nasm astrcpy_s函数 x86
作者:互联网
xxx.asm
%define p1 ebp+8
%define p2 ebp+12
%define p3 ebp+16
section .text
global dllmain
export astrcpy_s
dllmain:
mov eax,1
ret 12
astrcpy_s:
push ebp
mov ebp,esp
push ebx
mov eax,[p1] ; dst char ptr
mov ecx,[p2] ; dwDstSize
mov edx,[p3] ; src char ptr
.for:
;-------------------------------------;
; get src first char
;-------------------------------------;
mov bl,[edx]
;-------------------------------------;
; 检查src是否结束
;-------------------------------------;
test bl,bl
jz .return
;-------------------------------------;
; copy
;-------------------------------------;
mov [eax],bl
;-------------------------------------;
; 避免dst溢出
;-------------------------------------;
dec ecx
test ecx,ecx
jz .return
;-------------------------------------;
; next
;-------------------------------------;
inc eax
inc edx
jmp .for
.return:
pop ebx
mov esp,ebp
pop ebp
ret 12
c++:
#include <iostream>
#include <Windows.h>
typedef void (CALLBACK* astrcpy_s_t)(char* dest, size_t dest_size, const char* src);
astrcpy_s_t astrcpy_s;
int main()
{
HMODULE myDLL = LoadLibraryA("xxx.dll");
astrcpy_s = (astrcpy_s_t)GetProcAddress(myDLL, "astrcpy_s");
char r[100];
strcpy_s(r, sizeof(r), "123");
printf("%s\n", r); // 123
astrcpy_s(r, sizeof(r), "456");
printf("%s\n", r); // 456
//===============================//
strcpy_s(r, 2, "1");
printf("%s\n", r); // 1
astrcpy_s(r, 2, "2");
printf("%s\n", r); // 2
return 0;
}
标签:x86,mov,astrcpy,char,ebp,printf,-------------------------------------,nasm 来源: https://www.cnblogs.com/ajanuw/p/13723735.html