: Finder Interface Device Manager

Change the Boot Disk Icon

By David Dunham, Goleta, CA

I’ve been asked several times how my bootDiskIcon INIT works. I told the questioners that I’d answer in MacTutor.

Also, this is a short article. MacTutor needs more of them -- I know how to initialize Managers and handle events, and I certainly don’t need to see pictures in hexadecimal. (This isn’t just a snide remark directed at the editor, it’s a plea to those with nifty ideas that don’t need an entire application to show them off. Write a one or two page article!)

bootDiskIcon is a hack that came about because I don’t own an HD20. Apple insists on portraying their internal hard disk as an HD 20 on my desktop. I got so disgusted with this that I wrote an INIT to show something else, anything but an HD 20. ICN# 256, in fact. bootDiskIcon is inferior to programs like Façade-- it’s less flexible, and may not work with all hard disks -- but it was better than nothing, and it’s easy to understand.

The key to bootDiskIcon is the way the Finder handles disk icons. A pedantic digression: how does one find out how Finder handles icons? It’s not in Inside Macintosh. Therefore, it must be in a Technical Note. But Finder isn’t a category in the table of contents. So it’s off to the index but it’s not listed under “icon.” Luckily, it was one of the “Finder” Tech Notes, number 28. How did I know to keep looking? Because I’d seen it years ago when it came out, and knew it was there somewhere. Always skim every Tech Note -- not to memorize them, but to remember that they’re there.

When the Finder wants a disk icon, it gives the disk driver a Control call with csCode = 21. The driver returns a pointer to an ICN#. My first inclination was, why write code when you can change data? The ICN# must be part of the disk driver. The disk driver is part of Apple HD SC Setup. I found it there (it’s not a resource), changed it, and reinstalled the driver. This failed utterly -- there’s apparently a checksum.

If I couldn’t change the ICN# on disk, how about changing it in memory? I can get its address in memory by giving the driver a csCode = 21 call, then simply change the data. This is what bootDiskIcon does.

Before I get to what you’re all waiting for, the source code, I’ll mention the difference between patches and INITs. A patch is a change to a piece of code, almost always one of the traps. An INIT resource is any piece of code that runs at startup time (typically in a file of type INIT, cdev, or rdev). An INIT frequently installs a patch, but it could do anything at all, like playing a tune or subverting a disk driver’s icon.

More ideological baggage: INITs should announce their presence. Paul Mercer has a good way to do this, called ShowINIT. I’m told the source code’s available on AppleLink. I’ve modified it to handle color icons, and compiled the whole thing as a separate resource, SHOW 0. bootDiskIcon calls this code. You’re welcome to use it in any non-commercial (free or shareware) programs -- just use ResEdit to paste SHOW 0 into your own INIT file. You may not use it in public domain programs. These are those without a copyright holder, and I don’t want my code in the public domain. Don’t make the mistake of calling your free program “public domain.” Once you do, you can’t get it back (despite what Adobe thinks).

We can almost get to the code, but you might be wondering how to test it. It’s real inconvenient to reboot, just to see if a change worked. Luckily, you don’t have to. Remember that an INIT is just a piece of code that happens to get executed at boot time. You can often execute the same code at any time, and instruct your development system to make an INIT resource when you’re finished debugging. In bootDiskIcon’s case, I simply executed it, juggled into the Finder layer, and verified that I’d chant the code. It starts out by calling my SHOW resource -- the parameters are reversed from the way they’re defined because my ShowICON is defined as a Pascal procedure. My sloppiness in not defining it as such in this C program probably works only because this is an INIT -- if I trash the stack, it doesn’t much matter, since I’ll be returning to INIT 31 very soon.

The real work begins with finding out the driver refNum and drive of the first mounted disk (now you know why it’s called bootDiskIcon -- I told you it was a quick hack). I then find the address of the driver’s ICN#, get an ICN# of my own choice, and overwrite the driver’s using BlockMove.

#include <deviceMgr.h>
#include <hfs.h>

#define NIL 0L

void  main(void);/* Always use prototypes! */

void main() {
 Ptr    icn;
 int    error;   /* Shouldn’t really be write-only  */
 HParamBlockRec  pb;
 cntrlParam cpb;
 Handle handle;

 /* Show icon on the bottom of the screen */
 handle = GetResource(‘SHOW’,0); /* Get handle to the PROC */
 if (handle == 0L) { /* Something’s wrong (couldn’t load) */
 SysBeep(32);    /* Let somebody know */
 return;/* Don’t try to call it! */
 }
 HLock(handle);  /* Hold down the PROC */
 (**(ProcPtr *)handle)(-1,128);  
 /* ShowICON() -- note reversed parameters */
 HUnlock(handle);/* Let it float in the heap again */

 /* Change the icon */
 pb.volumeParam.ioNamePtr = NIL;
 pb.volumeParam.ioVolIndex = 1;  /* First mounted volume */
 error = PBHGetVInfo(&pb,FALSE);
 cpb.ioRefNum = pb.volumeParam.ioVDRefNum;
 cpb.ioVRefNum = pb.volumeParam.ioVDrvInfo;  
 /* drive (ioDrvNum) */
 cpb.csCode = 21;
 error = PBControl(&cpb,FALSE);
 icn = *(Ptr *)(&cpb.csParam[0]);
 handle = GetResource(‘ICN#’,256);
 BlockMove(*handle,icn,256L);
}

Known Bugs

Actually, these are rumored bugs, because it works for me! I’m told it doesn’t work with Jasmine disks where the driver puts the SCSI ID inside the flower. It probably doesn’t work with a boot floppy, because the Finder normally special cases the disk icon. (Furthermore, Finder probably doesn’t consider floppies to be “foreign drives.”)

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Kodi 15.0.beta1 - Powerful media center...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
DiskCatalogMaker 6.4.12 - Catalog your d...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast. Finder-like intuitive look and feel. Super-fast search algorithm. Can compress catalog data... Read more
Macs Fan Control 1.3.0.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
Lyn 1.5.11 - Lightweight image browser a...
Lyn is a lightweight and fast image browser and viewer designed for photographers, graphic artists and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it... Read more
NeoOffice 2014.11 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
LaunchBar 6.4 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Remotix 3.1.4 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
VOX 2.5.1 - Music player that supports m...
VOX is a beautiful music player that supports many filetypes. 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... Read more
Microsoft Remote Desktop 8.0.18 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more

Biz Builder Delux (Games)
Biz Builder Delux 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Ah, there's nothing like the rhythmic bustle of a burgeoning business burg... especially when you're the one building it... | Read more »
Auroch Digital is Bringing Back Games Wo...
| Read more »
Carbo - Handwriting in the Digital Age...
Carbo - Handwriting in the Digital Age 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Draggy Dead (Games)
Draggy Dead 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Ditch your dead end job and take up a rewarding career in Grave Robbing today!Guide the recently deceased to a fun filled life of... | Read more »
Bad Dinos (Games)
Bad Dinos 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Apple Watch isn't Great as a Fi...
| Read more »
Show the World What You See With Stre.am...
Live broadcasting is getting popular on mobile devices, which is why you can now get Stre.am, by Infinite Takes. [Read more] | Read more »
PhotoTime's 2.1 Update Adds Apple W...
The latest PhotoTime update is adding even more functionality to the handy photo organizing app. Yep, including Apple Watch support. [Read more] | Read more »
Oh My Glob! Adventure Time Puzzle Quest...
Finn and Jake are taking over D3 Go!'s popular puzzle game series in the upcoming Adventure Time Puzzle Quest. [Read more] | Read more »
Earthcore: Shattered Elements - Tips, Tr...
At first glance, Earthcore: Shattered Elements seems like a rather simple card-battling game. Once you’re introduced to skills that will change quite a bit. Even more so once you start to acquire hero cards. But it’s not so complicated that we... | Read more »

Price Scanner via MacPrices.net

Memorial Day Weekend Sale: New 27-inch 3.3GHz...
Best Buy has the new 27″ 3.3GHz 5K iMac on sale for $1899.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary... Read more
OtterBox Maximizes Portability, Productivity...
From the kitchen recipe book to the boarsroom presentation, the OtterBox Agility Tablet System turns tablets into one of the most versatile pieces of handheld technology available. Available now, the... Read more
Launch of New Car App Gallery and Open Develo...
Automatic, a company on a mission to bring the power of the Internet into every car, has announced the launch of the Automatic App Gallery, an app store for nearly every car or truck on the road... Read more
Memorial Day Weekend Sale: 13-inch 1.6GHz Mac...
Best Buy has the new 13″ 1.6GHz/128GB MacBook Air on sale for $849 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Memorial Day Weekend Sale: 27-inch 3.5GHz 5K...
Best Buy has the 27″ 3.5GHz 5K iMac on sale for $2099.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary.... Read more
Sale! 16GB iPad mini 3 for $349, save $50
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model. Read more
Price drop on 2014 15-inch Retina MacBook Pro...
B&H Photo has dropped prices on 2014 15″ Retina MacBook Pros by $200. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799.99 save $200 - 15″ 2.5GHz... Read more
With a Mission to Make Mobile Free, Scratch W...
Scratch Wireless, claiming to be the world’s first truly free mobile service, has announced the availability of a new Scratch-enabled Android smartphone, the Coolpad Arise. The smartphone is equipped... Read more
First-Ever Titanium Alloy Curved iPhone 6 Scr...
One of the most common problems with mobile phones is damage to the screens. The slightest drop can cause a dreaded spider web of gashes and cracks in the glass panel surface that can cost $hundreds... Read more
Preorder new 12-inch MacBook, $10 off, save o...
Adorama has new 12″ Retina MacBooks available for preorder for $10 off MSRP including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB... Read more

Jobs Board

*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
*Apple* TV Live Streaming Frameworks Test En...
**Job Summary** Work and contribute towards the engineering of Apple 's state-of-the-art products involving video, audio, and graphics in Interactive Media Group (IMG) at 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
Partner Marketing Manager, Merchant- *Apple*...
**Job Summary** The Apple Pay partner marketing team is looking for a marketing manager to develop and drive US marketing programs with our merchant partners. The right Read more
Technical Project Manager - *Apple* Pay - A...
**Job Summary** Apple Pay is seeking an experienced technical PM to…manage the on boarding of new merchants for the Apple Pay platform in the US Within this role you Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.