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This means it might contain formatting issues, incorrect code, conceptual problems, or other severe issues.
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{{task}} The task requires poking machine code directly into memory and executing it.
This is strictly for x86 (32 bit) architectures.
The machine code is the opcodes of the following simple program:
mov EAX, [ESP+4]
add EAX, [ESP+8]
ret
which translates into the following opcodes: (139 68 36 4 3 68 36 8 195) and in Hex this would correspond to the following: ("8B" "44" "24" "4" "3" "44" "24" "8" "C3")
;Task: Implement the following in your favorite programming language (take the common lisp code as an example if you wish):
- Poke the above opcodes into a memory pointer
- Execute it with the following arguments: [ESP+4] => unsigned-byte argument of value 7; [ESP+8] => unsigned-byte argument of value 12; The result would be 19.
- Free the Pointer
AutoHotkey
'''MCode Tutorial''' ([http://ahkscript.org/boards/viewtopic.php?f=7&t=32 Forum Thread])
'''MCode4GCC''' ([http://ahkscript.org/boards/viewtopic.php?f=6&t=4642 Forum Thread] | [https://github.com/joedf/MCode4GCC GitHub]) - An MCode generator using the GCC Compiler.
MCode(Var, "8B44240403442408C3")
MsgBox, % DllCall(&Var, "Char",7, "Char",12)
Var := ""
return
; http://www.autohotkey.com/board/topic/19483-machine-code-functions-bit-wizardry/
MCode(ByRef code, hex) { ; allocate memory and write Machine Code there
VarSetCapacity(code, StrLen(hex) // 2)
Loop % StrLen(hex) // 2
NumPut("0x" . SubStr(hex, 2 * A_Index - 1, 2), code, A_Index - 1, "Char")
}
BBC BASIC
{{works with|BBC BASIC for Windows}} '''Note''' that ''BBC BASIC for Windows'' includes an 80386/80486 assembler as standard!
REM Claim 9 bytes of memory
SYS "GlobalAlloc",0,9 TO code%
REM Poke machine code into it
P%=code%
[OPT 0
mov EAX, [ESP+4]
add EAX, [ESP+8]
ret
]
REM Run code
SYS code%,7,12 TO result%
PRINT result%
REM Free memory
SYS "GlobalFree",code%
END
C
#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
int test (int a, int b)
{
/*
mov EAX, [ESP+4]
add EAX, [ESP+8]
ret
*/
char code[] = {0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3};
void *buf;
int c;
/* copy code to executable buffer */
buf = mmap (0,sizeof(code),PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANON,-1,0);
memcpy (buf, code, sizeof(code));
/* run code */
c = ((int (*) (int, int))buf)(a, b);
/* free buffer */
munmap (buf, sizeof(code));
return c;
}
int main ()
{
printf("%d\n", test(7,12));
return 0;
}
COBOL
This solution is a 64-bit adaptation of the task, using the macOS ABI and 64-bit instructions. The assembly code in question is:
pushq %rbp
movq %rsp, %rbp
movl %edi, -0x4(%rbp)
movl %esi, -0x8(%rbp)
movl -0x4(%rbp), %esi
addl -0x8(%rbp), %esi
movl %esi, -0xc(%rbp)
movl -0xc(%rbp), %eax
popq %rbp
retq
The 64-bit "wrapper code" used by the PicoLisp and Go implementations have the parameters 7 and 12 baked into it, so I opted for a pure 64-bit implementation rather than manipulating the 64-bit stack to support the 32-bit instructions.
SOURCE FORMAT IS FIXED
IDENTIFICATION DIVISION.
PROGRAM-ID. MC.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 INSTRUCTIONS.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'55'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'48'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'E5'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'7D'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'FC'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'F8'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'8B'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'FC'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'03'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'F8'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'89'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'75'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'F4'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'8B'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'45'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'F4'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'5D'.
03 USAGE BINARY-CHAR UNSIGNED VALUE H'C3'.
01 MMAP.
03 MMAP-ADDR USAGE POINTER VALUE NULL.
03 MMAP-LEN USAGE BINARY-LONG UNSIGNED VALUE 24.
03 MMAP-PROT USAGE BINARY-INT VALUE H'0007'.
03 MMAP-FLAGS USAGE BINARY-INT VALUE H'1002'.
03 MMAP-FD USAGE BINARY-INT VALUE -1.
03 MMAP-OFFSET USAGE BINARY-LONG VALUE 0.
03 CODE-PTR USAGE PROCEDURE-POINTER.
01 ARG-A USAGE BINARY-INT VALUE 7.
01 ARG-B USAGE BINARY-INT VALUE 12.
01 RESULT USAGE BINARY-INT.
LINKAGE SECTION.
01 MACHINE-CODE PIC X(24).
PROCEDURE DIVISION.
MAIN SECTION.
PERFORM SET-UP.
CALL CODE-PTR USING
BY VALUE ARG-A
BY VALUE ARG-B
RETURNING RESULT.
DISPLAY RESULT.
PERFORM TEAR-DOWN.
STOP RUN.
SET-UP SECTION.
CALL 'mmap' USING
BY VALUE MMAP-ADDR
BY VALUE MMAP-LEN
BY VALUE MMAP-PROT
BY VALUE MMAP-FLAGS
BY VALUE MMAP-FD
BY VALUE MMAP-OFFSET
RETURNING CODE-PTR.
SET ADDRESS OF MACHINE-CODE TO CODE-PTR.
MOVE INSTRUCTIONS TO MACHINE-CODE.
TEAR-DOWN SECTION.
SET ADDRESS OF MACHINE-CODE TO NULL.
CALL 'munmap' USING
BY VALUE CODE-PTR
BY VALUE MMAP-LEN.
{{out}} +0000000019
Common Lisp
;;Note that by using the 'CFFI' library, one can apply this procedure portably in any lisp implementation;
;; in this code however I chose to demonstrate only the implementation-dependent programs.
;;CCL
;; Allocate a memory pointer and poke the opcode into it
(defparameter ptr (ccl::malloc 9))
(loop for i in '(139 68 36 4 3 68 36 8 195)
for j from 0 do
(setf (ccl::%get-unsigned-byte ptr j) i))
;; Execute with the required arguments and return the result as an unsigned-byte
(ccl::ff-call ptr :UNSIGNED-BYTE 7 :UNSIGNED-BYTE 12 :UNSIGNED-BYTE)
;; Output = 19
;; Free the pointer
(ccl::free ptr)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;SBCL
(defparameter mmap (list 139 68 36 4 3 68 36 8 195))
(defparameter pointer (sb-alien:make-alien sb-alien:unsigned-char (length mmap)))
(defparameter callp (loop for byte in mmap
for i from 0
do
(setf (sb-alien:deref pointer i) byte)
finally
(return (sb-alien:cast pointer (function integer integer integer)))))
(sb-alien:alien-funcall callp 7 12)
(loop for i from 0 below 18 collect (sb-alien:deref ptr i))
(sb-alien:free-alien pointer)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;CLISP
(defparameter mmap (list 139 68 36 4 3 68 36 8 195))
(defparameter POINTER (FFI:FOREIGN-ADDRESS (FFI:FOREIGN-ALLOCATE 'FFI:UINT8 :COUNT 9)))
(loop for i in mmap
for j from 0 do
(FUNCALL #'(SETF FFI:MEMORY-AS) i POINTER 'FFI:INT j))
(FUNCALL
(FFI:FOREIGN-FUNCTION POINTER
(LOAD-TIME-VALUE
(FFI:PARSE-C-TYPE
'(FFI:C-FUNCTION (:ARGUMENTS 'FFI:INT 'FFI:INT) (:RETURN-TYPE FFI:INT) (:LANGUAGE :STDC)))))
7 12)
(FFI:FOREIGN-FREE POINTER)
D
In D you usually use a nicer asm {} statement for similar purposes.
Generally new operating systems forbid execution of any address unless it's known to contain executable code. This is a basic version that unlike the C entry executes from array memory. This may crash on some operating systems.
int test(in int a, in int b) pure nothrow @nogc {
/*
mov EAX, [ESP+4]
add EAX, [ESP+8]
ret
*/
immutable ubyte[9] code = [0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3];
alias F = extern(C) int function(int, int) pure nothrow @nogc;
immutable f = cast(F)code.ptr;
return f(a, b); // Run code.
}
void main() {
import std.stdio;
test(7, 12).writeln;
}
{{out}} 19
Go
{{trans|C}}
This task requires the use of 'cgo' which enables Go to interface with C code by importing a pseudo-package called "C".
Although Go supports both 32-bit and 64-bit architectures, I'm writing this on a 64-bit Ubuntu 16.04 system. I've therefore utilized the PicoLisp entry's 'glue code' to enable the 32-bit code to run on it.
There doesn't appear to be a way to cast a pointer to a native buffer to a Go function pointer so that the machine code can be run directly. I've therefore written a C function to perform this step and embedded it in the program which 'cgo' allows us to do.
package main
import "fmt"
/*
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
typedef unsigned char byte;
typedef byte (*mcfunc) (byte, byte);
void runMachineCode(void *buf, byte a, byte b) {
mcfunc fp = (mcfunc)buf;
printf("%d\n", fp(a, b));
}
*/
import "C"
func main() {
code := []byte{
144, // Align
144,
106, 12, // Prepare stack
184, 7, 0, 0, 0,
72, 193, 224, 32,
80,
139, 68, 36, 4, 3, 68, 36, 8, // Rosetta task code
76, 137, 227, // Get result
137, 195,
72, 193, 227, 4,
128, 203, 2,
72, 131, 196, 16, // Clean up stack
195, // Return
}
le := len(code)
buf := C.mmap(nil, C.size_t(le), C.PROT_READ|C.PROT_WRITE|C.PROT_EXEC,
C.MAP_PRIVATE|C.MAP_ANON, -1, 0)
codePtr := C.CBytes(code)
C.memcpy(buf, codePtr, C.size_t(le))
var a, b byte = 7, 12
fmt.Printf("%d + %d = ", a, b)
C.runMachineCode(buf, C.byte(a), C.byte(b))
C.munmap(buf, C.size_t(le))
C.free(codePtr)
}
{{out}}
7 + 12 = 19
Julia
{{trans|C}} Julia cannot execute machine code directly, but can embed C and C++ with the Cxx library.
using Cxx
cxx"""
#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
int test (int a, int b)
{
/*
mov EAX, [ESP+4]
add EAX, [ESP+8]
ret
*/
char code[] = {0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3};
void *buf;
int c;
/* copy code to executable buffer */
buf = mmap (0,sizeof(code),PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANON,-1,0);
memcpy (buf, code, sizeof(code));
/* run code */
c = ((int (*) (int, int))buf)(a, b);
/* free buffer */
munmap (buf, sizeof(code));
return c;
}
int main ()
{
printf("%d\n", test(7,12));
return 0;
}
"""
julia_function = @cxx main()
julia_function()
Kotlin
{{trans|C}}
This task presents a number of issues for Kotlin Native which at the time of writing (August 2017) is still in the earlier stages of development:-
-
The language doesn't (yet) have an unsigned Byte type, though this is easily solved by subtracting 256 from unsigned values between 128 and 255 inclusive and then using the signed Byte type.
-
As far as x86 is concerned, the language is currently only targetting 64-bit platforms including Ubuntu 14.04 on which I'm writing this. Rather than rewrite the task using x64 opcodes, I've used the PicoLisp entry's 'glue code' to enable the 32-bit machine code to run on a 64-bit system.
-
There doesn't appear to be a way to cast a pointer to a native buffer to a Kotlin function pointer so that the machine code can be run. I've therefore written a 'one line' C helper function (in mcode.def) to perform this step and compiled it to a library (mcode.klib) so that it can be called from Kotlin code.
// mcode.def
---
static inline unsigned char runMachineCode(void *code, unsigned char a, unsigned char b) {
return ((unsigned char (*) (unsigned char, unsigned char))code)(a, b);
}
// Kotlin Native version 0.3
import kotlinx.cinterop.*
import string.*
import mman.*
import mcode.*
fun main(args: Array<String>) {
memScoped {
val bytes = byteArrayOf(
144 - 256, // Align
144 - 256,
106, 12, // Prepare stack
184 - 256, 7, 0, 0, 0,
72, 193 - 256, 224 - 256, 32,
80,
139 - 256, 68, 36, 4, 3, 68, 36, 8, // Rosetta task code
76, 137 - 256, 227 - 256, // Get result
137 - 256, 195 - 256,
72, 193 - 256, 227 - 256, 4,
128 - 256, 203 - 256, 2,
72, 131 - 256, 196 - 256, 16, // Clean up stack
195 - 256 // Return
)
val len = bytes.size
val code = allocArray<ByteVar>(len)
for (i in 0 until len) code[i] = bytes[i]
val buf = mmap(null, len.toLong(), PROT_READ or PROT_WRITE or PROT_EXEC,
MAP_PRIVATE or MAP_ANON, -1, 0)
memcpy(buf, code, len.toLong())
val a: Byte = 7
val b: Byte = 12
val c = runMachineCode(buf, a, b)
munmap(buf, len.toLong())
println("$a + $b = ${if(c >= 0) c.toInt() else c + 256}")
}
}
{{out}}
7 + 12 = 19
M2000 Interpreter
We can execute machine code, in a buffer for code. We can't push to stack and then call, we can use a buffer for data. If eax is non zero then error raised, with error number the eax number. When execute code the code buffer can't be used to write over. so we have to use a buffer for data for read/write data. This example perform these: At Datamem(1) put 500, eax=5100, eax add Datamem(1), eax add 5, store eax to Datamem(0). We have an option to clear eax, or use it to return value as error code. We have to leave all other registers, and stack as we found it. Both running in Wine (Linux 64bit) too
Module Checkit {
Buffer DataMem as Long*10
Return DataMem, 1:=500 ' second Long
Print Eval(DataMem, 1)+5100+5=5605
\\ Now we do math executing machine code
Buffer Code ExecMem as byte*1024
Address=0
EmbLong(0xb8, 5100) ' mov eax,5100
EmbByteByte(0x83, 0xC0, 5) ' add eax,0x5
EmbByteLong(0x3,0x5, DataMem(1)) ' add eax, [DataMem(1)]
EmbLong(0xa3, DataMem(0)) ' mov [DataMem(0)], eax
\\ split rem to execute xor eax eax (eax=0)
Rem : EmbByte(0x31, 0xC0) ' xor eax, eax
Ret() ' Return
\\
Try ok {
Execute Code ExecMem, 0
}
\\If Eax <>0 then we get error, so we read error as Uint()
\\ Error read once then change to zero
m=Uint(Error)
\\ Hex is Print Hexadecimal for unsigned numbers
Hex m
Print m=5605
Print Error=0, ok=False
Print Eval(DataMem, 0)=5605, Eval(DataMem, 0)
\\ sub used as Exit here
Sub Ret()
Return ExecMem, Address:=0xC3
Address++
End Sub
Sub EmbByteByte()
Return ExecMem, Address:=Number, Address+1:=Number, Address+2:=Number
Address+=3
End Sub
Sub EmbByte()
Return ExecMem, Address:=Number, Address+1:=Number
Address+=2
End Sub
Sub EmbLong()
Return ExecMem, Address:=Number, Address+1:=Number as Long
Address+=5
End Sub
Sub EmbByteLong()
Return ExecMem, Address:=Number, Address+1:=Number, Address+2:=Number as Long
Address+=6
End Sub
}
CheckIt
Using a lambda function with closures two buffers (buffers are objects in M2000 to handle memory blocks). This also add 12 +7 as the task want (but with no pushing to stack, but poke to data buffer)
Function MyAdd {
Buffer DataMem as Long*2
Buffer Code ExecMem as byte*32
Address=0
EmbByte(0x31, 0xC0)
EmbByteLong(0x3,0x5, DataMem(0)) ' add eax, [DataMem(0)]
EmbByteLong(0x3,0x5, DataMem(1)) ' add eax, [DataMem(1)]
EmbLong(0xa3, DataMem(0)) ' mov [DataMem(0)], eax
Rem :
EmbByte(0x31, 0xC0) ' xor eax, eax
Ret() ' Return
=lambda ExecMem, DataMem (a as double, b as double)-> {
Return DataMem, 0:=a, 1:=b
Try ok {
Execute Code ExecMem, 0
}
If not ok then {
=Uint(Error)
} Else {
=Eval(DataMem, 0)
}
}
Sub Ret()
Return ExecMem, Address:=0xC3
Address++
End Sub
Sub EmbByte()
Return ExecMem, Address:=Number, Address+1:=Number
Address+=2
End Sub
Sub EmbLong()
Return ExecMem, Address:=Number, Address+1:=Number as Long
Address+=5
End Sub
Sub EmbByteLong()
Return ExecMem, Address:=Number, Address+1:=Number, Address+2:=Number as Long
Address+=6
End Sub
}
\\ Produce a lambda function with machine code inside
UnsingedAdd=MyAdd()
Print UnsingedAdd(12, 7), UnsingedAdd(500, 100)
Nim
{{trans|C}}
import posix
when defined(macosx) or defined(bsd):
const MAP_ANONYMOUS = 0x1000
elif defined(solaris):
const MAP_ANONYMOUS = 0x100
else:
var
MAP_ANONYMOUS {.importc: "MAP_ANONYMOUS", header: "<sys/mman.h>".}: cint
proc test(a, b: cint): cint =
# mov EAX, [ESP+4]
# add EAX, [ESP+8]
var code = [0x8B'u8, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3]
# create executable buffer
var buf = mmap(nil, sizeof(code), PROT_READ or PROT_WRITE or PROT_EXEC,
MAP_PRIVATE or MAP_ANONYMOUS, -1, 0)
# copy code to buffer
copyMem(addr buf, addr code[0], sizeof(code))
# run code
{.emit: "`result` = ((int (*) (int, int))&`buf`)(`a`,`b`);".}
# free buffer
discard munmap(buf, sizeof(code))
echo test(7, 12)
PARI/GP
GP can't peek and poke into memory, but PARI can add in those capabilities via [[#C|C]]. {{trans|C}}
#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
#include <pari/pari.h>
int
test(int a, int b)
{
char code[] = {0x8B, 0x44, 0x24, 0x4, 0x3, 0x44, 0x24, 0x8, 0xC3};
void *buf;
int c;
/* copy code to executable buffer */
buf = mmap (0,sizeof(code),PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANON,-1,0);
memcpy (buf, code, sizeof(code));
/* run code */
c = ((int (*) (int, int))buf)(a, b);
/* free buffer */
munmap (buf, sizeof(code));
return c;
}
void
init_auto(void)
{
pari_printf("%d\n", test(7,12));
return 0;
}
Pascal
Tested under Linux with Freepascal 2.6.4-32BIt ( like the Code used ) cdecl doesn't work in Freepascal under Linux 64-bit
Program Example66;
{Inspired... program to demonstrate the MMap function. Freepascal docs }
Uses
BaseUnix,Unix;
const
code : array[0..9] of byte = ($8B, $44, $24, $4, $3, $44, $24, $8, $C3, $00);
a :longInt= 12;
b :longInt= 7;
type
tDummyFunc = function(a,b:LongInt):LongInt;cdecl;
Var
Len,k : cint;
P : Pointer;
begin
len := sizeof(code);
P:= fpmmap(nil,
len+1 ,
PROT_READ OR PROT_WRITE OR PROT_EXEC,
MAP_ANONYMOUS OR MAP_PRIVATE,
-1, // for MAP_ANONYMOUS
0);
If P = Pointer(-1) then
Halt(4);
for k := 0 to len-1 do
pChar(p)[k] := char(code[k]);
k := tDummyFunc(P)(a,b);
Writeln(a,'+',b,' = ',k);
if fpMUnMap(P,Len)<>0 Then
Halt(fpgeterrno);
end.
;output:
12+7 = 19
Phix
atom mem = allocate(9)
poke(mem,{#8B,#44,#24,#04,#03,#44,#24,#08,#C3})
constant mfunc = define_c_func({},mem,{C_INT,C_INT},C_INT)
?c_func(mfunc,{12,7})
free(mem)
In Phix the #ilASM statement (which has guards to allow 32/64/WIN/LNX variants) is usually used for inline assembly, for example (but sticking to the task):
atom mem = allocate(9)
poke(mem,{#8B,#44,#24,#04,#03,#44,#24,#08,#C3})
integer res
#ilASM{ mov eax,[mem]
call :%pLoadMint -- eax:=(int32)eax, in case mem>#3FFFFFFF
push 12
push 7
call eax
add esp,8
mov [res],eax }
?res
free(mem)
Better yet, albeit deviating somewhat from the task (and this runs on both 32 and 64 bit):
integer res
#ilASM{ jmp @f
::add
[32]
mov eax,[esp+4]
add eax,[esp+8]
[64]
mov rax,[rsp+8]
add rax,[rsp+16]
[]
ret
@@:
push 12
push 7
call :add
[32]
add esp,8
mov [res],eax
[64]
add rsp,16
mov [res],rax
[]
}
?res
All three cases output 19
PicoLisp
The following runs on 64-bit PicoLisp. Therefore we need some glue code to interface to the task's 32-bit code.
(setq P
(struct (native "@" "malloc" 'N 39) 'N
# Align
144 # nop
144 # nop
# Prepare stack
106 12 # pushq $12
184 7 0 0 0 # mov $7, %eax
72 193 224 32 # shl $32, %rax
80 # pushq %rax
# Rosetta task code
139 68 36 4 3 68 36 8
# Get result
76 137 227 # mov %r12, %rbx
137 195 # mov %eax, %ebx
72 193 227 4 # shl $4, %rbx
128 203 2 # orb $2, %bl
# Clean up stack
72 131 196 16 # add $16, %rsp
# Return
195 ) # ret
foo (>> 4 P) )
# Execute
(println (foo))
# Free memory
(native "@" "free" NIL P)
Output:
19
Python
{{works with|CPython|3.x}}
The ctypes module is meant for calling existing native code from Python, but you can get it to execute your own bytes with some tricks. The bulk of the code is spent establishing an executable memory area - once that's done, the actual execution takes just a few lines.
import ctypes
import os
from ctypes import c_ubyte, c_int
code = bytes([0x8b, 0x44, 0x24, 0x04, 0x03, 0x44, 0x24, 0x08, 0xc3])
code_size = len(code)
# copy code into an executable buffer
if (os.name == 'posix'):
import mmap
executable_map = mmap.mmap(-1, code_size, mmap.MAP_PRIVATE | mmap.MAP_ANON, mmap.PROT_READ | mmap.PROT_WRITE | mmap.PROT_EXEC)
# we must keep a reference to executable_map until the call, to avoid freeing the mapped memory
executable_map.write(code)
# the mmap object won't tell us the actual address of the mapping, but we can fish it out by allocating
# some ctypes object over its buffer, then asking the address of that
func_address = ctypes.addressof(c_ubyte.from_buffer(executable_map))
elif (os.name == 'nt'):
# the mmap module doesn't support protection flags on Windows, so execute VirtualAlloc instead
code_buffer = ctypes.create_string_buffer(code)
PAGE_EXECUTE_READWRITE = 0x40 # Windows constants that would usually come from header files
MEM_COMMIT = 0x1000
executable_buffer_address = ctypes.windll.kernel32.VirtualAlloc(0, code_size, MEM_COMMIT, PAGE_EXECUTE_READWRITE)
if (executable_buffer_address == 0):
print('Warning: Failed to enable code execution, call will likely cause a protection fault.')
func_address = ctypes.addressof(code_buffer)
else:
ctypes.memmove(executable_buffer_address, code_buffer, code_size)
func_address = executable_buffer_address
else:
# for other platforms, we just hope DEP isn't enabled
code_buffer = ctypes.create_string_buffer(code)
func_address = ctypes.addressof(code_buffer)
prototype = ctypes.CFUNCTYPE(c_int, c_ubyte, c_ubyte) # build a function prototype from return type and argument types
func = prototype(func_address) # build an actual function from the prototype by specifying the address
res = func(7,12)
print(res)
PureBasic
Using the Windows API:
CompilerIf #PB_Compiler_Processor <> #PB_Processor_x86
CompilerError "Code requires a 32-bit processor."
CompilerEndIf
; Machine code using the Windows API
Procedure MachineCodeVirtualAlloc(a,b)
*vm = VirtualAlloc_(#Null,?ecode-?scode,#MEM_COMMIT,#PAGE_EXECUTE_READWRITE)
If(*vm)
CopyMemory(?scode, *vm, ?ecode-?scode)
eax_result=CallFunctionFast(*vm,a,b)
VirtualFree_(*vm,0,#MEM_RELEASE)
ProcedureReturn eax_result
EndIf
EndProcedure
rv=MachineCodeVirtualAlloc( 7, 12)
MessageRequester("MachineCodeVirtualAlloc",Str(rv)+Space(50),#PB_MessageRequester_Ok)
#HEAP_CREATE_ENABLE_EXECUTE=$00040000
Procedure MachineCodeHeapCreate(a,b)
hHeap=HeapCreate_(#HEAP_CREATE_ENABLE_EXECUTE,?ecode-?scode,?ecode-?scode)
If(hHeap)
CopyMemory(?scode, hHeap, ?ecode-?scode)
eax_result=CallFunctionFast(hHeap,a,b)
HeapDestroy_(hHeap)
ProcedureReturn eax_result
EndIf
EndProcedure
rv=MachineCodeHeapCreate(7,12)
MessageRequester("MachineCodeHeapCreate",Str(rv)+Space(50),#PB_MessageRequester_Ok)
End
; 8B442404 mov eax,[esp+4]
; 03442408 add eax,[esp+8]
; C20800 ret 8
DataSection
scode:
Data.a $8B,$44,$24,$04,$03,$44,$24,$08,$C2,$08,$00
ecode:
EndDataSection
Racket
#lang racket/base
(require ffi/unsafe)
; set up access to racket internals
(define scheme-malloc-code
(get-ffi-obj 'scheme_malloc_code #f (_fun (len : _intptr) -> _pointer)))
(define scheme-free-code
(get-ffi-obj 'scheme_free_code #f (_fun _pointer -> _void)))
(define opcodes '(139 68 36 4 3 68 36 8 195))
(define code (scheme-malloc-code 64))
(for ([byte opcodes]
[i (in-naturals)])
(ptr-set! code _ubyte i byte))
(define function (cast code _pointer (_fun _ubyte _ubyte -> _ubyte)))
(function 7 12)
(scheme-free-code code)
Rust
This is heavily inspired by https://www.jonathanturner.org/2015/12/building-a-simple-jit-in-rust.html
Hence, only working on Linux (the only other way to disable memory execution protection on other OSes was to use other crates, which kind of defeats the purpose.)
extern crate libc;
#[cfg(all(
target_os = "linux",
any(target_pointer_width = "32", target_pointer_width = "64")
))]
fn main() {
use std::mem;
use std::ptr;
let page_size: usize = 4096;
let (bytes, size): (Vec<u8>, usize) = if cfg!(target_pointer_width = "32") {
(
vec![0x8b, 0x44, 0x24, 0x04, 0x03, 0x44, 0x24, 0x08, 0xc3],
9,
)
} else {
(vec![0x48, 0x89, 0xf8, 0x48, 0x01, 0xf0, 0xc3], 7)
};
let f: fn(u8, u8) -> u8 = unsafe {
let mut page: *mut libc::c_void = ptr::null_mut();
libc::posix_memalign(&mut page, page_size, size);
libc::mprotect(
page,
size,
libc::PROT_EXEC | libc::PROT_READ | libc::PROT_WRITE,
);
let contents: *mut u8 = page as *mut u8;
ptr::copy(bytes.as_ptr(), contents, 9);
mem::transmute(contents)
};
let return_value = f(7, 12);
println!("Returned value: {}", return_value);
assert_eq!(return_value, 19);
}
#[cfg(any(
not(target_os = "linux"),
not(any(target_pointer_width = "32", target_pointer_width = "64"))
))]
fn main() {
println!("Not supported on this platform.");
}
Scala
PEEK, POKE and inserting machine opcode makes your system vulnerable which is not quite professional.
Considered to be more harmful than useful.
Swift
{{trans|C}}
Using 64-bit glue code since Swift has limited 32-bit support on x86.
import Foundation
typealias TwoIntsOneInt = @convention(c) (Int, Int) -> Int
let code = [
144, // Align
144,
106, 12, // Prepare stack
184, 7, 0, 0, 0,
72, 193, 224, 32,
80,
139, 68, 36, 4, 3, 68, 36, 8, // Rosetta task code
76, 137, 227, // Get result
137, 195,
72, 193, 227, 4,
128, 203, 2,
72, 131, 196, 16, // Clean up stack
195, // Return
] as [UInt8]
func fudge(x: Int, y: Int) -> Int {
let buf = mmap(nil, code.count, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0)
memcpy(buf, code, code.count)
let fun = unsafeBitCast(buf, to: TwoIntsOneInt.self)
let ret = fun(x, y)
munmap(buf, code.count)
return ret
}
print(fudge(x: 7, y: 12))
Tcl
{{trans|C}} {{libheader|Critcl}}
package require critcl
critcl::ccode {
#include <sys/mman.h>
}
# Define a command using C. The C is embedded in Tcl, and will be
# built into a shared library at runtime. Note that Tcl does not
# provide a native way of doing this sort of thing; this thunk is
# mandatory.
critcl::cproc runMachineCode {Tcl_Obj* codeObj int a int b} int {
int size, result;
unsigned char *code = Tcl_GetByteArrayFromObj(codeObj, &size);
void *buf;
/* copy code to executable buffer */
buf = mmap(0, (size_t) size, PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANON, -1, 0);
memcpy(buf, code, (size_t) size);
/* run code */
result = ((int (*) (int, int)) buf)(a, b);
/* dispose buffer */
munmap(buf, (size_t) size);
return result;
}
# But now we have our thunk, we can execute arbitrary binary blobs
set code [binary format c* {0x8B 0x44 0x24 0x4 0x3 0x44 0x24 0x8 0xC3}]
puts [runMachineCode $code 7 12]
Note that it would be more common to put that thunk in its own package (e.g., machineCodeThunk) and then just do something like this:
package require machineCodeThunk 1.0
set code [binary format c* {0x8B 0x44 0x24 0x4 0x3 0x44 0x24 0x8 0xC3}]
puts [runMachineCode $code 7 12]
{{omit from|Mathematica}}