pngmem.c
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pngmem.c
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	/* pngmem.c - stub functions for memory allocation
	*
	* Last changed in libpng 1.5.4 [July 7, 2011]
	* Copyright (c) 1998-2011 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 memory allocation. Users who
	* need special memory handling are expected to supply replacement
	* functions for png_malloc() and png_free(), and to use
	* png_create_read_struct_2() and png_create_write_struct_2() to
	* identify the replacement functions.
	*/

	#include "pngpriv.h"

	#if defined(PNG_READ_SUPPORTED) \|\| defined(PNG_WRITE_SUPPORTED)

	/* Borland DOS special memory handler */
	#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
	/* If you change this, be sure to change the one in png.h also */

	/* Allocate memory for a png_struct. The malloc and memset can be replaced
	by a single call to calloc() if this is thought to improve performance. */
	PNG_FUNCTION(png_voidp /* PRIVATE */,
	png_create_struct,(int type),PNG_ALLOCATED)
	{
	# ifdef PNG_USER_MEM_SUPPORTED
	return (png_create_struct_2(type, NULL, NULL));
	}

	/* Alternate version of png_create_struct, for use with user-defined malloc. */
	PNG_FUNCTION(png_voidp /* PRIVATE */,
	png_create_struct_2,(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr),
	PNG_ALLOCATED)
	{
	# endif /* PNG_USER_MEM_SUPPORTED */
	png_size_t size;
	png_voidp struct_ptr;

	if (type == PNG_STRUCT_INFO)
	size = png_sizeof(png_info);

	else if (type == PNG_STRUCT_PNG)
	size = png_sizeof(png_struct);

	else
	return (png_get_copyright(NULL));

	# ifdef PNG_USER_MEM_SUPPORTED
	if (malloc_fn != NULL)
	{
	png_struct dummy_struct;
	png_structp png_ptr = &dummy_struct;
	png_ptr->mem_ptr=mem_ptr;
	struct_ptr = (*(malloc_fn))(png_ptr, (png_uint_32)size);
	}

	else
	# endif /* PNG_USER_MEM_SUPPORTED */
	struct_ptr = (png_voidp)farmalloc(size);
	if (struct_ptr != NULL)
	png_memset(struct_ptr, 0, size);

	return (struct_ptr);
	}

	/* Free memory allocated by a png_create_struct() call */
	void /* PRIVATE */
	png_destroy_struct(png_voidp struct_ptr)
	{
	# ifdef PNG_USER_MEM_SUPPORTED
	png_destroy_struct_2(struct_ptr, NULL, NULL);
	}

	/* Free memory allocated by a png_create_struct() call */
	void /* PRIVATE */
	png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
	png_voidp mem_ptr)
	{
	# endif
	if (struct_ptr != NULL)
	{
	# ifdef PNG_USER_MEM_SUPPORTED
	if (free_fn != NULL)
	{
	png_struct dummy_struct;
	png_structp png_ptr = &dummy_struct;
	png_ptr->mem_ptr=mem_ptr;
	(*(free_fn))(png_ptr, struct_ptr);
	return;
	}

	# endif /* PNG_USER_MEM_SUPPORTED */
	farfree (struct_ptr);
	}
	}

	/* Allocate memory. For reasonable files, size should never exceed
	* 64K. However, zlib may allocate more then 64K if you don't tell
	* it not to. See zconf.h and png.h for more information. zlib does
	* need to allocate exactly 64K, so whatever you call here must
	* have the ability to do that.
	*
	* Borland seems to have a problem in DOS mode for exactly 64K.
	* It gives you a segment with an offset of 8 (perhaps to store its
	* memory stuff). zlib doesn't like this at all, so we have to
	* detect and deal with it. This code should not be needed in
	* Windows or OS/2 modes, and only in 16 bit mode. This code has
	* been updated by Alexander Lehmann for version 0.89 to waste less
	* memory.
	*
	* Note that we can't use png_size_t for the "size" declaration,
	* since on some systems a png_size_t is a 16-bit quantity, and as a
	* result, we would be truncating potentially larger memory requests
	* (which should cause a fatal error) and introducing major problems.
	*/
	PNG_FUNCTION(png_voidp,PNGAPI
	png_calloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ret;

	ret = (png_malloc(png_ptr, size));

	if (ret != NULL)
	png_memset(ret,0,(png_size_t)size);

	return (ret);
	}

	PNG_FUNCTION(png_voidp,PNGAPI
	png_malloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ret;

	if (png_ptr == NULL \|\| size == 0)
	return (NULL);

	# ifdef PNG_USER_MEM_SUPPORTED
	if (png_ptr->malloc_fn != NULL)
	ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));

	else
	ret = (png_malloc_default(png_ptr, size));

	if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out of memory");

	return (ret);
	}

	PNG_FUNCTION(png_voidp,PNGAPI
	png_malloc_default,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ret;
	# endif /* PNG_USER_MEM_SUPPORTED */

	if (png_ptr == NULL \|\| size == 0)
	return (NULL);

	# ifdef PNG_MAX_MALLOC_64K
	if (size > (png_uint_32)65536L)
	{
	png_warning(png_ptr, "Cannot Allocate > 64K");
	ret = NULL;
	}

	else
	# endif

	if (size != (size_t)size)
	ret = NULL;

	else if (size == (png_uint_32)65536L)
	{
	if (png_ptr->offset_table == NULL)
	{
	/* Try to see if we need to do any of this fancy stuff */
	ret = farmalloc(size);
	if (ret == NULL \|\| ((png_size_t)ret & 0xffff))
	{
	int num_blocks;
	png_uint_32 total_size;
	png_bytep table;
	int i, mem_level, window_bits;
	png_byte huge * hptr;
	int window_bits

	if (ret != NULL)
	{
	farfree(ret);
	ret = NULL;
	}

	window_bits =
	png_ptr->zlib_window_bits >= png_ptr->zlib_text_window_bits ?
	png_ptr->zlib_window_bits : png_ptr->zlib_text_window_bits;

	if (window_bits > 14)
	num_blocks = (int)(1 << (window_bits - 14));

	else
	num_blocks = 1;

	mem_level =
	png_ptr->zlib_mem_level >= png_ptr->zlib_text_mem_level ?
	png_ptr->zlib_mem_level : png_ptr->zlib_text_mem_level;

	if (mem_level >= 7)
	num_blocks += (int)(1 << (mem_level - 7));

	else
	num_blocks++;

	total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;

	table = farmalloc(total_size);

	if (table == NULL)
	{
	# ifndef PNG_USER_MEM_SUPPORTED
	if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out Of Memory"); /* Note "O", "M" */

	else
	png_warning(png_ptr, "Out Of Memory");
	# endif
	return (NULL);
	}

	if ((png_size_t)table & 0xfff0)
	{
	# ifndef PNG_USER_MEM_SUPPORTED
	if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr,
	"Farmalloc didn't return normalized pointer");

	else
	png_warning(png_ptr,
	"Farmalloc didn't return normalized pointer");
	# endif
	return (NULL);
	}

	png_ptr->offset_table = table;
	png_ptr->offset_table_ptr = farmalloc(num_blocks *
	png_sizeof(png_bytep));

	if (png_ptr->offset_table_ptr == NULL)
	{
	# ifndef PNG_USER_MEM_SUPPORTED
	if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out Of memory"); /* Note "O", "m" */

	else
	png_warning(png_ptr, "Out Of memory");
	# endif
	return (NULL);
	}

	hptr = (png_byte huge *)table;
	if ((png_size_t)hptr & 0xf)
	{
	hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
	hptr = hptr + 16L; /* "hptr += 16L" fails on Turbo C++ 3.0 */
	}

	for (i = 0; i < num_blocks; i++)
	{
	png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
	hptr = hptr + (png_uint_32)65536L; /* "+=" fails on TC++3.0 */
	}

	png_ptr->offset_table_number = num_blocks;
	png_ptr->offset_table_count = 0;
	png_ptr->offset_table_count_free = 0;
	}
	}

	if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
	{
	# ifndef PNG_USER_MEM_SUPPORTED
	if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out of Memory"); /* Note "O" and "M" */

	else
	png_warning(png_ptr, "Out of Memory");
	# endif
	return (NULL);
	}

	ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
	}

	else
	ret = farmalloc(size);

	# ifndef PNG_USER_MEM_SUPPORTED
	if (ret == NULL)
	{
	if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out of memory"); /* Note "o" and "m" */

	else
	png_warning(png_ptr, "Out of memory"); /* Note "o" and "m" */
	}
	# endif

	return (ret);
	}

	/* Free a pointer allocated by png_malloc(). In the default
	* configuration, png_ptr is not used, but is passed in case it
	* is needed. If ptr is NULL, return without taking any action.
	*/
	void PNGAPI
	png_free(png_structp png_ptr, png_voidp ptr)
	{
	if (png_ptr == NULL \|\| ptr == NULL)
	return;

	# ifdef PNG_USER_MEM_SUPPORTED
	if (png_ptr->free_fn != NULL)
	{
	(*(png_ptr->free_fn))(png_ptr, ptr);
	return;
	}

	else
	png_free_default(png_ptr, ptr);
	}

	void PNGAPI
	png_free_default(png_structp png_ptr, png_voidp ptr)
	{
	# endif /* PNG_USER_MEM_SUPPORTED */

	if (png_ptr == NULL \|\| ptr == NULL)
	return;

	if (png_ptr->offset_table != NULL)
	{
	int i;

	for (i = 0; i < png_ptr->offset_table_count; i++)
	{
	if (ptr == png_ptr->offset_table_ptr[i])
	{
	ptr = NULL;
	png_ptr->offset_table_count_free++;
	break;
	}
	}
	if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
	{
	farfree(png_ptr->offset_table);
	farfree(png_ptr->offset_table_ptr);
	png_ptr->offset_table = NULL;
	png_ptr->offset_table_ptr = NULL;
	}
	}

	if (ptr != NULL)
	farfree(ptr);
	}

	#else /* Not the Borland DOS special memory handler */

	/* Allocate memory for a png_struct or a png_info. The malloc and
	memset can be replaced by a single call to calloc() if this is thought
	to improve performance noticably. */
	PNG_FUNCTION(png_voidp /* PRIVATE */,
	png_create_struct,(int type),PNG_ALLOCATED)
	{
	# ifdef PNG_USER_MEM_SUPPORTED
	return (png_create_struct_2(type, NULL, NULL));
	}

	/* Allocate memory for a png_struct or a png_info. The malloc and
	memset can be replaced by a single call to calloc() if this is thought
	to improve performance noticably. */
	PNG_FUNCTION(png_voidp /* PRIVATE */,
	png_create_struct_2,(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr),
	PNG_ALLOCATED)
	{
	# endif /* PNG_USER_MEM_SUPPORTED */
	png_size_t size;
	png_voidp struct_ptr;

	if (type == PNG_STRUCT_INFO)
	size = png_sizeof(png_info);

	else if (type == PNG_STRUCT_PNG)
	size = png_sizeof(png_struct);

	else
	return (NULL);

	# ifdef PNG_USER_MEM_SUPPORTED
	if (malloc_fn != NULL)
	{
	png_struct dummy_struct;
	png_structp png_ptr = &dummy_struct;
	png_ptr->mem_ptr=mem_ptr;
	struct_ptr = (*(malloc_fn))(png_ptr, size);

	if (struct_ptr != NULL)
	png_memset(struct_ptr, 0, size);

	return (struct_ptr);
	}
	# endif /* PNG_USER_MEM_SUPPORTED */

	# if defined(__TURBOC__) && !defined(__FLAT__)
	struct_ptr = (png_voidp)farmalloc(size);
	# else
	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	struct_ptr = (png_voidp)halloc(size, 1);
	# else
	struct_ptr = (png_voidp)malloc(size);
	# endif
	# endif

	if (struct_ptr != NULL)
	png_memset(struct_ptr, 0, size);

	return (struct_ptr);
	}


	/* Free memory allocated by a png_create_struct() call */
	void /* PRIVATE */
	png_destroy_struct(png_voidp struct_ptr)
	{
	# ifdef PNG_USER_MEM_SUPPORTED
	png_destroy_struct_2(struct_ptr, NULL, NULL);
	}

	/* Free memory allocated by a png_create_struct() call */
	void /* PRIVATE */
	png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
	png_voidp mem_ptr)
	{
	# endif /* PNG_USER_MEM_SUPPORTED */
	if (struct_ptr != NULL)
	{
	# ifdef PNG_USER_MEM_SUPPORTED
	if (free_fn != NULL)
	{
	png_struct dummy_struct;
	png_structp png_ptr = &dummy_struct;
	png_ptr->mem_ptr=mem_ptr;
	(*(free_fn))(png_ptr, struct_ptr);
	return;
	}
	# endif /* PNG_USER_MEM_SUPPORTED */
	# if defined(__TURBOC__) && !defined(__FLAT__)
	farfree(struct_ptr);

	# else
	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	hfree(struct_ptr);

	# else
	free(struct_ptr);

	# endif
	# endif
	}
	}

	/* Allocate memory. For reasonable files, size should never exceed
	* 64K. However, zlib may allocate more then 64K if you don't tell
	* it not to. See zconf.h and png.h for more information. zlib does
	* need to allocate exactly 64K, so whatever you call here must
	* have the ability to do that.
	*/

	PNG_FUNCTION(png_voidp,PNGAPI
	png_calloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ret;

	ret = (png_malloc(png_ptr, size));

	if (ret != NULL)
	png_memset(ret,0,(png_size_t)size);

	return (ret);
	}

	PNG_FUNCTION(png_voidp,PNGAPI
	png_malloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ret;

	# ifdef PNG_USER_MEM_SUPPORTED
	if (png_ptr == NULL \|\| size == 0)
	return (NULL);

	if (png_ptr->malloc_fn != NULL)
	ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));

	else
	ret = (png_malloc_default(png_ptr, size));

	if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out of Memory");

	return (ret);
	}

	PNG_FUNCTION(png_voidp,PNGAPI
	png_malloc_default,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ret;
	# endif /* PNG_USER_MEM_SUPPORTED */

	if (png_ptr == NULL \|\| size == 0)
	return (NULL);

	# ifdef PNG_MAX_MALLOC_64K
	if (size > (png_uint_32)65536L)
	{
	# ifndef PNG_USER_MEM_SUPPORTED
	if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Cannot Allocate > 64K");

	else
	# endif
	return NULL;
	}
	# endif

	/* Check for overflow */
	# if defined(__TURBOC__) && !defined(__FLAT__)

	if (size != (unsigned long)size)
	ret = NULL;

	else
	ret = farmalloc(size);

	# else
	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	if (size != (unsigned long)size)
	ret = NULL;

	else
	ret = halloc(size, 1);

	# else
	if (size != (size_t)size)
	ret = NULL;

	else
	ret = malloc((size_t)size);
	# endif
	# endif

	# ifndef PNG_USER_MEM_SUPPORTED
	if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	png_error(png_ptr, "Out of Memory");
	# endif

	return (ret);
	}

	/* Free a pointer allocated by png_malloc(). If ptr is NULL, return
	* without taking any action.
	*/
	void PNGAPI
	png_free(png_structp png_ptr, png_voidp ptr)
	{
	if (png_ptr == NULL \|\| ptr == NULL)
	return;

	# ifdef PNG_USER_MEM_SUPPORTED
	if (png_ptr->free_fn != NULL)
	{
	(*(png_ptr->free_fn))(png_ptr, ptr);
	return;
	}

	else
	png_free_default(png_ptr, ptr);
	}

	void PNGAPI
	png_free_default(png_structp png_ptr, png_voidp ptr)
	{
	if (png_ptr == NULL \|\| ptr == NULL)
	return;

	# endif /* PNG_USER_MEM_SUPPORTED */

	# if defined(__TURBOC__) && !defined(__FLAT__)
	farfree(ptr);

	# else
	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	hfree(ptr);

	# else
	free(ptr);

	# endif
	# endif
	}
	#endif /* Not Borland DOS special memory handler */

	/* This function was added at libpng version 1.2.3. The png_malloc_warn()
	* function will set up png_malloc() to issue a png_warning and return NULL
	* instead of issuing a png_error, if it fails to allocate the requested
	* memory.
	*/
	PNG_FUNCTION(png_voidp,PNGAPI
	png_malloc_warn,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
	{
	png_voidp ptr;
	png_uint_32 save_flags;
	if (png_ptr == NULL)
	return (NULL);

	save_flags = png_ptr->flags;
	png_ptr->flags\|=PNG_FLAG_MALLOC_NULL_MEM_OK;
	ptr = (png_voidp)png_malloc((png_structp)png_ptr, size);
	png_ptr->flags=save_flags;
	return(ptr);
	}


	#ifdef PNG_USER_MEM_SUPPORTED
	/* This function is called when the application wants to use another method
	* of allocating and freeing memory.
	*/
	void PNGAPI
	png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
	malloc_fn, png_free_ptr free_fn)
	{
	if (png_ptr != NULL)
	{
	png_ptr->mem_ptr = mem_ptr;
	png_ptr->malloc_fn = malloc_fn;
	png_ptr->free_fn = free_fn;
	}
	}

	/* This function returns a pointer to the mem_ptr associated with the user
	* functions. The application should free any memory associated with this
	* pointer before png_write_destroy and png_read_destroy are called.
	*/
	png_voidp PNGAPI
	png_get_mem_ptr(png_const_structp png_ptr)
	{
	if (png_ptr == NULL)
	return (NULL);

	return ((png_voidp)png_ptr->mem_ptr);
	}
	#endif /* PNG_USER_MEM_SUPPORTED */
	#endif /* PNG_READ_SUPPORTED \|\| PNG_WRITE_SUPPORTED */

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