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index.js
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index.js
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'use strict'
var crypto = require('crypto')
var Transform = require('stream').Transform
module.exports = checksumStream
function checksumStream (opts) {
opts = opts || {}
var hash = crypto.createHash(opts.algorithm || 'sha1')
var streamSize = 0
var stream = new Transform({
transform: function (chunk, enc, cb) {
streamSize += chunk.length
hash.update(chunk, enc)
cb(null, chunk, enc)
},
flush: function (cb) {
var streamDigest = hash.digest('hex')
if (typeof opts.size === 'number' && streamSize !== opts.size) {
return cb(sizeError(opts.size, streamSize))
} else if (opts.digest && streamDigest !== opts.digest) {
return cb(checksumError(opts.digest, streamDigest))
} else {
stream.emit('size', streamSize)
stream.emit('digest', streamDigest)
return cb()
}
}
})
return stream
}
function sizeError (expected, found) {
var err = new Error('stream data size mismatch')
err.expected = expected
err.found = found
err.code = 'EBADSIZE'
return err
}
function checksumError (expected, found) {
var err = new Error('checksum failed')
err.code = 'EBADCHECKSUM'
err.expected = expected
err.found = found
return err
}