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int 21,3A

Posted on 1998-10-01
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Last Modified: 2010-04-16
How can i substitute int 21,3A with my own int?
And how can i see what dir is beeng removed when the user uses int 21,3A (rmdir)?
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Question by:zoranc
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4 Comments
 
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Expert Comment

by:kellyjj
ID: 1215723
you can intercept the intr, and then process it with your own proc.  This very similar to what you would do with the tick timer.
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daitt earned 50 total points
ID: 1215724
INT 21h is an interrupt handled by DOS. 3Ah is the function number (specified by AH) within INT 21h. So you can replace INT 21h only (by GETINTVEC and SETINTVEC):

type myproc=procedure;
var oldint:pointer;
begin
   GetIntVec($21,oldint);
   SetIntVec($21,@myFunc);
{ do something }
   keep(0);
end.

then build a function to handle INT21, only process AH=3Ah function, every other AH will be pass to oldint(a pointer to old INT21h):
procedure myFunc(AH:byte);interrupt;
begin
   if AH=$3A then
      begin
   {do something}
      end
   else
       begin
         {Jump to oldint}
      end;
end.

About the way to get the name of the directory being removed, I'll answer later. Try the code above (maybe you will have to write some assembler codes)

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Expert Comment

by:daitt
ID: 1215725
I'm sorry I'm so busy. Please give me your E-Mail address to finish my promise (about the way to get directory name).
Daitt@yahoo.com
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Author Comment

by:zoranc
ID: 1215726
my e-mail address is  : nade@mol.com.mk
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