AliOS Things API VFS Guide

API INDEX

• 1 aos_open
• 2 aos_close
• 3 aos_read
• 4 aos_write
• 5 aos_ioctl
• 6 aos_poll
• 7 aos_fcntl
• 8 aos_lseek
• 9 aos_sync
• 10 aos_stat
• 11 aos_unlink
• 12 aos_rename
• 13 aos_opendir
• 14 aos_closedir
• 15 aos_readdir
• 16 aos_mkdir

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1-aos_open

int aos_open(const char *path, int flags)

• Description

  Open the file or device by its path.

• Parameters

  IN/OUT	NAME	DESC
  [in]	path	the path of the file or device to open.
  [in]	flags	the mode of open operation.

• Returns

  the new file descriptor, negative error on failure.

2-aos_close

int aos_close(int fd)

• Description

  Close the file or device by its file descriptor.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptor of the file or device.

• Returns

  0 on success, negative error on failure.

3-aos_read

ssize_t aos_read(int fd, void *buf, size_t nbytes)

• Description

  Read the contents of a file or device into a buffer.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptor of the file or device.
  [in]	nbytes	the number of bytes to read.
  [out]	buf	the buffer to read in to.

• Returns

  The number of bytes read, 0 at end of file, negative error on failure.

4-aos_write

ssize_t aos_write(int fd, const void *buf, size_t nbytes)

• Description

  Write the contents of a buffer to file or device.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptor of the file or device.
  [in]	nbytes	the number of bytes to write.
  [in]	buf	the buffer to write from.

• Returns

  The number of bytes written, negative error on failure.

5-aos_ioctl

int aos_ioctl(int fd, int cmd, unsigned long arg)

• Description

  This is a wildcard API for sending controller specific commands.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptior of the file or device.
  [in]	cmd	A controller specific command.
  [in]	arg	Argument to the command, interpreted according to the command.

• Returns

  any return from the command.

6-aos_poll

int aos_poll(struct pollfd *fds, int nfds, int timeout)

• Description

  A mechanism to multiplex input/output over a set of file descriptors. For every file descriptor provided, poll() examines it for any events registered for that particular file descriptor.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fds	a point to the array of pollfd struct carrying a file descriptor and bitmasks of events.
  [in]	nfhs	number of file descriptors.
  [in]	timeout	timer value to timeout or -1 for loop forever.

• Returns

  number of file descriptors selected (for which revents is non-zero). 0 if timed out with nothing selected. -1 for error.

7-aos_fcntl

int aos_fcntl(int fd, int cmd, int val)

• Description

  Performs one of the operations described below on the open file descriptor, The operation is determined by cmd.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptor of the file or device.
  [in]	cmd	the operation of the file or device.
  [in]	val	it depends on whether cmd need params.

• Returns

  0 on success, negative error on failure.

8-aos_lseek

off_t aos_lseek(int fd, off_t offset, int whence)

• Description

  Move the file position to a given offset from a given location.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptor of the file.
  [in]	offset	The offset from whence to move to.
  [in]	whence	The start of where to seek.SEEK_SET to start from beginning of file.SEEK_CUR to start from current position in file.SEEK_END to start from end of file.

• Returns

  The new offset of the file.

9-aos_sync

int aos_sync(int fd)

• Description

  Flush any buffers associated with the file.

• Parameters

  IN/OUT	NAME	DESC
  [in]	fd	the file descriptor of the file.

• Returns

  0 on success, negative error code on failure.

10-aos_stat

int aos_stat(const char *path, struct stat *st)

• Description

  Store information about the file in a stat structure.

• Parameters

  IN/OUT	NAME	DESC
  [in]	path	The path of the file to find information about.
  [out]	st	The stat buffer to write to.

• Returns

  0 on success, negative error code on failure.

11-aos_unlink

int aos_unlink(const char *path)

• Description

  Remove a file from the filesystem.

• Parameters

  IN/OUT	NAME	DESC
  [in]	path	The path of the file to remove.

• Returns

  0 on success, negative error code on failure.

12-aos_rename

int aos_rename(const char *oldpath, const char *newpath)

• Description

  Rename a file in the filesystem.

• Parameters

  IN/OUT	NAME	DESC
  [in]	oldpath	The path of the file to rename.
  [in]	newpath	The path to rename it to.

• Returns

  0 on success, negative error code on failure.

13-aos_opendir

aos_dir_t *aos_opendir(const char *path)

• Description

  Open a directory on the filesystem.

• Parameters

  IN/OUT	NAME	DESC
  [in]	path	the path of the directory to open.

• Returns

  a point of directory stream on success, NULL on failure.

14-aos_closedir

int aos_closedir(aos_dir_t *dir)

• Description

  Close a directory.

• Parameters

  IN/OUT	NAME	DESC
  [in]	dir	the handle of the directory to close.

• Returns

  0 on success, negative error code on failure.

15-aos_readdir

aos_dirent_t *aos_readdir(aos_dir_t *dir)

• Description

  Read the next directory entry.

• Parameters

  IN/OUT	NAME	DESC
  [in]	dir	the handle of the directory to read.

• Returns

  a pointer to a dirent structure.

16-aos_mkdir

int aos_mkdir(const char *path)

• Description

  Create the directory, if they do not already exist.

• Parameters

  IN/OUT	NAME	DESC
  [in]	path	the path of the directory.

• Returns

  0 on success, negative error code on failure.