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 buffered = require('pull-buffered')
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var pack = require('./lib/pack')
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function handleOption(options, 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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      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 capabilitiesSource() {
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  return pull.once([
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    'option',
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    'connect',
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  ].join('\n') + '\n\n')
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}
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function split2(str, delim) {
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  var i = str.indexOf(delim || ' ')
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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 split3(str) {
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  var args = split2(str)
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  return [args[0]].concat(split2(args[1]))
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}
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function optionSource(cmd, options) {
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  var args = split2(cmd)
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  var msg = handleOption(options, 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 pull.once(msg + '\n')
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}
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// transform ref objects into lines
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function listRefs(read) {
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  var ended
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  return function (abort, cb) {
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    if (ended) return cb(ended)
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    read(abort, function (end, ref) {
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      ended = end
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      if (end === true) cb(null, '\n')
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      if (end) cb(end)
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      else cb(null,
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        [ref.value, ref.name].concat(ref.attrs || []).join(' ') + '\n')
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    })
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  }
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}
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// upload-pack: fetch to client
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function uploadPack(read, haveObject, getObjects, refSource, wantSink, options) {
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  /* multi_ack thin-pack side-band side-band-64k ofs-delta shallow no-progress
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   * include-tag multi_ack_detailed symref=HEAD:refs/heads/master
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   * agent=git/2.7.0 */
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  var sendRefs = receivePackHeader([
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  ], refSource, false)
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  var lines = packLineDecode(read, options)
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  var readHave = lines.haves()
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  var acked
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  var commonHash
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  var sendPack
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  var earlyDisconnect
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  // Packfile negotiation
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  return cat([
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    packLineEncode(cat([
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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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        if (acked) return cb(true)
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        // read upload request (wants list) from client
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        var readWant = lines.wants(wantsDone)
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        readWant(null, function (end, want) {
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          if (end === true) {
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            // client disconnected before sending wants
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            earlyDisconnect = true
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            cb(true)
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          } else if (end) {
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            cb(end)
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          } else {
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            wantSink(readWant)
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          }
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        })
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        function wantsDone(err) {
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          // console.error('wants done', err, earlyDisconnect)
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          if (err) return cb(err)
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          if (earlyDisconnect) return cb(true)
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          // Read upload haves (haves list).
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          // On first obj-id that we have, ACK
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          // If we have none, NAK.
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          // TODO: implement multi_ack_detailed
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          readHave(null, function next(end, have) {
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            if (end === true) {
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              // found no common object
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              acked = true
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              cb(null, 'NAK')
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            } else if (end)
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              cb(end)
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            else if (have.type != 'have')
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              cb(new Error('Unknown have' + JSON.stringify(have)))
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            else
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              haveObject(have.hash, function (haveIt) {
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                if (!haveIt)
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                  return readHave(null, next)
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                commonHash = haveIt
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                acked = true
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                cb(null, 'ACK ' + have.hash)
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              })
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          })
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        }
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      },
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    ])),
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    function havesDone(abort, cb) {
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      // console.error("haves done", abort && typeof abort, sendPack && typeof sendPack, abort, earlyDisconnect)
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      if (abort || earlyDisconnect) return cb(abort || true)
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      // send pack file to client
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      if (!sendPack)
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        getObjects(commonHash, function (err, numObjects, readObject) {
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          sendPack = pack.encode(numObjects, readObject)
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          havesDone(abort, cb)
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        })
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      else
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        sendPack(abort, cb)
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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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        if (data)
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          data += '\n'
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        else
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          data = ''
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        var len = data ? data.length + 4 : 0
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        var hexLen = ('000' + len.toString(16)).substr(-4)
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        var pkt = hexLen + data
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        // console.error('>', JSON.stringify(pkt))
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        cb(end, pkt)
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      }
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    })
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  }
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}
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function rev(str) {
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  return str === '0000000000000000000000000000000000000000' ? null : str
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}
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/* pull-stream/source.js */
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function abortCb(cb, abort, onAbort) {
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  cb(abort)
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  onAbort && onAbort(abort === true ? null: abort)
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  return
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}
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function packLineDecode(read, options) {
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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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  function readPackLine(abort, cb) {
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    if (ended) return cb(ended)
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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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      if (!len)
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        return cb(null, new Buffer(''))
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      // TODO: figure out this -4 thing
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      b.chunks(len - 4)(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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  function readPackLineStr(abort, cb) {
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    if (ended) return cb(ended)
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    readPackLine(abort, function (end, buf) {
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      if (ended = end) return cb(end)
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      // trim newline
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      var len = buf.length
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      if (buf[len - 1] == 0xa)
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        len--
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      var line = buf.toString('ascii', 0, len)
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      cb(null, line)
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    })
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  }
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  function readUpdate(abort, cb) {
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    readPackLine(abort, function (end, line) {
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      if (end) return cb(end)
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      if (options.verbosity >= 2)
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        console.error('line', line.toString('ascii'))
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      if (!line.length) return cb(true)
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      var args = split3(line.toString('ascii'))
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      var args2 = split2(args[2], '\0')
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      var caps = args2[1]
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      if (caps && options.verbosity >= 2)
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        console.error('update capabilities:', caps)
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      cb(null, {
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        old: rev(args[0]),
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        new: rev(args[1]),
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        name: args2[0]
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      })
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    })
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  }
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  function havesWants(onEnd) {
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    return function readWant(abort, cb) {
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      readPackLineStr(abort, function (end, line) {
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        if (end) return abortCb(cb, end, onEnd)
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        if (options.verbosity >= 2)
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          console.error('line', line)
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        // if (!line.length) return cb(true)
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        if (!line.length || line == 'done')
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          return abortCb(cb, true, onEnd)
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        var args = split3(line)
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        var caps = args[2]
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        if (caps && options.verbosity >= 2)
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          console.error('want capabilities:', caps)
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        cb(null, {
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          type: args[0],
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          hash: args[1],
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        })
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      })
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    }
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  }
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  b.packLines = readPackLine
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  b.updates = readUpdate
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  b.wants = b.haves = havesWants
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  return b
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}
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// run a callback when a pipeline ends
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// TODO: find a better way to do this
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function onThroughEnd(onEnd) {
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  return function (read) {
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    return function (end, cb) {
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      read(end, function (end, data) {
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        cb(end, data)
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        if (end)
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          onEnd(end === true ? null : end)
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      })
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    }
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  }
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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, refSource, usePlaceholder) {
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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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    refSource(abort, function (end, ref) {
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      ended = end
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      var name = ref && ref.name
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      var value = ref && ref.value
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      if (first && usePlaceholder) {
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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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          value = '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, value + ' ' + name)
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    })
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  }
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}
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// receive-pack: push from client
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function receivePack(read, objectSink, refSource, refSink, options) {
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  var ended
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  var sendRefs = receivePackHeader([
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    'delete-refs',
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  ], refSource, true)
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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, options)
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        pull(
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          lines.updates,
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          onThroughEnd(refsDone),
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          refSink
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        )
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        function refsDone(err) {
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          if (err) return cb(err)
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          pull(
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            lines.passthrough,
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            pack.decode(cb),
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            objectSink
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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 objectSink = opts.objectSink
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  var haveObject = opts.haveObject || function (hash, cb) { cb(false) }
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  var getObjects = opts.getObjects || function (id, cb) {
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    cb(null, 0, pull.empty())
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  }
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  var refSource = opts.refSource || pull.empty()
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  var refSink = opts.refSink || pull.drain()
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  var wantSink = opts.wantSink || pull.drain()
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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 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, haveObject, getObjects, refSource,
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          wantSink, options))
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      case 'git-receive-pack':
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        return prepend('\n', receivePack(read, objectSink, refSource,
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          refSink, options))
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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()
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      case 'list':
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        return listRefs(refSource)
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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], options)
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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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