The f_open function creates a file object to be used to access the file.
FRESULT f_open ( FIL* FileObject, /* Pointer to the blank file object structure */ const TCHAR* FileName, /* Pointer to the file neme */ BYTE ModeFlags /* Mode flags */ );
| Value | Description |
|---|---|
| FA_READ | Specifies read access to the object. Data can be read from the file. Combine with FA_WRITE for read-write access. |
| FA_WRITE | Specifies write access to the object. Data can be written to the file. Combine with FA_READ for read-write access. |
| FA_OPEN_EXISTING | Opens the file. The function fails if the file is not existing. (Default) |
| FA_OPEN_ALWAYS | Opens the file if it is existing. If not, a new file is created. To append data to the file, use f_lseek function after file open in this method. |
| FA_CREATE_NEW | Creates a new file. The function fails with FR_EXIST if the file is existing. |
| FA_CREATE_ALWAYS | Creates a new file. If the file is existing, it is truncated and overwritten. |
FR_OK, FR_DISK_ERR, FR_INT_ERR, FR_NOT_READY, FR_NO_FILE, FR_NO_PATH, FR_INVALID_NAME, FR_DENIED, FR_EXIST, FR_WRITE_PROTECTED, FR_INVALID_DRIVE, FR_NOT_ENABLED, FR_NO_FILESYSTEM, FR_TIMEOUT, FR_LOCKED, FR_NOT_ENOUGH_CORE, FR_TOO_MANY_OPEN_FILES
After f_open function succeeded, the file object is valid. The file object is used for subsequent read/write functions to identify the file. When close an open file object, use f_close function. If the modified file is not closed, the file data can be collapsed.
If duplicated file open is needed, read here carefully.
Before using any file function, a work area (file system object) must be registered to the logical drive with f_mount function. All API functions except for f_fdisk function can work after this procedure.
Always available. The mode flags, FA_WRITE, FA_CREATE_ALWAYS, FA_CREATE_NEW and FA_OPEN_ALWAYS, are not available when _FS_READONLY == 1.
void main (void)
{
FATFS fs[2]; /* Work area (file system object) for logical drives */
FIL fsrc, fdst; /* file objects */
BYTE buffer[4096]; /* file copy buffer */
FRESULT res; /* FatFs function common result code */
UINT br, bw; /* File read/write count */
/* Register work area for each volume (Always succeeds regardless of disk status) */
f_mount(0, &fs[0]);
f_mount(1, &fs[1]);
/* Open source file on the drive 1 */
res = f_open(&fsrc, "1:srcfile.dat", FA_OPEN_EXISTING | FA_READ);
if (res) die(res);
/* Create destination file on the drive 0 */
res = f_open(&fdst, "0:dstfile.dat", FA_CREATE_ALWAYS | FA_WRITE);
if (res) die(res);
/* Copy source to destination */
for (;;) {
res = f_read(&fsrc, buffer, sizeof(buffer), &br); /* Read a chunk of src file */
if (res || br == 0) break; /* error or eof */
res = f_write(&fdst, buffer, br, &bw); /* Write it to the dst file */
if (res || bw < br) break; /* error or disk full */
}
/* Close open files */
f_close(&fsrc);
f_close(&fdst);
/* Unregister work area prior to discard it */
f_mount(0, NULL);
f_mount(1, NULL);
}