Created
March 1, 2023 08:30
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CarBufferWriter for synchronous in-memory CAR creation
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import fs from 'fs' | |
import { CarBufferWriter } from '@ipld/car' | |
import { CID } from 'multiformats/cid' | |
import * as json from 'multiformats/codecs/json' | |
import * as raw from 'multiformats/codecs/raw' | |
import { sha256 } from 'multiformats/hashes/sha2' | |
/** | |
* @param {CID} root | |
* @param {Block[]} blocks | |
* @returns {Uint8Array} car | |
*/ | |
function createCARSync (root, blocks) { | |
const headerSize = CarBufferWriter.headerLength({ roots: [root] }) | |
const bufferSize = blocks.reduce((size, block) => size + CarBufferWriter.blockLength(block), headerSize) | |
const car = CarBufferWriter.createWriter(new ArrayBuffer(bufferSize), { roots: [root] }) | |
blocks.forEach(b => car.write(b)) | |
blocks.forEach(b => console.log(b.cid.toString())) | |
return car.close() | |
} | |
function createRawBlock (str) { | |
const bytes = new TextEncoder().encode(str) | |
const hash = sha256.digest(raw.encode(bytes)) | |
const cid = CID.create(1, raw.code, hash) | |
return { cid, bytes } | |
} | |
function createJsonBlock (obj) { | |
const bytes = json.encode(obj) | |
const hash = sha256.digest(bytes) | |
const cid = CID.create(1, json.code, hash) | |
return { cid, bytes } | |
} | |
function main () { | |
const blocks = ['a', 'a', 'b', 'c'].map(createRawBlock) | |
const root = blocks.at(-1).cid | |
const car = createCARSync(root, blocks) | |
fs.writeFileSync('dupe.car', car) | |
} | |
main() |
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