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63 lines
1.6 KiB
63 lines
1.6 KiB
const crypto = require('crypto')
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const fs = require('fs')
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const stream = require('stream')
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const { promisify } = require('util')
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const ALGORITHM = 'SHA256'
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// 4MB default block size
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const BLOCK_SIZE = 4 * 1024 * 1024
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const pipeline = promisify(stream.pipeline)
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function hashBlock (block) {
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return crypto.createHash(ALGORITHM).update(block).digest('hex')
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}
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async function getFileIntegrity (path) {
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const fileHash = crypto.createHash(ALGORITHM)
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const blocks = []
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let currentBlockSize = 0
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let currentBlock = []
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await pipeline(
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fs.createReadStream(path),
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new stream.PassThrough({
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decodeStrings: false,
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transform (_chunk, encoding, callback) {
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fileHash.update(_chunk)
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function handleChunk (chunk) {
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const diffToSlice = Math.min(BLOCK_SIZE - currentBlockSize, chunk.byteLength)
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currentBlockSize += diffToSlice
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currentBlock.push(chunk.slice(0, diffToSlice))
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if (currentBlockSize === BLOCK_SIZE) {
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blocks.push(hashBlock(Buffer.concat(currentBlock)))
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currentBlock = []
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currentBlockSize = 0
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}
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if (diffToSlice < chunk.byteLength) {
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handleChunk(chunk.slice(diffToSlice))
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}
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}
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handleChunk(_chunk)
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callback()
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},
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flush (callback) {
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blocks.push(hashBlock(Buffer.concat(currentBlock)))
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currentBlock = []
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callback()
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}
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})
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)
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return {
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algorithm: ALGORITHM,
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hash: fileHash.digest('hex'),
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blockSize: BLOCK_SIZE,
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blocks: blocks
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}
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}
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module.exports = getFileIntegrity
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