wrong logic here to create blank PNG image in memory

src/pngimage.cpp

@@ -31,7 +31,7 @@ EXIV2_RCSID("@(#) $Id$")
 
 // *****************************************************************************
 
-//#define DEBUG 1
+#define DEBUG 1
 
 // *****************************************************************************
 // included header files
@@ -78,10 +78,18 @@ namespace Exiv2 {
     {
         if (create)
         {
-            if (io_->open())
+            if (io_->open() == 0)
             {
+#ifdef DEBUG
+                std::cerr << "Exiv2::PngImage:: Creating PNG image to memory\n";
+#endif
                 IoCloser closer(*io_);
-                io_->write(pngBlank, sizeof(pngBlank));
+                if (io_->write(pngBlank, sizeof(pngBlank)) != sizeof(pngBlank))
+                {
+#ifdef DEBUG
+                    std::cerr << "Exiv2::PngImage:: Failed to create PNG image on memory\n";
+#endif
+                }
             }
         }
     } // PngImage::PngImage

src/pngimage.hpp

@@ -78,7 +78,6 @@ namespace Exiv2
               method to get a temporary reference.
           @param create Specifies if an existing image should be read (false)
               or if a new file should be created (true).
-              This option is not yet implemented.
          */
         PngImage(BasicIo::AutoPtr io, bool create);
         //@}