虚拟文件系统

#include <stdio.h>
#include <string.h>
#include "sys/stat.h"
#include "fcntl.h"
#include "unistd.h"

#define LOS_OK 0
#define LOS_NOK -1

int main(void)
{
    int ret;
    int fd = -1;
    ssize_t len;
    off_t off;
    char mntName[20] = "/storage";
    char devName[20] = "/dev/mmcblk0p0";
    char dirName[20] = "/storage/test";
    char fileName[20] = "/storage/test/file.txt";
    char writeBuf[20] = "Hello OpenHarmony!";
    char readBuf[20] = {0};

    /* 创建目录“/storage” */
    ret = mkdir(mntName, 0777);
    if (ret != LOS_OK) {
        printf("mkdir failed.\n");
        return LOS_NOK;
    }

    /* 挂载设备“/dev/mmcblk0p0”到“/storage” */
    ret = mount(devName, mntName, "vfat", 0, 0);
    if (ret != LOS_OK) {
        printf("mount failed.\n");
        return LOS_NOK;
    }

    /* 创建目录“/storage/test” */
    ret = mkdir(dirName, 0777);
    if (ret != LOS_OK) {
        printf("mkdir failed.\n");
        return LOS_NOK;
    }

    /* 创建可读写文件“/storage/test/file.txt” */
    fd = open(fileName, O_RDWR | O_CREAT, 0777);
    if (fd < 0) {
        printf("open file failed.\n");
        return LOS_NOK;
    }

    /* 将writeBuf中的内容写入文件 */
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }

    /* 将文件内容刷入存储设备中 */
    ret = fsync(fd);
    if (ret != LOS_OK) {
        printf("fsync failed.\n");
        return LOS_NOK;
    }

    /* 将读写指针偏移至文件头 */
    off = lseek(fd, 0, SEEK_SET);
    if (off != 0) {
        printf("lseek failed.\n");
        return LOS_NOK;
    }

    /* 将文件内容读出至readBuf中，读取长度为readBuf大小 */
    len = read(fd, readBuf, sizeof(readBuf));
    if (len != strlen(readBuf)) {
        printf("read file failed.\n");
        return LOS_NOK;
    }
    printf("%s\n", readBuf);

    /* 关闭文件 */
    ret = close(fd);
    if (ret != LOS_OK) {
        printf("close failed.\n");
        return LOS_NOK;
    }

    /* 删除文件“/storage/test/file.txt” */
    ret = unlink(fileName);
    if (ret != LOS_OK) {
        printf("unlink failed.\n");
        return LOS_NOK;
    }

    /* 删除目录“/storage/test” */
    ret = rmdir(dirName);
    if (ret != LOS_OK) {
        printf("rmdir failed.\n");
        return LOS_NOK;
    }

    /* 卸载分区“/storage” */
    ret = umount(mntName);
    if (ret != LOS_OK) {
        printf("umount failed.\n");
        return LOS_NOK;
    }

    /* 删除目录“/storage” */
    ret = rmdir(mntName);
    if (ret != LOS_OK) {
        printf("rmdir failed.\n");
        return LOS_NOK;
    }

    return LOS_OK;
}

Hello OpenHarmony!