devilfish-dbms/repairdb.js

a database that based on key-value map and is successful in deal with saved in disk and high-performance in select that act as a memory-based database

const fs = require('fs');
const path = require('path');

function repairJSONDBFile(dbFilePath) {
    let raw;
    try {
        raw = fs.readFileSync(dbFilePath, 'utf8');
    } catch (err) {
        console.error('读取数据库文件失败:', err.message);
        return false;
    }

    // 先尝试直接解析
    try {
        JSON.parse(raw);
        console.log('数据库文件未损坏，无需修复');
        return true;
    } catch (e) {
        // 继续修复
    }

    // 尝试从尾部裁剪，找到能被JSON.parse解析的最大前缀
    let lastGood = null;
    let lastGoodStr = '';
    let step = 1;
    for (let i = raw.length; i > 0; i -= step) {
        let candidate = raw.slice(0, i);
        // 尝试补全右大括号
        let fixed = candidate;
        let leftCount = (fixed.match(/{/g) || []).length;
        let rightCount = (fixed.match(/}/g) || []).length;
        if (leftCount > rightCount) {
            fixed += ']]}}'.repeat(leftCount - rightCount);
        }
        try {
            let obj = JSON.parse(fixed);
            lastGood = obj;
            lastGoodStr = fixed;
            break;
        } catch (e) {
            // 继续裁剪
        }
    }

    if (lastGood) {
        // 备份原始文件
        fs.copyFileSync(dbFilePath, dbFilePath + '.bak');
        // 写入修复文件
        fs.writeFileSync(dbFilePath + '.repaired', lastGoodStr, 'utf8');
        console.log('已修复数据库文件，修复版为：' + dbFilePath + '.repaired');
        return true;
    } else {
        console.log('无法修复数据库文件');
        return false;
    }
}

// 用法
const dbFile = process.argv[2];
if (!dbFile) {
    console.log('用法: node repairdb.js yourdb.db');
    process.exit(1);
}
repairJSONDBFile(dbFile);