typedef struct stat {
    dev_t       st_dev;     /* ID of device containing file */
    ino_t       st_ino;     /* inode number */ 
    mode_t      st_mode;    /* protection */
    nlink_t     st_nlink;   /* number of hard links */
    uid_t       st_uid;     /* user ID of owner */
    gid_t       st_gid;     /* group ID of owner  */
    dev_t       st_rdev;    /* device ID (if special file) */
    off_t       st_size;    /* total size, in bytes */
    time_t      st_atime;   /* time of last access */
    long        st_spare1; 
    time_t      st_mtime;   /* time of last modification */
    long        st_spare2;
    time_t      st_ctime;   /* time of last status change */
    long        st_spare3; 
    blksize_t   st_blksize; /* blocksize for filesystem I/O */
    blkcnt_t    st_blocks;  /* number of blocks allocated */
    long        st_spare4[2];
} ms_stat_t;

typedef struct dirent {
    char            d_name[MS_IO_NAME_BUF_SIZE];

#define DT_UNKNOWN  0U
#define DT_FIFO     1U
#define DT_CHR      2U
#define DT_DIR      4U
#define DT_BLK      6U
#define DT_REG      8U
#define DT_LNK      10U
#define DT_SOCK     12U
#define DT_WHT      14U
    ms_uint8_t      d_type;
} ms_dirent_t;

typedef struct ms_statvfs {
    ms_uint32_t     f_bsize;    /* Optimal transfer block size */
    ms_uint32_t     f_frsize;   /* Allocation unit size */
    ms_uint32_t     f_blocks;   /* Size of FS in f_frsize units */
    ms_uint32_t     f_bfree;    /* Number of free blocks */
    ms_uint32_t     f_files;    /* Number of avail files */
    ms_uint32_t     f_ffree;    /* Number of free files */
    const char     *f_dev;      /* Block device path */
    const char     *f_mnt;      /* Mount point path */
    const char     *f_fsname;   /* File system name */
} ms_statvfs_t;

typedef struct pollfd {
    /*
     * Standard fields
     */
    int             fd;                /*  The descriptor being polled         */
    ms_pollevent_t  events;            /*  The input event flags               */
    ms_pollevent_t  revents;           /*  The output event flags              */

    /*
     * Non-standard fields used internally by MS-RTOS
     */
    ms_handle_t     semcid;            /*  Semaphore used to post output event */
    ms_ptr_t        priv;              /*  For use by drivers                  */
} ms_pollfd_t;

int ms_io_chdir(const char *path);

char *ms_io_getcwd(char *buf, ms_size_t size);

int ms_io_creat(const char *path, ms_mode_t mode);

int ms_io_open(const char *path, int oflag, ms_mode_t mode);

int ms_io_close(int fd);

int ms_io_fcntl(int fd, int cmd, int arg);

int ms_io_fstat(int fd, ms_stat_t *buf);

int ms_io_isatty(int fd);

int ms_io_fsync(int fd);

int ms_io_fdatasync(int fd);

int ms_io_ftruncate(int fd, ms_off_t len);

int ms_io_ioctl(int fd, int cmd, ms_ptr_t arg);

int ms_io_dup(int fd);

int ms_io_dup2(int fd, int to);

ms_off_t ms_io_lseek(int fd, ms_off_t offset, int whence);

ms_ssize_t ms_io_read(int fd, ms_ptr_t buf, ms_size_t len);

ms_ssize_t ms_io_write(int fd, ms_const_ptr_t buf, ms_size_t len);

static MS_FORCE_INLINE ms_off_t ms_io_tell(int fd)
{
    return ms_io_lseek(fd, 0, SEEK_CUR);
}

int ms_io_poll(ms_pollfd_t *fds, ms_nfds_t nfds, int timeout);

int ms_io_select(int maxfd, ms_fd_set_t *readfds, ms_fd_set_t *writefds, 
                   ms_fd_set_t *errorfds, ms_timeval_t *timeout);

int ms_io_link(const char *path1, const char *path2);

int ms_io_rename(const char *old, const char *_new);

int ms_io_stat(const char *path, ms_stat_t *buf);

int ms_io_lstat(const char *path, ms_stat_t *buf);

int ms_io_statvfs(const char *path, ms_statvfs_t *buf);

int ms_io_unlink(const char *path);

int ms_io_mkdir(const char *path, ms_mode_t mode);

int ms_io_rmdir(const char *path);

int ms_io_access(const char *path, int amode);

int ms_io_truncate(const char *path, ms_off_t len);

int ms_io_sync(void);

ms_err_t ms_io_mkfs(const char *path, ms_const_ptr_t param);

ms_err_t ms_io_mount(const char *mnt_path, const char *dev_path, const char *fs_name, ms_const_ptr_t param);

ms_err_t ms_io_mount_ex(const char *mnt_path, const char *dev_path, const char *fs_name, ms_const_ptr_t param,
                        ms_callback_t on_umount, ms_ptr_t on_umount_arg);

ms_err_t ms_io_unmount(const char *mnt_path, ms_const_ptr_t param);

MS_DIR *ms_io_opendir(const char *path);

int ms_io_closedir(MS_DIR *dir);

int ms_io_readdir_r(MS_DIR *dir, ms_dirent_t *entry, ms_dirent_t **result);

int ms_io_rewinddir(MS_DIR *dir);

int ms_io_seekdir(MS_DIR *dir, long loc);

long ms_io_telldir(MS_DIR *dir);

// 当前工作目录
int chdir(const char *path);
char *getcwd(char *buf, size_t size);

// 文件
int creat(const char *path, mode_t mode);
int open(const char *path, int oflag, ... /* mode */);
int close(int fd);
int fcntl(int fd, int cmd, ... /* arg */);
int fstat(int fd, struct stat *buf);
int isatty(int fd);
int fsync(int fd);
int fdatasync(int fd);
int ftruncate(int fd, off_t len);
int ioctl(int fd, int cmd, void *arg);
int dup(int fd);
int dup2(int fd, int to);
off_t lseek(int fd, off_t offset, int whence);
ssize_t read(int fd, void *buf, size_t len);
ssize_t write(int fd, const void *buf, size_t len);

// 多路 IO 复用
int poll(pollfd_t *fds, nfds_t nfds, int timeout);
int select(int maxfd, fd_set *readfds, fd_set *writefds, 
             fd_set *errorfds, struct timeval *timeout);

// 文件系统
int link(const char *path1, const char *path2);
int rename(const char *old, const char *_new);
int stat(const char *path, struct stat *buf);
int lstat(const char *path, struct stat *buf);
int unlink(const char *path);
int mkdir(const char *path, mode_t mode);
int rmdir(const char *path);
int access(const char *path, int amode);
int truncate(const char *path, off_t len);
void sync(void);

// 目录流
DIR *opendir(const char *path);
int closedir(DIR *dir);
int readdir_r(DIR *dir, struct dirent *entry, struct dirent **result);
struct dirent *readdir(DIR *dir); // 不可重入，不推荐使用
int rewinddir(DIR *dir);
int seekdir(DIR *dir, long loc);
long telldir(DIR *dir);