51 lines
2.1 KiB
JavaScript
51 lines
2.1 KiB
JavaScript
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// zip.js —— 零依赖 ZIP 解压（stored/deflate），供技能安装与热更新复用。
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"use strict";
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const fs = require("fs");
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const path = require("path");
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const zlib = require("zlib");
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// 解析中央目录，把 zip 内容写入 destDir；返回写出的文件数。
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function extractZip(buf, destDir) {
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// 找 EOCD（0x06054b50），从尾部回扫
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let eocd = -1;
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for (let i = buf.length - 22; i >= 0 && i >= buf.length - 22 - 65536; i--) {
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if (buf.readUInt32LE(i) === 0x06054b50) { eocd = i; break; }
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}
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if (eocd < 0) throw new Error("不是有效的 zip（找不到 EOCD）");
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const count = buf.readUInt16LE(eocd + 10);
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let ptr = buf.readUInt32LE(eocd + 16); // 中央目录起始偏移
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let written = 0;
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for (let n = 0; n < count; n++) {
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if (buf.readUInt32LE(ptr) !== 0x02014b50) break;
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const method = buf.readUInt16LE(ptr + 10);
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const compSize = buf.readUInt32LE(ptr + 20);
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const nameLen = buf.readUInt16LE(ptr + 28);
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const extraLen = buf.readUInt16LE(ptr + 30);
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const commentLen = buf.readUInt16LE(ptr + 32);
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const localOff = buf.readUInt32LE(ptr + 42);
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const name = buf.toString("utf8", ptr + 46, ptr + 46 + nameLen);
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ptr += 46 + nameLen + extraLen + commentLen;
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// 读本地头，定位数据
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if (buf.readUInt32LE(localOff) !== 0x04034b50) continue;
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const lNameLen = buf.readUInt16LE(localOff + 26);
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const lExtraLen = buf.readUInt16LE(localOff + 28);
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const dataStart = localOff + 30 + lNameLen + lExtraLen;
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const comp = buf.subarray(dataStart, dataStart + compSize);
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// 防目录穿越
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const safe = name.replace(/\\/g, "/").replace(/^\/+/, "");
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if (safe.includes("../")) continue;
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const outPath = path.join(destDir, safe);
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if (safe.endsWith("/")) { fs.mkdirSync(outPath, { recursive: true }); continue; }
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fs.mkdirSync(path.dirname(outPath), { recursive: true });
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let data;
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if (method === 0) data = comp;
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else if (method === 8) data = zlib.inflateRawSync(comp);
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else throw new Error(`不支持的压缩方式 ${method}`);
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fs.writeFileSync(outPath, data);
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written++;
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}
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return written;
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}
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module.exports = { extractZip };
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