libc/valloc: support valloc

MIRTOS-424

Change-Id: Ieb425a77b0a8d758956996d201223a0050ae4920
Signed-off-by: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>

include/stdlib.h

@@ -200,6 +200,7 @@ size_t    wcstombs(FAR char *dst, FAR const wchar_t *src, size_t len);
 /* Memory Management */
 
 FAR void *malloc(size_t);
+FAR void *valloc(size_t);
 void      free(FAR void *);
 FAR void *realloc(FAR void *, size_t);
 FAR void *memalign(size_t, size_t);

libs/libc/stdlib/Make.defs

@@ -26,6 +26,7 @@ CSRCS += lib_itoa.c lib_labs.c lib_llabs.c lib_realpath.c lib_bsearch.c
 CSRCS += lib_rand.c lib_posix_memalign.c lib_qsort.c lib_srand.c lib_strtol.c
 CSRCS += lib_strtoll.c lib_strtoul.c lib_strtoull.c lib_strtod.c lib_strtof.c
 CSRCS += lib_strtold.c lib_checkbase.c lib_mktemp.c lib_mkstemp.c lib_mkdtemp.c
+CSRCS += lib_valloc.c
 
 ifeq ($(CONFIG_LIBC_WCHAR),y)
 CSRCS += lib_mblen.c lib_mbtowc.c lib_wctomb.c

libs/libc/stdlib/lib_valloc.c

@@ -0,0 +1,51 @@
+/****************************************************************************
+ * libs/libc/stdlib/lib_valloc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdlib.h>
+#include <unistd.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: valloc
+ *
+ * Description:
+ *   valloc has the same effect as malloc(), except that the allocated
+ *   memory is aligned to a page boundary.
+ *
+ * Input Parameters:
+ *   size - Specifies the size (in bytes) of the allocated block of memory.
+ *   If size is zero, a unique pointer to the heap is returned.
+ *
+ * Returned Value:
+ *   The address of the allocated memory (NULL on failure to allocate)
+ *
+ ****************************************************************************/
+
+FAR void *valloc(size_t size)
+{
+  return memalign(sysconf(_SC_PAGESIZE), size);
+}