wt_file_block.cpp

#include <iostream>
#include <stdio.h>
#include <string.h>

#include "include/wt_file.h"
#include "include/wt_utils.h"

WTBlockReader::WTBlockReader(struct wt_file_reader* reader) {
    wt_r = reader;
    assert(wt_r != NULL);
};

int WTBlockReader::readCell(wt_cell_unpack_t* unpack_c, int offset) {
    WTUtils utils;

    /* Get start of the cell from the mapped memory region */
    uint8_t* cell = static_cast<uint8_t*>(wt_r->map) + offset;

    unpack_c->prefix = 0;
    unpack_c->data = NULL;
    unpack_c->size = 0;
    unpack_c->len = 0;

    wt_cell_header_t c_head;
    std::memcpy(&c_head, cell, sizeof(wt_cell_header_t));
    unpack_c->desc = c_head.__chunk[0];

    /* Short cell type */
    switch (unpack_c->desc & WT_CELL_SHORT_TYPE_MASK) {
        case WT_CELL_KEY_SHORT:
        case WT_CELL_VALUE_SHORT:
            unpack_c->size = (unpack_c->desc >> WT_CELL_SHORT_SHIFT);
            unpack_c->data = new uint8_t[unpack_c->size];
            std::memcpy(unpack_c->data, (c_head.__chunk + 1), unpack_c->size);
            unpack_c->len = 1 + unpack_c->size; /* desc + data */
            return (unpack_c->len);
        case WT_CELL_KEY_SHORT_PFX:
            unpack_c->prefix = c_head.__chunk[1];
            unpack_c->size = (unpack_c->desc >> WT_CELL_SHORT_SHIFT);
            unpack_c->data = new uint8_t[unpack_c->size];
            std::memcpy(unpack_c->data, (c_head.__chunk + 2), unpack_c->size);
            unpack_c->len = 2 + unpack_c->size; /* desc + prefix + data */
            return (unpack_c->len);
    }

    /* Long cell type */

    /* Advance to the cell data */
    const uint8_t* cell_data = cell + 1;
    uint64_t sz;

    switch (unpack_c->desc & WT_CELL_LONG_TYPE_MASK) {
        /* TODO: Handle other cell types */
        case WT_CELL_ADDR_DEL:
        case WT_CELL_ADDR_INT:
        case WT_CELL_ADDR_LEAF:
        case WT_CELL_ADDR_LEAF_NO:
        case WT_CELL_KEY:
        case WT_CELL_KEY_PFX:
        case WT_CELL_VALUE:
            utils.unpackUInt(&cell_data, &sz);
            if (unpack_c->desc == WT_CELL_KEY || unpack_c->desc == WT_CELL_KEY_PFX ||
                (unpack_c->desc == WT_CELL_VALUE && !(unpack_c->desc & WT_CELL_64V)))
                sz += WT_CELL_SIZE_ADJUST;

            unpack_c->size = (uint32_t)sz;
            unpack_c->data = new uint8_t[unpack_c->size];
            std::memcpy(unpack_c->data, cell_data, unpack_c->size);
            unpack_c->len = (cell_data + unpack_c->size) - cell;
            return (unpack_c->len);
    }
    /* TODO: Handle unrecognized used case better */
    return -1;
}