git ssb

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var url = require('url')
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var path = require('path')
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var fs = require('fs')
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var blobsDir = path.resolve(__dirname, '../../blobs')
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exports.requireBlob = function (id) {
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  var m = /^\&([0-9a-zA-Z\/+=]{44})\.(sha256)$/.exec(id)
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  if (!m) throw new Error('invalid blob id: ' + id)
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  var hex = new Buffer(m[1], 'base64').toString('hex')
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  return require(path.join(blobsDir, m[2], hex.substr(0, 2), hex.substr(2)))
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}
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exports.name = 'blob-modules'
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exports.version = '1.0.0'
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exports.manifest = {
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}
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exports.init = function (sbot, config) {
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  if (!sbot.ws || !sbot.ws.use) return console.trace('missing ssb-ws')
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  var prefix = '/blob-modules'
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  var dir = path.join(config.path, 'blob-modules')
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  blobsDir = path.join(config.path, 'blobs')
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  var mtimes = {}
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  console.log('[blob-modules] init. dir:', dir, 'prefix:', prefix)
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  function getModule(resolved, tried, cb) {
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    try {
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      var module = require(resolved)
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      return cb(null, module)
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    } catch(e) {
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      if (!tried && e && (e.code === 'ENOENT' || e.code === 'MODULE_NOT_FOUND')) {
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        var m = /(sha256)\/([0-9a-f]{2})\/([0-9a-f]{62})/.exec(e.path || e.message)
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        if (!m) throw e
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        var blobId = '&' + new Buffer(m[2] + m[3], 'hex').toString('base64') + '.' + m[1]
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        if (!sbot.blobs) return cb(new Error('Missing ssb-blobs plugin'))
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        if (typeof sbot.blobs.want !== 'function') return cb(new Error('missing blobs.want method'))
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        return sbot.blobs.want(blobId, function (err, has) {
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          if (err) return cb(new Error('Unable to get blob: ' + (err.stack || err)))
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          if (!has) return cb(new Error('Unable to get blob'))
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          getModule(resolved, true, cb)
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        })
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      }
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      return cb(e)
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    }
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  }
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  sbot.ws.use(function (req, res, next) {
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    if (prefix !== req.url.substr(0, prefix.length)) return next()
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    if (prefix === req.url) {
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      res.writeHead(302, {Location: path.basename(prefix) + '/'})
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      return res.end()
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    }
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    try {
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      req.uri = url.parse(req.url.substr(prefix.length), true)
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      var resolved = require.resolve(path.join(dir, req.uri.pathname))
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      var prevMtime = mtimes[resolved]
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      var mtime = fs.statSync(resolved).mtime.getTime()
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      if (mtime !== prevMtime) {
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        delete require.cache[resolved]
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      }
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      getModule(resolved, false, gotModule)
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    } catch(e) {
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      return gotError(e)
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    }
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    function gotError(err) {
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      try {
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        res.writeHead(err.code === 'ENOENT' || err.code === 'MODULE_NOT_FOUND' ? 404 : 500)
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      } finally {
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        res.end(err.stack || err)
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      }
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    }
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    function gotModule(err, module) {
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      if (err) return gotError(err)
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      try {
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        module(req, res, sbot, config)
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      } catch(e) {
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        gotError(e)
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      }
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    }
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  })
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}
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