APDL Public Domain 1/APDL_PD1A.iso/fileutils/imageprot/!Help

Text File | 1995-03-27 | 9.5 KB | 201 lines

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   ImageProtect                                Version 1.01 (27 Jan 1995)
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         This program is © 1995 James Freeman. All Rights Reserved.

                It is FREEWARE.  Use is at the owner’s risk.
              (For details, please read the conditions below.)

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  G E N E R A L   I N F O R M A T I O N
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             Sattinger’s Law: It works better if you plug it in.
 ––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Arthur Bloch

 Program:  ImageProtect

 Purpose:  Prevents the accidental deletion of non-empty image files.

 Requires: RISC OS 3.1x or later.

 Features: * Module takes up only 476 bytes.
           * Hand-written in ARM code.


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  W H O ?   W H A T ?   W H E N ?   H O W ?
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           It ain’t what a man don’t know that makes him a fool,
                    but what he does know that ain’t so.
 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Josh Billings

 This program was written in ARM using Zap 1·20 and SAsm 1·45.  This text
 reader was created by ViewHelp 1·15.  My thanks to Dominic Symes and
 David Radford for putting these programs into the public domain.  SAsm
 is shareware and written by David Holden.

 If you use any of this code in an application of your own (PD or Freeware
 only, mind), please give me credit.  I’ll email you the source if you
 *really* want it.  (Don’t know why anyone would :-)

 Apologies if you use a territory other than UK on your Arc - text within
 the program is in English only.

 I give no guarantee that this program will work correctly on all machines
 and all configurations - but it works for me.  Take it or leave it.


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  S U M M A R Y
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                  Nothing is so useless as a general maxim.
 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Thomas Macaulay

 This directory contains:

 !Help.*                               Help text and reader.
 ImageProt                             The module.

 With RISC OS 3 came image files; and what a difference they made :-)  If
 you don’t know what an image file is, examples are archives and PC
 partitions.  They may look like directories, but are actually files and
 are still treated as such in one important respect: they can be very
 easily deleted.

 To illustrate this difference, here are a couple of examples.

  * You delete a directory from the Filer menu on the desktop.
    The Filer Action Window recursively deletes each unlocked file within
    the directory; locked files are safe.

  * You delete an image from the Filer menu on the desktop.
    If the image is unlocked, it will be immediately deleted, whether or
    not there are any locked files inside.  Very worrying.  And not very
    nice if you accidentally lose a 4Mb PC partition (for example).

 “OK,” you might say, “the solution is simple - I’ll just lock the image
 file against deletion.”  Well, that’s what I thought, but trying this with
 my archives showed up a problem - write accesses to a locked file fail
 even if the file has write access (‘LWR/’ for example).

 In other words, I can either have safe archives which I can’t write to, or
 archives that I can write to but that I can also very easily delete by
 accident.  And why did I write this program?  Because I learnt first hand
 how easy it was to accidentally delete an archive.

 Loading the module activates the protection.  Now trying to delete an
 image file which contains other files will generate an error.

 If you like this program, please drop me a quick line.  I’m not asking for
 money, but I normally spend a lot of time getting my programs ‘just right’
 - just one line of email would be nice :-)


 FURTHER DETAILS
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 The module only concerns itself with whether or not the image file is
 empty (ie. does not contain other files; this has nothing to do with the
 image file length since an archive may be empty but still have a nominal
 file length for the header information etc).  Whether any files within the
 image are locked or not is immaterial.

 But what happens when you *do* want to delete an image file?  Well, there
 are two alternatives.

  * Choose ‘Options ⇨ Force’ from the Filer menu.  When enabled, this sets
    a bit in CMOS RAM.  This bit is checked for by ImageProtect; if it is
    set, the module disables its protection.  To enable it .. yep, you’ve
    guessed it, just untick the option on the Filer menu.  Note that the
    options menu provided by Filer Action Window does not set the CMOS RAM
    options and so will have no effect on ImageProtect.

  * Change the image’s filetype to (say) text, and then delete it.

 TECHNICAL DETAILS
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 Note that the module only claims FileV (the vector for OS_File).  This
 means that it can intercept deletes from the desktop and also prevent
 *Delete and *Remove from the command line.

 Most importantly, it does not claim FSCV (the vector for OS_FSControl)
 which is used (amongst other things) for *Wipe.  In other words, *Wipe may
 still be used to get rid of those now hard-to-delete archives :-)


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  P R O G R A M   H I S T O R Y
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             The World Record holder for blowing a bugle whilst
              riding a bike uphill dragging four hundredweight
             of pig iron and holding his breath is buried at...
 ––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Spike Milligan

 1.00 First version for RISC OS 3·10.
 1.01 Check on CMOS ‘force’ bit.
      FIRST RELEASE VERSION, uploaded to Hensa, sent to APDL.


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  L A S T   W O R D S
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           Die, my dear doctor? That’s the last thing I shall do.
 ––––––––––––––––––––––––––––––––––––––––––––––––– Lord Palmerston (Attrib)

  * Distribution - terms and conditions:
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    This program is “freeware”; this means ‘freely distributable’.  You
    may give a copy to anyone but there must be no charge.  For PD and
    shareware libraries, a small fee for the costs of discs, postage and
    administration is allowed, provided that the cost of the disc upon
    which this software is included is NOT MORE THAN UK£1·75 for an 800K
    disc, or £2·50 for a 1600K disc.  All files connected with this
    application must be distributed in an UNALTERED state.
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  * PLEASE NOTE THAT THIS PROGRAM IS NOT PUBLIC DOMAIN.

  * If you have any queries, praises or bug reports (please be specific)
    you may contact me at the address below.  I may be contacted via
    Pasture Hill Cottage, Stobarts Lane, Low Worsall, Yarm, Cleveland,
    TS15 9PJ, (England).  Even better, email me at my JANET address:
    ‘[e-mail]’.

  * Legal note:
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    The expression ‘the author’ means Mr James P Freeman.  The text
    following applies to files within this package written by the author;
    any other files are subject to different conditions.  The author
    retains full copyright of this software.  Distribution is subject to
    the conditions above.  This software is supplied ‘as is.’  USE IS
    ENTIRELY AT THE USER’S OWN RISK.  It carries NO WARRANTY, express or
    implied, and NO GUARANTEE is given of its MERCHANTABILITY, SUITABILITY
    or FITNESS FOR ANY PURPOSE.  The author accepts no responsibility
    whatsoever and under no circumstances will be liable for any damage,
    whether physical or economic, or any direct, indirect or consequential
    loss arising through, or in any way connected with, the use or misuse
    of this software or any files or routines contained herein - even if
    the author has been advised of the possibility of such loss.  The
    author reserves the right to amend this notice and/or alter the
    distribution conditions of this software package at any time.
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  * What..?  You still reading?


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  E R R A T U M
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                  This slip has been inserted by mistake.
 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Alisdair Gray