src/png/pngmem.c


/* pngmem.c - stub functions for memory allocation
 *
 * libpng 1.2.5rc3 - September 18, 2002
 * For conditions of distribution and use, see copyright notice in png.h
 * Copyright (c) 1998-2002 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 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.
 */

#define PNG_INTERNAL
#include "png.h"

/* 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_voidp /* PRIVATE */
png_create_struct(int type)
{
#ifdef PNG_USER_MEM_SUPPORTED
   return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
}

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

   if (type == PNG_STRUCT_INFO)
     size = sizeof(png_info);
   else if (type == PNG_STRUCT_PNG)
     size = sizeof(png_struct);
   else
     return (png_get_copyright());

#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, png_free_ptr_NULL, png_voidp_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_voidp PNGAPI
png_malloc(png_structp png_ptr, png_uint_32 size)
{
   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));
       if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
          png_error(png_ptr, "Out of memory!");
       return (ret);
   }
   else
       return png_malloc_default(png_ptr, size);
}

png_voidp PNGAPI
png_malloc_default(png_structp png_ptr, png_uint_32 size)
{
   png_voidp ret;
#endif /* PNG_USER_MEM_SUPPORTED */

#ifdef PNG_MAX_MALLOC_64K
   if (size > (png_uint_32)65536L)
      png_error(png_ptr, "Cannot Allocate > 64K");
#endif

   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;
            png_byte huge * hptr;

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

            if(png_ptr->zlib_window_bits > 14)
               num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
            else
               num_blocks = 1;
            if (png_ptr->zlib_mem_level >= 7)
               num_blocks += (int)(1 << (png_ptr->zlib_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)
            {
               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.");
               return (NULL);
            }

            if ((png_size_t)table & 0xfff0)
            {
               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");
               return (NULL);
            }

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

            if (png_ptr->offset_table_ptr == 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.");
               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)
      {
         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.");
         return (NULL);
      }

      ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
   }
   else
      ret = farmalloc(size);

   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" */
   }

   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->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_voidp /* PRIVATE */
png_create_struct(int type)
{
#ifdef PNG_USER_MEM_SUPPORTED
   return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_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_voidp /* PRIVATE */
png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
{
#endif /* PNG_USER_MEM_SUPPORTED */
   png_size_t size;
   png_voidp struct_ptr;

   if (type == PNG_STRUCT_INFO)
      size = sizeof(png_info);
   else if (type == PNG_STRUCT_PNG)
      size = 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__)
   if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
   if ((struct_ptr = (png_voidp)halloc(size,1)) != NULL)
# else
   if ((struct_ptr = (png_voidp)malloc(size)) != NULL)
# endif
#endif
   {
      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, png_free_ptr_NULL, png_voidp_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_voidp PNGAPI
png_malloc(png_structp png_ptr, png_uint_32 size)
{
   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));
       if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
          png_error(png_ptr, "Out of Memory!");
       return (ret);
   }
   else
       return (png_malloc_default(png_ptr, size));
}

png_voidp PNGAPI
png_malloc_default(png_structp png_ptr, png_uint_32 size)
{
   png_voidp ret;
#endif /* PNG_USER_MEM_SUPPORTED */

#ifdef PNG_MAX_MALLOC_64K
   if (size > (png_uint_32)65536L)
   {
      if(png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
         png_error(png_ptr, "Cannot Allocate > 64K");
      else
         return NULL;
   }
#endif

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

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

   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 */

#if defined(PNG_1_0_X)
#  define png_malloc_warn png_malloc
#else
/* This function was added at libpng version 1.2.3.  The png_malloc_warn()
 * function will issue a png_warning and return NULL instead of issuing a
 * png_error, if it fails to allocate the requested memory.
 */
png_voidp PNGAPI
png_malloc_warn(png_structp png_ptr, png_uint_32 size)
{
   png_voidp ptr;
   png_uint_32 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);
}
#endif

png_voidp PNGAPI
png_memcpy_check (png_structp png_ptr, png_voidp s1, png_voidp s2,
   png_uint_32 length)
{
   png_size_t size;

   size = (png_size_t)length;
   if ((png_uint_32)size != length)
      png_error(png_ptr,"Overflow in png_memcpy_check.");

   return(png_memcpy (s1, s2, size));
}

png_voidp PNGAPI
png_memset_check (png_structp png_ptr, png_voidp s1, int value,
   png_uint_32 length)
{
   png_size_t size;

   size = (png_size_t)length;
   if ((png_uint_32)size != length)
      png_error(png_ptr,"Overflow in png_memset_check.");

   return (png_memset (s1, value, size));

}

#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)
{
   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_structp png_ptr)
{
   return ((png_voidp)png_ptr->mem_ptr);
}
#endif /* PNG_USER_MEM_SUPPORTED */
Commit	Line	Data
	1
	2	/* pngmem.c - stub functions for memory allocation
	3	*
	4	* libpng 1.2.5rc3 - September 18, 2002
	5	* For conditions of distribution and use, see copyright notice in png.h
	6	* Copyright (c) 1998-2002 Glenn Randers-Pehrson
	7	* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
	8	* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
	9	*
	10	* This file provides a location for all memory allocation. Users who
	11	* need special memory handling are expected to supply replacement
	12	* functions for png_malloc() and png_free(), and to use
	13	* png_create_read_struct_2() and png_create_write_struct_2() to
	14	* identify the replacement functions.
	15	*/
	16
	17	#define PNG_INTERNAL
	18	#include "png.h"
	19
	20	/* Borland DOS special memory handler */
	21	#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
	22	/* if you change this, be sure to change the one in png.h also */
	23
	24	/* Allocate memory for a png_struct. The malloc and memset can be replaced
	25	by a single call to calloc() if this is thought to improve performance. */
	26	png_voidp /* PRIVATE */
	27	png_create_struct(int type)
	28	{
	29	#ifdef PNG_USER_MEM_SUPPORTED
	30	return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
	31	}
	32
	33	/* Alternate version of png_create_struct, for use with user-defined malloc. */
	34	png_voidp /* PRIVATE */
	35	png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
	36	{
	37	#endif /* PNG_USER_MEM_SUPPORTED */
	38	png_size_t size;
	39	png_voidp struct_ptr;
	40
	41	if (type == PNG_STRUCT_INFO)
	42	size = sizeof(png_info);
	43	else if (type == PNG_STRUCT_PNG)
	44	size = sizeof(png_struct);
	45	else
	46	return (png_get_copyright());
	47
	48	#ifdef PNG_USER_MEM_SUPPORTED
	49	if(malloc_fn != NULL)
	50	{
	51	png_struct dummy_struct;
	52	png_structp png_ptr = &dummy_struct;
	53	png_ptr->mem_ptr=mem_ptr;
	54	struct_ptr = (*(malloc_fn))(png_ptr, (png_uint_32)size);
	55	}
	56	else
	57	#endif /* PNG_USER_MEM_SUPPORTED */
	58	struct_ptr = (png_voidp)farmalloc(size));
	59	if (struct_ptr != NULL)
	60	png_memset(struct_ptr, 0, size);
	61	return (struct_ptr);
	62	}
	63
	64	/* Free memory allocated by a png_create_struct() call */
	65	void /* PRIVATE */
	66	png_destroy_struct(png_voidp struct_ptr)
	67	{
	68	#ifdef PNG_USER_MEM_SUPPORTED
	69	png_destroy_struct_2(struct_ptr, png_free_ptr_NULL, png_voidp_NULL);
	70	}
	71
	72	/* Free memory allocated by a png_create_struct() call */
	73	void /* PRIVATE */
	74	png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
	75	png_voidp mem_ptr)
	76	{
	77	#endif
	78	if (struct_ptr != NULL)
	79	{
	80	#ifdef PNG_USER_MEM_SUPPORTED
	81	if(free_fn != NULL)
	82	{
	83	png_struct dummy_struct;
	84	png_structp png_ptr = &dummy_struct;
	85	png_ptr->mem_ptr=mem_ptr;
	86	(*(free_fn))(png_ptr, struct_ptr);
	87	return;
	88	}
	89	#endif /* PNG_USER_MEM_SUPPORTED */
	90	farfree (struct_ptr);
	91	}
	92	}
	93
	94	/* Allocate memory. For reasonable files, size should never exceed
	95	* 64K. However, zlib may allocate more then 64K if you don't tell
	96	* it not to. See zconf.h and png.h for more information. zlib does
	97	* need to allocate exactly 64K, so whatever you call here must
	98	* have the ability to do that.
	99	*
	100	* Borland seems to have a problem in DOS mode for exactly 64K.
	101	* It gives you a segment with an offset of 8 (perhaps to store its
	102	* memory stuff). zlib doesn't like this at all, so we have to
	103	* detect and deal with it. This code should not be needed in
	104	* Windows or OS/2 modes, and only in 16 bit mode. This code has
	105	* been updated by Alexander Lehmann for version 0.89 to waste less
	106	* memory.
	107	*
	108	* Note that we can't use png_size_t for the "size" declaration,
	109	* since on some systems a png_size_t is a 16-bit quantity, and as a
	110	* result, we would be truncating potentially larger memory requests
	111	* (which should cause a fatal error) and introducing major problems.
	112	*/
	113
	114	png_voidp PNGAPI
	115	png_malloc(png_structp png_ptr, png_uint_32 size)
	116	{
	117	png_voidp ret;
	118
	119	if (png_ptr == NULL \|\| size == 0)
	120	return (NULL);
	121
	122	#ifdef PNG_USER_MEM_SUPPORTED
	123	if(png_ptr->malloc_fn != NULL)
	124	{
	125	ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
	126	if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	127	png_error(png_ptr, "Out of memory!");
	128	return (ret);
	129	}
	130	else
	131	return png_malloc_default(png_ptr, size);
	132	}
	133
	134	png_voidp PNGAPI
	135	png_malloc_default(png_structp png_ptr, png_uint_32 size)
	136	{
	137	png_voidp ret;
	138	#endif /* PNG_USER_MEM_SUPPORTED */
	139
	140	#ifdef PNG_MAX_MALLOC_64K
	141	if (size > (png_uint_32)65536L)
	142	png_error(png_ptr, "Cannot Allocate > 64K");
	143	#endif
	144
	145	if (size == (png_uint_32)65536L)
	146	{
	147	if (png_ptr->offset_table == NULL)
	148	{
	149	/* try to see if we need to do any of this fancy stuff */
	150	ret = farmalloc(size);
	151	if (ret == NULL \|\| ((png_size_t)ret & 0xffff))
	152	{
	153	int num_blocks;
	154	png_uint_32 total_size;
	155	png_bytep table;
	156	int i;
	157	png_byte huge * hptr;
	158
	159	if (ret != NULL)
	160	{
	161	farfree(ret);
	162	ret = NULL;
	163	}
	164
	165	if(png_ptr->zlib_window_bits > 14)
	166	num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
	167	else
	168	num_blocks = 1;
	169	if (png_ptr->zlib_mem_level >= 7)
	170	num_blocks += (int)(1 << (png_ptr->zlib_mem_level - 7));
	171	else
	172	num_blocks++;
	173
	174	total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;
	175
	176	table = farmalloc(total_size);
	177
	178	if (table == NULL)
	179	{
	180	if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	181	png_error(png_ptr, "Out Of Memory."); /* Note "O" and "M" */
	182	else
	183	png_warning(png_ptr, "Out Of Memory.");
	184	return (NULL);
	185	}
	186
	187	if ((png_size_t)table & 0xfff0)
	188	{
	189	if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	190	png_error(png_ptr,
	191	"Farmalloc didn't return normalized pointer");
	192	else
	193	png_warning(png_ptr,
	194	"Farmalloc didn't return normalized pointer");
	195	return (NULL);
	196	}
	197
	198	png_ptr->offset_table = table;
	199	png_ptr->offset_table_ptr = farmalloc(num_blocks *
	200	sizeof (png_bytep));
	201
	202	if (png_ptr->offset_table_ptr == NULL)
	203	{
	204	if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	205	png_error(png_ptr, "Out Of memory."); /* Note "O" and "M" */
	206	else
	207	png_warning(png_ptr, "Out Of memory.");
	208	return (NULL);
	209	}
	210
	211	hptr = (png_byte huge *)table;
	212	if ((png_size_t)hptr & 0xf)
	213	{
	214	hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
	215	hptr = hptr + 16L; /* "hptr += 16L" fails on Turbo C++ 3.0 */
	216	}
	217	for (i = 0; i < num_blocks; i++)
	218	{
	219	png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
	220	hptr = hptr + (png_uint_32)65536L; /* "+=" fails on TC++3.0 */
	221	}
	222
	223	png_ptr->offset_table_number = num_blocks;
	224	png_ptr->offset_table_count = 0;
	225	png_ptr->offset_table_count_free = 0;
	226	}
	227	}
	228
	229	if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
	230	{
	231	if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	232	png_error(png_ptr, "Out of Memory."); /* Note "o" and "M" */
	233	else
	234	png_warning(png_ptr, "Out of Memory.");
	235	return (NULL);
	236	}
	237
	238	ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
	239	}
	240	else
	241	ret = farmalloc(size);
	242
	243	if (ret == NULL)
	244	{
	245	if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	246	png_error(png_ptr, "Out of memory."); /* Note "o" and "m" */
	247	else
	248	png_warning(png_ptr, "Out of memory."); /* Note "o" and "m" */
	249	}
	250
	251	return (ret);
	252	}
	253
	254	/* free a pointer allocated by png_malloc(). In the default
	255	configuration, png_ptr is not used, but is passed in case it
	256	is needed. If ptr is NULL, return without taking any action. */
	257	void PNGAPI
	258	png_free(png_structp png_ptr, png_voidp ptr)
	259	{
	260	if (png_ptr == NULL \|\| ptr == NULL)
	261	return;
	262
	263	#ifdef PNG_USER_MEM_SUPPORTED
	264	if (png_ptr->free_fn != NULL)
	265	{
	266	(*(png_ptr->free_fn))(png_ptr, ptr);
	267	return;
	268	}
	269	else png_free_default(png_ptr, ptr);
	270	}
	271
	272	void PNGAPI
	273	png_free_default(png_structp png_ptr, png_voidp ptr)
	274	{
	275	#endif /* PNG_USER_MEM_SUPPORTED */
	276
	277	if (png_ptr->offset_table != NULL)
	278	{
	279	int i;
	280
	281	for (i = 0; i < png_ptr->offset_table_count; i++)
	282	{
	283	if (ptr == png_ptr->offset_table_ptr[i])
	284	{
	285	ptr = NULL;
	286	png_ptr->offset_table_count_free++;
	287	break;
	288	}
	289	}
	290	if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
	291	{
	292	farfree(png_ptr->offset_table);
	293	farfree(png_ptr->offset_table_ptr);
	294	png_ptr->offset_table = NULL;
	295	png_ptr->offset_table_ptr = NULL;
	296	}
	297	}
	298
	299	if (ptr != NULL)
	300	{
	301	farfree(ptr);
	302	}
	303	}
	304
	305	#else /* Not the Borland DOS special memory handler */
	306
	307	/* Allocate memory for a png_struct or a png_info. The malloc and
	308	memset can be replaced by a single call to calloc() if this is thought
	309	to improve performance noticably. */
	310	png_voidp /* PRIVATE */
	311	png_create_struct(int type)
	312	{
	313	#ifdef PNG_USER_MEM_SUPPORTED
	314	return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
	315	}
	316
	317	/* Allocate memory for a png_struct or a png_info. The malloc and
	318	memset can be replaced by a single call to calloc() if this is thought
	319	to improve performance noticably. */
	320	png_voidp /* PRIVATE */
	321	png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
	322	{
	323	#endif /* PNG_USER_MEM_SUPPORTED */
	324	png_size_t size;
	325	png_voidp struct_ptr;
	326
	327	if (type == PNG_STRUCT_INFO)
	328	size = sizeof(png_info);
	329	else if (type == PNG_STRUCT_PNG)
	330	size = sizeof(png_struct);
	331	else
	332	return (NULL);
	333
	334	#ifdef PNG_USER_MEM_SUPPORTED
	335	if(malloc_fn != NULL)
	336	{
	337	png_struct dummy_struct;
	338	png_structp png_ptr = &dummy_struct;
	339	png_ptr->mem_ptr=mem_ptr;
	340	struct_ptr = (*(malloc_fn))(png_ptr, size);
	341	if (struct_ptr != NULL)
	342	png_memset(struct_ptr, 0, size);
	343	return (struct_ptr);
	344	}
	345	#endif /* PNG_USER_MEM_SUPPORTED */
	346
	347	#if defined(__TURBOC__) && !defined(__FLAT__)
	348	if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
	349	#else
	350	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	351	if ((struct_ptr = (png_voidp)halloc(size,1)) != NULL)
	352	# else
	353	if ((struct_ptr = (png_voidp)malloc(size)) != NULL)
	354	# endif
	355	#endif
	356	{
	357	png_memset(struct_ptr, 0, size);
	358	}
	359
	360	return (struct_ptr);
	361	}
	362
	363
	364	/* Free memory allocated by a png_create_struct() call */
	365	void /* PRIVATE */
	366	png_destroy_struct(png_voidp struct_ptr)
	367	{
	368	#ifdef PNG_USER_MEM_SUPPORTED
	369	png_destroy_struct_2(struct_ptr, png_free_ptr_NULL, png_voidp_NULL);
	370	}
	371
	372	/* Free memory allocated by a png_create_struct() call */
	373	void /* PRIVATE */
	374	png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
	375	png_voidp mem_ptr)
	376	{
	377	#endif /* PNG_USER_MEM_SUPPORTED */
	378	if (struct_ptr != NULL)
	379	{
	380	#ifdef PNG_USER_MEM_SUPPORTED
	381	if(free_fn != NULL)
	382	{
	383	png_struct dummy_struct;
	384	png_structp png_ptr = &dummy_struct;
	385	png_ptr->mem_ptr=mem_ptr;
	386	(*(free_fn))(png_ptr, struct_ptr);
	387	return;
	388	}
	389	#endif /* PNG_USER_MEM_SUPPORTED */
	390	#if defined(__TURBOC__) && !defined(__FLAT__)
	391	farfree(struct_ptr);
	392	#else
	393	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	394	hfree(struct_ptr);
	395	# else
	396	free(struct_ptr);
	397	# endif
	398	#endif
	399	}
	400	}
	401
	402	/* Allocate memory. For reasonable files, size should never exceed
	403	64K. However, zlib may allocate more then 64K if you don't tell
	404	it not to. See zconf.h and png.h for more information. zlib does
	405	need to allocate exactly 64K, so whatever you call here must
	406	have the ability to do that. */
	407
	408	png_voidp PNGAPI
	409	png_malloc(png_structp png_ptr, png_uint_32 size)
	410	{
	411	png_voidp ret;
	412
	413	if (png_ptr == NULL \|\| size == 0)
	414	return (NULL);
	415
	416	#ifdef PNG_USER_MEM_SUPPORTED
	417	if(png_ptr->malloc_fn != NULL)
	418	{
	419	ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
	420	if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	421	png_error(png_ptr, "Out of Memory!");
	422	return (ret);
	423	}
	424	else
	425	return (png_malloc_default(png_ptr, size));
	426	}
	427
	428	png_voidp PNGAPI
	429	png_malloc_default(png_structp png_ptr, png_uint_32 size)
	430	{
	431	png_voidp ret;
	432	#endif /* PNG_USER_MEM_SUPPORTED */
	433
	434	#ifdef PNG_MAX_MALLOC_64K
	435	if (size > (png_uint_32)65536L)
	436	{
	437	if(png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	438	png_error(png_ptr, "Cannot Allocate > 64K");
	439	else
	440	return NULL;
	441	}
	442	#endif
	443
	444	#if defined(__TURBOC__) && !defined(__FLAT__)
	445	ret = farmalloc(size);
	446	#else
	447	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	448	ret = halloc(size, 1);
	449	# else
	450	ret = malloc((size_t)size);
	451	# endif
	452	#endif
	453
	454	if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
	455	png_error(png_ptr, "Out of Memory");
	456
	457	return (ret);
	458	}
	459
	460	/* Free a pointer allocated by png_malloc(). If ptr is NULL, return
	461	without taking any action. */
	462	void PNGAPI
	463	png_free(png_structp png_ptr, png_voidp ptr)
	464	{
	465	if (png_ptr == NULL \|\| ptr == NULL)
	466	return;
	467
	468	#ifdef PNG_USER_MEM_SUPPORTED
	469	if (png_ptr->free_fn != NULL)
	470	{
	471	(*(png_ptr->free_fn))(png_ptr, ptr);
	472	return;
	473	}
	474	else png_free_default(png_ptr, ptr);
	475	}
	476	void PNGAPI
	477	png_free_default(png_structp png_ptr, png_voidp ptr)
	478	{
	479	if (png_ptr == NULL \|\| ptr == NULL)
	480	return;
	481
	482	#endif /* PNG_USER_MEM_SUPPORTED */
	483
	484	#if defined(__TURBOC__) && !defined(__FLAT__)
	485	farfree(ptr);
	486	#else
	487	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	488	hfree(ptr);
	489	# else
	490	free(ptr);
	491	# endif
	492	#endif
	493	}
	494
	495	#endif /* Not Borland DOS special memory handler */
	496
	497	#if defined(PNG_1_0_X)
	498	# define png_malloc_warn png_malloc
	499	#else
	500	/* This function was added at libpng version 1.2.3. The png_malloc_warn()
	501	* function will issue a png_warning and return NULL instead of issuing a
	502	* png_error, if it fails to allocate the requested memory.
	503	*/
	504	png_voidp PNGAPI
	505	png_malloc_warn(png_structp png_ptr, png_uint_32 size)
	506	{
	507	png_voidp ptr;
	508	png_uint_32 save_flags=png_ptr->flags;
	509
	510	png_ptr->flags\|=PNG_FLAG_MALLOC_NULL_MEM_OK;
	511	ptr = (png_voidp)png_malloc((png_structp)png_ptr, size);
	512	png_ptr->flags=save_flags;
	513	return(ptr);
	514	}
	515	#endif
	516
	517	png_voidp PNGAPI
	518	png_memcpy_check (png_structp png_ptr, png_voidp s1, png_voidp s2,
	519	png_uint_32 length)
	520	{
	521	png_size_t size;
	522
	523	size = (png_size_t)length;
	524	if ((png_uint_32)size != length)
	525	png_error(png_ptr,"Overflow in png_memcpy_check.");
	526
	527	return(png_memcpy (s1, s2, size));
	528	}
	529
	530	png_voidp PNGAPI
	531	png_memset_check (png_structp png_ptr, png_voidp s1, int value,
	532	png_uint_32 length)
	533	{
	534	png_size_t size;
	535
	536	size = (png_size_t)length;
	537	if ((png_uint_32)size != length)
	538	png_error(png_ptr,"Overflow in png_memset_check.");
	539
	540	return (png_memset (s1, value, size));
	541
	542	}
	543
	544	#ifdef PNG_USER_MEM_SUPPORTED
	545	/* This function is called when the application wants to use another method
	546	* of allocating and freeing memory.
	547	*/
	548	void PNGAPI
	549	png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
	550	malloc_fn, png_free_ptr free_fn)
	551	{
	552	png_ptr->mem_ptr = mem_ptr;
	553	png_ptr->malloc_fn = malloc_fn;
	554	png_ptr->free_fn = free_fn;
	555	}
	556
	557	/* This function returns a pointer to the mem_ptr associated with the user
	558	* functions. The application should free any memory associated with this
	559	* pointer before png_write_destroy and png_read_destroy are called.
	560	*/
	561	png_voidp PNGAPI
	562	png_get_mem_ptr(png_structp png_ptr)
	563	{
	564	return ((png_voidp)png_ptr->mem_ptr);
	565	}
	566	#endif /* PNG_USER_MEM_SUPPORTED */