XFA: Upgrade libpng to 1.6.20.

third_party/lpng_v163/pngrio.c

-/* pngrio.c - functions for data input
- *
- * Last changed in libpng 1.6.0 [February 14, 2013]
- * Copyright (c) 1998-2013 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 input.  Users who need
- * special handling are expected to write a function that has the same
- * arguments as this and performs a similar function, but that possibly
- * has a different input method.  Note that you shouldn't change this
- * function, but rather write a replacement function and then make
- * libpng use it at run time with png_set_read_fn(...).
- */
-
-#include "pngpriv.h"
-
-#ifdef PNG_READ_SUPPORTED
-
-/* Read the data from whatever input you are using.  The default routine
- * reads from 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 reads.  This should never be asked
- * to read more then 64K on a 16 bit machine.
- */
-void /* PRIVATE */
-png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length)
-{
-   png_debug1(4, "reading %d bytes", (int)length);
-
-   if (png_ptr->read_data_fn != NULL)
-      (*(png_ptr->read_data_fn))(png_ptr, data, length);
-
-   else
-      png_error(png_ptr, "Call to NULL read function");
-}
-
-#ifdef PNG_STDIO_SUPPORTED
-/* This is the function that does the actual reading of data.  If you are
- * not reading from a standard C stream, you should create a replacement
- * read_data function and use it at run time with png_set_read_fn(), rather
- * than changing the library.
- */
-void PNGCBAPI
-png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
-{
-   png_size_t check;
-
-   if (png_ptr == NULL)
-      return;
-
-   /* fread() returns 0 on error, so it is OK to store this in a png_size_t
-    * instead of an int, which is what fread() actually returns.
-    */
-   check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr));
-
-   if (check != length)
-      png_error(png_ptr, "Read Error");
-}
-#endif
-
-/* This function allows the application to supply a new input function
- * for libpng if standard C streams aren't being used.
- *
- * This function takes as its arguments:
- *
- * png_ptr      - pointer to a png input data structure
- *
- * io_ptr       - pointer to user supplied structure containing info about
- *                the input functions.  May be NULL.
- *
- * read_data_fn - pointer to a new input function that takes as its
- *                arguments a pointer to a png_struct, a pointer to
- *                a location where input data can be stored, and a 32-bit
- *                unsigned int that is the number of bytes to be read.
- *                To exit and output any fatal error messages the new write
- *                function should call png_error(png_ptr, "Error msg").
- *                May be NULL, in which case libpng's default function will
- *                be used.
- */
-void PNGAPI
-png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr,
-   png_rw_ptr read_data_fn)
-{
-   if (png_ptr == NULL)
-      return;
-
-   png_ptr->io_ptr = io_ptr;
-
-#ifdef PNG_STDIO_SUPPORTED
-   if (read_data_fn != NULL)
-      png_ptr->read_data_fn = read_data_fn;
-
-   else
-      png_ptr->read_data_fn = png_default_read_data;
-#else
-   png_ptr->read_data_fn = read_data_fn;
-#endif
-
-   /* It is an error to write to a read device */
-   if (png_ptr->write_data_fn != NULL)
-   {
-      png_ptr->write_data_fn = NULL;
-      png_warning(png_ptr,
-          "Can't set both read_data_fn and write_data_fn in the"
-          " same structure");
-   }
-
-#ifdef PNG_WRITE_FLUSH_SUPPORTED
-   png_ptr->output_flush_fn = NULL;
-#endif
-}
-#endif /* PNG_READ_SUPPORTED */