#
# Copyright 2017, Intel Corporation
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in
# the documentation and/or other materials provided with the
# distribution.
#
# * Neither the name of the copyright holder nor the names of its
# contributors may be used to endorse or promote products derived
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#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# A program with a syscall instruction.
# This only serves for testing syscall_intercept's ability to
# patch syscalls in the main executable object of a process.
.intel_syntax noprefix
.global main;
.text
main:
cmp rdi, 2 # cmp argc with 2
jl 0f # jump if argc < 2
add rsi, 8 # inc argv
mov rsi, [rsi] # syscall argument: argv[1]
mov rdi, rsi # copy argv[1] to rdi
xor rcx, rcx
not rcx
shr rcx, 1 # scan -- max iteration count: SSIZE_MAX
sub al, al # scan -- byte to look for: '\0'
cld # scan -- setup direction: forward
repne scasb # scan memory to find null terminator
sub rdi, rsi # compute strlen
mov rdx, rdi # syscall argument: buffer len
mov rdi, 1 # syscall argument: stdout
mov rax, 1 # syscall number: SYS_write
syscall
mov rdi, 1 # syscall argument: stdout
lea rsi, [rip + newline] # syscall argument: buffer
mov rdx, 1 # syscall argument: length
mov rax, 1 # syscall number: SYS_write
syscall
mov rax, 0 # return 0
ret
0: mov rax, 1 # return 1
ret
.data
newline: .byte 0xa