library/memory_buffer_alloc.c - mirror/mbed-tls - TrustedFirmware Git Browser

 /*
  *  Buffer-based memory allocator
  *
  *  Copyright (C) 2006-2013, Brainspark B.V.
  *
  *  This file is part of PolarSSL (http://www.polarssl.org)
  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
  *
  *  All rights reserved.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License along
  *  with this program; if not, write to the Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */

 #include "polarssl/config.h"

 #if defined(POLARSSL_MEMORY_C) && defined(POLARSSL_MEMORY_BUFFER_ALLOC_C)

 #include "polarssl/memory.h"

 #include <string.h>

 #if defined(POLARSSL_MEMORY_DEBUG)
 #include <stdio.h>
 #if defined(POLARSSL_MEMORY_BACKTRACE)
 #include <execinfo.h>
 #endif
 #endif

 #define MAGIC1       0xFF00AA55
 #define MAGIC2       0xEE119966
 #define MAX_BT 20

 typedef struct _memory_header memory_header;
 struct _memory_header
 {
     size_t          magic1;
     size_t          size;
     size_t          alloc;
     memory_header   *prev;
     memory_header   *next;
     memory_header   *prev_free;
     memory_header   *next_free;
 #if defined(POLARSSL_MEMORY_BACKTRACE)
     char            **trace;
     size_t          trace_count;
 #endif
     size_t          magic2;
 };

 typedef struct
 {
     unsigned char   *buf;
     size_t          len;
     memory_header   *first;
     memory_header   *first_free;
     size_t          current_alloc_size;
     int             verify;
 #if defined(POLARSSL_MEMORY_DEBUG)
     size_t          malloc_count;
     size_t          free_count;
     size_t          total_used;
     size_t          maximum_used;
     size_t          header_count;
 #endif
 }
 buffer_alloc_ctx;

 static buffer_alloc_ctx heap;

 #if defined(POLARSSL_MEMORY_DEBUG)
 static void debug_header( memory_header *hdr )
 {
 #if defined(POLARSSL_MEMORY_BACKTRACE)
     size_t i;
 #endif

     fprintf( stderr, "HDR:  PTR(%10u), PREV(%10u), NEXT(%10u), ALLOC(%u), SIZE(%10u)\n",
             (size_t) hdr, (size_t) hdr->prev, (size_t) hdr->next,
             hdr->alloc, hdr->size );
     fprintf( stderr, "      FPREV(%10u), FNEXT(%10u)\n",
             (size_t) hdr->prev_free, (size_t) hdr->next_free );

 #if defined(POLARSSL_MEMORY_BACKTRACE)
     fprintf( stderr, "TRACE: \n" );
     for( i = 0; i < hdr->trace_count; i++ )
         fprintf( stderr, "%s\n", hdr->trace[i] );
     fprintf( stderr, "\n" );
 #endif
 }

 static void debug_chain()
 {
     memory_header *cur = heap.first;

     fprintf( stderr, "\nBlock list\n" );
     while( cur != NULL )
     {
         debug_header( cur );
         cur = cur->next;
     }

     fprintf( stderr, "Free list\n" );
     cur = heap.first_free;

     while( cur != NULL )
     {
         debug_header( cur );
         cur = cur->next_free;
     }
 }
 #endif /* POLARSSL_MEMORY_DEBUG */

 static int verify_header( memory_header *hdr )
 {
     if( hdr->magic1 != MAGIC1 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: MAGIC1 mismatch\n" );
 #endif
         return( 1 );
     }

     if( hdr->magic2 != MAGIC2 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: MAGIC2 mismatch\n" );
 #endif
         return( 1 );
     }

     if( hdr->alloc > 1 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: alloc has illegal value\n" );
 #endif
         return( 1 );
     }

     if( hdr->prev != NULL && hdr->prev == hdr->next )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: prev == next\n" );
 #endif
         return( 1 );
     }

     if( hdr->prev_free != NULL && hdr->prev_free == hdr->next_free )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: prev_free == next_free\n" );
 #endif
         return( 1 );
     }

     return( 0 );
 }

 static int verify_chain()
 {
     memory_header *prv = heap.first, *cur = heap.first->next;

     if( verify_header( heap.first ) != 0 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: verification of first header failed\n" );
 #endif
         return( 1 );
     }

     if( heap.first->prev != NULL )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: verification failed: first->prev != NULL\n" );
 #endif
         return( 1 );
     }

     while( cur != NULL )
     {
         if( verify_header( cur ) != 0 )
         {
 #if defined(POLARSSL_MEMORY_DEBUG)
             fprintf( stderr, "FATAL: verification of header failed\n" );
 #endif
             return( 1 );
         }

         if( cur->prev != prv )
         {
 #if defined(POLARSSL_MEMORY_DEBUG)
             fprintf( stderr, "FATAL: verification failed: cur->prev != prv\n" );
 #endif
             return( 1 );
         }

         prv = cur;
         cur = cur->next;
     }

     return( 0 );
 }

 static void *buffer_alloc_malloc( size_t len )
 {
     memory_header *new, *cur = heap.first_free;
     unsigned char *p;
 #if defined(POLARSSL_MEMORY_BACKTRACE)
     void *trace_buffer[MAX_BT];
     size_t trace_cnt;
 #endif

     if( heap.buf == NULL || heap.first == NULL )
         return( NULL );

     if( len % POLARSSL_MEMORY_ALIGN_MULTIPLE )
     {
         len -= len % POLARSSL_MEMORY_ALIGN_MULTIPLE;
         len += POLARSSL_MEMORY_ALIGN_MULTIPLE;
     }

     // Find block that fits
     //
     while( cur != NULL )
     {
         if( cur->size >= len )
             break;

         cur = cur->next_free;
     }

     if( cur == NULL )
         return( NULL );

     if( cur->alloc != 0 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: block in free_list but allocated data\n" );
 #endif
         exit( 1 );
     }

 #if defined(POLARSSL_MEMORY_DEBUG)
     heap.malloc_count++;
 #endif

     // Found location, split block if > memory_header + 4 room left
     //
     if( cur->size - len < sizeof(memory_header) + POLARSSL_MEMORY_ALIGN_MULTIPLE )
     {
         cur->alloc = 1;

         // Remove from free_list
         //
         if( cur->prev_free != NULL )
             cur->prev_free->next_free = cur->next_free;
         else
             heap.first_free = cur->next_free;

         if( cur->next_free != NULL )
             cur->next_free->prev_free = cur->prev_free;

         cur->prev_free = NULL;
         cur->next_free = NULL;

 #if defined(POLARSSL_MEMORY_DEBUG)
         heap.total_used += cur->size;
         if( heap.total_used > heap.maximum_used)
             heap.maximum_used = heap.total_used;
 #endif
 #if defined(POLARSSL_MEMORY_BACKTRACE)
         trace_cnt = backtrace( trace_buffer, MAX_BT );
         cur->trace = backtrace_symbols( trace_buffer, trace_cnt );
         cur->trace_count = trace_cnt;
 #endif

         if( ( heap.verify & MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 )
             exit( 1 );

         return ( (unsigned char *) cur ) + sizeof(memory_header);
     }

     p = ( (unsigned char *) cur ) + sizeof(memory_header) + len;
     new = (memory_header *) p;

     new->size = cur->size - len - sizeof(memory_header);
     new->alloc = 0;
     new->prev = cur;
     new->next = cur->next;
 #if defined(POLARSSL_MEMORY_BACKTRACE)
     new->trace = NULL;
     new->trace_count = 0;
 #endif
     new->magic1 = MAGIC1;
     new->magic2 = MAGIC2;

     if( new->next != NULL )
         new->next->prev = new;

     // Replace cur with new in free_list
     //
     new->prev_free = cur->prev_free;
     new->next_free = cur->next_free;
     if( new->prev_free != NULL )
         new->prev_free->next_free = new;
     else
         heap.first_free = new;

     if( new->next_free != NULL )
         new->next_free->prev_free = new;

     cur->alloc = 1;
     cur->size = len;
     cur->next = new;
     cur->prev_free = NULL;
     cur->next_free = NULL;

 #if defined(POLARSSL_MEMORY_DEBUG)
     heap.header_count++;
     heap.total_used += cur->size;
     if( heap.total_used > heap.maximum_used)
         heap.maximum_used = heap.total_used;
 #endif
 #if defined(POLARSSL_MEMORY_BACKTRACE)
     trace_cnt = backtrace( trace_buffer, MAX_BT );
     cur->trace = backtrace_symbols( trace_buffer, trace_cnt );
     cur->trace_count = trace_cnt;
 #endif

     if( ( heap.verify & MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 )
         exit( 1 );

     return ( (unsigned char *) cur ) + sizeof(memory_header);
 }

 static void buffer_alloc_free( void *ptr )
 {
     memory_header *hdr, *old = NULL;
     unsigned char *p = (unsigned char *) ptr;


     if( ptr == NULL || heap.buf == NULL || heap.first == NULL )
         return;

     if( p < heap.buf || p > heap.buf + heap.len )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: polarssl_free() outside of managed space\n" );
 #endif
         exit( 1 );
     }

     p -= sizeof(memory_header);
     hdr = (memory_header *) p;

     if( verify_header( hdr ) != 0 )
         exit( 1 );

     if( hdr->alloc != 1 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         fprintf( stderr, "FATAL: polarssl_free() on unallocated data\n" );
 #endif
         exit( 1 );
     }

     hdr->alloc = 0;

 #if defined(POLARSSL_MEMORY_DEBUG)
     heap.free_count++;
     heap.total_used -= hdr->size;
 #endif

     // Regroup with block before
     //
     if( hdr->prev != NULL && hdr->prev->alloc == 0 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         heap.header_count--;
 #endif
         hdr->prev->size += sizeof(memory_header) + hdr->size;
         hdr->prev->next = hdr->next;
         old = hdr;
         hdr = hdr->prev;

         if( hdr->next != NULL )
             hdr->next->prev = hdr;

 #if defined(POLARSSL_MEMORY_BACKTRACE)
         free( old->trace );
 #endif
         memset( old, 0, sizeof(memory_header) );
     }

     // Regroup with block after
     //
     if( hdr->next != NULL && hdr->next->alloc == 0 )
     {
 #if defined(POLARSSL_MEMORY_DEBUG)
         heap.header_count--;
 #endif
         hdr->size += sizeof(memory_header) + hdr->next->size;
         old = hdr->next;
         hdr->next = hdr->next->next;

         if( hdr->prev_free != NULL || hdr->next_free != NULL )
         {
             if( hdr->prev_free != NULL )
                 hdr->prev_free->next_free = hdr->next_free;
             else
                 heap.first_free = hdr->next_free;

             if( hdr->next_free != NULL )
                 hdr->next_free->prev_free = hdr->prev_free;
         }

         hdr->prev_free = old->prev_free;
         hdr->next_free = old->next_free;

         if( hdr->prev_free != NULL )
             hdr->prev_free->next_free = hdr;
         else
             heap.first_free = hdr;

         if( hdr->next_free != NULL )
             hdr->next_free->prev_free = hdr;

         if( hdr->next != NULL )
             hdr->next->prev = hdr;

 #if defined(POLARSSL_MEMORY_BACKTRACE)
         free( old->trace );
 #endif
         memset( old, 0, sizeof(memory_header) );
     }

     // Prepend to free_list if we have not merged
     // (Does not have to stay in same order as prev / next list)
     //
     if( old == NULL )
     {
         hdr->next_free = heap.first_free;
         heap.first_free->prev_free = hdr;
         heap.first_free = hdr;
     }

 #if defined(POLARSSL_MEMORY_BACKTRACE)
     hdr->trace = NULL;
     hdr->trace_count = 0;
 #endif

     if( ( heap.verify & MEMORY_VERIFY_FREE ) && verify_chain() != 0 )
         exit( 1 );
 }

 int memory_buffer_alloc_verify()
 {
     return verify_chain();
 }

 #if defined(POLARSSL_MEMORY_DEBUG)
 void memory_buffer_alloc_status()
 {
     fprintf( stderr,
              "Current use: %u blocks / %u bytes, max: %u bytes, malloc / free: %u / %u\n",
              heap.header_count, heap.total_used, heap.maximum_used,
              heap.malloc_count, heap.free_count );

     if( heap.first->next == NULL )
         fprintf( stderr, "All memory de-allocated in stack buffer\n" );
     else
     {
         fprintf( stderr, "Memory currently allocated:\n" );
         debug_chain();
     }
 }
 #endif /* POLARSSL_MEMORY_BUFFER_ALLOC_DEBUG */

 int memory_buffer_alloc_init( unsigned char *buf, size_t len )
 {
     polarssl_malloc = buffer_alloc_malloc;
     polarssl_free = buffer_alloc_free;

     memset( &heap, 0, sizeof(buffer_alloc_ctx) );
     memset( buf, 0, len );

     heap.buf = buf;
     heap.len = len;

     heap.first = (memory_header *) buf;
     heap.first->size = len - sizeof(memory_header);
     heap.first->magic1 = MAGIC1;
     heap.first->magic2 = MAGIC2;
     heap.first_free = heap.first;
     return( 0 );
 }

 #endif /* POLARSSL_MEMORY_C && POLARSSL_MEMORY_BUFFER_ALLOC_C */
	/*
	* Buffer-based memory allocator
	*
	* Copyright (C) 2006-2013, Brainspark B.V.
	*
	* This file is part of PolarSSL (http://www.polarssl.org)
	* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
	*
	* All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	#include "polarssl/config.h"

	#if defined(POLARSSL_MEMORY_C) && defined(POLARSSL_MEMORY_BUFFER_ALLOC_C)

	#include "polarssl/memory.h"

	#include <string.h>

	#if defined(POLARSSL_MEMORY_DEBUG)
	#include <stdio.h>
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	#include <execinfo.h>
	#endif
	#endif

	#define MAGIC1 0xFF00AA55
	#define MAGIC2 0xEE119966
	#define MAX_BT 20

	typedef struct _memory_header memory_header;
	struct _memory_header
	{
	size_t magic1;
	size_t size;
	size_t alloc;
	memory_header *prev;
	memory_header *next;
	memory_header *prev_free;
	memory_header *next_free;
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	char **trace;
	size_t trace_count;
	#endif
	size_t magic2;
	};

	typedef struct
	{
	unsigned char *buf;
	size_t len;
	memory_header *first;
	memory_header *first_free;
	size_t current_alloc_size;
	int verify;
	#if defined(POLARSSL_MEMORY_DEBUG)
	size_t malloc_count;
	size_t free_count;
	size_t total_used;
	size_t maximum_used;
	size_t header_count;
	#endif
	}
	buffer_alloc_ctx;

	static buffer_alloc_ctx heap;

	#if defined(POLARSSL_MEMORY_DEBUG)
	static void debug_header( memory_header *hdr )
	{
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	size_t i;
	#endif

	fprintf( stderr, "HDR: PTR(%10u), PREV(%10u), NEXT(%10u), ALLOC(%u), SIZE(%10u)\n",
	(size_t) hdr, (size_t) hdr->prev, (size_t) hdr->next,
	hdr->alloc, hdr->size );
	fprintf( stderr, " FPREV(%10u), FNEXT(%10u)\n",
	(size_t) hdr->prev_free, (size_t) hdr->next_free );

	#if defined(POLARSSL_MEMORY_BACKTRACE)
	fprintf( stderr, "TRACE: \n" );
	for( i = 0; i < hdr->trace_count; i++ )
	fprintf( stderr, "%s\n", hdr->trace[i] );
	fprintf( stderr, "\n" );
	#endif
	}

	static void debug_chain()
	{
	memory_header *cur = heap.first;

	fprintf( stderr, "\nBlock list\n" );
	while( cur != NULL )
	{
	debug_header( cur );
	cur = cur->next;
	}

	fprintf( stderr, "Free list\n" );
	cur = heap.first_free;

	while( cur != NULL )
	{
	debug_header( cur );
	cur = cur->next_free;
	}
	}
	#endif /* POLARSSL_MEMORY_DEBUG */

	static int verify_header( memory_header *hdr )
	{
	if( hdr->magic1 != MAGIC1 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: MAGIC1 mismatch\n" );
	#endif
	return( 1 );
	}

	if( hdr->magic2 != MAGIC2 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: MAGIC2 mismatch\n" );
	#endif
	return( 1 );
	}

	if( hdr->alloc > 1 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: alloc has illegal value\n" );
	#endif
	return( 1 );
	}

	if( hdr->prev != NULL && hdr->prev == hdr->next )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: prev == next\n" );
	#endif
	return( 1 );
	}

	if( hdr->prev_free != NULL && hdr->prev_free == hdr->next_free )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: prev_free == next_free\n" );
	#endif
	return( 1 );
	}

	return( 0 );
	}

	static int verify_chain()
	{
	memory_header prv = heap.first, cur = heap.first->next;

	if( verify_header( heap.first ) != 0 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: verification of first header failed\n" );
	#endif
	return( 1 );
	}

	if( heap.first->prev != NULL )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: verification failed: first->prev != NULL\n" );
	#endif
	return( 1 );
	}

	while( cur != NULL )
	{
	if( verify_header( cur ) != 0 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: verification of header failed\n" );
	#endif
	return( 1 );
	}

	if( cur->prev != prv )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: verification failed: cur->prev != prv\n" );
	#endif
	return( 1 );
	}

	prv = cur;
	cur = cur->next;
	}

	return( 0 );
	}

	static void *buffer_alloc_malloc( size_t len )
	{
	memory_header new, cur = heap.first_free;
	unsigned char *p;
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	void *trace_buffer[MAX_BT];
	size_t trace_cnt;
	#endif

	if( heap.buf == NULL \|\| heap.first == NULL )
	return( NULL );

	if( len % POLARSSL_MEMORY_ALIGN_MULTIPLE )
	{
	len -= len % POLARSSL_MEMORY_ALIGN_MULTIPLE;
	len += POLARSSL_MEMORY_ALIGN_MULTIPLE;
	}

	// Find block that fits
	//
	while( cur != NULL )
	{
	if( cur->size >= len )
	break;

	cur = cur->next_free;
	}

	if( cur == NULL )
	return( NULL );

	if( cur->alloc != 0 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: block in free_list but allocated data\n" );
	#endif
	exit( 1 );
	}

	#if defined(POLARSSL_MEMORY_DEBUG)
	heap.malloc_count++;
	#endif

	// Found location, split block if > memory_header + 4 room left
	//
	if( cur->size - len < sizeof(memory_header) + POLARSSL_MEMORY_ALIGN_MULTIPLE )
	{
	cur->alloc = 1;

	// Remove from free_list
	//
	if( cur->prev_free != NULL )
	cur->prev_free->next_free = cur->next_free;
	else
	heap.first_free = cur->next_free;

	if( cur->next_free != NULL )
	cur->next_free->prev_free = cur->prev_free;

	cur->prev_free = NULL;
	cur->next_free = NULL;

	#if defined(POLARSSL_MEMORY_DEBUG)
	heap.total_used += cur->size;
	if( heap.total_used > heap.maximum_used)
	heap.maximum_used = heap.total_used;
	#endif
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	trace_cnt = backtrace( trace_buffer, MAX_BT );
	cur->trace = backtrace_symbols( trace_buffer, trace_cnt );
	cur->trace_count = trace_cnt;
	#endif

	if( ( heap.verify & MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 )
	exit( 1 );

	return ( (unsigned char *) cur ) + sizeof(memory_header);
	}

	p = ( (unsigned char *) cur ) + sizeof(memory_header) + len;
	new = (memory_header *) p;

	new->size = cur->size - len - sizeof(memory_header);
	new->alloc = 0;
	new->prev = cur;
	new->next = cur->next;
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	new->trace = NULL;
	new->trace_count = 0;
	#endif
	new->magic1 = MAGIC1;
	new->magic2 = MAGIC2;

	if( new->next != NULL )
	new->next->prev = new;

	// Replace cur with new in free_list
	//
	new->prev_free = cur->prev_free;
	new->next_free = cur->next_free;
	if( new->prev_free != NULL )
	new->prev_free->next_free = new;
	else
	heap.first_free = new;

	if( new->next_free != NULL )
	new->next_free->prev_free = new;

	cur->alloc = 1;
	cur->size = len;
	cur->next = new;
	cur->prev_free = NULL;
	cur->next_free = NULL;

	#if defined(POLARSSL_MEMORY_DEBUG)
	heap.header_count++;
	heap.total_used += cur->size;
	if( heap.total_used > heap.maximum_used)
	heap.maximum_used = heap.total_used;
	#endif
	#if defined(POLARSSL_MEMORY_BACKTRACE)
	trace_cnt = backtrace( trace_buffer, MAX_BT );
	cur->trace = backtrace_symbols( trace_buffer, trace_cnt );
	cur->trace_count = trace_cnt;
	#endif

	if( ( heap.verify & MEMORY_VERIFY_ALLOC ) && verify_chain() != 0 )
	exit( 1 );

	return ( (unsigned char *) cur ) + sizeof(memory_header);
	}

	static void buffer_alloc_free( void *ptr )
	{
	memory_header hdr, old = NULL;
	unsigned char p = (unsigned char ) ptr;


	if( ptr == NULL \|\| heap.buf == NULL \|\| heap.first == NULL )
	return;

	if( p < heap.buf \|\| p > heap.buf + heap.len )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: polarssl_free() outside of managed space\n" );
	#endif
	exit( 1 );
	}

	p -= sizeof(memory_header);
	hdr = (memory_header *) p;

	if( verify_header( hdr ) != 0 )
	exit( 1 );

	if( hdr->alloc != 1 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	fprintf( stderr, "FATAL: polarssl_free() on unallocated data\n" );
	#endif
	exit( 1 );
	}

	hdr->alloc = 0;

	#if defined(POLARSSL_MEMORY_DEBUG)
	heap.free_count++;
	heap.total_used -= hdr->size;
	#endif

	// Regroup with block before
	//
	if( hdr->prev != NULL && hdr->prev->alloc == 0 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	heap.header_count--;
	#endif
	hdr->prev->size += sizeof(memory_header) + hdr->size;
	hdr->prev->next = hdr->next;
	old = hdr;
	hdr = hdr->prev;

	if( hdr->next != NULL )
	hdr->next->prev = hdr;

	#if defined(POLARSSL_MEMORY_BACKTRACE)
	free( old->trace );
	#endif
	memset( old, 0, sizeof(memory_header) );
	}

	// Regroup with block after
	//
	if( hdr->next != NULL && hdr->next->alloc == 0 )
	{
	#if defined(POLARSSL_MEMORY_DEBUG)
	heap.header_count--;
	#endif
	hdr->size += sizeof(memory_header) + hdr->next->size;
	old = hdr->next;
	hdr->next = hdr->next->next;

	if( hdr->prev_free != NULL \|\| hdr->next_free != NULL )
	{
	if( hdr->prev_free != NULL )
	hdr->prev_free->next_free = hdr->next_free;
	else
	heap.first_free = hdr->next_free;

	if( hdr->next_free != NULL )
	hdr->next_free->prev_free = hdr->prev_free;
	}

	hdr->prev_free = old->prev_free;
	hdr->next_free = old->next_free;

	if( hdr->prev_free != NULL )
	hdr->prev_free->next_free = hdr;
	else
	heap.first_free = hdr;

	if( hdr->next_free != NULL )
	hdr->next_free->prev_free = hdr;

	if( hdr->next != NULL )
	hdr->next->prev = hdr;

	#if defined(POLARSSL_MEMORY_BACKTRACE)
	free( old->trace );
	#endif
	memset( old, 0, sizeof(memory_header) );
	}

	// Prepend to free_list if we have not merged
	// (Does not have to stay in same order as prev / next list)
	//
	if( old == NULL )
	{
	hdr->next_free = heap.first_free;
	heap.first_free->prev_free = hdr;
	heap.first_free = hdr;
	}

	#if defined(POLARSSL_MEMORY_BACKTRACE)
	hdr->trace = NULL;
	hdr->trace_count = 0;
	#endif

	if( ( heap.verify & MEMORY_VERIFY_FREE ) && verify_chain() != 0 )
	exit( 1 );
	}

	int memory_buffer_alloc_verify()
	{
	return verify_chain();
	}

	#if defined(POLARSSL_MEMORY_DEBUG)
	void memory_buffer_alloc_status()
	{
	fprintf( stderr,
	"Current use: %u blocks / %u bytes, max: %u bytes, malloc / free: %u / %u\n",
	heap.header_count, heap.total_used, heap.maximum_used,
	heap.malloc_count, heap.free_count );

	if( heap.first->next == NULL )
	fprintf( stderr, "All memory de-allocated in stack buffer\n" );
	else
	{
	fprintf( stderr, "Memory currently allocated:\n" );
	debug_chain();
	}
	}
	#endif /* POLARSSL_MEMORY_BUFFER_ALLOC_DEBUG */

	int memory_buffer_alloc_init( unsigned char *buf, size_t len )
	{
	polarssl_malloc = buffer_alloc_malloc;
	polarssl_free = buffer_alloc_free;

	memset( &heap, 0, sizeof(buffer_alloc_ctx) );
	memset( buf, 0, len );

	heap.buf = buf;
	heap.len = len;

	heap.first = (memory_header *) buf;
	heap.first->size = len - sizeof(memory_header);
	heap.first->magic1 = MAGIC1;
	heap.first->magic2 = MAGIC2;
	heap.first_free = heap.first;
	return( 0 );
	}

	#endif /* POLARSSL_MEMORY_C && POLARSSL_MEMORY_BUFFER_ALLOC_C */