src/png/pngmem.c


/* pngmem.c - stub functions for memory allocation
 *
 * libpng 1.0.3 - January 14, 1999
 * For conditions of distribution and use, see copyright notice in png.h
 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
 * Copyright (c) 1996, 1997 Andreas Dilger
 * Copyright (c) 1998, 1999 Glenn Randers-Pehrson
 *
 * 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
png_create_struct(int type)
{
#ifdef PNG_USER_MEM_SUPPORTED
   return (png_create_struct_2(type, NULL));
}

/* Alternate version of png_create_struct, for use with user-defined malloc. */
png_voidp
png_create_struct_2(int type, png_malloc_ptr malloc_fn)
{
#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_voidp)NULL);

#ifdef PNG_USER_MEM_SUPPORTED
   if(malloc_fn != NULL)
   {
      if ((struct_ptr = (*(malloc_fn))(NULL, size)) != NULL)
         png_memset(struct_ptr, 0, size);
         return (struct_ptr);
   }
#endif /* PNG_USER_MEM_SUPPORTED */
   if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
   {
      png_memset(struct_ptr, 0, size);
   }
   return (struct_ptr);
}


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

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

/* 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
png_malloc(png_structp png_ptr, png_uint_32 size)
{
#ifndef PNG_USER_MEM_SUPPORTED
   png_voidp ret;
#endif
   if (png_ptr == NULL || size == 0)
      return ((png_voidp)NULL);

#ifdef PNG_USER_MEM_SUPPORTED
   if(png_ptr->malloc_fn != NULL)
       return ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, size));
   else
       return png_malloc_default(png_ptr, size);
}

png_voidp
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;
            }

            num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
            if (num_blocks < 1)
               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)
            {
               png_error(png_ptr, "Out Of Memory."); /* Note "O" and "M" */
            }

            if ((png_size_t)table & 0xfff0)
            {
               png_error(png_ptr, "Farmalloc didn't return normalized pointer");
            }

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

            if (png_ptr->offset_table_ptr == NULL)
            {
               png_error(png_ptr, "Out Of memory.");
            }

            hptr = (png_byte huge *)table;
            if ((png_size_t)hptr & 0xf)
            {
               hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
               hptr += 16L;
            }
            for (i = 0; i < num_blocks; i++)
            {
               png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
               hptr += (png_uint_32)65536L;
            }

            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)
         png_error(png_ptr, "Out of Memory.");

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

   if (ret == NULL)
   {
      png_error(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
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);
      ptr = NULL;
      return;
   }
   else png_free_default(png_ptr, ptr);
}

void
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);
      ptr = NULL;
   }
}

#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
png_create_struct(int type)
{
#ifdef PNG_USER_MEM_SUPPORTED
   return (png_create_struct_2(type, 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
png_create_struct_2(int type, png_malloc_ptr malloc_fn)
{
#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_voidp)NULL);

#ifdef PNG_USER_MEM_SUPPORTED
   if(malloc_fn != NULL)
   {
      if ((struct_ptr = (*(malloc_fn))(NULL, size)) != 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
png_destroy_struct(png_voidp struct_ptr)
{
#ifdef PNG_USER_MEM_SUPPORTED
   png_destroy_struct_2(struct_ptr, (png_free_ptr)NULL);
}

/* Free memory allocated by a png_create_struct() call */
void
png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn)
{
#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;
         (*(free_fn))(png_ptr, struct_ptr);
         struct_ptr = NULL;
         return;
      }
#endif /* PNG_USER_MEM_SUPPORTED */
#if defined(__TURBOC__) && !defined(__FLAT__)
      farfree(struct_ptr);
      struct_ptr = NULL;
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
      hfree(struct_ptr);
      struct_ptr = NULL;
# else
      free(struct_ptr);
      struct_ptr = NULL;
# 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
png_malloc(png_structp png_ptr, png_uint_32 size)
{
#ifndef PNG_USER_MEM_SUPPORTED
   png_voidp ret;
#endif
   if (png_ptr == NULL || size == 0)
      return ((png_voidp)NULL);

#ifdef PNG_USER_MEM_SUPPORTED
   if(png_ptr->malloc_fn != NULL)
       return ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, size));
   else
       return (png_malloc_default(png_ptr, size));
}
png_voidp
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 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_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
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);
      ptr = NULL;
      return;
   }
   else png_free_default(png_ptr, ptr);
}
void
png_free_default(png_structp png_ptr, png_voidp ptr)
{
#endif /* PNG_USER_MEM_SUPPORTED */

#if defined(__TURBOC__) && !defined(__FLAT__)
   farfree(ptr);
   ptr = NULL;
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
   hfree(ptr);
   ptr = NULL;
# else
   free(ptr);
   ptr = NULL;
# endif
#endif
}

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

png_voidp
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
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
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
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 1.0.3 - January 14, 1999
	5	* For conditions of distribution and use, see copyright notice in png.h
	6	* Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
	7	* Copyright (c) 1996, 1997 Andreas Dilger
	8	* Copyright (c) 1998, 1999 Glenn Randers-Pehrson
	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
	27	png_create_struct(int type)
	28	{
	29	#ifdef PNG_USER_MEM_SUPPORTED
	30	return (png_create_struct_2(type, NULL));
	31	}
	32
	33	/* Alternate version of png_create_struct, for use with user-defined malloc. */
	34	png_voidp
	35	png_create_struct_2(int type, png_malloc_ptr malloc_fn)
	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_voidp)NULL);
	47
	48	#ifdef PNG_USER_MEM_SUPPORTED
	49	if(malloc_fn != NULL)
	50	{
	51	if ((struct_ptr = (*(malloc_fn))(NULL, size)) != NULL)
	52	png_memset(struct_ptr, 0, size);
	53	return (struct_ptr);
	54	}
	55	#endif /* PNG_USER_MEM_SUPPORTED */
	56	if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
	57	{
	58	png_memset(struct_ptr, 0, size);
	59	}
	60	return (struct_ptr);
	61	}
	62
	63
	64	/* Free memory allocated by a png_create_struct() call */
	65	void
	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);
	70	}
	71
	72	/* Free memory allocated by a png_create_struct() call */
	73	void
	74	png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn)
	75	{
	76	#endif
	77	if (struct_ptr != NULL)
	78	{
	79	#ifdef PNG_USER_MEM_SUPPORTED
	80	if(free_fn != NULL)
	81	{
	82	png_struct dummy_struct;
	83	png_structp png_ptr = &dummy_struct;
	84	(*(free_fn))(png_ptr, struct_ptr);
	85	struct_ptr = NULL;
	86	return;
	87	}
	88	#endif /* PNG_USER_MEM_SUPPORTED */
	89	farfree (struct_ptr);
	90	struct_ptr = NULL;
	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	png_voidp
	114	png_malloc(png_structp png_ptr, png_uint_32 size)
	115	{
	116	#ifndef PNG_USER_MEM_SUPPORTED
	117	png_voidp ret;
	118	#endif
	119	if (png_ptr == NULL \|\| size == 0)
	120	return ((png_voidp)NULL);
	121
	122	#ifdef PNG_USER_MEM_SUPPORTED
	123	if(png_ptr->malloc_fn != NULL)
	124	return ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, size));
	125	else
	126	return png_malloc_default(png_ptr, size);
	127	}
	128
	129	png_voidp
	130	png_malloc_default(png_structp png_ptr, png_uint_32 size)
	131	{
	132	png_voidp ret;
	133	#endif /* PNG_USER_MEM_SUPPORTED */
	134
	135	#ifdef PNG_MAX_MALLOC_64K
	136	if (size > (png_uint_32)65536L)
	137	png_error(png_ptr, "Cannot Allocate > 64K");
	138	#endif
	139
	140	if (size == (png_uint_32)65536L)
	141	{
	142	if (png_ptr->offset_table == NULL)
	143	{
	144	/* try to see if we need to do any of this fancy stuff */
	145	ret = farmalloc(size);
	146	if (ret == NULL \|\| ((png_size_t)ret & 0xffff))
	147	{
	148	int num_blocks;
	149	png_uint_32 total_size;
	150	png_bytep table;
	151	int i;
	152	png_byte huge * hptr;
	153
	154	if (ret != NULL)
	155	{
	156	farfree(ret);
	157	ret = NULL;
	158	}
	159
	160	num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
	161	if (num_blocks < 1)
	162	num_blocks = 1;
	163	if (png_ptr->zlib_mem_level >= 7)
	164	num_blocks += (int)(1 << (png_ptr->zlib_mem_level - 7));
	165	else
	166	num_blocks++;
	167
	168	total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;
	169
	170	table = farmalloc(total_size);
	171
	172	if (table == NULL)
	173	{
	174	png_error(png_ptr, "Out Of Memory."); /* Note "O" and "M" */
	175	}
	176
	177	if ((png_size_t)table & 0xfff0)
	178	{
	179	png_error(png_ptr, "Farmalloc didn't return normalized pointer");
	180	}
	181
	182	png_ptr->offset_table = table;
	183	png_ptr->offset_table_ptr = farmalloc(num_blocks *
	184	sizeof (png_bytep));
	185
	186	if (png_ptr->offset_table_ptr == NULL)
	187	{
	188	png_error(png_ptr, "Out Of memory.");
	189	}
	190
	191	hptr = (png_byte huge *)table;
	192	if ((png_size_t)hptr & 0xf)
	193	{
	194	hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
	195	hptr += 16L;
	196	}
	197	for (i = 0; i < num_blocks; i++)
	198	{
	199	png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
	200	hptr += (png_uint_32)65536L;
	201	}
	202
	203	png_ptr->offset_table_number = num_blocks;
	204	png_ptr->offset_table_count = 0;
	205	png_ptr->offset_table_count_free = 0;
	206	}
	207	}
	208
	209	if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
	210	png_error(png_ptr, "Out of Memory.");
	211
	212	ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
	213	}
	214	else
	215	ret = farmalloc(size);
	216
	217	if (ret == NULL)
	218	{
	219	png_error(png_ptr, "Out of memory."); /* Note "o" and "m" */
	220	}
	221
	222	return (ret);
	223	}
	224
	225	/* free a pointer allocated by png_malloc(). In the default
	226	configuration, png_ptr is not used, but is passed in case it
	227	is needed. If ptr is NULL, return without taking any action. */
	228	void
	229	png_free(png_structp png_ptr, png_voidp ptr)
	230	{
	231	if (png_ptr == NULL \|\| ptr == NULL)
	232	return;
	233
	234	#ifdef PNG_USER_MEM_SUPPORTED
	235	if (png_ptr->free_fn != NULL)
	236	{
	237	(*(png_ptr->free_fn))(png_ptr, ptr);
	238	ptr = NULL;
	239	return;
	240	}
	241	else png_free_default(png_ptr, ptr);
	242	}
	243
	244	void
	245	png_free_default(png_structp png_ptr, png_voidp ptr)
	246	{
	247	#endif /* PNG_USER_MEM_SUPPORTED */
	248
	249	if (png_ptr->offset_table != NULL)
	250	{
	251	int i;
	252
	253	for (i = 0; i < png_ptr->offset_table_count; i++)
	254	{
	255	if (ptr == png_ptr->offset_table_ptr[i])
	256	{
	257	ptr = NULL;
	258	png_ptr->offset_table_count_free++;
	259	break;
	260	}
	261	}
	262	if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
	263	{
	264	farfree(png_ptr->offset_table);
	265	farfree(png_ptr->offset_table_ptr);
	266	png_ptr->offset_table = NULL;
	267	png_ptr->offset_table_ptr = NULL;
	268	}
	269	}
	270
	271	if (ptr != NULL)
	272	{
	273	farfree(ptr);
	274	ptr = NULL;
	275	}
	276	}
	277
	278	#else /* Not the Borland DOS special memory handler */
	279
	280	/* Allocate memory for a png_struct or a png_info. The malloc and
	281	memset can be replaced by a single call to calloc() if this is thought
	282	to improve performance noticably.*/
	283	png_voidp
	284	png_create_struct(int type)
	285	{
	286	#ifdef PNG_USER_MEM_SUPPORTED
	287	return (png_create_struct_2(type, NULL));
	288	}
	289
	290	/* Allocate memory for a png_struct or a png_info. The malloc and
	291	memset can be replaced by a single call to calloc() if this is thought
	292	to improve performance noticably.*/
	293	png_voidp
	294	png_create_struct_2(int type, png_malloc_ptr malloc_fn)
	295	{
	296	#endif /* PNG_USER_MEM_SUPPORTED */
	297	png_size_t size;
	298	png_voidp struct_ptr;
	299
	300	if (type == PNG_STRUCT_INFO)
	301	size = sizeof(png_info);
	302	else if (type == PNG_STRUCT_PNG)
	303	size = sizeof(png_struct);
	304	else
	305	return ((png_voidp)NULL);
	306
	307	#ifdef PNG_USER_MEM_SUPPORTED
	308	if(malloc_fn != NULL)
	309	{
	310	if ((struct_ptr = (*(malloc_fn))(NULL, size)) != NULL)
	311	png_memset(struct_ptr, 0, size);
	312	return (struct_ptr);
	313	}
	314	#endif /* PNG_USER_MEM_SUPPORTED */
	315
	316	#if defined(__TURBOC__) && !defined(__FLAT__)
	317	if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
	318	#else
	319	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	320	if ((struct_ptr = (png_voidp)halloc(size,1)) != NULL)
	321	# else
	322	if ((struct_ptr = (png_voidp)malloc(size)) != NULL)
	323	# endif
	324	#endif
	325	{
	326	png_memset(struct_ptr, 0, size);
	327	}
	328
	329	return (struct_ptr);
	330	}
	331
	332
	333	/* Free memory allocated by a png_create_struct() call */
	334	void
	335	png_destroy_struct(png_voidp struct_ptr)
	336	{
	337	#ifdef PNG_USER_MEM_SUPPORTED
	338	png_destroy_struct_2(struct_ptr, (png_free_ptr)NULL);
	339	}
	340
	341	/* Free memory allocated by a png_create_struct() call */
	342	void
	343	png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn)
	344	{
	345	#endif /* PNG_USER_MEM_SUPPORTED */
	346	if (struct_ptr != NULL)
	347	{
	348	#ifdef PNG_USER_MEM_SUPPORTED
	349	if(free_fn != NULL)
	350	{
	351	png_struct dummy_struct;
	352	png_structp png_ptr = &dummy_struct;
	353	(*(free_fn))(png_ptr, struct_ptr);
	354	struct_ptr = NULL;
	355	return;
	356	}
	357	#endif /* PNG_USER_MEM_SUPPORTED */
	358	#if defined(__TURBOC__) && !defined(__FLAT__)
	359	farfree(struct_ptr);
	360	struct_ptr = NULL;
	361	#else
	362	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	363	hfree(struct_ptr);
	364	struct_ptr = NULL;
	365	# else
	366	free(struct_ptr);
	367	struct_ptr = NULL;
	368	# endif
	369	#endif
	370	}
	371	}
	372
	373
	374	/* Allocate memory. For reasonable files, size should never exceed
	375	64K. However, zlib may allocate more then 64K if you don't tell
	376	it not to. See zconf.h and png.h for more information. zlib does
	377	need to allocate exactly 64K, so whatever you call here must
	378	have the ability to do that. */
	379
	380	png_voidp
	381	png_malloc(png_structp png_ptr, png_uint_32 size)
	382	{
	383	#ifndef PNG_USER_MEM_SUPPORTED
	384	png_voidp ret;
	385	#endif
	386	if (png_ptr == NULL \|\| size == 0)
	387	return ((png_voidp)NULL);
	388
	389	#ifdef PNG_USER_MEM_SUPPORTED
	390	if(png_ptr->malloc_fn != NULL)
	391	return ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, size));
	392	else
	393	return (png_malloc_default(png_ptr, size));
	394	}
	395	png_voidp
	396	png_malloc_default(png_structp png_ptr, png_uint_32 size)
	397	{
	398	png_voidp ret;
	399	#endif /* PNG_USER_MEM_SUPPORTED */
	400
	401	#ifdef PNG_MAX_MALLOC_64K
	402	if (size > (png_uint_32)65536L)
	403	png_error(png_ptr, "Cannot Allocate > 64K");
	404	#endif
	405
	406	#if defined(__TURBOC__) && !defined(__FLAT__)
	407	ret = farmalloc(size);
	408	#else
	409	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	410	ret = halloc(size, 1);
	411	# else
	412	ret = malloc((size_t)size);
	413	# endif
	414	#endif
	415
	416	if (ret == NULL)
	417	{
	418	png_error(png_ptr, "Out of Memory");
	419	}
	420
	421	return (ret);
	422	}
	423
	424	/* Free a pointer allocated by png_malloc(). If ptr is NULL, return
	425	without taking any action. */
	426	void
	427	png_free(png_structp png_ptr, png_voidp ptr)
	428	{
	429	if (png_ptr == NULL \|\| ptr == NULL)
	430	return;
	431
	432	#ifdef PNG_USER_MEM_SUPPORTED
	433	if (png_ptr->free_fn != NULL)
	434	{
	435	(*(png_ptr->free_fn))(png_ptr, ptr);
	436	ptr = NULL;
	437	return;
	438	}
	439	else png_free_default(png_ptr, ptr);
	440	}
	441	void
	442	png_free_default(png_structp png_ptr, png_voidp ptr)
	443	{
	444	#endif /* PNG_USER_MEM_SUPPORTED */
	445
	446	#if defined(__TURBOC__) && !defined(__FLAT__)
	447	farfree(ptr);
	448	ptr = NULL;
	449	#else
	450	# if defined(_MSC_VER) && defined(MAXSEG_64K)
	451	hfree(ptr);
	452	ptr = NULL;
	453	# else
	454	free(ptr);
	455	ptr = NULL;
	456	# endif
	457	#endif
	458	}
	459
	460	#endif /* Not Borland DOS special memory handler */
	461
	462	png_voidp
	463	png_memcpy_check (png_structp png_ptr, png_voidp s1, png_voidp s2,
	464	png_uint_32 length)
	465	{
	466	png_size_t size;
	467
	468	size = (png_size_t)length;
	469	if ((png_uint_32)size != length)
	470	png_error(png_ptr,"Overflow in png_memcpy_check.");
	471
	472	return(png_memcpy (s1, s2, size));
	473	}
	474
	475	png_voidp
	476	png_memset_check (png_structp png_ptr, png_voidp s1, int value,
	477	png_uint_32 length)
	478	{
	479	png_size_t size;
	480
	481	size = (png_size_t)length;
	482	if ((png_uint_32)size != length)
	483	png_error(png_ptr,"Overflow in png_memset_check.");
	484
	485	return (png_memset (s1, value, size));
	486
	487	}
	488
	489	#ifdef PNG_USER_MEM_SUPPORTED
	490	/* This function is called when the application wants to use another method
	491	* of allocating and freeing memory.
	492	*/
	493	void
	494	png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
	495	malloc_fn, png_free_ptr free_fn)
	496	{
	497	png_ptr->mem_ptr = mem_ptr;
	498	png_ptr->malloc_fn = malloc_fn;
	499	png_ptr->free_fn = free_fn;
	500	}
	501
	502	/* This function returns a pointer to the mem_ptr associated with the user
	503	* functions. The application should free any memory associated with this
	504	* pointer before png_write_destroy and png_read_destroy are called.
	505	*/
	506	png_voidp
	507	png_get_mem_ptr(png_structp png_ptr)
	508	{
	509	return ((png_voidp)png_ptr->mem_ptr);
	510	}
	511	#endif /* PNG_USER_MEM_SUPPORTED */