m2m_fs_open

M2M_T_FS_HANDLE m2m_fs_open(CHAR *filename, INT32 mode)

Description: the function opens the file using the given path/filename, and mode. It returns the file handle. The function does not create the required directory if missing. See m2m_fs_create(...) to create the directories.

Parameters:
filename: pointer to the zero-terminated string containing the file name and path if it is already

existing.

mode: open mode, see table below:

OPEN MODE

INITIAL CONDITIONS:

The file must exist, if it does not exist à Error: M2M_F_ERR_NOTFOUND

M2M_FS_OPEN_READ

- For Reading:

- After opening, the reading starts from the first character of the file.

- File data pointer can be moved to perform reading from the selected file position.

The file data pointer must not point to the last file character, if reading is tried à

Error: M2M_F_ERR_ UNKNOWN.

- No Writing:

- If writing is tried à Error: M2M_F_ERR_NOTOPEN

M2M_FS_OPEN_MODIFY

- For Reading:

- After opening, the reading starts from the first character of the file.

- File data pointer can be moved to perform reading from the selected file position.

The file data pointer must not point to the last file character, if reading is tried à

Error: M2M_F_ERR_ UNKNOWN

- For Writing:

- After opening, the writing start from the beginning of the file. The writing puts new
characters on the old ones.

- File data pointer can be moved to perform writing on existing characters starting
from the selected position. The writing is not limited; consequently, the file size can
be incremented.

OPEN MODE

INITIAL CONDITIONS:

Creates the file if it does not exist. If the file exists, appends or puts new characters on the old ones

M2M_FS_OPEN_APPEND

- For Writing:

- After opening, the writing starts from the end of the file (self-seek to the EOF).

- File data pointer can be moved to perform writing on existing characters starting
from the selected position. The writing is not limited; consequently, the file size can
be incremented.

- No Reading:

- If reading is tried àError: M2M_F_ERR_NOTOPEN

OPEN MODE

INITIAL CONDITIONS:

Creates the file if it does not exist. If the file exists, truncates it to ‘0’ bytes.

M2M_FS_OPEN_WRITE

M2M_FS_OPEN_CREATE

- For Writing:

- After opening, allows consecutive writings in append mode (self-seek to the EOF)
starting from the beginning of the file.

- File data pointer can be moved to perform writing on existing characters starting
from the selected position. The writing is not limited; consequently, the file size can
be incremented.

- No Reading:

- If reading is tried àError: M2M_F_ERR_NOTOPEN, regardless of the position of
the file data pointer.

M2M_FS_OPEN_TRUNCATE

- For Writing:

- After opening, allows consecutive writings in append mode (self-seek to the EOF)
starting from the beginning of the file.

- File data pointer can be moved to perform writing on existing characters starting
from the selected position. The writing is not limited; consequently, the file size can
be incremented.

- For Reading:

- File data pointer can be moved to perform reading. The file data pointer must not
point to the last file character. If reading is tried à Error M2M_F_ERR_ UNKNOWN

Return value:
on success: pointer to the file handle
on failure: NULL

NOTE: m2m_fs_last_error function returns the failure reason.

Examples: ‎19.1.1 Open and Close