From ca3dea3470ad5045f8ab8934f8c8ef847365add8 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Mon, 16 Jan 2017 17:22:05 -0800
Subject: [PATCH] writer: better failsafes. optimize.

---
 lib/coins/coins.js        |  6 +---
 lib/utils/staticwriter.js | 58 +++++++++++++++++++++++++++------------
 lib/utils/writer.js       | 41 +++++++++++++++++----------
 3 files changed, 68 insertions(+), 37 deletions(-)

diff --git a/lib/coins/coins.js b/lib/coins/coins.js
index 21d97b1d..5615e81c 100644
--- a/lib/coins/coins.js
+++ b/lib/coins/coins.js
@@ -700,8 +700,6 @@ CoinEntry.prototype.getSize = function getSize() {
  */
 
 CoinEntry.prototype.toWriter = function toWriter(bw) {
-  var raw;
-
   if (!this.raw) {
     assert(this.output);
     compress.output(this.output, bw);
@@ -712,9 +710,7 @@ CoinEntry.prototype.toWriter = function toWriter(bw) {
   // didn't use it, it's still in its
   // compressed form. Just write it back
   // as a buffer for speed.
-  raw = this.raw.slice(this.offset, this.offset + this.size);
-
-  bw.writeBytes(raw);
+  bw.copy(this.raw, this.offset, this.offset + this.size);
 
   return bw;
 };
diff --git a/lib/utils/staticwriter.js b/lib/utils/staticwriter.js
index de4f3625..0609aa3b 100644
--- a/lib/utils/staticwriter.js
+++ b/lib/utils/staticwriter.js
@@ -323,58 +323,80 @@ StaticWriter.prototype.writeBytes = function writeBytes(value) {
 
 StaticWriter.prototype.writeVarBytes = function writeVarBytes(value) {
   this.writeVarint(value.length);
-
-  if (value.length === 0)
-    return;
-
   this.writeBytes(value);
 };
 
+/**
+ * Copy bytes.
+ * @param {Buffer} value
+ * @param {Number} start
+ * @param {Number} end
+ */
+
+StaticWriter.prototype.copy = function copy(value, start, end) {
+  var len = end - start;
+
+  if (len === 0)
+    return;
+
+  value.copy(this.data, this.written, start, end);
+  this.written += len;
+};
+
 /**
  * Write string to buffer.
- * @param {String|Buffer} value
+ * @param {String} value
  * @param {String?} enc - Any buffer-supported encoding.
  */
 
 StaticWriter.prototype.writeString = function writeString(value, enc) {
-  if (typeof value !== 'string')
-    return this.writeBytes(value);
+  var size;
 
   if (value.length === 0)
     return;
 
-  this.written += this.data.write(value, this.written, enc);
+  size = Buffer.byteLength(value, enc);
+
+  this.data.write(value, this.written, enc);
+
+  this.written += size;
 };
 
 /**
- * Write a hash/hex-string.
- * @param {Hash|Buffer}
+ * Write a 32 byte hash.
+ * @param {Hash} value
  */
 
 StaticWriter.prototype.writeHash = function writeHash(value) {
-  this.writeString(value, 'hex');
+  if (typeof value !== 'string') {
+    assert(value.length === 32);
+    return this.writeBytes(value);
+  }
+  assert(value.length === 64);
+  this.data.write(value, this.written, 'hex');
+  this.written += 32;
 };
 
 /**
  * Write a string with a varint length before it.
- * @param {String|Buffer}
+ * @param {String}
  * @param {String?} enc - Any buffer-supported encoding.
  */
 
 StaticWriter.prototype.writeVarString = function writeVarString(value, enc) {
   var size;
 
-  if (typeof value !== 'string')
-    return this.writeVarBytes(value);
+  if (value.length === 0) {
+    this.writeVarint(0);
+    return;
+  }
 
   size = Buffer.byteLength(value, enc);
 
   this.writeVarint(size);
+  this.data.write(value, this.written, enc);
 
-  if (value.length === 0)
-    return;
-
-  this.writeString(value, enc);
+  this.written += size;
 };
 
 /**
diff --git a/lib/utils/writer.js b/lib/utils/writer.js
index 6355aa73..6d94aee5 100644
--- a/lib/utils/writer.js
+++ b/lib/utils/writer.js
@@ -433,44 +433,60 @@ BufferWriter.prototype.writeVarBytes = function writeVarBytes(value) {
   this.ops.push(new WriteOp(BYTES, value));
 };
 
+/**
+ * Copy bytes.
+ * @param {Buffer} value
+ * @param {Number} start
+ * @param {Number} end
+ */
+
+BufferWriter.prototype.copy = function copy(value, start, end) {
+  assert(end >= start);
+  value = value.slice(start, end);
+  this.writeBytes(value);
+};
+
 /**
  * Write string to buffer.
- * @param {String|Buffer} value
+ * @param {String} value
  * @param {String?} enc - Any buffer-supported encoding.
  */
 
 BufferWriter.prototype.writeString = function writeString(value, enc) {
-  if (typeof value !== 'string')
-    return this.writeBytes(value);
-
-  this.written += Buffer.byteLength(value, enc);
-
   if (value.length === 0)
     return;
 
+  this.written += Buffer.byteLength(value, enc);
   this.ops.push(new WriteOp(STR, value, enc));
 };
 
 /**
- * Write a hash/hex-string.
- * @param {Hash|Buffer}
+ * Write a 32 byte hash.
+ * @param {Hash} value
  */
 
 BufferWriter.prototype.writeHash = function writeHash(value) {
+  if (typeof value !== 'string') {
+    assert(value.length === 32);
+    return this.writeBytes(value);
+  }
+  assert(value.length === 64);
   this.writeString(value, 'hex');
 };
 
 /**
  * Write a string with a varint length before it.
- * @param {String|Buffer}
+ * @param {String}
  * @param {String?} enc - Any buffer-supported encoding.
  */
 
 BufferWriter.prototype.writeVarString = function writeVarString(value, enc) {
   var size;
 
-  if (typeof value !== 'string')
-    return this.writeVarBytes(value);
+  if (value.length === 0) {
+    this.ops.push(new WriteOp(VARINT, 0));
+    return;
+  }
 
   size = Buffer.byteLength(value, enc);
 
@@ -479,9 +495,6 @@ BufferWriter.prototype.writeVarString = function writeVarString(value, enc) {
 
   this.ops.push(new WriteOp(VARINT, size));
 
-  if (value.length === 0)
-    return;
-
   this.ops.push(new WriteOp(STR, value, enc));
 };