From 74f0d4abcd8de84283858fe144772e688669e46a Mon Sep 17 00:00:00 2001
From: Sebastian Holtermann <sebholt@xwmw.org>
Date: Wed, 10 Aug 2016 10:35:19 +0200
Subject: [PATCH] cmCryptoHash: New byte hash to string function

---
 Source/cmCryptoHash.cxx | 31 +++++++++++++++++++++++++++++++
 Source/cmCryptoHash.h   |  7 +++++++
 2 files changed, 38 insertions(+)

diff --git a/Source/cmCryptoHash.cxx b/Source/cmCryptoHash.cxx
index 8d60c1f1a..59b9abdb9 100644
--- a/Source/cmCryptoHash.cxx
+++ b/Source/cmCryptoHash.cxx
@@ -34,6 +34,37 @@ CM_AUTO_PTR<cmCryptoHash> cmCryptoHash::New(const char* algo)
   }
 }
 
+bool cmCryptoHash::IntFromHexDigit(char input, char& output)
+{
+  if (input >= '0' && input <= '9') {
+    output = char(input - '0');
+    return true;
+  } else if (input >= 'a' && input <= 'f') {
+    output = char(input - 'a' + 0xA);
+    return true;
+  } else if (input >= 'A' && input <= 'F') {
+    output = char(input - 'A' + 0xA);
+    return true;
+  }
+  return false;
+}
+
+std::string cmCryptoHash::ByteHashToString(
+  const std::vector<unsigned char>& hash)
+{
+  // Map from 4-bit index to hexadecimal representation.
+  static char const hex[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
+                                '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+
+  std::string res;
+  for (std::vector<unsigned char>::const_iterator vit = hash.begin();
+       vit != hash.end(); ++vit) {
+    res.push_back(hex[(*vit) >> 4]);
+    res.push_back(hex[(*vit) & 0xF]);
+  }
+  return res;
+}
+
 std::string cmCryptoHash::HashString(const std::string& input)
 {
   this->Initialize();
diff --git a/Source/cmCryptoHash.h b/Source/cmCryptoHash.h
index 84dea9b08..80ab26925 100644
--- a/Source/cmCryptoHash.h
+++ b/Source/cmCryptoHash.h
@@ -29,6 +29,13 @@ public:
   /// @return A valid auto pointer if algo is supported or
   ///         an invalid/NULL pointer otherwise
   static CM_AUTO_PTR<cmCryptoHash> New(const char* algo);
+  /// @brief Converts a hex character to its binary value (4 bits)
+  /// @arg input Hex character [0-9a-fA-F].
+  /// @arg output Binary value of the input character (4 bits)
+  /// @return True if input was a valid hex character
+  static bool IntFromHexDigit(char input, char& output);
+  /// @brief Converts a byte hash to a sequence of hex character pairs
+  static std::string ByteHashToString(const std::vector<unsigned char>& hash);
   /// @brief Calculates a hash string from string input data
   /// @return Sequence of hex characters pairs for each byte of the binary hash
   std::string HashString(const std::string& input);