I was going for less bytes, hence the push/pop/push shenanigans. There must be an easier way to do this. Why does BSD require the syscall on the top of the stack *and* in EAX?

getchar.asm

getchar:                      ; read a byte from stdin
        push    0
        mov     eax, esp
        push    1
        push    eax
        push    STDIN_FILENO
        push    SYS_READ
        pop     eax
        push    eax
        int     80h
        test    eax, eax
        je      exit
        add     esp, 16
        pop     eax
        ret