[英]Can't write raw data on SD card under Linux in C
I am trying to write raw data on my SD card under Linux Ubuntu 14.04. 我试图在Linux Ubuntu 14.04下将原始数据写入SD卡。
I need this cause I want to write my own "filesystem" from which I can easily read under microcontroller (arm based). 我需要这个原因,因为我想编写自己的“文件系统”,可以在微控制器(基于ARM)下轻松读取。
I am able to read data from SD card, but when I try to write some it gives me an error of: 我能够从SD卡读取数据,但是当我尝试写一些数据时,出现以下错误:
" Operation not permitted
". “
Operation not permitted
”。
This is the code I'm using: 这是我正在使用的代码:
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h> /* open */
#include <unistd.h> /* exit */
#include <sys/ioctl.h> /* ioctl */
#include <errno.h>
#define DEVICE "/dev/sdb1" /* SD card */
int main()
{
int file_desc, ret_val;
char msg[512];
msg[0] = 'H';
char answer[512];
file_desc = open(DEVICE, O_RDWR);
if(file_desc < 0)
printf("failed to open the device \n");
ret_val = write(file_desc, msg, 512);
fsync(file_desc);
printf("%d\n", ret_val);
printf("%d\n", errno);
read(file_desc, answer, 512);
printf("message read is %s\n", answer);
close(file_desc);
return 0;
}
As I said, I can open file in read/write
mode and read data from it, but in these lines: 就像我说的那样,我可以以
read/write
模式打开文件并从中读取数据,但是在以下行中:
ret_val = write(file_desc, msg, 512);
fsync(file_desc);
printf("%d\n", ret_val);
printf("%d\n", errno);
I get ret_val = -1
(which means error), and errno = 1
(which means " Operation not permitted"). 我得到
ret_val = -1
(这意味着错误),而errno = 1
(这意味着“不允许操作”)。
I would be very grateful for any advice that would help me write raw data on my SD card. 对于能帮助我将原始数据写入SD卡的任何建议,我将不胜感激。
在继续操作之前,请检查卡/适配器的侧面是否有写保护开关,并确保其已关闭(如果有)。
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