memcpy 导致 fwrite 写出的文件是0字节。

Question

都是win10 的系统，都是使用的mysys2 编译的代码，

一台电脑正常运行，一台电脑 有问题
//////这里是标记
memcpy(all_encode_buf+count_gid*(pw.pw_len+12),encode_split,4*sizeof(u32));

这句memcpy 这样写，fwrite 运行都正常写出文件内容正确

//////这里是标记
memcpy(all_encode_buf+count_gid*(pw.pw_len+12)+4,encode_split,4*sizeof(u32));

只是加上偏移4个，一台电脑运行正常，另外一台电脑出现fwrite 出来的文件是0字节。

        //------------------------------------------------------------------------  
        pw_t pw;
        u32 encode_step = (pw.pw_len+12)*sizeof(u32);
        u32 * all_encode_buf =(u32 *)malloc(encode_step*(pws_cnt));
        u32 encode_split[4] ={pw.pw_len,pw.pw_len,pw.pw_len,pw.pw_len};
        u32 encode_end[4]   ={0x0b0b0b0b,0x0b0b0b0b,0x0b0b0b0b,0x0b0b0b0b};
        int index_encode =0;

        for(u32 count_gid = 0;count_gid < pws_cnt ;count_gid++)
        {           
        const int rc = gidd_to_pw_t (hashcat_ctx, device_param, count_gid, &pw);
        printf("pass = %08X,%08X,%08X,%08X\r\n",pw.i[0],pw.i[1],pw.i[2],pw.i[3]);
        pbkdf2_sha256_tmp_t tmps;

        int CL_rc = hc_clEnqueueReadBuffer (hashcat_ctx, device_param->command_queue,device_param->d_tmps, CL_TRUE, count_gid * sizeof (pbkdf2_sha256_tmp_t), sizeof (pbkdf2_sha256_tmp_t), &tmps, 0, NULL, NULL);
        printf("%08X ,%08X,%08X,%08X,%08X,%08X,%08X,%08X\r\n",tmps.out[0],tmps.out[1],tmps.out[2],tmps.out[3],tmps.out[4],tmps.out[5],tmps.out[6],tmps.out[7]);
        if (CL_rc == -1) return -1;

        if (rc == -1) return -1;

//////这里是标记
        memcpy(all_encode_buf+count_gid*(pw.pw_len+12),encode_split,4*sizeof(u32)); 
        }

        FILE *fp1 = fopen("test.txt","ab");  
        fwrite(encode_end,sizeof(u32),4,fp1);  
        fclose(fp1);  

              FILE *fp = fopen ("123", "ab");

Answer 1

fwrite数据长度加255