C - 写入二进制失败（重写文件）

Question

我不确定我在做什么错，试图编写一个简单的程序，在重命名后运行后加密。当该方法运行两次时，它应该做同样的事情，但它解密文件。第一个版本可以工作，但是它留下了旧版本，并且创建了一个新版本，并且我想要一个程序，我可以运行一次来​​加密并再次解密，以允许我在过程中更改文件扩展名，以方便起见。

当我运行该程序时，它在fwrite（）上崩溃。

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

    #define KEY '&' 

    int main(void) 
    { 
     FILE *fp; // file pointer 
     size_t size, test; // file size 
     char src_file[FILENAME_MAX], dst_file[FILENAME_MAX]; 
     int orig_char, new_char; 
     int i = 0; 

     printf("Enter the name of the source file \"file.ext\": "); 
     scanf("%s", src_file); 
     if ((fp = fopen(src_file, "rb")) == NULL) { // open file 
      fprintf(stderr, "Can't open \"%s\"\n", src_file); 
      exit(EXIT_FAILURE); 
     } 

     fseek(fp, 0, SEEK_END); // find the end of file 
     size = ftell(fp);  // file size 
     fseek(fp, 0, SEEK_SET); // set file position to start 
     unsigned char buffer[size], *temp = buffer; //buffer 
     test = fread(buffer, sizeof(buffer[0]), size, fp); 
     printf("size written: %d, size of file: %d\n", test, size); 
     if (test != size) { 
      fprintf(stderr, "Error: operation fwrite failed!\n"); 
      exit(EXIT_FAILURE); 
     } 
     fclose(fp); 

     printf("Enter the name of the destination file \"file.ext\": "); 
     scanf("%s", dst_file); 
     if ((fp = fopen(src_file, "wb")) == NULL) { 
      fprintf(stderr, "Can't open \"%s\"\n", dst_file); 
      exit(EXIT_FAILURE); 
     } 
     puts("Test1"); 
     for (i = 0; (size_t)i < size && orig_char != EOF; i++, temp++) { 
      orig_char = (int) *temp; 
      new_char = orig_char^KEY; 
      *temp = new_char; 
     } 
     puts("Test3"); 
     test = fwrite(buffer, sizeof(buffer[0]), size, fp); 
     fclose(fp); 
     free(buffer); 
     if ((rename(src_file, dst_file)) != 0) 
      fprintf(stderr, "Failed to rename file, make sure file doesn't" \ 
        "already exist!\n"); 

     return 0; 
    } 

Answer 1

这是我在任何情况下，最终的代码别人遇到这个问题，我清理了一点点，并增加了循环特性抵消多个文件。我还添加了一些错误恢复。

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

    #define KEY '&' 

    int main(void) 
    { 
     FILE *fp; // file pointer 
     size_t size, test; // file size 
     char src_file[FILENAME_MAX], dst_file[FILENAME_MAX]; 
     char ch = 'Y'; 
     int orig_char, new_char; 
     int i = 0; 

     while (toupper(ch) != 'N') { 
      printf("Enter the name of the source file \"file.ext\": "); 
      scanf("%s", src_file); 
      while ((fp = fopen(src_file, "rb")) == NULL) { // open file 
       fprintf(stderr, "Can't open \"%s\"\n", src_file); 
       printf("Enter the name of the source file \"file.ext\": "); 
       scanf("%s", src_file); 
      } 

      fseek(fp, 0, SEEK_END); // find the end of file 
      size = ftell(fp);  // file size 
      fseek(fp, 0, SEEK_SET); // set file position to start 
      unsigned char buffer[size], *temp = buffer; // buffer 
      // send file to buffer 
      test = fread(buffer, sizeof(buffer[0]), size, fp); 
      printf("size written: %d, size of file: %d\n", test, size); 
      if (test != size) { 
       fprintf(stderr, "Error: operation fwrite failed!\n"); 
       system("Press any key to continue"); 
       exit(EXIT_FAILURE); 
      } 
      fclose(fp); 

      while ((fp = fopen(src_file, "wb")) == NULL) { 
       fprintf(stderr, "Can't open \"%s\"\n", src_file); 
       printf("Enter the name of the source file \"file.ext\": "); 
       scanf("%s", src_file); 
      } 
      // offset buffer data 
      for (i = 0; (size_t)i < size && orig_char != EOF; i++, temp++) { 
       orig_char = (int) *temp; 
       new_char = orig_char^KEY; 
       *temp = new_char; 
      } 
      // write buffer to file 
      test = fwrite(buffer, sizeof(buffer[0]), size, fp); 
      fclose(fp); 
      printf("Enter the file's new name \"file.ext\": "); 
      scanf("%s", dst_file); 
      while ((rename(src_file, dst_file)) != 0) { 
       fprintf(stderr, "Failed to rename file, make sure file doesn't already       exist!\n"); 
      } 
      printf("size written: %d, size of file: %d\n", test, size); 
      printf("File Successfully offset\n\n"); 
      printf("Would you like to continue: "); 
      scanf(" %c", &ch); 
     } 

     return 0; 
    }