amiga-clib2/library/stdlib_realloc.c

/*
 * $Id: stdlib_realloc.c,v 1.2 2004-12-24 18:31:38 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2004 by Olaf Barthel <olsen@sourcery.han.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _STDLIB_MEM_DEBUG_H
#include "stdlib_mem_debug.h"
#endif /* _STDLIB_MEM_DEBUG_H */

/****************************************************************************/

#ifndef _STDLIB_HEADERS_H
#include "stdlib_headers.h"
#endif /* _STDLIB_HEADERS_H */

/****************************************************************************/

#undef realloc

/****************************************************************************/

__static void *
__realloc(void *ptr,size_t size,const char * file,int line)
{
	void * result = NULL;

	ENTER();

	SHOWPOINTER(ptr);
	SHOWVALUE(size);

	assert( (int)size >= 0 );

	if(ptr == NULL)
	{
		D(("calling malloc(%ld)",size));

		result = __malloc(size,file,line);
	}
	else if (size == 0)
	{
		D(("calling free(0x%08lx)",ptr));

		__free(ptr,file,line);
	}
	else
	{
		struct MemoryNode * mn;
		BOOL reallocate;

		assert( ptr != NULL && size > 0 );

		/* Try to find the allocation in the list. */
		mn = __find_memory_node(ptr);

		#ifdef __MEM_DEBUG
		{
			/* If we managed to find the memory allocation,
			 * reallocate it.
			 */
			if(mn == NULL)
			{
				SHOWMSG("allocation not found");

				kprintf("[%s] %s:%ld:Address for realloc(0x%08lx,%ld) not known.\n",__program_name,file,line,ptr,size);

				/* Apparently, the address did not qualify for
				 * reallocation.
				 */
				errno = ENOMEM;
				goto out;
			}
		}
		#else
		{
			assert( mn != NULL );
		}
		#endif /* __MEM_DEBUG */

		if(mn == NULL || mn->mn_NeverFree)
		{
			SHOWMSG("cannot free this chunk");

			errno = ENOMEM;
			goto out;
		}

		/* Don't do anything unless the size of the allocation has really
		 * changed.
		 */
		#if defined(__MEM_DEBUG)
		{
			reallocate = (mn->mn_Size != size);
		}
		#else
		{
			if(size > mn->mn_Size)
			{
				/* Allocation size should grow. */
				reallocate = TRUE;
			}
			else
			{
				size_t rounded_allocation_size;

				/* Round the total allocation size to the operating system
				 * granularity.
				 */
				rounded_allocation_size = __get_allocation_size(size);

				assert( rounded_allocation_size >= size );

				/* Optimization: If the block size shrinks by less than half the
				 *               original allocation size, do not reallocate the
				 *               block and do not copy over the contents of the old
				 *               allocation. We also take into account that the
				 *               actual size of the allocation is affected by a
				 *               certain operating system imposed granularity.
				 */
				reallocate = (rounded_allocation_size < mn->mn_Size && rounded_allocation_size <= mn->mn_Size / 2);
			}
		}
		#endif /* __MEM_DEBUG */

		if(reallocate)
		{
			void * new_ptr;

			D(("realloc() size has changed; old=%ld, new=%ld",mn->mn_Size,size));

			/* We allocate the new memory chunk before we
			   attempt to replace the old. */
			new_ptr = __malloc(size,file,line);
			if(new_ptr == NULL)
			{
				SHOWMSG("could not reallocate memory");

				errno = ENOMEM;
				goto out;
			}

			/* Copy the contents of the old allocation to the new buffer. */
			if(size > mn->mn_Size)
				size = mn->mn_Size;

			memmove(new_ptr,ptr,size);

			/* Free the old allocation. Since we already know which memory
			   node is associated with it, we don't call __free() here. */
			__free_memory_node(mn,file,line);

			result = new_ptr;
		}
		else
		{
			D(("size didn't actually change that much (%ld -> %ld); returning memory block as is.",mn->mn_Size,size));

			/* No change in size. */
			result = ptr;
		}
	}

 out:

	if(result == NULL)
		SHOWMSG("ouch! realloc failed");

	RETURN(result);
	return(result);
}

/****************************************************************************/

#if NOT defined(__MEM_DEBUG)

/****************************************************************************/

void *
realloc(void *ptr,size_t size)
{
	void * result;

	result = __realloc(ptr,size,NULL,0);

	return(result);
}

/****************************************************************************/

#endif /* __MEM_DEBUG */