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3184947a25
This implements a new chunk parse implementation that can be shared, it is currently shared by the progressive reader and the sequential one (not, yet, the writer). The patch also implements shared transform handling that is used throughout. Signed-off-by: John Bowler <jbowler@acm.org>
110 lines
3.6 KiB
C
110 lines
3.6 KiB
C
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/* pngrio.c - functions for data input
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*
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* Last changed in libpng 1.7.0 [(PENDING RELEASE)]
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* Copyright (c) 1998-2015 Glenn Randers-Pehrson
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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*
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* This file provides a location for all input. Users who need
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* special handling are expected to write a function that has the same
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* arguments as this and performs a similar function, but that possibly
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* has a different input method. Note that you shouldn't change this
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* function, but rather write a replacement function and then make
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* libpng use it at run time with png_set_read_fn(...).
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*/
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#include "pngpriv.h"
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#define PNG_SRC_FILE PNG_SRC_FILE_rio
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#ifdef PNG_READ_SUPPORTED
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/* Read the data from whatever input you are using. The default routine
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* reads from a file pointer. Note that this routine sometimes gets called
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* with very small lengths, so you should implement some kind of simple
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* buffering if you are using unbuffered reads. This should never be asked
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* to read more than 64K on a 16 bit machine.
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*/
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void /* PRIVATE */
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png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length)
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{
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png_debug1(4, "reading %d bytes", (int)length);
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if (png_ptr->rw_data_fn != NULL)
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png_ptr->rw_data_fn(png_ptr, data, length);
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else
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png_app_error(png_ptr, "No read function");
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}
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#ifdef PNG_STDIO_SUPPORTED
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/* This is the function that does the actual reading of data. If you are
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* not reading from a standard C stream, you should create a replacement
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* read_data function and use it at run time with png_set_read_fn(), rather
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* than changing the library.
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*/
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void PNGCBAPI
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png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
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{
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png_size_t check;
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if (png_ptr == NULL)
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return;
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/* fread() returns 0 on error, so it is OK to store this in a png_size_t
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* instead of an int, which is what fread() actually returns.
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*/
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check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr));
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if (check != length)
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png_error(png_ptr, "Read Error");
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}
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#endif /* STDIO */
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/* This function allows the application to supply a new input function
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* for libpng if standard C streams aren't being used.
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*
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* This function takes as its arguments:
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*
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* png_ptr - pointer to a png input data structure
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*
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* io_ptr - pointer to user supplied structure containing info about
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* the input functions. May be NULL.
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*
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* read_data_fn - pointer to a new input function that takes as its
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* arguments a pointer to a png_struct, a pointer to
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* a location where input data can be stored, and a 32-bit
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* unsigned int that is the number of bytes to be read.
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* To exit and output any fatal error messages the new write
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* function should call png_error(png_ptr, "Error msg").
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* May be NULL, in which case libpng's default function will
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* be used.
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*/
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void PNGAPI
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png_set_read_fn(png_structrp png_ptr, png_voidp io_ptr,
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png_rw_ptr read_data_fn)
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{
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if (png_ptr == NULL)
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return;
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if (!png_ptr->read_struct)
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{
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png_app_error(png_ptr, "cannot set a read function on a write struct");
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return;
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}
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if (read_data_fn == NULL)
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{
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png_app_error(png_ptr, "API change: png_set_read_fn requires a function");
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return;
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}
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png_ptr->io_ptr = io_ptr;
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png_ptr->rw_data_fn = read_data_fn;
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}
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#endif /* READ */
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