Write arguments on stack to stdout in Linux: How do i count the number of char's in each argument?
From: aaron (ashy_20_at_hotmail.com)
Date: 05/25/04
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Date: Tue, 25 May 2004 05:34:13 +0000 (UTC)
I have been trying to write to stdout the arguments passed to the program.
My code works fine currently except that i have to specify how many char's
to write.
How do i find out how many char's are in the argument?
I had a look at the "String and Character Translation Instructions"
section of the "Intel 80386 Reference Programmer's Manual" but i still
dont understand what these instructions do.
Here is my code:
**********************
section .text
global _start
_start:
pop ebp ;argc
pop ecx ;get program name off stack
argument:
dec ebp ;minus the last argument
pop ecx ;get argument
mov edx,5 ;argument length - This is the problem bit.
;write to stdout
mov eax,4 ;write syscall
mov ebx,1 ;to stdout
int 80h ;call kernel
;loop back to argument if there are any arguments left
cmp ebp,0 ;see if any arguments left
jne argument;get the next one if there is
;exit
mov eax,1 ;exit syscall
mov ebx,0 ;return success
int 80h ;call kernel
*********************************
I have been assembling it with nasm and linking it with ld like this:
nasm -f elf args.asm
ld -s -o args args.o
and running it with various arguments like this:
<aaron@Ashy 01:52 PM:~/coding/assembly>$ ./args hello there
hellothere<aaron@Ashy 01:52 PM:~/coding/assembly>$
How can i count the number of char's in each argument?
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