82 lines
3.3 KiB
ArmAsm
82 lines
3.3 KiB
ArmAsm
;; Copyright (C) 2019 Jeremiah Orians
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;; This file is part of mescc-tools.
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;;
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;; mescc-tools is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;;
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;; mescc-tools is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;
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;; You should have received a copy of the GNU General Public License
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;; along with mescc-tools. If not, see <http://www.gnu.org/licenses/>.
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section .text
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global _start
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;; Register usage:
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;; R15 => OUTPUT
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;; R14 => Buffer
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;; R13 => INPUT
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; Where the ELF Header is going to hit
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; Simply jump to _start
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; Our main function
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_start:
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pop rax ;·Get·the·number·of·arguments
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pop rdi ;·Get·the·program·name
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pop rdi ;·Get·the·actual·output name
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mov rsi, 577 ; Prepare file as O_WRONLY|O_CREAT|O_TRUNC
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mov rdx, 384 ; Prepare file as RW for owner only (600 in octal)
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mov rax, 2 ;·the·syscall·number·for·open()
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syscall ; Now open that file
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mov r15, rax ; Preserve the file pointer we were given
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mov rax, 12 ; the Syscall # for SYS_BRK
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mov rdi, 0 ; Get current brk
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syscall ; Let the kernel do the work
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mov r14, rax ; Set our malloc pointer
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mov rax, 12 ; the Syscall # for SYS_BRK
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mov rdi, r14 ; Using current pointer
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add rdi, 0x100000 ; Allocate 1MB
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syscall ; Let the kernel do the work
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core:
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pop rdi ;·Get·the·actual·input name
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cmp rdi, 0 ; Check for null string
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je done ; Hit null be done
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mov rsi, 0 ;·prepare·read_only
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mov rdx, 0 ; prevent any interactions
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mov rax, 2 ;·the·syscall·number·for·open()
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syscall ; Now open that damn file
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mov r13, rax ; Protect INPUT
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keep:
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mov rdx, 0x100000 ; set the size of chars we want
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mov rsi, r14 ; Where to put it
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mov rdi, r13 ; Where are we reading from
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mov rax, 0 ; the syscall number for read
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syscall ; call the Kernel
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push rax ; Protect the number of bytes read
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mov rdx, rax ; Number of bytes to write
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mov rsi, r14 ; What we are writing
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mov rdi, r15 ; Write to target file
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mov rax, 1 ; the syscall number for write
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syscall ; call the Kernel
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pop rax ; Get bytes read
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cmp rax, 0x100000 ; Check if buffer was fully used
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je keep ; Keep looping if was full
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jmp core ; Otherwise move to next file
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done:
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; program completed Successfully
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mov rdi, 0 ; All is well
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mov rax, 0x3c ; put the exit syscall number in eax
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syscall ; Call it a good day
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