implement the simple_malloc with sbrk sys call

simple_malloc.c

@@ -0,0 +1,23 @@
+#include <assert.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "simple_malloc.h"
+
+/**
+ * A simple implementation of memory allocating function.
+ *
+ * @param size the size of the memory that should be allocated.
+ * @return If the sbrk failed, returns NULL. Otherwise, returns p, which is the starting point of the allocated memory.
+ */
+void *simpleMalloc(size_t size) {
+    void *p = sbrk(0);
+    void *request = sbrk(size);
+
+    if (request == (void *)-1) {
+        return NULL; //sbrk failed
+    } else {
+        assert(p == request); //Not thread safe.
+        return p;
+    }
+}

simple_malloc.h

@@ -0,0 +1,9 @@
+#ifndef SIMPLE_MALLOC_H
+#define SIMPLE_MALLOC_H
+
+#include <sys/types.h>
+
+/* The simple implementation of memory allocating function. */
+void *simple_malloc(size_t size);
+
+#endif