git ssb

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var packCodec = require('js-git/lib/pack-codec')
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var pull = require('pull-stream')
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var cat = require('pull-cat')
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var pushable = require('pull-pushable')
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var buffered = require('pull-buffered')
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var options = {
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  verbosity: 1,
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  progress: false
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}
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function handleOption(name, value) {
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  switch (name) {
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    case 'verbosity':
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      options.verbosity = +value || 0
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      // console.error("ok verbo")
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      return true
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    case 'progress':
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      options.progress = !!value && value !== 'false'
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      return true
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    default:
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      console.error('unknown option', name + ': ' + value)
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      return false
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  }
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}
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function capabilitiesCmd(read) {
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  read(null, function next(end, data) {
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    if(end === true) return
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    if(end) throw end
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    console.log(data)
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    read(null, next)
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  })
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}
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// return a source that delivers some data and then ends
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// TODO: use pull.once and abortCb for this
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function endSource(data) {
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  var done
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  return function (end, cb) {
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    if (done) return cb(true)
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    done = true
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    cb(null, data)
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  }
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}
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function capabilitiesSource(prefix) {
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  return endSource([
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    'option',
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    'connect',
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    'refspec refs/heads/*:refs/' + prefix + '/heads/*',
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    'refspec refs/tags/*:refs/' + prefix + '/tags/*',
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  ].join('\n') + '\n\n')
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}
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function split2(str) {
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  var i = str.indexOf(' ')
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  return (i === -1) ? [str, ''] : [
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    str.substr(0, i),
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    str.substr(i + 1)
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  ]
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}
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function optionSource(cmd) {
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  var args = split2(cmd)
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  var msg = handleOption(args[0], args[1])
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  msg = (msg === true) ? 'ok'
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      : (msg === false) ? 'unsupported'
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      : 'error ' + msg
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  return endSource(msg + '\n')
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}
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function listSource() {
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  return endSource([
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    /* TODO */
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  ].join('\n') + '\n\n')
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}
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function createHash() {
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  var hash = crypto.createHash('sha256')
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  var hasher = pull.through(function (data) {
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    hash.update(data)
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  }, function () {
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    hasher.digest = '&'+hash.digest('base64')+'.sha256'
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  })
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  return hasher
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}
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function uploadPack(read) {
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  return function (abort, cb) {
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    cb('upload pack not implemented')
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  }
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  // throw new Error('upload pack')
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}
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function getRefs() {
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  return pull.values([
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    {
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      hash: '78beaedba9878623cea3862cf18e098cfb901e10',
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      name: 'refs/heads/master'
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    },
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    {
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      hash: '78beaedba9878623cea3862cf18e098cfb901e10',
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      name: 'refs/remotes/cel/master'
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    }
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  ])
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  /*
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  return function (err, cb) {
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    if (err === true) return
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    if (err) throw err
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    // TODO
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    cb(true)
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  }
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  */
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}
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function packLineEncode(read) {
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  var ended
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  return function (end, cb) {
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    if (ended) return cb(ended)
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    read(end, function (end, data) {
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      if (ended = end) {
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        cb(end)
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      } else {
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        var len = data ? data.length + 5 : 0
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        cb(end, ('000' + len.toString(16)).substr(-4) + data + '\n')
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      }
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    })
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  }
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}
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function packLineDecode(read) {
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  var b = buffered(read)
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  var readPrefix = b.chunks(4)
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  var ended
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  b.packLines = function (abort, cb) {
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    readPrefix(abort, function (end, buf) {
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      if (ended = end) return cb(end)
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      var len = parseInt(buf, 16)
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      b.chunks(len)(null, function (end, buf) {
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        if (ended = end) return cb(end)
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        cb(end, buf)
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      })
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    })
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  }
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  return b
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}
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/*
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TODO: investigate capabilities
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report-status delete-refs side-band-64k quiet atomic ofs-delta
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*/
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// Get a line for each ref that we have. The first line also has capabilities.
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// Wrap with packLineEncode.
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function receivePackHeader(capabilities) {
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  var readRef = getRefs()
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  var first = true
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  var ended
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  return function (abort, cb) {
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    if (ended) return cb(true)
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    readRef(abort, function (end, ref) {
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      ended = end
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      var name = ref && ref.name
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      var hash = ref && ref.hash
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      if (first) {
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        first = false
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        if (end) {
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          // use placeholder data if there are no refs
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          hash = '0000000000000000000000000000000000000000'
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          name = 'capabilities^{}'
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        }
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        name += '\0' + capabilities.join(' ')
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      } else if (end) {
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        return cb(true)
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      }
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      cb(null, hash + ' ' + name)
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    })
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  }
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}
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function receiveActualPack(read, objectSink, onEnd) {
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  var objects = pushable()
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  packCodec.decodePack(function (obj) {
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    if (obj) pushable.push(obj)
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    else     pushable.end()
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  })
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  objectSink(objects)
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}
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function receivePack(read, objectSink) {
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  var ended
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  var sendRefs = receivePackHeader([])
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  function receiveRefs(readLine, cb) {
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    var refs = []
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    readLine(null, function next(end, line) {
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      /*
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      if (end === true)
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        cb(new Error('refs line ended early'))
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      else */
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      if (end)
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        cb(end)
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      else if (line === '')
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        cb(null, refs)
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      else {
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        var args = split2(line)
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        refs.push({
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          hash: args[0],
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          name: args[1]
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        })
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        readLine(null, next)
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      }
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    })
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  }
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  return packLineEncode(
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    cat([
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      // send our refs
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      sendRefs,
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      pull.once(''),
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      function (abort, cb) {
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        if (abort) return
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        // receive their refs
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        var lines = packLineDecode(read)
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        receiveRefs(lines.packLines, function (err, refs) {
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          if (refs)
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            console.error('refs', refs, err)
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          if (err) return cb(err)
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          // receive the pack
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          receiveActualPack(lines.passthrough, objectSink, function (err) {
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            if (err) return cb(err)
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            cb(true)
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          })
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        })
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      },
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      pull.once('unpack ok')
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    ])
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  )
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}
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function prepend(data, read) {
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  var done
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  return function (end, cb) {
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    if (done) {
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      read(end, cb)
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    } else {
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      done = true
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      cb(null, data)
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    }
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  }
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}
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module.exports = function (opts) {
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  var ended
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  var prefix = opts.prefix
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  var objectSink = opts.objectSink
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  function handleConnect(cmd, read) {
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    var args = split2(cmd)
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    switch (args[0]) {
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      case 'git-upload-pack':
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        return prepend('\n', uploadPack(read))
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      case 'git-receive-pack':
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        return prepend('\n', receivePack(read), objectSink)
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      default:
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        return pull.error(new Error('Unknown service ' + args[0]))
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    }
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  }
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  function handleCommand(line, read) {
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    var args = split2(line)
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    switch (args[0]) {
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      case 'capabilities':
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        return capabilitiesSource(prefix)
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      case 'list':
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        return listSource()
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      case 'connect':
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        return handleConnect(args[1], read)
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      case 'option':
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        return optionSource(args[1])
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      default:
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        return pull.error(new Error('Unknown command ' + line))
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    }
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  }
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  return function (read) {
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    var b = buffered()
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    b(read)
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    var command
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    function getCommand(cb) {
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      b.lines(null, function next(end, line) {
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        if (ended = end)
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          return cb(end)
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        if (line == '')
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          return b.lines(null, next)
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        if (options.verbosity > 1)
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          console.error('command:', line)
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        var cmdSource = handleCommand(line, b.passthrough)
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        cb(null, cmdSource)
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      })
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    }
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    return function next(abort, cb) {
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      if (ended) return cb(ended)
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      if (!command) {
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        if (abort) return
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        getCommand(function (end, cmd) {
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          command = cmd
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          next(end, cb)
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        })
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        return
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      }
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      command(abort, function (err, data) {
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        if (err) {
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          command = null
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          if (err !== true)
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            cb(err, data)
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          else
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            next(abort, cb)
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        } else {
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          cb(null, data)
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        }
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      })
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    }
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  }
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}
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