From 878370c29af1c61ba43ff32fbed661e883d742e2 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Thu, 27 Feb 2014 13:55:19 +0900
Subject: [PATCH] gurantee allocators return NULL given size is zero

---
 include/picrin.h |  3 ++-
 src/gc.c         | 27 +++++++++++++++++++++++----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/include/picrin.h b/include/picrin.h
index 9edf3826..eb42720c 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -130,7 +130,8 @@ enum pic_parser_res {
   /* if parser is successfully done, return the number of exprs (>= 0) */
 };
 
-void *pic_alloc(pic_state *, size_t);
+void *pic_malloc(pic_state *, size_t);
+#define pic_alloc(pic,size) pic_malloc(pic,size) /* obsoleted */
 void *pic_realloc(pic_state *, void *, size_t);
 void *pic_calloc(pic_state *, size_t, size_t);
 struct pic_object *pic_obj_alloc(pic_state *, size_t, enum pic_tt);
diff --git a/src/gc.c b/src/gc.c
index f5c5e777..26d81341 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -42,6 +42,7 @@ struct pic_heap {
   struct heap_page *pages;
 };
 
+
 static void
 heap_init(struct pic_heap *heap)
 {
@@ -113,12 +114,28 @@ add_heap_page(pic_state *pic)
   pic->heap->pages = page;
 }
 
+static void *
+alloc(void *ptr, size_t size)
+{
+  if (size == 0) {
+    if (ptr) {
+      free(ptr);
+    }
+    return NULL;
+  }
+  if (ptr) {
+    return realloc(ptr, size);
+  } else {
+    return malloc(size);
+  }
+}
+
 void *
-pic_alloc(pic_state *pic, size_t size)
+pic_malloc(pic_state *pic, size_t size)
 {
   void *ptr;
 
-  ptr = malloc(size);
+  ptr = alloc(NULL, size);
   if (ptr == NULL && size > 0) {
     pic_abort(pic, "memory exhausted");
   }
@@ -128,7 +145,7 @@ pic_alloc(pic_state *pic, size_t size)
 void *
 pic_realloc(pic_state *pic, void *ptr, size_t size)
 {
-  ptr = realloc(ptr, size);
+  ptr = alloc(ptr, size);
   if (ptr == NULL && size > 0) {
     pic_abort(pic, "memory exhausted");
   }
@@ -140,10 +157,12 @@ pic_calloc(pic_state *pic, size_t count, size_t size)
 {
   void *ptr;
 
-  ptr = calloc(count ,size);
+  size *= count;
+  ptr = alloc(NULL, size);
   if (ptr == NULL && size > 0) {
     pic_abort(pic, "memory exhausted");
   }
+  memset(ptr, 0, size);
   return ptr;
 }