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Listing 2. Assembly Expansion for setuid

_setuid:
subl $4,%exp
pushl %ebx
movzwl 12(%esp),%eax
movl %eax,4(%esp)
movl $23,%eax
movl 4(%esp),%ebx
int $0x80
movl %eax,%edx
testl %edx,%edx
jge L2
negl %edx
movl %edx,_errno
movl $-1,%eax
popl %ebx
addl $4,%esp
ret
L2:
movl %edx,%eax
popl %ebx
addl $4,%esp
ret