Fixed a string allocation problem.

modules/juce_core/memory/juce_MemoryBlock.cpp

@@ -265,7 +265,7 @@ void MemoryBlock::copyTo (void* const dst, int offset, size_t num) const noexcep
 
 String MemoryBlock::toString() const
 {
-    return String (CharPointer_UTF8 (data), size);
+    return String::fromUTF8 (data, size);
 }
 
 //==============================================================================

modules/juce_core/streams/juce_InputStream.cpp

@@ -175,8 +175,7 @@ String InputStream::readString()
         }
     }
 
-    return String (CharPointer_UTF8 (data),
-                   CharPointer_UTF8 (data + i));
+    return String::fromUTF8 (data, i);
 }
 
 String InputStream::readNextLine()

modules/juce_core/text/juce_String.cpp

@@ -1897,7 +1897,7 @@ struct StringEncodingConverter
             return CharPointerType_Dest (reinterpret_cast <const DestChar*> (&emptyChar));
 
         CharPointerType_Src text (source.getCharPointer());
-        const size_t extraBytesNeeded = CharPointerType_Dest::getBytesRequiredFor (text);
+        const size_t extraBytesNeeded = CharPointerType_Dest::getBytesRequiredFor (text) + sizeof (typename CharPointerType_Dest::CharType);
         const size_t endOffset = (text.sizeInBytes() + 3) & ~3u; // the new string must be word-aligned or many Windows
                                                                 // functions will fail to read it correctly!
         source.preallocateBytes (endOffset + extraBytesNeeded);
@@ -1993,9 +1993,14 @@ String String::fromUTF8 (const char* const buffer, int bufferSizeBytes)
 {
     if (buffer != nullptr)
     {
-        if (bufferSizeBytes < 0) return String (CharPointer_UTF8 (buffer));
-        if (bufferSizeBytes > 0) return String (CharPointer_UTF8 (buffer),
-                                                CharPointer_UTF8 (buffer + bufferSizeBytes));
+        if (bufferSizeBytes < 0)
+            return String (CharPointer_UTF8 (buffer));
+
+        if (bufferSizeBytes > 0)
+        {
+            jassert (CharPointer_UTF8::isValidString (buffer, bufferSizeBytes));
+            return String (CharPointer_UTF8 (buffer), CharPointer_UTF8 (buffer + bufferSizeBytes));
+        }
     }
 
     return String();