我必须编写应该以64字节块的.txt文件读取文本的代码，加密每个块然后将其写入另一个.txt文件。现在我希望能够读取64字节块并在不对目标文件进行任何更改的情况下编写它们。我知道我的代码存在很多问题，但我无法弄清楚如何解决它们，所以非常感谢任何帮助和建议。这就是我设法做的事情。
.386
.model flat, stdcall
includelib msvcrt.lib
extern exit: proc
extern printf: proc
extern scanf: proc
extern fscanf: proc
extern fprintf: proc
extern fopen: proc
extern fclose: proc
public start
.data
type_read db "r",0
type_write db "w", 0
destination db "destination.txt",0 ;name of destination file
fscanf_format db "%lld",0
fprintf_format db "%lld",0
msg_start db "Source file path:",0
source dd 0 ;name of source file
source_format db "%s", 0
block64 dq 0
pointer_source db 0
pointer_destination dd 0
.code
start:
mov eax,0
push offset msg_start
call printf
add esp,4
; read name source file
push offset source
push offset source_format
call scanf
add esp,8
; open source file
push offset type_read
push offset sursa
call fopen
add esp,8
mov pointer_source,eax ;save source pointer eax
; open destination file
push offset type_write
push offset destination
call fopen
add esp,8
mov pointer_destination,ebx
reading:
;file reading
push offset block64 ;offset of qword variable
push offset fscanf_format ;format string "%lld",0
push pointer_source ;file pointer
call fscanf
add esp,16
;i tried to write what i've read to file destination.txt but i am not sure how to
pop ebx
sub esp,8
cmp eax,0ffffffffh;end of file?
je finish
end reading
finish:
push 0
call exit
end finish
end start
答案 0 :(得分：2)
更新，问题从64位块更改为64字节块，显然是由第三人（请参阅问题后的评论，或查看编辑历史记录）。下面两个例子，一个用于使用fscanf / fprintf的64位，一个用于使用fread / fwrite的64字节块。
没有解释使用哪种加密方案。这可能会影响每个块的字节数，例如AES，它执行16字节块（较小的块必须填充为16字节）。
使用Microsoft masm（ml.exe）进行64位拷贝的工作示例。
.data
block64 dd 0,0 ;two dd's for 64 bits
pointer_source dd 0 ;source FILE * value
pointer_destination dd 0 ;dest FILE * value
msg_start db "Source file path:",0
source db " " ;name of source file (read in)
destination db "destination.txt",0 ;name of destination file
fscanf_format db "%lld",0
fprintf_format db "%lld",10,0 ;added new line
source_format db "%s", 0
type_read db "r",0
type_write db "w", 0
.code
; ...
push offset msg_start
call printf
add esp,4
; read name source file
push offset source
push offset source_format
call scanf
add esp,8
; open source file
push offset type_read
push offset source
call fopen
add esp,8
mov pointer_source,eax ;save source FILE *
; open destination file
push offset type_write
push offset destination
call fopen
add esp,8
mov pointer_destination,eax ;save destination FILE *
reading:
push offset block64
push offset fscanf_format
mov eax,pointer_source ;push file pointer value
push eax
call fscanf
add esp,12 ;restore esp
cmp eax,0ffffffffh ;br if end of file
je finish
mov eax,block64+4 ;push 64 bit block
push eax ;
mov eax,block64 ;
push eax ;
push offset fprintf_format ;push ptr to format string
mov eax,pointer_destination ;push file pointer value
push eax ;
call fprintf ;print value
add esp,16 ;restore esp
jmp short reading ;short is optional
;
finish:
mov eax,pointer_destination ;push file pointer value
push eax ;
call fclose ;close file
add esp,4
mov eax,pointer_source ;push file pointer value
push eax
call fclose ;close file
add esp,4
push dword ptr 0 ;(masm needs dword ptr)
call exit
64字节块复制的示例。
.data
block64 db 64 dup (0) ;64 byte buffer
pointer_source dd 0 ;source FILE * value
pointer_destination dd 0 ;dest FILE * value
msg_start db "Source file path:",0
source db " " ;name of source file (read in)
destination db "destination.txt",0 ;name of destination file
source_format db "%s", 0
type_read db "rb",0 ;read binary
type_write db "wb", 0 ;write binary
.code
; ...
push offset msg_start
call printf
add esp,4
; read name source file
push offset source
push offset source_format
call scanf
add esp,8
; open source file
push offset type_read
push offset source
call fopen
add esp,8
mov pointer_source,eax ;save source FILE *
; open destination file
push offset type_write
push offset destination
call fopen
add esp,8
mov pointer_destination,eax ;save destination FILE *
reading:
mov eax,pointer_source ;push FILE * value
push eax
push dword ptr 64 ;count
push dword ptr 1 ;size
push offset block64 ;ptr to buffer
call fread ;read 64 bytes (or less)
add esp,16 ;restore esp
test eax,eax ;br if end file
je finish
mov ebx,pointer_destination ;push file pointer value (ebx)
push ebx ;
push eax ;count
push dword ptr 1 ;size
push offset block64 ;ptr to buffer
call fwrite ;write 64 bytes (or less)
add esp,16 ;restore esp
jmp short reading ;short is optional
;
finish:
mov eax,pointer_destination ;push file pointer value
push eax ;
call fclose ;close file
add esp,4
mov eax,pointer_source ;push file pointer value
push eax
call fclose ;close file
add esp,4
push dword ptr 0
call exit