diff --git a/lib/buffer.js b/lib/buffer.js index 1a9f7caeb5aba9..09db899d19d76f 100644 --- a/lib/buffer.js +++ b/lib/buffer.js @@ -216,6 +216,14 @@ Buffer.concat = function(list, length) { pos += buf.length; } + // Note: `length` is always equal to `buffer.length` at this point + if (pos < length) { + // Zero-fill the remaining bytes if the specified `length` was more than + // the actual total length, i.e. if we have some remaining allocated bytes + // there were not initialized. + buffer.fill(0, pos, length); + } + return buffer; }; diff --git a/test/simple/test-buffer-concat.js b/test/simple/test-buffer-concat.js index 858d6924f95fac..ea237cd6d6089c 100644 --- a/test/simple/test-buffer-concat.js +++ b/test/simple/test-buffer-concat.js @@ -38,4 +38,22 @@ assert(flatOne === one[0]); assert(flatLong.toString() === (new Array(10+1).join('asdf'))); assert(flatLongLen.toString() === (new Array(10+1).join('asdf'))); +var ones = new Buffer(10).fill('1'); +var empty = new Buffer(0); + +assert.equal(Buffer.concat([], 100).toString(), ''); +assert.equal(Buffer.concat([ones], 0).toString(), ones.toString()); // 0.12.x +assert.equal(Buffer.concat([ones], 10).toString(), ones.toString()); +assert.equal(Buffer.concat([ones, ones], 10).toString(), ones.toString()); +assert.equal(Buffer.concat([empty, ones]).toString(), ones.toString()); +assert.equal(Buffer.concat([ones, empty, empty]).toString(), ones.toString()); + +// The tail should be zero-filled +assert.equal( + Buffer.concat([empty, empty], 100).toString(), + new Buffer(100).fill(0).toString()); +assert.equal( + Buffer.concat([empty, ones], 40).toString(), + Buffer.concat([ones, new Buffer(30).fill(0)]).toString()); + console.log("ok");