zlib: fix decompression of empty data streams

add4b0a made the assumption that compressed data would never lead to an empty decompressed stream. Fix that by explicitly checking the number of read bytes. PR-URL: #17042 Fixes: #17041 Refs: #13322 Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Evan Lucas <[email protected]> Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: James M Snell <[email protected]>
nodejs · Dec 11, 2017 · fa01fe6 · fa01fe6
1 parent 035a24e
commit fa01fe6
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diff --git a/lib/zlib.js b/lib/zlib.js
@@ -95,6 +95,8 @@ function zlibBufferOnEnd() {
   var err;
   if (this.nread >= kMaxLength) {
     err = new errors.RangeError('ERR_BUFFER_TOO_LARGE');
+  } else if (this.nread === 0) {
+    buf = Buffer.alloc(0);
   } else {
     var bufs = this.buffers;
     buf = (bufs.length === 1 ? bufs[0] : Buffer.concat(bufs, this.nread));
@@ -485,6 +487,9 @@ function processChunkSync(self, chunk, flushFlag) {
 
   _close(self);
 
+  if (nread === 0)
+    return Buffer.alloc(0);
+
   return (buffers.length === 1 ? buffers[0] : Buffer.concat(buffers, nread));
 }
 

diff --git a/test/parallel/test-zlib-empty-buffer.js b/test/parallel/test-zlib-empty-buffer.js
@@ -0,0 +1,26 @@
+'use strict';
+const common = require('../common');
+const zlib = require('zlib');
+const { inspect, promisify } = require('util');
+const assert = require('assert');
+const emptyBuffer = new Buffer(0);
+
+common.crashOnUnhandledRejection();
+
+(async function() {
+  for (const [ compress, decompress, method ] of [
+    [ zlib.deflateRawSync, zlib.inflateRawSync, 'raw sync' ],
+    [ zlib.deflateSync, zlib.inflateSync, 'deflate sync' ],
+    [ zlib.gzipSync, zlib.gunzipSync, 'gzip sync' ],
+    [ promisify(zlib.deflateRaw), promisify(zlib.inflateRaw), 'raw' ],
+    [ promisify(zlib.deflate), promisify(zlib.inflate), 'deflate' ],
+    [ promisify(zlib.gzip), promisify(zlib.gunzip), 'gzip' ]
+  ]) {
+    const compressed = await compress(emptyBuffer);
+    const decompressed = await decompress(compressed);
+    assert.deepStrictEqual(
+      emptyBuffer, decompressed,
+      `Expected ${inspect(compressed)} to match ${inspect(decompressed)} ` +
+      `to match for ${method}`);
+  }
+})();