7z-iterator

7z-iterator

Extract contents from 7z archive type using an iterator API using streams or paths. Use stream interface and pipe transforms to add decompression algorithms.

// asyncIterator

``js
var assert = require('assert');
var fs = require('fs');
var SevenZipIterator = require('7z-iterator');

(async function() {
let iterator = new SevenZipIterator('/path/to/archive');

try {
const links = [];
for await (const entry of iterator) {
if (entry.type === 'link') links.unshift(entry);
else if (entry.type === 'symlink') links.push(entry);
else await entry.create(dest, options);
}

// create links after directories and files
for (const entry of links) await entry.create(dest, options);
} catch (err) {
}

iterator.destroy();
iterator = null;
})();

(async function() {
let iterator = new SevenZipIterator(fs.createReadStream('/path/to/archive'));

try {
const links = [];
for await (const entry of iterator) {
if (entry.type === 'link') links.unshift(entry);
else if (entry.type === 'symlink') links.push(entry);
else await entry.create(dest, options);
}

// create links after directories and files
for (const entry of links) await entry.create(dest, options);
} catch (err) {
}

iterator.destroy();
iterator = null;
})();
`

// Async / Await

`js
var assert = require('assert');
var SevenZipIterator = require('7z-iterator');

// one by one
(async function() {
let iterator = new SevenZipIterator('/path/to/archive');

const links = [];
let entry = await iterator.next();
while (entry) {
if (entry.type === 'link') links.unshift(entry);
else if (entry.type === 'symlink') links.push(entry);
else await entry.create(dest, options);
entry = await iterator.next();
}

// create links after directories and files
for (entry of links) {
await entry.create(dest, options);
}
iterator.destroy();
iterator = null;
})();

// infinite concurrency
(async function() {
let iterator = new SevenZipIterator('/path/to/archive');

try {
const links = [];
await iterator.forEach(
async function (entry) {
if (entry.type === 'link') links.unshift(entry);
else if (entry.type === 'symlink') links.push(entry);
else await entry.create(dest, options);
},
{ concurrency: Infinity }
);

// create links after directories and files
for (const entry of links) await entry.create(dest, options);
} catch (err) {
aseert.ok(!err);
}

iterator.destroy();
iterator = null;
})();
`

// Callbacks

`js
var assert = require('assert');
var Queue = require('queue-cb');
var SevenZipIterator = require('7z-iterator');

var iterator = new SevenZipIterator('/path/to/archive');

// one by one
var links = [];
iterator.forEach(
function (entry, callback) {
if (entry.type === 'link') {
links.unshift(entry);
callback();
} else if (entry.type === 'symlink') {
links.push(entry);
callback();
} else entry.create(dest, options, callback);
},
{ callbacks: true, concurrency: 1 },
function (err) {

// create links after directories and files
var queue = new Queue();
for (var index = 0; index < links.length; index++) {
var entry = links[index];
queue.defer(entry.create.bind(entry, dest, options));
}
queue.await(callback);

iterator.destroy();
iterator = null;
}
);
``

Limitations

$3

This library supports Node.js 0.8+ but has memory limits on older versions:

| Node.js Version | Maximum Single Buffer | Notes |
|-----------------|----------------------|-------|
| 0.8 - 4.x | ~1073 MB (0x3fffffff) | Hard limit due to kMaxLength |
| 6.x - 7.x | ~1073 MB | Uint8Array limit |
| 8.x - 9.x | ~2 GB | Buffer limit |
| 10+ | ~2.1 GB (2^31-1) | Buffer.allocUnsafe limit |

$3

- LZMA2: Streams incrementally, memory efficient, works on all Node versions
- LZMA1: Requires loading entire folder into memory before decompression. Fails on archives with folders larger than the buffer limit above.

$3

| Archive Type | Node 0.8-4.x | Node 6+ | Node 8+ | Node 10+ |
|--------------|--------------|---------|---------|----------|
| Small archives (< 1GB) | Works | Works | Works | Works |
| LZMA2 archives (> 1GB) | Fails | Fails | Works | Works |
| LZMA1 archives (> 1GB) | Fails | Fails | Fails | Fails |

For large LZMA1 archives, use Node 8+ or re-archive using LZMA2 format.