在C程序中複製文件？

Question

我試圖將一個惡意文件複製到一個文本文件。所以基本上我想把mal文件的內容複製到文本文件中。 mal文件名稱爲test1.mal，txt文件名稱爲output.txt。這是我的，但它保持打印出錯讀取文件。

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 



int main(void) { 

char content[255]; 
char newcontent[255]; 

FILE *fp1, *fp2; 
fp1 = fopen("test1.mal", "r"); 
fp2 = fopen("output.txt", "w"); 

if(fp1 == NULL || fp2 == NULL) 
{ 
printf("error reading file\n"); 
exit(0); 
} 
printf("files open correct\n"); 
while(fgets(content, sizeof (content), fp1) !=NULL) 
{ 
fputs(content, stdout); 
strcpy (content, newcontent); 
} 

printf("%s", newcontent); 
printf("text received\n"); 

while(fgets(content, sizeof(content), fp1) !=NULL) 
{ 
fprintf(fp2, newcontent); 
} 
printf("file created and text copied"); 

fclose(fp1); 
fclose(fp2); 
return 0; 
} 

Answer 1

張貼的代碼中有幾個問題，其中許多在評論到OP的提問表示。

以下代碼是執行所需操作的一種方法。

它完全編譯並執行適當的錯誤檢查

注：來電perror()將輸出到stderr，封閉的文本和OS認爲操作失敗的原因。

注：使用open()，close()，read()，write()因爲沒有保證輸入.mal文件不包含嵌入的NULL字符。

#include <stdio.h> // perror() 
#include <stdlib.h> // exit(), EXIT_FAILURE 


#include <unistd.h> // read(), write(), close() 
#include <sys/types.h> 
#include <sys/stat.h> 
#include <fcntl.h> // open() 

// declare the size of the buffers with a meaningful name 
// do not use 'magic' numbers 
#define BUFF_SIZE 255 

int main(void) 
{ 

    char content[ BUFF_SIZE ]; 

    int fin; 
    int fout; 

    if(0 > (fin = open("test1.mal", O_RDONLY))) 
    { 
     perror("open for read of test1.mal failed"); 
     exit(EXIT_FAILURE); 
    } 

    // implied else, open successful 

    if(0 > (fout = open("output.txt", O_WRONLY))) 
    { 
     perror("open for write of output.txt failed"); 
     close(fin); 
     exit(EXIT_FAILURE); 
    } 

    // implied else, fopen successful 

    printf("files open correct\n"); 

    ssize_t readCount; 
    while(0 < (readCount = read(fin, content, sizeof(content)))) 
    { 
     //fputs(content, stdout); // are you sure the file contents are printable? 
     if(readCount != write(fout, content, (size_t)readCount)) 
     { // then write error occured 
      perror("write of data to output file failed"); 
      close(fin); 
      close(fout); 
      exit(EXIT_FAILURE); 
     } 

     // implied else, write successful 
    } 

    if(0 > readCount) 
    { // then read error occurred 
     perror("read of file failed"); 
     close(fin); 
     close(fout); 
     exit(EXIT_FAILURE); 
    } 

    // implied else, complete file copied 

    printf("file created and text copied\n"); 

    close(fin); 
    close(fout); 
    return 0; 
} // end function: main