1 files changed, 32 insertions, 27 deletions
diff --git a/deps/npm/node_modules/tar/lib/large-numbers.js b/deps/npm/node_modules/tar/lib/large-numbers.js
index ff49992630..3e5c99255a 100644
--- a/deps/npm/node_modules/tar/lib/large-numbers.js
+++ b/deps/npm/node_modules/tar/lib/large-numbers.js
@@ -1,12 +1,13 @@
 'use strict'
 // Tar can encode large and negative numbers using a leading byte of
-// 0xff for negative, and 0x80 for positive.  The trailing byte in the
-// section will always be 0x20, or in some implementations 0x00.
-// this module encodes and decodes these things.
+// 0xff for negative, and 0x80 for positive.
 
 const encode = exports.encode = (num, buf) => {
-  buf[buf.length - 1] = 0x20
-  if (num < 0)
+  if (!Number.isSafeInteger(num))
+    // The number is so large that javascript cannot represent it with integer
+    // precision.
+    throw TypeError('cannot encode number outside of javascript safe integer range')
+  else if (num < 0)
     encodeNegative(num, buf)
   else
     encodePositive(num, buf)
@@ -15,13 +16,10 @@ const encode = exports.encode = (num, buf) => {
 
 const encodePositive = (num, buf) => {
   buf[0] = 0x80
-  for (var i = buf.length - 2; i > 0; i--) {
-    if (num === 0)
-      buf[i] = 0
-    else {
-      buf[i] = num % 0x100
-      num = Math.floor(num / 0x100)
-    }
+
+  for (var i = buf.length; i > 1; i--) {
+    buf[i-1] = num & 0xff
+    num = Math.floor(num / 0x100)
   }
 }
 
@@ -29,21 +27,16 @@ const encodeNegative = (num, buf) => {
   buf[0] = 0xff
   var flipped = false
   num = num * -1
-  for (var i = buf.length - 2; i > 0; i--) {
-    var byte
-    if (num === 0)
-      byte = 0
-    else {
-      byte = num % 0x100
-      num = Math.floor(num / 0x100)
-    }
+  for (var i = buf.length; i > 1; i--) {
+    var byte = num & 0xff
+    num = Math.floor(num / 0x100)
     if (flipped)
-      buf[i] = onesComp(byte)
+      buf[i-1] = onesComp(byte)
     else if (byte === 0)
-      buf[i] = 0
+      buf[i-1] = 0
     else {
       flipped = true
-      buf[i] = twosComp(byte)
+      buf[i-1] = twosComp(byte)
     }
   }
 }
@@ -51,8 +44,20 @@ const encodeNegative = (num, buf) => {
 const parse = exports.parse = (buf) => {
   var post = buf[buf.length - 1]
   var pre = buf[0]
-  return pre === 0x80 ? pos(buf.slice(1, buf.length - 1))
-   : twos(buf.slice(1, buf.length - 1))
+  var value;
+  if (pre === 0x80)
+    value = pos(buf.slice(1, buf.length))
+  else if (pre === 0xff)
+    value = twos(buf)
+  else
+    throw TypeError('invalid base256 encoding')
+
+  if (!Number.isSafeInteger(value))
+    // The number is so large that javascript cannot represent it with integer
+    // precision.
+    throw TypeError('parsed number outside of javascript safe integer range')
+
+  return value
 }
 
 const twos = (buf) => {
@@ -71,9 +76,9 @@ const twos = (buf) => {
       f = twosComp(byte)
     }
     if (f !== 0)
-      sum += f * Math.pow(256, len - i - 1)
+      sum -= f * Math.pow(256, len - i - 1)
   }
-  return sum * -1
+  return sum
 }
 
 const pos = (buf) => {