哪位老兄有strcpy_s的实现代码？

[pang2042]

哪位老兄有strcpy_s的实现代码，麻烦发一下，学习，最好是比较权威点的代码，经过验证的。

[仙度瑞城]

strcpy_s是微软为了安全性考虑自己添加的函数，和strcpy不同

[iamnobody]

page ,132
title strcat - concatenate (append) one string to another
;***
;strcat.asm - contains strcat() and strcpy() routines
;
; Copyright (c) Microsoft Corporation. All rights reserved.
;
;Purpose:
; STRCAT concatenates (appends) a copy of the source string to the
; end of the destination string, returning the destination string.
;
;*******************************************************************************

.xlist
include cruntime.inc
.list


page
;***
;char *strcat(dst, src) - concatenate (append) one string to another
;
;Purpose:
; Concatenates src onto the end of dest. Assumes enough
; space in dest.
;
; Algorithm:
; char * strcat (char * dst, char * src)
; {
; char * cp = dst;
;
; while( *cp )
; ++cp; /* Find end of dst */
; while( *cp++ = *src++ )
; ; /* Copy src to end of dst */
; return( dst );
; }
;
;Entry:
; char *dst - string to which "src" is to be appended
; const char *src - string to be appended to the end of "dst"
;
;Exit:
; The address of "dst" in EAX
;
;Uses:
; EAX, ECX
;
;Exceptions:
;
;*******************************************************************************

page
;***
;char *strcpy(dst, src) - copy one string over another
;
;Purpose:
; Copies the string src into the spot specified by
; dest; assumes enough room.
;
; Algorithm:
; char * strcpy (char * dst, char * src)
; {
; char * cp = dst;
;
; while( *cp++ = *src++ )
; ; /* Copy src over dst */
; return( dst );
; }
;
;Entry:
; char * dst - string over which "src" is to be copied
; const char * src - string to be copied over "dst"
;
;Exit:
; The address of "dst" in EAX
;
;Uses:
; EAX, ECX
;
;Exceptions:
;*******************************************************************************


CODESEG

% public strcat, strcpy ; make both functions available
strcpy proc \
dst:ptr byte, \
src:ptr byte

OPTION PROLOGUE:NONE, EPILOGUE:NONE

push edi ; preserve edi
mov edi,[esp+8] ; edi points to dest string
jmp short copy_start

strcpy endp

align 16

strcat proc \
dst:ptr byte, \
src:ptr byte

OPTION PROLOGUE:NONE, EPILOGUE:NONE

.FPO ( 0, 2, 0, 0, 0, 0 )

mov ecx,[esp+4] ; ecx -> dest string
push edi ; preserve edi
test ecx,3 ; test if string is aligned on 32 bits
je short find_end_of_dest_string_loop

dest_misaligned: ; simple byte loop until string is aligned
mov al,byte ptr [ecx]
add ecx,1
test al,al
je short start_byte_3
test ecx,3
jne short dest_misaligned

align 4

find_end_of_dest_string_loop:
mov eax,dword ptr [ecx] ; read 4 bytes
mov edx,7efefeffh
add edx,eax
xor eax,-1
xor eax,edx
add ecx,4
test eax,81010100h
je short find_end_of_dest_string_loop
; found zero byte in the loop
mov eax,[ecx - 4]
test al,al ; is it byte 0
je short start_byte_0
test ah,ah ; is it byte 1
je short start_byte_1
test eax,00ff0000h ; is it byte 2
je short start_byte_2
test eax,0ff000000h ; is it byte 3
je short start_byte_3
jmp short find_end_of_dest_string_loop
; taken if bits 24-30 are clear and bit
; 31 is set
start_byte_3:
lea edi,[ecx - 1]
jmp short copy_start
start_byte_2:
lea edi,[ecx - 2]
jmp short copy_start
start_byte_1:
lea edi,[ecx - 3]
jmp short copy_start
start_byte_0:
lea edi,[ecx - 4]
; jmp short copy_start

; edi points to the end of dest string.
copy_start::
mov ecx,[esp+0ch] ; ecx -> sorc string
test ecx,3 ; test if string is aligned on 32 bits
je short main_loop_entrance

src_misaligned: ; simple byte loop until string is aligned
mov dl,byte ptr [ecx]
add ecx,1
test dl,dl
je short byte_0
mov [edi],dl
add edi,1
test ecx,3
jne short src_misaligned
jmp short main_loop_entrance

main_loop: ; edx contains first dword of sorc string
mov [edi],edx ; store one more dword
add edi,4 ; kick dest pointer
main_loop_entrance:
mov edx,7efefeffh
mov eax,dword ptr [ecx] ; read 4 bytes

add edx,eax
xor eax,-1

xor eax,edx
mov edx,[ecx] ; it's in cache now

add ecx,4 ; kick dest pointer
test eax,81010100h

je short main_loop
; found zero byte in the loop
; main_loop_end:
test dl,dl ; is it byte 0
je short byte_0
test dh,dh ; is it byte 1
je short byte_1
test edx,00ff0000h ; is it byte 2
je short byte_2
test edx,0ff000000h ; is it byte 3
je short byte_3
jmp short main_loop ; taken if bits 24-30 are clear and bit
; 31 is set
byte_3:
mov [edi],edx
mov eax,[esp+8] ; return in eax pointer to dest string
pop edi
ret
byte_2:
mov [edi],dx
mov eax,[esp+8] ; return in eax pointer to dest string
mov byte ptr [edi+2],0
pop edi
ret
byte_1:
mov [edi],dx
mov eax,[esp+8] ; return in eax pointer to dest string
pop edi
ret
byte_0:
mov [edi],dl
mov eax,[esp+8] ; return in eax pointer to dest string
pop edi
ret

strcat endp

end

[贪食蛇男]

errno_t __cdecl _FUNC_NAME(_CHAR *_DEST, size_t _SIZE, const _CHAR *_SRC)
{
    _CHAR *p;
    size_t available;

    /* validation section */
    _VALIDATE_STRING(_DEST, _SIZE);
    _VALIDATE_POINTER_RESET_STRING(_SRC, _DEST, _SIZE);

    p = _DEST;
    available = _SIZE;
    while ((*p++ = *_SRC++) != 0 && --available > 0)
    {
    }

    if (available == 0)
    {
        _RESET_STRING(_DEST, _SIZE);
        _RETURN_BUFFER_TOO_SMALL(_DEST, _SIZE);
    }
    _FILL_STRING(_DEST, _SIZE, _SIZE - available + 1);
    _RETURN_NO_ERROR;
}

[贪食蛇男]

你用VS建立个工程，调用这个函数，然后调试跟进去看就OK了

[jackyjkchen]

vs2010DE

/***
*tcscpy_s.inl - general implementation of _tcscpy_s
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       This file contains the general algorithm for strcpy_s and its variants.
*
****/

_FUNC_PROLOGUE
errno_t __cdecl _FUNC_NAME(_CHAR *_DEST, size_t _SIZE, const _CHAR *_SRC)
{
    _CHAR *p;
    size_t available;

    /* validation section */
    _VALIDATE_STRING(_DEST, _SIZE);
    _VALIDATE_POINTER_RESET_STRING(_SRC, _DEST, _SIZE);

    p = _DEST;
    available = _SIZE;
    while ((*p++ = *_SRC++) != 0 && --available > 0)
    {
    }

    if (available == 0)
    {
        _RESET_STRING(_DEST, _SIZE);
        _RETURN_BUFFER_TOO_SMALL(_DEST, _SIZE);
    }
    _FILL_STRING(_DEST, _SIZE, _SIZE - available + 1);
    _RETURN_NO_ERROR;
}

[iamnobody]

搞错了，上面的是strcpy()的

strcpy_s 不知道搞什么，写了一大堆检测什么的东西，不看也罢

[wintree]

errno_t strcpy_s(
char *strDestination,
size_t numberOfElements,
const char *strSource
);
errno_t wcscpy_s(
wchar_t *strDestination,
size_t numberOfElements,
const wchar_t *strSource
);
errno_t _mbscpy_s(
unsigned char *strDestination,
size_t numberOfElements,
const unsigned char *strSource
);
template <size_t size>
errno_t strcpy_s(
char (&strDestination)[size],
const char *strSource
); // C++ only
template <size_t size>
errno_t wcscpy_s(
wchar_t (&strDestination)[size],
const wchar_t *strSource
); // C++ only
template <size_t size>
errno_t _mbscpy_s(
unsigned char (&strDestination)[size],
const unsigned char *strSource
); // C++ only

[紫色动力]

在VSTS里用右键就能查看啊