XFA: Upgrade libpng to 1.6.20.

third_party/libpng/pngwio.c

 
 /* pngwio.c - functions for data output
  *
- * Last changed in libpng 1.6.0 [February 14, 2013]
- * Copyright (c) 1998-2013 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 1998-2014 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
  * and license in png.h
  *
  * This file provides a location for all output.  Users who need
  * special handling are expected to write functions that have the same
  * arguments as these and perform similar functions, but that possibly
  * use different output methods.  Note that you shouldn't change these
  * functions, but rather write replacement functions and then change
  * them at run time with png_set_write_fn(...).
  */
+
 #include "pngpriv.h"
 
 #ifdef PNG_WRITE_SUPPORTED
 
 /* Write the data to whatever output you are using.  The default routine
  * writes to a file pointer.  Note that this routine sometimes gets called
  * with very small lengths, so you should implement some kind of simple
  * buffering if you are using unbuffered writes.  This should never be asked
- * to write more than 64K on a 16 bit machine.
+ * to write more than 64K on a 16-bit machine.
  */
 
 void /* PRIVATE */
 png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
 {
    /* NOTE: write_data_fn must not change the buffer! */
    if (png_ptr->write_data_fn != NULL )
       (*(png_ptr->write_data_fn))(png_ptr, png_constcast(png_bytep,data),
          length);
 
@@ skipping 102 matching lines @@
 
    if (output_flush_fn != NULL)
       png_ptr->output_flush_fn = output_flush_fn;
 
    else
       png_ptr->output_flush_fn = png_default_flush;
 
 #  else
    png_ptr->output_flush_fn = output_flush_fn;
 #  endif
-#endif /* PNG_WRITE_FLUSH_SUPPORTED */
+#else
+   PNG_UNUSED(output_flush_fn)
+#endif /* WRITE_FLUSH */
 
+#ifdef PNG_READ_SUPPORTED
    /* It is an error to read while writing a png file */
    if (png_ptr->read_data_fn != NULL)
    {
       png_ptr->read_data_fn = NULL;
 
       png_warning(png_ptr,
           "Can't set both read_data_fn and write_data_fn in the"
           " same structure");
    }
+#endif
 }
-#endif /* PNG_WRITE_SUPPORTED */
+#endif /* WRITE */