handle malloc(), free(), casts and assignments involving pointers to variables, memory, or cast from integer constants

demofiles/memory-leak.c

@@ -8,6 +8,7 @@ int main() {
     for (int i = 0;  i < 10;  ++i) {
 	int *ptr = malloc(sizeof(*ptr));
 	assert(ptr != 0);
+	printf("%p\n", ptr);
 	*ptr = i;
     }
     return 0;

demofiles/multiple-free.c

@@ -6,8 +6,8 @@
 
 int main() {
   int *ptr = malloc(sizeof(*ptr));
-  assert(ptr);
-  free(ptr);
-  free(ptr);
+  assert(ptr != 0);
+  free(ptr);  printf("%p\n", ptr);
+  free(ptr);  printf("%p\n", ptr);
   return 0;
 }

demofiles/null-pointer.c

@@ -3,7 +3,7 @@
 #include <stdio.h>
 
 int main() {
-  char *ptr = NULL;
-  printf("%s\n", ptr);
-  return 0;
+    char *ptr = (void *)0; // NULL
+    printf("%s\n", ptr);
+    return 0;
 }

include/stdlib.h

@@ -1 +1,2 @@
 extern void *malloc(long size);
+extern void    free(void *pointer);