[PATCH] added malloc usable size and test

[zack leung]

closes #4503
---
 cpukit/include/rtems/libcsupport.h        |  5 +++
 cpukit/libcsupport/src/mallocusablesize.c | 48 +++++++++++++++++++++++
 spec/build/cpukit/librtemscpu.yml         |  1 +
 testsuites/libtests/malloctest/init.c     | 15 ++++++-
 4 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 cpukit/libcsupport/src/mallocusablesize.c

diff --git a/cpukit/include/rtems/libcsupport.h
b/cpukit/include/rtems/libcsupport.h
index f4be4cfc9a..5110ab0fbe 100644
--- a/cpukit/include/rtems/libcsupport.h
+++ b/cpukit/include/rtems/libcsupport.h
@@ -74,6 +74,11 @@ extern size_t malloc_free_space(void);
  */
 extern int malloc_info(Heap_Information_block *the_info);

+/**
+ * @brief Find the usable size of the block of memory .
+ */
+extern size_t malloc_usable_size(void *ptr);
+
 /*
  *  Prototypes required to install newlib reentrancy user extension
  */
diff --git a/cpukit/libcsupport/src/mallocusablesize.c
b/cpukit/libcsupport/src/mallocusablesize.c
new file mode 100644
index 0000000000..b7e573023a
--- /dev/null
+++ b/cpukit/libcsupport/src/mallocusablesize.c
@@ -0,0 +1,48 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ *  Copyright (C) 2022 zacchaeus leung
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/libcsupport.h>
+#include <rtems/malloc.h>
+#include <rtems/score/heapimpl.h>
+
+size_t malloc_usable_size( void *ptr ) {
+
+  Heap_Control *heap_ptr ;
+  size_t size;
+  if ( ptr == NULL ) {
+    return 0;
+  }
+
+  heap_ptr = malloc_get_heap_pointer();
+  _Heap_Size_of_alloc_area( heap_ptr, ptr, &size );
+
+  return size;
+}
diff --git a/spec/build/cpukit/librtemscpu.yml
b/spec/build/cpukit/librtemscpu.yml
index c224937348..2ef11e7e2d 100644
--- a/spec/build/cpukit/librtemscpu.yml
+++ b/spec/build/cpukit/librtemscpu.yml
@@ -670,6 +670,7 @@ source:
 - cpukit/libcsupport/src/lseek.c
 - cpukit/libcsupport/src/lstat.c
 - cpukit/libcsupport/src/malloc.c
+- cpukit/libcsupport/src/mallocusablesize.c
 - cpukit/libcsupport/src/malloc_deferred.c
 - cpukit/libcsupport/src/malloc_dirtier.c
 - cpukit/libcsupport/src/malloc_walk.c
diff --git a/testsuites/libtests/malloctest/init.c
b/testsuites/libtests/malloctest/init.c
index a33764177d..871edb540e 100644
--- a/testsuites/libtests/malloctest/init.c
+++ b/testsuites/libtests/malloctest/init.c
@@ -1362,6 +1362,18 @@ static void test_alloc_zero_size(void)
   rtems_test_assert( p == NULL );
   rtems_test_assert( errno == -1 );
 }
+static void test_usablesize(void)
+{
+  int * a = malloc(sizeof( int )*100);
+  int alloc_size=sizeof( int ) *100 ;
+  rtems_test_assert( malloc_usable_size( a ) <= alloc_size +
CPU_HEAP_ALIGNMENT );
+  free(a);
+
+  char * b = malloc(sizeof ( char ) 100);
+  int alloc_size 2= sizeof ( char ) *100 ;
+  rtems_test_assert( malloc_usable_size ( b ) <= alloc_size2 +
CPU_HEAP_ALIGNMENT);
+  free( b );
+}

 rtems_task Init(
   rtems_task_argument argument
@@ -1405,6 +1417,7 @@ rtems_task Init(
   test_protected_heap_info();
   test_rtems_heap_allocate_aligned_with_boundary();
   test_rtems_malloc();
+  test_usablesize();
   test_rtems_calloc();
   test_greedy_allocate();
   test_alloc_zero_size();
@@ -1524,4 +1537,4 @@ RTEMS_SYSINIT_ITEM(
   test_early_malloc,
   RTEMS_SYSINIT_INITIAL_EXTENSIONS,
   RTEMS_SYSINIT_ORDER_FIRST
-);
+);
\ No newline at end of file
-- 
2.35.1