extern FILE *fopen_for_writing(const char *path);
extern FILE *fopen_or_warn(const char *path, const char *mode);
+/*
+ * FREE_AND_NULL(ptr) is like free(ptr) followed by ptr = NULL. Note
+ * that ptr is used twice, so don't pass e.g. ptr++.
+ */
+#define FREE_AND_NULL(p) do { free(p); (p) = NULL; } while (0)
+
#define ALLOC_ARRAY(x, alloc) (x) = xmalloc(st_mult(sizeof(*(x)), (alloc)))
#define REALLOC_ARRAY(x, alloc) (x) = xrealloc((x), st_mult(sizeof(*(x)), (alloc)))