FRESULT f_expand()

in fs/fatfs/src/ff.c [5049:5128]

• 75 lines of code
• 31 McCabe index (conditional complexity)

FRESULT f_expand (
	FIL* fp,		/* Pointer to the file object */
	FSIZE_t fsz,	/* File size to be expanded to */
	BYTE opt		/* Operation mode 0:Find and prepare or 1:Find and allocate */
)
{
	FRESULT res;
	FATFS *fs;
	DWORD n, clst, stcl, scl, ncl, tcl, lclst;


	res = validate(&fp->obj, &fs);		/* Check validity of the file object */
	if (res != FR_OK || (res = (FRESULT)fp->err) != FR_OK) LEAVE_FF(fs, res);
	if (fsz == 0 || fp->obj.objsize != 0 || !(fp->flag & FA_WRITE)) LEAVE_FF(fs, FR_DENIED);
#if _FS_EXFAT
	if (fs->fs_type != FS_EXFAT && fsz >= 0x100000000) LEAVE_FF(fs, FR_DENIED);	/* Check if in size limit */
#endif
	n = (DWORD)fs->csize * SS(fs);	/* Cluster size */
	tcl = (DWORD)(fsz / n) + ((fsz & (n - 1)) ? 1 : 0);	/* Number of clusters required */
	stcl = fs->last_clst; lclst = 0;
	if (stcl < 2 || stcl >= fs->n_fatent) stcl = 2;

#if _FS_EXFAT
	if (fs->fs_type == FS_EXFAT) {
		scl = find_bitmap(fs, stcl, tcl);			/* Find a contiguous cluster block */
		if (scl == 0) res = FR_DENIED;				/* No contiguous cluster block was found */
		if (scl == 0xFFFFFFFF) res = FR_DISK_ERR;
		if (res == FR_OK) {
			if (opt) {
				res = change_bitmap(fs, scl, tcl, 1);	/* Mark the cluster block 'in use' */
				lclst = scl + tcl - 1;
			} else {
				lclst = scl - 1;
			}
		}
	} else
#endif
	{
		scl = clst = stcl; ncl = 0;
		for (;;) {	/* Find a contiguous cluster block */
			n = get_fat(&fp->obj, clst);
			if (++clst >= fs->n_fatent) clst = 2;
			if (n == 1) { res = FR_INT_ERR; break; }
			if (n == 0xFFFFFFFF) { res = FR_DISK_ERR; break; }
			if (n == 0) {	/* Is it a free cluster? */
				if (++ncl == tcl) break;	/* Break if a contiguous cluster block is found */
			} else {
				scl = clst; ncl = 0;		/* Not a free cluster */
			}
			if (clst == stcl) { res = FR_DENIED; break; }	/* No contiguous cluster? */
		}
		if (res == FR_OK) {
			if (opt) {
				for (clst = scl, n = tcl; n; clst++, n--) {	/* Create a cluster chain on the FAT */
					res = put_fat(fs, clst, (n == 1) ? 0xFFFFFFFF : clst + 1);
					if (res != FR_OK) break;
					lclst = clst;
				}
			} else {
				lclst = scl - 1;
			}
		}
	}

	if (res == FR_OK) {
		fs->last_clst = lclst;		/* Set suggested start cluster to start next */
		if (opt) {
			fp->obj.sclust = scl;		/* Update object allocation information */
			fp->obj.objsize = fsz;
			if (_FS_EXFAT) fp->obj.stat = 2;	/* Set status 'contiguous chain' */
			fp->flag |= FA_MODIFIED;
			if (fs->free_clst  < fs->n_fatent - 2) {	/* Update FSINFO */
				fs->free_clst -= tcl;
				fs->fsi_flag |= 1;
			}
		}
	}

	LEAVE_FF(fs, res);
}