Cleaner/safer code

Author: flanglet

src/io/CompressedInputStream.cpp

@@ -845,8 +845,8 @@ T DecodingTask<T>::run()
             return T(*_data, blockId, 0, 0, 0, "Success");
         }
 
-        istreambuf<char> buf(reinterpret_cast<char*>(&_data->_array[0]), streamsize(r));
-        iostream ios(&buf);
+        ifixedbuf buf(reinterpret_cast<char*>(&_data->_array[0]), streamsize(r));
+        istream ios(&buf);
         ibs = (streamPerTask == true) ? new DefaultInputBitStream(ios) : _ibs;
 
         // Extract block header from bitstream

src/io/CompressedOutputStream.cpp

@@ -705,7 +705,7 @@ T EncodingTask<T>::run()
         }
 
         _data->_index = 0;
-        ostreambuf<char> buf(reinterpret_cast<char*>(&_data->_array[_data->_index]), streamsize(_data->_length));
+        ofixedbuf buf(reinterpret_cast<char*>(&_data->_array[_data->_index]), streamsize(_data->_length));
         ostream os(&buf);
         DefaultOutputBitStream obs(os);
 

src/transform/ROLZCodec.cpp

@@ -471,7 +471,7 @@ bool ROLZCodec1::inverse(SliceArray<byte>& input, SliceArray<byte>& output, int
         try
         {
             // Decode literal, length and match index buffers
-            istreambuf<char> buffer(reinterpret_cast<char*>(&src[srcIdx]), max(min(count - srcIdx, sizeChunk + 16), 65536));
+            ifixedbuf buffer(reinterpret_cast<char*>(&src[srcIdx]), max(min(count - srcIdx, sizeChunk + 16), 65536));
             istream is(&buffer);
             DefaultInputBitStream ibs(is, 65536);
             const int litLen = int(ibs.readBits(32));

src/util.hpp

@@ -23,23 +23,36 @@ limitations under the License.
 #include "types.hpp"
 
 
-
 // Ahem ... Visual Studio
-// This ostreambuf class is required because Microsoft cannot bother to implement
-// streambuf::pubsetbuf().
-template <typename T>
-struct ostreambuf : public std::basic_streambuf<T, std::char_traits<T> >
-{
-    ostreambuf(T* buffer, std::streamsize length) {
-       this->setp(buffer, &buffer[length]);
+// This code is required because Microsoft cannot bother to implement streambuf::pubsetbuf().
+// Also On libstdc++, pubsetbuf() silently ignores the supplied buffer and leaves internal pointers null.
+
+class ifixedbuf : public std::streambuf {
+public:
+    ifixedbuf(char* data, std::size_t size) {
+        // Always manually set the read pointers.
+        // pubsetbuf() is unreliable on libstdc++, and MSVC doesn't implement it.
+        this->setg(data, data, data + size);
+    }
+};
+
+class ofixedbuf : public std::streambuf {
+public:
+    ofixedbuf(char* data, std::size_t size) {
+        // Always set buffer manually — pubsetbuf is useless on libstdc++
+        this->setp(data, data + size);
+    }
+
+    std::size_t written() const {
+        return this->pptr() - this->pbase();
     }
 };
 
-template <typename T>
-struct istreambuf : public std::basic_streambuf<T, std::char_traits<T> >
-{
-    istreambuf(T* buffer, std::streamsize length) {
-       this->setg(buffer, buffer, &buffer[length]);
+class iofixedbuf : public std::streambuf {
+public:
+    iofixedbuf(char* data, std::size_t size) {
+        this->setg(data, data, data + size);
+        this->setp(data, data + size);
     }
 };