This package provides the necessary code to efficiently:
npm install @merlin4/zipThis package provides the necessary code to efficiently:
1. Read the directory of ZIP files.
2. Extract the contents from ZIP files.
3. Recover ZIP files that are partially damaged / missing a central directory.
``ts
import { readZipDirectory, unzipToFile } from "@merlin4/zip";
import { FileHandle, open } from "node:fs/promises";
import { resolve as pathResolve } from "node:path";
async function main() {
let fileHandle: FileHandle | undefined;
try {
const zipPath = pathResolve("./data/example.zip");
const outDir = pathResolve("./temp/example");
// open zip file
fileHandle = await open(zipPath, "r");
// read the zip's table of contents
const directory = await readZipDirectory(fileHandle);
// unzip all of the files
for (const entry of directory.entries) {
const outPath = pathResolve(outDir, entry.fileName);
await unzipToFile(fileHandle, entry, outPath);
}
} finally {
if (fileHandle) {
await fileHandle.close();
}
}
}
main();
``
This package doesn't currently support the ZIP64 file format for large files (over 4GB)
CPU & Memory performance are both very important to this package. As such, a significant effort has been made to stream the data and efficiently use buffers to reduce the memory needed to process ZIP files.
As such, the code leverages low-level c-style techniques of reducing memory usage and reusing buffers where possible.
When reviewing/modifying the code in this package please consult the specification for the ZIP file format.
1. https://en.wikipedia.org/wiki/ZIP_(file_format)
2. https://users.cs.jmu.edu/buchhofp/forensics/formats/pkzip.html
3. https://www.loc.gov/preservation/digital/formats/fdd/fdd000354.shtml
4. https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.9.TXT