libcsupport/src/rtems_heap_extend_via_sbrk.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  *  @file
0005  *
0006  *  @brief RTEMS Extend Heap via Sbrk
0007  *  @ingroup MallocSupport
0008  */
0009
0010 /*
0011  * Copyright (c) 2012 embedded brains GmbH & Co. KG
0012  *
0013  * Redistribution and use in source and binary forms, with or without
0014  * modification, are permitted provided that the following conditions
0015  * are met:
0016  * 1. Redistributions of source code must retain the above copyright
0017  *    notice, this list of conditions and the following disclaimer.
0018  * 2. Redistributions in binary form must reproduce the above copyright
0019  *    notice, this list of conditions and the following disclaimer in the
0020  *    documentation and/or other materials provided with the distribution.
0021  *
0022  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0023  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0024  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0025  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0026  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0027  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0028  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0029  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0030  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0031  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0032  * POSSIBILITY OF SUCH DAMAGE.
0033  */
0034
0035 #ifdef HAVE_CONFIG_H
0036 #include "config.h"
0037 #endif
0038
0039 #include <unistd.h>
0040
0041 #include <rtems/malloc.h>
0042
0043 #include "malloc_p.h"
0044
0045 static ptrdiff_t RTEMS_Malloc_Sbrk_amount;
0046
0047 void rtems_heap_set_sbrk_amount( ptrdiff_t sbrk_amount )
0048 {
0049   RTEMS_Malloc_Sbrk_amount = sbrk_amount;
0050 }
0051
0052 void *rtems_heap_extend_via_sbrk(
0053   Heap_Control *heap,
0054   size_t alloc_size
0055 )
0056 {
0057   ptrdiff_t sbrk_amount = RTEMS_Malloc_Sbrk_amount;
0058   ptrdiff_t sbrk_size = (ptrdiff_t) alloc_size;
0059   ptrdiff_t misaligned = sbrk_amount != 0 ? sbrk_size % sbrk_amount : 0;
0060   void *return_this = NULL;
0061
0062   if ( misaligned != 0 ) {
0063     sbrk_size += sbrk_amount - misaligned;
0064   }
0065
0066   if ( sbrk_size > 0 && sbrk_amount > 0 ) {
0067     void *area_begin = sbrk( sbrk_size );
0068
0069     if ( area_begin != (void *) -1 ) {
0070       bool ok = _Protected_heap_Extend( heap, area_begin, sbrk_size );
0071
0072       if ( ok ) {
0073         return_this = _Protected_heap_Allocate( heap, alloc_size );
0074       } else {
0075         sbrk( -sbrk_size );
0076       }
0077     }
0078   }
0079
0080   return return_this;
0081 }