; safe.asm   for testing protections within sections
; Assemble:	nasm -f elf -l safe.lst  safe.asm
; Link:		gcc -o safe  safe.o
; Run:		safe
; Output:
; it should stop with a system caught error

        global main		; the standard gcc entry point
        extern	printf		; the C function, to be called
        section .rodata		; read only data section, variables
a:	dd	5		; int a=5;
fmt:    db "Bad, still running",10,0


        section .text           ; Code section. not writeable
main:				; the program label for the entry point
        push    ebp		; set up stack frame
        mov     ebp,esp

	mov	eax,0x789abcde
	mov	[a],eax		; should be error, read only section
        push    dword fmt	; address of ctrl string
        call    printf		; Call C function
        add     esp,4		; pop stack, 1 push times 4 bytes

        mov     esp, ebp	; take down stack frame
        pop     ebp		; same as "leave" op

	mov	eax,0		;  normal, no error, return value
	ret			; return