+ if (fd->seek_pos < 0)
+ {
+ fdb->errors |= BATTFS_NEGATIVE_SEEK_ERR;
+ return total_write;
+ }
+
+ if (fd->seek_pos > fd->size)
+ {
+ /* Handle writing when seek pos if far over EOF */
+ if (!loadPage(disk, fdb->start[fdb->max_off], &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_LOADPAGE_ERR;
+ return total_write;
+ }
+
+ /* Fill unused space of first page with 0s */
+ uint8_t dummy = 0;
+ pgaddr_t zero_bytes = MIN(fd->seek_pos - fd->size, (kfile_off_t)(disk->data_size - curr_hdr.fill));
+ while (zero_bytes--)
+ {
+ if (disk->bufferWrite(disk, curr_hdr.fill, &dummy, 1) != 1)
+ {
+ fdb->errors |= BATTFS_DISK_BUFFERWR_ERR;
+ return total_write;
+ }
+ curr_hdr.fill++;
+ fd->size++;
+ disk->free_bytes--;
+ disk->cache_dirty = true;
+ }
+ setBufferHdr(disk, &curr_hdr);
+
+ /* Allocate the missing pages first. */
+ pgoff_t missing_pages = fd->seek_pos / disk->data_size - fdb->max_off;
+
+ if (missing_pages)
+ {
+ LOG_INFO("missing pages: %d\n", missing_pages);
+ flushBuffer(disk);
+
+ /* Fill page buffer with 0 to avoid filling unused pages with garbage */
+ for (pgaddr_t off = 0; off < disk->data_size; off++)
+ {
+ if (disk->bufferWrite(disk, off, &dummy, 1) != 1)
+ {
+ fdb->errors |= BATTFS_DISK_BUFFERWR_ERR;
+ return total_write;
+ }
+ }
+
+ while (missing_pages--)
+ {
+ zero_bytes = MIN((kfile_off_t)disk->data_size, fd->seek_pos - fd->size);
+ /* Get the new page needed */
+ if (!getNewPage(disk, (fdb->start - disk->page_array) + fdb->max_off + 1, fdb->inode, fdb->max_off + 1, &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_GETNEWPAGE_ERR;
+ return total_write;
+ }
+
+ /* Update size and free space left */
+ fd->size += zero_bytes;
+ disk->free_bytes -= zero_bytes;
+
+ curr_hdr.fill = zero_bytes;
+ setBufferHdr(disk, &curr_hdr);
+
+ fdb->max_off++;
+ }
+ }
+ }
+ else if (!getBufferHdr(disk, &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_BUFFERRD_ERR;
+ return total_write;
+ }