C语言实现任何文件的加密解密功能

//#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include<time.h>
#include<sys/stat.h>
#pragma warning(disable:4996)
//加密
void Encryption(char *p, size_t n)
{
 for (int i = 0; i < n;++i)
 {
 *p += 7;
 }
}
//解密
void Decrypt(char *p, size_t n)
{
 for (int i = 0; i < n;++i)
 {
 *p -= 7;
 }
}
char *EnOrDe = {0};
int main(int argc, char *args[])
{
 clock_t c1 = clock();//系统当前时间，毫秒为单位
 char *FileNameSrc = (char *)calloc(160, sizeof(char));//待操作文件
 char *p2 = (char *)calloc(200, sizeof(char));//操作后文件名
 //从命令行获取文件名和要处理的操作
 FileNameSrc = args[1];//文件名，包含路径
 char *p1 = args[1];
 EnOrDe = args[2];//en表示加密，de表示解密
 /*FileNameSrc = "E:\\iPhone6-new.txt" ;
 char *p1 = FileNameSrc;
 EnOrDe = "de";*/
 /**********处理生成新的文件名***********/
 //char *p2 = { 0 };
 /*FileNameSrc = p1;*/
 //printf("%s\n", FileNameSrc);
 //printf("%s\n", EnOrDe);
 int index = 0;
 while (*p1)
 {
 if (*p1!='.')
 {
 *p2 = *p1;
 p2++;
 p1++;
 index++;
 }
 else if (*p1 == '.')
 {
 *p2 = '_';
 p2++;
 *p2 = 'H';
 p2++;
 *p2 = '.';
 p2++;
 p1++;
 index+=2;
 }
 }
 printf("\n");
 printf("信息摘要：\n");
 printf("--------------------------------------\n");
 printf("原文件:%s\n", FileNameSrc);
 printf("操作:%s （en——加密，de——解密）\n", EnOrDe);
 printf("预计结果文件:%s\n", p2 - index - 1);
 printf("--------------------------------------\n\n");
 printf("请稍后，玩命处理中......\n");
 char *FileNameDst = p2 - index - 1;
 FILE *pr = fopen(FileNameSrc, "rb");
 FILE *pw = fopen(FileNameDst, "wb");
 struct stat st = { 0 };
 size_t fileSize = st.st_size;//以字节为单位
 //char *buf = NULL;
 //if (fileSize<1024*1024)//小于1M
 //{
 // buf = malloc(sizeof(char) * 1024 * 20);//分配20K
 //}
 //else
 //{
 // buf = malloc(sizeof(char)*fileSize / 10);
 //}
 char *buf = calloc(1024 * 1024 * 25, sizeof(int));//分配100M
 /*************定义函数指针***************/
 void(*pFunc)(char *, size_t);
 pFunc = NULL;
 if (strcmp(EnOrDe, "en") == 0)
 {
 pFunc = Encryption;
 }
 else if (strcmp(EnOrDe, "de") == 0)
 {
 pFunc = Decrypt;
 }
 /*************定义函数指针***************/
 while (!feof(pr))
 {
 //memset(buf, 0, sizeof(buf));//calloc自动初始化为0
 size_t res = fread(buf, sizeof(char), sizeof(buf), pr);
 pFunc(buf, res);
 fwrite(buf, sizeof(char), res, pw);
 }
 fclose(pr);
 fclose(pw);
 printf("\n");
 printf("--------------------------------------\n");
 printf("执行成功！\n所在目录:%s\n", FileNameDst);
 clock_t c2 = clock();//系统当前时间，毫秒为单位
 printf("耗时:%u毫秒\n", c2-c1);
 printf("--------------------------------------\n");
 return 0;
}