1995-09-26 10:22:39 +00:00
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1996-01-10 08:56:49 +00:00
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/* pngio.c - stub functions for i/o and memory allocation
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1995-09-26 10:22:39 +00:00
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1996-01-10 08:56:49 +00:00
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libpng 1.0 beta 2 - version 0.86
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1995-09-26 10:22:39 +00:00
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For conditions of distribution and use, see copyright notice in png.h
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1996-01-10 08:56:49 +00:00
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Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
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January 10, 1996
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1995-09-26 10:22:39 +00:00
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This file provides a location for all input/output. Users which need
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1995-12-19 09:22:19 +00:00
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special handling are expected to write functions which have the same
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arguments as these, and perform similar functions, but possibly have
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different I/O methods. Note that you shouldn't change these functions,
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but rather write replacement functions and then change them at run
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time with png_set_write_fn(...) or png_set_read_fn(...), etc */
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1995-09-26 10:22:39 +00:00
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1995-12-19 09:22:19 +00:00
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#define PNG_INTERNAL
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1995-09-26 10:22:39 +00:00
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#include "png.h"
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1996-01-10 08:56:49 +00:00
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/* Write the data to whatever output you are using. The default routine
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writes to 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 writes. This should never be asked
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to write more then 64K on a 16 bit machine. The cast to png_size_t is
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there to quiet warnings of certain compilers. */
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1995-12-19 09:22:19 +00:00
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void
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png_write_data(png_structp png_ptr, png_bytep data, png_uint_32 length)
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{
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if (png_ptr->write_data_fn)
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(*(png_ptr->write_data_fn))(png_ptr, data, length);
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else
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png_error(png_ptr, "Call to NULL write function");
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}
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1996-01-10 08:56:49 +00:00
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/* This is the function which does the actual writing of data. If you are
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not writing to a standard C stream, you should create a replacement
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write_data function and use it at run time with png_set_write_fn(), rather
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than changing the library. */
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1995-09-26 10:22:39 +00:00
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#ifndef USE_FAR_KEYWORD
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1995-12-19 09:22:19 +00:00
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void
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png_default_write_data(png_structp png_ptr, png_bytep data, png_uint_32 length)
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1995-09-26 10:22:39 +00:00
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{
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png_uint_32 check;
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check = fwrite(data, 1, (png_size_t)length, png_ptr->fp);
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if (check != length)
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{
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1995-12-19 09:22:19 +00:00
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png_error(png_ptr, "Write Error");
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1995-09-26 10:22:39 +00:00
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}
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}
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1995-12-19 09:22:19 +00:00
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#else
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1995-09-26 10:22:39 +00:00
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/* this is the model-independent version. Since the standard I/O library
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can't handle far buffers in the medium and small models, we have to copy
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1995-12-19 09:22:19 +00:00
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the data.
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1995-09-26 10:22:39 +00:00
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*/
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#define NEAR_BUF_SIZE 1024
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#define MIN(a,b) (a <= b ? a : b)
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#ifdef _MSC_VER
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/* for FP_OFF */
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#include <dos.h>
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#endif
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1995-12-19 09:22:19 +00:00
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void
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png_default_write_data(png_structp png_ptr, png_bytep data, png_uint_32 length)
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1995-09-26 10:22:39 +00:00
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{
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png_uint_32 check;
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png_byte *n_data;
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1995-12-19 09:22:19 +00:00
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1995-09-26 10:22:39 +00:00
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/* Check if data really is near. If so, use usual code. */
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#ifdef _MSC_VER
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1995-12-19 09:22:19 +00:00
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/* do it this way just to quiet warning */
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FP_OFF(n_data) = FP_OFF(data);
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if (FP_SEG(n_data) == FP_SEG(data))
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1995-09-26 10:22:39 +00:00
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#else
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1995-12-19 09:22:19 +00:00
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/* this works in MSC also but with lost segment warning */
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n_data = (png_byte *)data;
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if ((png_bytep)n_data == data)
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#endif
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1995-09-26 10:22:39 +00:00
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{
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check = fwrite(n_data, 1, (png_size_t)length, png_ptr->fp);
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}
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1995-12-19 09:22:19 +00:00
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else
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1995-09-26 10:22:39 +00:00
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{
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png_byte buf[NEAR_BUF_SIZE];
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png_size_t written, remaining, err;
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check = 0;
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remaining = (png_size_t)length;
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1995-12-19 09:22:19 +00:00
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do
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{
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written = MIN(NEAR_BUF_SIZE, remaining);
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png_memcpy(buf, data, written); /* copy far buffer to near buffer */
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1995-09-26 10:22:39 +00:00
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err = fwrite(buf, 1, written, png_ptr->fp);
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1995-12-19 09:22:19 +00:00
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if (err != written)
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1995-09-26 10:22:39 +00:00
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break;
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1995-12-19 09:22:19 +00:00
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else
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check += err;
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1995-09-26 10:22:39 +00:00
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data += written;
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remaining -= written;
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}
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1995-12-19 09:22:19 +00:00
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while (remaining != 0);
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}
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if (check != length)
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{
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png_error(png_ptr, "Write Error");
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}
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1995-09-26 10:22:39 +00:00
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}
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#endif
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1996-01-10 08:56:49 +00:00
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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 then 64K on a 16 bit machine. The cast to png_size_t is
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there to quiet some compilers */
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1995-12-19 09:22:19 +00:00
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void
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png_read_data(png_structp png_ptr, png_bytep data, png_uint_32 length)
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{
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#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
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if (png_ptr->read_mode == PNG_READ_PUSH_MODE)
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{
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png_push_fill_buffer(png_ptr, data, length);
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}
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else
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#endif
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{
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if (png_ptr->read_data_fn)
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(*(png_ptr->read_data_fn))(png_ptr, data, length);
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else
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png_error(png_ptr, "Call to NULL read function");
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}
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}
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1996-01-10 08:56:49 +00:00
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/* This is the function which 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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1995-09-26 10:22:39 +00:00
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#ifndef USE_FAR_KEYWORD
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1995-12-19 09:22:19 +00:00
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void
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png_default_read_data(png_structp png_ptr, png_bytep data, png_uint_32 length)
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1995-09-26 10:22:39 +00:00
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{
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png_uint_32 check;
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check = fread(data, 1, (size_t)length, png_ptr->fp);
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if (check != length)
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{
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1995-12-19 09:22:19 +00:00
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png_error(png_ptr, "Read Error");
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1995-09-26 10:22:39 +00:00
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}
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}
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#else
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1995-12-19 09:22:19 +00:00
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void
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png_default_read_data(png_structp png_ptr, png_bytep data, png_uint_32 length)
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1995-09-26 10:22:39 +00:00
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{
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png_uint_32 check;
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png_byte *n_data;
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1995-12-19 09:22:19 +00:00
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1995-09-26 10:22:39 +00:00
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/* Check if data really is near. If so, use usual code. */
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#ifdef _MSC_VER
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/* do it this way just to quiet warning */
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1995-12-19 09:22:19 +00:00
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FP_OFF(n_data) = FP_OFF(data);
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if (FP_SEG(n_data) == FP_SEG(data))
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1995-09-26 10:22:39 +00:00
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#else
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/* this works in MSC also but with lost segment warning */
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1995-12-19 09:22:19 +00:00
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n_data = (png_byte *)data;
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if ((PNG_BYTEP )n_data == data)
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#endif
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1995-09-26 10:22:39 +00:00
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{
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check = fread(n_data, 1, (size_t)length, png_ptr->fp);
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1995-12-19 09:22:19 +00:00
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}
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1995-09-26 10:22:39 +00:00
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else
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{
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png_byte buf[NEAR_BUF_SIZE];
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png_size_t read, remaining, err;
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check = 0;
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remaining = (png_size_t)length;
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do
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{
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1995-12-19 09:22:19 +00:00
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read = MIN(NEAR_BUF_SIZE, remaining);
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1995-09-26 10:22:39 +00:00
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err = fread(buf, 1, read, png_ptr->fp);
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1995-12-19 09:22:19 +00:00
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png_memcpy(data, buf, read); /* copy far buffer to near buffer */
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1995-09-26 10:22:39 +00:00
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if(err != read)
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break;
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else
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1995-12-19 09:22:19 +00:00
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check += err;
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1995-09-26 10:22:39 +00:00
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data += read;
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1995-12-19 09:22:19 +00:00
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remaining -= read;
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}
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while (remaining != 0);
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}
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if (check != length)
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{
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png_error(png_ptr, "read Error");
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}
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1995-09-26 10:22:39 +00:00
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}
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#endif
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1995-11-28 17:22:13 +00:00
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#if defined(PNG_WRITE_FLUSH_SUPPORTED)
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1995-12-19 09:22:19 +00:00
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void
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png_flush(png_struct *png_ptr)
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1995-11-28 17:22:13 +00:00
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{
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1995-12-19 09:22:19 +00:00
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if (png_ptr->output_flush_fn)
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(*(png_ptr->output_flush_fn))(png_ptr);
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1995-11-28 17:22:13 +00:00
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}
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1995-12-19 09:22:19 +00:00
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void
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png_default_flush(png_struct *png_ptr)
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1995-11-28 17:22:13 +00:00
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{
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1995-12-19 09:22:19 +00:00
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if (png_ptr->fp)
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fflush(png_ptr->fp);
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1995-11-28 17:22:13 +00:00
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}
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#endif
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/* This function allows the application to supply new output functions for
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1995-12-19 09:22:19 +00:00
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libpng if standard C streams aren't being used.
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This function takes as its arguments:
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png_ptr - pointer to a png output data structure
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io_ptr - pointer to user supplied structure containing info about
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the output functions. May be NULL.
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write_data_fn - pointer to a new output function which takes as its
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arguments a pointer to a png_struct, a pointer to
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data to be written, and a 32-bit unsigned int which is
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the number of bytes to be written. The new write
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1996-01-10 08:56:49 +00:00
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function should call png_error("Error msg")
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1995-12-19 09:22:19 +00:00
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to exit and output any fatal error messages.
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flush_data_fn - pointer to a new flush function which takes as its
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arguments a pointer to a png_struct. After a call to
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the flush function, there should be no data in any buffers
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or pending transmission. If the output method doesn't do
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any buffering of ouput, this parameter can be NULL. If
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PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng
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compile time, output_flush_fn will be ignored, although
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it must be supplied for compatibility. */
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1995-11-28 17:22:13 +00:00
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void
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1995-12-19 09:22:19 +00:00
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png_set_write_fn(png_structp png_ptr, png_voidp io_ptr, png_rw_ptr write_data_fn,
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png_flush_ptr output_flush_fn)
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1995-11-28 17:22:13 +00:00
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{
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1995-12-19 09:22:19 +00:00
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png_ptr->io_ptr = io_ptr;
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1995-11-28 17:22:13 +00:00
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1995-12-19 09:22:19 +00:00
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if (write_data_fn)
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png_ptr->write_data_fn = write_data_fn;
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else
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png_ptr->write_data_fn = png_default_write_data;
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1995-11-28 17:22:13 +00:00
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#if defined(PNG_WRITE_FLUSH_SUPPORTED)
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1995-12-19 09:22:19 +00:00
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if (output_flush_fn == NULL)
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png_ptr->output_flush_fn = png_default_flush;
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else
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png_ptr->output_flush_fn = output_flush_fn;
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1995-11-28 17:22:13 +00:00
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#endif /* PNG_WRITE_FLUSH_SUPPORTED */
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1995-12-19 09:22:19 +00:00
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/* It is an error to read while writing a png file */
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png_ptr->read_data_fn = NULL;
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1995-11-28 17:22:13 +00:00
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}
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/* This function allows the application to supply a new input function
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1995-12-19 09:22:19 +00:00
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for libpng if standard C streams aren't being used.
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This function takes as its arguments:
|
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png_ptr - pointer to a png input data structure
|
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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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read_data_fn - pointer to a new input function which takes as it's
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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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1996-01-10 08:56:49 +00:00
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unsigned int which 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"). */
|
1995-11-28 17:22:13 +00:00
|
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void
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png_set_read_fn(png_struct *png_ptr, void *io_ptr, png_rw_ptr read_data_fn)
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{
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1995-12-19 09:22:19 +00:00
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png_ptr->io_ptr = io_ptr;
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1995-11-28 17:22:13 +00:00
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|
1995-12-19 09:22:19 +00:00
|
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|
if (read_data_fn)
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png_ptr->read_data_fn = read_data_fn;
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else
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png_ptr->read_data_fn = png_default_read_data;
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1995-11-28 17:22:13 +00:00
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1995-12-19 09:22:19 +00:00
|
|
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/* It is an error to write to a read device */
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png_ptr->write_data_fn = NULL;
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1995-11-28 17:22:13 +00:00
|
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|
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
|
1995-12-19 09:22:19 +00:00
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png_ptr->output_flush_fn = NULL;
|
1995-11-28 17:22:13 +00:00
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|
|
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
|
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|
|
}
|
|
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/* This function returns a pointer to the io_ptr associated with the user
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1995-12-19 09:22:19 +00:00
|
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|
functions. The application should free any memory associated with this
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|
|
pointer before png_write_destroy and png_read_destroy are called. */
|
1995-11-28 17:22:13 +00:00
|
|
|
void *
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|
|
png_get_io_ptr(png_struct *png_ptr)
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|
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|
{
|
1995-12-19 09:22:19 +00:00
|
|
|
return png_ptr->io_ptr;
|
1995-11-28 17:22:13 +00:00
|
|
|
}
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|
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|
1996-01-10 08:56:49 +00:00
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/* Initialize the default input/output functions for the png file. If you
|
|
|
|
change the read, or write routines, you can call either png_set_read_fn()
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|
|
or png_set_write_fn() instead of png_init_io(). */
|
1995-11-28 17:22:13 +00:00
|
|
|
void
|
1995-12-19 09:22:19 +00:00
|
|
|
png_init_io(png_structp png_ptr, FILE *fp)
|
1995-11-28 17:22:13 +00:00
|
|
|
{
|
1995-12-19 09:22:19 +00:00
|
|
|
png_ptr->fp = fp;
|
|
|
|
png_ptr->read_data_fn = png_default_read_data;
|
|
|
|
png_ptr->write_data_fn = png_default_write_data;
|
|
|
|
#ifdef PNG_WRITE_FLUSH_SUPPORTED
|
|
|
|
png_ptr->output_flush_fn = png_default_flush;
|
|
|
|
#endif
|
1995-11-28 17:22:13 +00:00
|
|
|
}
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|