+ BattFsSuper *disk = fdb->disk;
+ const uint8_t *buf = (const uint8_t *)_buf;
+
+ size_t total_write = 0;
+ pgoff_t pg_offset;
+ pgaddr_t addr_offset;
+ pgaddr_t wr_len;
+ BattFsPageHeader curr_hdr;
+ pgcnt_t new_page;
+
+ if (fd->seek_pos < 0)
+ {
+ fdb->errors |= BATTFS_NEGATIVE_SEEK_ERR;
+ return total_write;
+ }
+
+ if (fd->seek_pos > fd->size)
+ {
+ if (!readHdr(disk, fdb->start[fdb->max_off], &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_READ_ERR;
+ return total_write;
+ }
+
+ new_page = renewPage(disk, fdb->start[fdb->max_off]);
+ if (new_page == NO_SPACE)
+ {
+ fdb->errors |= BATTFS_DISK_SPACEOVER_ERR;
+ return total_write;
+ }
+
+ kblock_copy(disk->dev, fdb->start[fdb->max_off], new_page);
+ fdb->start[fdb->max_off] = new_page;
+
+ /* 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 (kblock_write(disk->dev, new_page, &dummy, curr_hdr.fill, 1) != 1)
+ {
+ fdb->errors |= BATTFS_DISK_WRITE_ERR;
+ return total_write;
+ }
+ curr_hdr.fill++;
+ fd->size++;
+ disk->free_bytes--;
+ }
+ curr_hdr.seq++;
+ if (!writeHdr(disk, new_page, &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_WRITE_ERR;
+ return total_write;
+ }
+
+ /* 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);
+
+ while (missing_pages--)
+ {
+ zero_bytes = MIN((kfile_off_t)disk->data_size, fd->seek_pos - fd->size);
+
+ new_page = allocateNewPage(disk, (fdb->start - disk->page_array) + fdb->max_off + 1, fdb->inode);
+ if (new_page == NO_SPACE)
+ {
+ fdb->errors |= BATTFS_DISK_SPACEOVER_ERR;
+ return total_write;
+ }
+
+
+ /* Fill page buffer with 0 to avoid filling unused pages with garbage */
+ for (pgaddr_t off = 0; off < disk->data_size; off++)
+ {
+ if (kblock_write(disk->dev, new_page, &dummy, off, 1) != 1)
+ {
+ fdb->errors |= BATTFS_DISK_WRITE_ERR;
+ return total_write;
+ }
+ }
+ curr_hdr.inode = fdb->inode;
+ curr_hdr.pgoff = ++fdb->max_off;
+ curr_hdr.fill = zero_bytes;
+ curr_hdr.seq = 0;
+
+ if (!writeHdr(disk, new_page, &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_WRITE_ERR;
+ return total_write;
+ }
+
+ /* Update size and free space left */
+ fd->size += zero_bytes;
+ disk->free_bytes -= zero_bytes;
+ }
+ }
+ }
+
+ while (size)
+ {
+ pg_offset = fd->seek_pos / disk->data_size;
+ addr_offset = fd->seek_pos % disk->data_size;
+ wr_len = MIN(size, (size_t)(disk->data_size - addr_offset));
+
+ /* Handle write outside EOF */
+ if (pg_offset > fdb->max_off)
+ {
+ LOG_INFO("New page needed, pg_offset %d, pos %d\n", pg_offset, (int)((fdb->start - disk->page_array) + pg_offset));
+
+ new_page = allocateNewPage(disk, (fdb->start - disk->page_array) + pg_offset, fdb->inode);
+ if (new_page == NO_SPACE)
+ {
+ fdb->errors |= BATTFS_DISK_SPACEOVER_ERR;
+ return total_write;
+ }
+
+ curr_hdr.inode = fdb->inode;
+ curr_hdr.pgoff = pg_offset;
+ curr_hdr.fill = 0;
+ curr_hdr.seq = 0;
+ fdb->max_off = pg_offset;
+ }
+ else
+ {
+ if (!readHdr(disk, fdb->start[pg_offset], &curr_hdr))
+ {
+ fdb->errors |= BATTFS_DISK_READ_ERR;
+ return total_write;
+ }
+
+ new_page = renewPage(disk, fdb->start[pg_offset]);
+ if (new_page == NO_SPACE)
+ {
+ fdb->errors |= BATTFS_DISK_SPACEOVER_ERR;
+ return total_write;
+ }
+
+ LOG_INFO("Re-writing page %d to %d\n", fdb->start[pg_offset], new_page);
+ if (kblock_copy(disk->dev, fdb->start[pg_offset], new_page) != 0)
+ {
+ fdb->errors |= BATTFS_DISK_WRITE_ERR;
+ return total_write;
+ }
+ fdb->start[pg_offset] = new_page;
+ curr_hdr.seq++;
+ }
+ //LOG_INFO("writing to buffer for page %d, offset %d, size %d\n", disk->curr_page, addr_offset, wr_len);
+ if (kblock_write(disk->dev, new_page, buf, addr_offset, wr_len) != wr_len)
+ {
+ fdb->errors |= BATTFS_DISK_WRITE_ERR;
+ return total_write;
+ }
+
+ size -= wr_len;
+ fd->seek_pos += wr_len;
+ total_write += wr_len;
+ buf += wr_len;
+ fill_t fill_delta = MAX((int32_t)(addr_offset + wr_len) - curr_hdr.fill, (int32_t)0);
+ disk->free_bytes -= fill_delta;
+ fd->size += fill_delta;
+ curr_hdr.fill += fill_delta;