From bcc1bd9752e3ef04a23d5b8a48b6ca1cf917133b Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Thu, 4 Oct 2018 11:25:39 +1000
Subject: [PATCH] HAL_ChibiOS: added realloc implementation

needed for AP_Scripting
---
 .../AP_HAL_ChibiOS/hwdef/common/malloc.c      | 41 +++++++++++++++++++
 libraries/AP_HAL_ChibiOS/hwdef/common/stdio.h |  1 +
 2 files changed, 42 insertions(+)

diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/malloc.c b/libraries/AP_HAL_ChibiOS/hwdef/common/malloc.c
index ce5c1fc33f..6703f278c9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/malloc.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/malloc.c
@@ -214,4 +214,45 @@ size_t mem_available(void)
     return totalp;
 }
 
+/*
+  realloc implementation thanks to wolfssl, used by AP_Scripting
+ */
+void *realloc(void *addr, size_t size)
+{
+    union heap_header *hp;
+    uint32_t prev_size, new_size;
+
+    void *ptr;
+
+    if(addr == NULL) {
+        return chHeapAlloc(NULL, size);
+    }
+
+    /* previous allocated segment is preceded by an heap_header */
+    hp = addr - sizeof(union heap_header);
+    prev_size = hp->used.size; /* size is always multiple of 8 */
+
+    /* check new size memory alignment */
+    if (size % 8 == 0) {
+        new_size = size;
+    } else {
+        new_size = ((int) (size / 8)) * 8 + 8;
+    }
+
+    if(prev_size >= new_size) {
+        return addr;
+    }
+
+    ptr = chHeapAlloc(NULL, size);
+    if (ptr == NULL) {
+        return NULL;
+    }
+
+    memcpy(ptr, addr, prev_size);
+
+    chHeapFree(addr);
+
+    return ptr;
+}
+
 #endif // CH_CFG_USE_HEAP
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.h b/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.h
index b57111f8f2..6435a22f91 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.h
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.h
@@ -42,6 +42,7 @@ int vsscanf (const char *buf, const char *s, va_list ap);
 void *malloc(size_t size);
 void *calloc(size_t nmemb, size_t size);
 void free(void *ptr);
+void *realloc(void *ptr, size_t size);
 
 extern int (*vprintf_console_hook)(const char *fmt, va_list arg);