[#94] Backend

https://project.mdnd-it.cc/work_packages/94

SerpentRace_Backend/node_modules/block-stream2/index.js

@@ -0,0 +1,69 @@
+const { Transform } = require('readable-stream')
+
+class Block extends Transform {
+  constructor (size, opts = {}) {
+    super(opts)
+
+    if (typeof size === 'object') {
+      opts = size
+      size = opts.size
+    }
+
+    this.size = size || 512
+
+    const { nopad, zeroPadding = true } = opts
+
+    if (nopad) this._zeroPadding = false
+    else this._zeroPadding = !!zeroPadding
+
+    this._buffered = []
+    this._bufferedBytes = 0
+  }
+
+  _transform (buf, enc, next) {
+    this._bufferedBytes += buf.length
+    this._buffered.push(buf)
+
+    while (this._bufferedBytes >= this.size) {
+      this._bufferedBytes -= this.size
+
+      // Assemble the buffers that will compose the final block
+      const blockBufs = []
+      let blockBufsBytes = 0
+      while (blockBufsBytes < this.size) {
+        const b = this._buffered.shift()
+
+        if (blockBufsBytes + b.length <= this.size) {
+          blockBufs.push(b)
+          blockBufsBytes += b.length
+        } else {
+          // If the last buffer is larger than needed for the block, just
+          // use the needed part
+          const neededSize = this.size - blockBufsBytes
+          blockBufs.push(b.slice(0, neededSize))
+          blockBufsBytes += neededSize
+          this._buffered.unshift(b.slice(neededSize))
+        }
+      }
+
+      // Then concat just those buffers, leaving the rest untouched in _buffered
+      this.push(Buffer.concat(blockBufs, this.size))
+    }
+    next()
+  }
+
+  _flush () {
+    if (this._bufferedBytes && this._zeroPadding) {
+      const zeroes = Buffer.alloc(this.size - this._bufferedBytes)
+      this._buffered.push(zeroes)
+      this.push(Buffer.concat(this._buffered))
+      this._buffered = null
+    } else if (this._bufferedBytes) {
+      this.push(Buffer.concat(this._buffered))
+      this._buffered = null
+    }
+    this.push(null)
+  }
+}
+
+module.exports = Block