tree-wide: introduce free_and_replace helper

It's a common pattern, so add a helper for it. A macro is necessary
because a function that takes a pointer to a pointer would be type specific,
similarly to cleanup functions. Seems better to use a macro.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/basic/alloc-util.h b/src/basic/alloc-util.h
index ceeee519b7..a44dd473c1 100644
--- a/src/basic/alloc-util.h
+++ b/src/basic/alloc-util.h
@@ -43,6 +43,14 @@ static inline void *mfree(void *memory) {
         return NULL;
 }
 
+#define free_and_replace(a, b)                  \
+        ({                                      \
+                free(a);                        \
+                (a) = (b);                      \
+                (b) = NULL;                     \
+                0;                              \
+        })
+
 void* memdup(const void *p, size_t l) _alloc_(2);
 
 static inline void freep(void *p) {