Function write_interior_page

internal/cbm/sqlite_writer.c:581–622

Write a completed interior page to disk and record it as a parent. Returns updated parent_count, or -1 on allocation failure.

// Write a completed interior page to disk and record it as a parent.
// Returns updated parent_count, or -1 on allocation failure.
static int write_interior_page(PageBuilder *pb, uint8_t *page, int cell_count, int content_offset,
                               uint32_t right_child_page, const PageRef *children,
                               int right_child_idx, bool is_index, PageRef **parents,
                               int parent_count, int *parent_cap) {
    pb->next_page = cbm_skip_pending_byte(pb->next_page);
    uint32_t pnum = pb->next_page++;
    page[0] = is_index ? INTERIOR_INDEX_FLAG : INTERIOR_TABLE_FLAG;
    put_u16(page + HDR_FREEBLOCK_OFF, 0);
    put_u16(page + HDR_CELLCOUNT_OFF, (uint16_t)cell_count);
    put_u16(page + HDR_CONTENT_OFF, (uint16_t)content_offset);
    page[HDR_FRAGBYTES_OFF] = 0;
    put_u32(page + HDR_RIGHTCHILD_OFF, right_child_page);

    (void)fseek(pb->fp, (long)(pnum - SKIP_ONE) * CBM_PAGE_SIZE, SEEK_SET);
    (void)fwrite(page, SKIP_ONE, CBM_PAGE_SIZE, pb->fp);

    if (parent_count >= *parent_cap) {
        int old_pcap = *parent_cap;
        *parent_cap = old_pcap == 0 ? INITIAL_PARENT_CAP : old_pcap * GROWTH_FACTOR;
        PageRef *tmp = (PageRef *)realloc(*parents, *parent_cap * sizeof(PageRef));
        if (!tmp) {
            free(*parents);
            *parents = NULL;
            return CBM_NOT_FOUND;
        }
        *parents = tmp;
        memset(&(*parents)[old_pcap], 0,
               ((size_t)*parent_cap - (size_t)old_pcap) * sizeof(PageRef));
    }
    (*parents)[parent_count].page_num = pnum;
    (*parents)[parent_count].max_key = children[right_child_idx].max_key;
    if (is_index && children[right_child_idx].sep_cell) {
        int slen = children[right_child_idx].sep_cell_len;
        (*parents)[parent_count].sep_cell = (uint8_t *)malloc(slen);
        memcpy((*parents)[parent_count].sep_cell, children[right_child_idx].sep_cell, slen);
        (*parents)[parent_count].sep_cell_len = slen;
    } else {
        (*parents)[parent_count].sep_cell = NULL;
        (*parents)[parent_count].sep_cell_len = 0;
    }
    return parent_count + SKIP_ONE;
}

// Free a PageRef array (sep_cell allocations), unless it's the original leaves.
static void free_children(PageRef *children, int child_count, const PageRef *leaves) {