This repository has been archived on 2023-11-11. You can view files and clone it, but cannot push or open issues or pull requests.
libpng/pngrio.c

162 lines
5.2 KiB
C
Raw Normal View History

1996-06-05 20:50:50 +00:00
/* pngrio.c - functions for data input
1998-01-01 13:13:13 +00:00
*
2004-09-04 18:25:08 +00:00
* libpng 1.2.7rc1 - September 4, 2004
1998-01-01 13:13:13 +00:00
* For conditions of distribution and use, see copyright notice in png.h
2004-07-18 03:45:44 +00:00
* Copyright (c) 1998-2004 Glenn Randers-Pehrson
2000-06-04 19:29:29 +00:00
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
1998-01-01 13:13:13 +00:00
*
1998-05-21 14:27:50 +00:00
* 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
1998-01-01 13:13:13 +00:00
* function, but rather write a replacement function and then make
* libpng use it at run time with png_set_read_fn(...).
*/
1996-06-05 20:50:50 +00:00
#define PNG_INTERNAL
#include "png.h"
/* 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
1997-05-16 07:46:07 +00:00
to read more then 64K on a 16 bit machine. */
2000-05-06 19:09:57 +00:00
void /* PRIVATE */
1997-05-16 07:46:07 +00:00
png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
1996-06-05 20:50:50 +00:00
{
2001-05-18 09:54:50 +00:00
png_debug1(4,"reading %d bytes\n", (int)length);
1997-05-16 07:46:07 +00:00
if (png_ptr->read_data_fn != NULL)
1996-06-05 20:50:50 +00:00
(*(png_ptr->read_data_fn))(png_ptr, data, length);
else
png_error(png_ptr, "Call to NULL read function");
}
1998-01-04 04:40:55 +00:00
#if !defined(PNG_NO_STDIO)
1998-05-21 14:27:50 +00:00
/* This is the function that does the actual reading of data. If you are
1996-06-05 20:50:50 +00:00
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. */
#ifndef USE_FAR_KEYWORD
2002-05-01 16:51:26 +00:00
void PNGAPI
1997-05-16 07:46:07 +00:00
png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
1996-06-05 20:50:50 +00:00
{
1997-05-16 07:46:07 +00:00
png_size_t check;
/* 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.
*/
2000-07-10 12:48:54 +00:00
#if defined(_WIN32_WCE)
if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
check = 0;
#else
1997-05-16 07:46:07 +00:00
check = (png_size_t)fread(data, (png_size_t)1, length,
2000-07-08 18:19:41 +00:00
(png_FILE_p)png_ptr->io_ptr);
2000-07-10 12:48:54 +00:00
#endif
1996-06-05 20:50:50 +00:00
if (check != length)
png_error(png_ptr, "Read Error");
}
#else
/* this is the model-independent version. Since the standard I/O library
can't handle far buffers in the medium and small models, we have to copy
the data.
*/
1998-12-29 17:47:59 +00:00
1996-06-05 20:50:50 +00:00
#define NEAR_BUF_SIZE 1024
#define MIN(a,b) (a <= b ? a : b)
1998-12-29 17:47:59 +00:00
2000-05-06 19:09:57 +00:00
static void /* PRIVATE */
1997-05-16 07:46:07 +00:00
png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
1996-06-05 20:50:50 +00:00
{
1997-05-16 07:46:07 +00:00
int check;
1996-06-05 20:50:50 +00:00
png_byte *n_data;
2000-07-08 18:19:41 +00:00
png_FILE_p io_ptr;
1996-06-05 20:50:50 +00:00
/* Check if data really is near. If so, use usual code. */
1997-01-17 07:34:35 +00:00
n_data = (png_byte *)CVT_PTR_NOCHECK(data);
2000-07-08 18:19:41 +00:00
io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr);
1996-06-05 20:50:50 +00:00
if ((png_bytep)n_data == data)
{
2000-07-10 12:48:54 +00:00
#if defined(_WIN32_WCE)
if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) )
check = 0;
#else
1997-05-16 07:46:07 +00:00
check = fread(n_data, 1, length, io_ptr);
2000-07-10 12:48:54 +00:00
#endif
1996-06-05 20:50:50 +00:00
}
else
{
png_byte buf[NEAR_BUF_SIZE];
png_size_t read, remaining, err;
check = 0;
1997-05-16 07:46:07 +00:00
remaining = length;
1996-06-05 20:50:50 +00:00
do
{
read = MIN(NEAR_BUF_SIZE, remaining);
2000-07-10 12:48:54 +00:00
#if defined(_WIN32_WCE)
if ( !ReadFile((HANDLE)(io_ptr), buf, read, &err, NULL) )
err = 0;
#else
1997-05-16 07:46:07 +00:00
err = fread(buf, (png_size_t)1, read, io_ptr);
2000-07-10 12:48:54 +00:00
#endif
1996-06-05 20:50:50 +00:00
png_memcpy(data, buf, read); /* copy far buffer to near buffer */
if(err != read)
break;
else
check += err;
data += read;
remaining -= read;
}
while (remaining != 0);
}
1998-02-07 16:20:57 +00:00
if ((png_uint_32)check != (png_uint_32)length)
1996-06-05 20:50:50 +00:00
png_error(png_ptr, "read Error");
}
#endif
1998-01-04 04:40:55 +00:00
#endif
1996-06-05 20:50:50 +00:00
/* 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.
1998-05-21 14:27:50 +00:00
read_data_fn - pointer to a new input function that takes as its
1996-06-05 20:50:50 +00:00
arguments a pointer to a png_struct, a pointer to
a location where input data can be stored, and a 32-bit
1998-05-21 14:27:50 +00:00
unsigned int that is the number of bytes to be read.
1996-06-05 20:50:50 +00:00
To exit and output any fatal error messages the new write
function should call png_error(png_ptr, "Error msg"). */
2000-05-06 19:09:57 +00:00
void PNGAPI
1996-06-05 20:50:50 +00:00
png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
png_rw_ptr read_data_fn)
{
png_ptr->io_ptr = io_ptr;
1998-01-04 04:40:55 +00:00
#if !defined(PNG_NO_STDIO)
1997-05-16 07:46:07 +00:00
if (read_data_fn != NULL)
1996-06-05 20:50:50 +00:00
png_ptr->read_data_fn = read_data_fn;
else
2002-05-01 16:51:26 +00:00
png_ptr->read_data_fn = png_default_read_data;
1998-01-04 04:40:55 +00:00
#else
png_ptr->read_data_fn = read_data_fn;
#endif
1996-06-05 20:50:50 +00:00
/* It is an error to write to a read device */
1998-06-06 20:31:35 +00:00
if (png_ptr->write_data_fn != NULL)
{
png_ptr->write_data_fn = NULL;
png_warning(png_ptr,
"It's an error to set both read_data_fn and write_data_fn in the ");
png_warning(png_ptr,
"same structure. Resetting write_data_fn to NULL.");
}
1996-06-05 20:50:50 +00:00
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
png_ptr->output_flush_fn = NULL;
1999-12-10 15:43:02 +00:00
#endif
1996-06-05 20:50:50 +00:00
}