git ssb

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var crypto = require('crypto')
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var pull = require('pull-stream')
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exports.createHash = function (type) {
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  var hash = crypto.createHash(type)
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  var hasher = pull.through(hash.update.bind(hash))
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  var digest
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  hasher.hash = hash
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  hasher.digest = hash.digest.bind(hash)
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  hasher.readDigest = function (abort, cb) {
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    if (digest) cb(true)
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    else cb(null, digest = hash.digest())
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  }
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  return hasher
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}
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exports.createGitObjectHash = function (objectType, objectLength) {
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  var hasher = exports.createHash('sha1')
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  hasher.hash.update(objectType + ' ' + objectLength + '\0')
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  return hasher
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}
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