Add cmBase32Encoder class

Source/CMakeLists.txt

@@ -166,6 +166,7 @@ endif()
 #
 set(SRCS
   cmArchiveWrite.cxx
+  cmBase32.cxx
   cmBootstrapCommands1.cxx
   cmBootstrapCommands2.cxx
   cmCacheManager.cxx

Source/cmBase32.cxx

@@ -0,0 +1,108 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2016 Sebastian Holtermann <sebholt@xwmw.org>
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+#include "cmBase32.h"
+
+// -- Static functions
+
+static const unsigned char Base32EncodeTable[33] =
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
+
+inline unsigned char Base32EncodeChar(int schar)
+{
+  return Base32EncodeTable[schar];
+}
+
+void Base32Encode5(const unsigned char src[5], char dst[8])
+{
+  // [0]:5 bits
+  dst[0] = Base32EncodeChar((src[0] >> 3) & 0x1F);
+  // [0]:3 bits + [1]:2 bits
+  dst[1] = Base32EncodeChar(((src[0] << 2) & 0x1C) + ((src[1] >> 6) & 0x03));
+  // [1]:5 bits
+  dst[2] = Base32EncodeChar((src[1] >> 1) & 0x1F);
+  // [1]:1 bit + [2]:4 bits
+  dst[3] = Base32EncodeChar(((src[1] << 4) & 0x10) + ((src[2] >> 4) & 0x0F));
+  // [2]:4 bits + [3]:1 bit
+  dst[4] = Base32EncodeChar(((src[2] << 1) & 0x1E) + ((src[3] >> 7) & 0x01));
+  // [3]:5 bits
+  dst[5] = Base32EncodeChar((src[3] >> 2) & 0x1F);
+  // [3]:2 bits + [4]:3 bit
+  dst[6] = Base32EncodeChar(((src[3] << 3) & 0x18) + ((src[4] >> 5) & 0x07));
+  // [4]:5 bits
+  dst[7] = Base32EncodeChar((src[4] << 0) & 0x1F);
+}
+
+// -- Class methods
+
+cmBase32Encoder::cmBase32Encoder()
+{
+}
+
+cmBase32Encoder::~cmBase32Encoder()
+{
+}
+
+std::string cmBase32Encoder::encodeString(const unsigned char* input,
+                                          size_t len, bool padding)
+{
+  std::string res;
+
+  static const size_t blockSize = 5;
+  static const size_t bufferSize = 8;
+  char buffer[bufferSize];
+
+  const unsigned char* end = input + len;
+  while ((input + blockSize) <= end) {
+    Base32Encode5(input, buffer);
+    res.append(buffer, bufferSize);
+    input += blockSize;
+  }
+
+  size_t remain(end - input);
+  if (remain != 0) {
+    // Temporary source buffer filled up with 0s
+    unsigned char extended[blockSize];
+    for (size_t ii = 0; ii != remain; ++ii) {
+      extended[ii] = input[ii];
+    }
+    for (size_t ii = remain; ii != blockSize; ++ii) {
+      extended[ii] = 0;
+    }
+
+    Base32Encode5(extended, buffer);
+    size_t numPad(0);
+    switch (remain) {
+      case 1:
+        numPad = 6;
+        break;
+      case 2:
+        numPad = 4;
+        break;
+      case 3:
+        numPad = 3;
+        break;
+      case 4:
+        numPad = 1;
+        break;
+      default:
+        break;
+    }
+    res.append(buffer, bufferSize - numPad);
+    if (padding) {
+      for (size_t ii = 0; ii != numPad; ++ii) {
+        res.push_back(paddingChar);
+      }
+    }
+  }
+
+  return res;
+}

Source/cmBase32.h

@@ -0,0 +1,42 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2016 Sebastian Holtermann <sebholt@xwmw.org>
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+#ifndef cmBase32_h
+#define cmBase32_h
+
+#include <cmConfigure.h> // IWYU pragma: keep
+
+#include <stddef.h>
+#include <string>
+
+/** \class cmBase32Encoder
+ * \brief Encodes a byte sequence to a Base32 byte sequence according to
+ * RFC4648
+ *
+ */
+class cmBase32Encoder
+{
+public:
+  static const char paddingChar = '=';
+
+public:
+  cmBase32Encoder();
+  ~cmBase32Encoder();
+
+  // Encodes the given input byte sequence into a string
+  // @arg input Input data pointer
+  // @arg len Input data size
+  // @arg padding Flag to append "=" on demand
+  std::string encodeString(const unsigned char* input, size_t len,
+                           bool padding = true);
+};
+
+#endif