Introduce TAKR_PTR and use it

Author: ssahani

src/netlog/netlog-manager.c

@@ -484,8 +484,6 @@ int manager_new(Manager **ret, const char *state_file, const char *cursor) {
         if (r < 0)
                 return r;
 
-        *ret = m;
-        m = NULL;
-
+        *ret = TAKE_PTR(m);
         return 0;
 }

src/netlog/netlog-network.c

@@ -207,6 +207,7 @@ int manager_open_network_socket(Manager *m) {
         if (SYSLOG_TRANSMISSION_PROTOCOL_TCP == m->protocol) {
                 union sockaddr_union sa;
                 socklen_t salen;
+
                 switch (m->address.sockaddr.sa.sa_family) {
                         case AF_INET:
                                 sa = (union sockaddr_union) {
@@ -228,6 +229,7 @@ int manager_open_network_socket(Manager *m) {
                                 r = -EAFNOSUPPORT;
                                 goto fail;
                 }
+
                 r = connect(m->socket, &m->address.sockaddr.sa, salen);
                 if (r < 0 && errno != EINPROGRESS) {
                         r = -errno;

src/share/macro.h

@@ -399,4 +399,15 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
         }                                                       \
         struct __useless_struct_to_allow_trailing_semicolon__
 
+/* Takes inspiration from Rust's Option::take() method: reads and returns a pointer, but at the same time
+ * resets it to NULL. See: https://doc.rust-lang.org/std/option/enum.Option.html#method.take */
+#define TAKE_PTR(ptr)                           \
+        ({                                      \
+                typeof(ptr) *_pptr_ = &(ptr);   \
+                typeof(ptr) _ptr_ = *_pptr_;    \
+                *_pptr_ = NULL;                 \
+                _ptr_;                          \
+        })
+
+
 #include "log.h"