From 4d480c8a3fe3c58eeb083ea544c6f9e991606692 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 19 Apr 2014 23:25:44 +0200
Subject: [PATCH] Exception instead of assigning 0 in case of wrong vector
 length

---
 src/test/uint256_tests.cpp | 10 +++++-----
 src/uint256.h              | 15 ++++++++++-----
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/test/uint256_tests.cpp b/src/test/uint256_tests.cpp
index 815babf10..8e4b63c8b 100644
--- a/src/test/uint256_tests.cpp
+++ b/src/test/uint256_tests.cpp
@@ -160,11 +160,11 @@ BOOST_AUTO_TEST_CASE( basics ) // constructors, equality, inequality
     tmpS = ~R2S; BOOST_CHECK(tmpS == ~R2S);
     tmpS = ~MaxS; BOOST_CHECK(tmpS == ~MaxS);
 
-    // Wrong length must give 0
-    BOOST_CHECK(uint256(std::vector<unsigned char>(OneArray,OneArray+31)) == 0);
-    BOOST_CHECK(uint256(std::vector<unsigned char>(OneArray,OneArray+20)) == 0);
-    BOOST_CHECK(uint160(std::vector<unsigned char>(OneArray,OneArray+32)) == 0);
-    BOOST_CHECK(uint160(std::vector<unsigned char>(OneArray,OneArray+19)) == 0);
+    // Wrong length must throw exception.
+    BOOST_CHECK_THROW(uint256(std::vector<unsigned char>(OneArray,OneArray+31)), uint_error);
+    BOOST_CHECK_THROW(uint256(std::vector<unsigned char>(OneArray,OneArray+20)), uint_error);
+    BOOST_CHECK_THROW(uint160(std::vector<unsigned char>(OneArray,OneArray+32)), uint_error);
+    BOOST_CHECK_THROW(uint160(std::vector<unsigned char>(OneArray,OneArray+19)), uint_error);
 }
 
 void shiftArrayRight(unsigned char* to, const unsigned char* from, unsigned int arrayLength, unsigned int bitsToShift) 
diff --git a/src/uint256.h b/src/uint256.h
index a3f783587..b6365bb36 100644
--- a/src/uint256.h
+++ b/src/uint256.h
@@ -6,6 +6,8 @@
 #ifndef BITCOIN_UINT256_H
 #define BITCOIN_UINT256_H
 
+#include <assert.h>
+#include <stdexcept>
 #include <stdint.h>
 #include <stdio.h>
 #include <string>
@@ -19,6 +21,11 @@ inline signed char HexDigit(char c)
     return p_util_hexdigit[(unsigned char)c];
 }
 
+class uint_error : public std::runtime_error {
+public:
+    explicit uint_error(const std::string& str) : std::runtime_error(str) {}
+};
+
 /** Template base class for unsigned big integers. */
 template<unsigned int BITS>
 class base_uint
@@ -62,11 +69,9 @@ public:
 
     explicit base_uint(const std::vector<unsigned char>& vch)
     {
-        if (vch.size() == sizeof(pn)) {
-            memcpy(pn, &vch[0], sizeof(pn));
-        } else {
-            *this = 0;
-        }
+        if (vch.size() != sizeof(pn))
+            throw uint_error("Converting vector of wrong size to base_uint");
+        memcpy(pn, &vch[0], sizeof(pn));
     }
 
     bool operator!() const