文件操作--大文件的加密和搬运

#include "stdlib.h"
#include "stdio.h"
#include "string.h"

int fileEnc(char* fileDestinationPath, char* fileSourcePath)
{
    FILE *fileDestination = NULL;
    FILE *fileSource = NULL;
    int ret = 0;
    int buf[4096];
    int plainlen = 0;
    int writelen = 0;

    if(fileDestinationPath==NULL || fileSourcePath==NULL)
    {
        ret = -5;
        return ret;
    }
//1.打开文件
// 注意: 源文件打开的方式是二进制的只读
//         目标文件打开方式是二进制的只写
    fileDestination = fopen(fileDestinationPath, "wb");
    if(fileDestination==NULL)
    {
        ret = -1;
        goto End;
    }
    fileSource = fopen(fileSourcePath, "rb");
    if(fileSource==NULL)
    {
        ret = -2;
        goto End;
    }
//2.按4K读入数据fread()
    while(!feof(fileSource))
    {
        plainlen = fread(buf, 1, 4096, fileSource);
        // 当这个文件的大小小于4K的时候
        if(feof(fileSource))
        {
            break;
        }
    }
    writelen = fwrite(buf, 1, plainlen, fileDestination);
    if(writelen!=plainlen)
    {
        ret = -3;
        goto End;
    }

End:
    if(fileDestination!=NULL)
        fclose(fileDestination);
    if(fileSource!=NULL)
        fclose(fileSource);

    return ret;
}


int main()
{
    char* fileDestinationpath = NULL;
    char* fileSourcepath = NULL;
    int ret = 0;
    fileSourcepath = "C:/1.txt";
    fileDestinationpath = "C:/2.txt";

    ret = fileEnc(fileDestinationpath, fileSourcepath);
    if(ret == -5)
    {
        printf("func: fileEnc err: fopenfileDestinationPath==NULL || fileSourcePath==NULL %d", ret);
    }
    if(ret==-1)
    {
        printf("func: fileEnc err: fopen(fileDestinationPath) %d", ret);
    }
    if(ret==-2)
    {
        printf("func: fileEnc err: fopen(fileSourcePath) %d", ret);
    }

    return 0;
}