Add CLOSE_AND_REPLACE helper

Similar to free_and_replace. I think this should be uppercase to make it
clear that this is a macro. free_and_replace should probably be uppercased
too.

src/basic/fd-util.c

@@ -731,8 +731,7 @@ int fd_duplicate_data_fd(int fd) {
                 if (f != 0)
                         return -errno;
 
-                safe_close(copy_fd);
-                copy_fd = TAKE_FD(tmp_fd);
+                CLOSE_AND_REPLACE(copy_fd, tmp_fd);
 
                 remains = mfree(remains);
                 remains_size = 0;
@@ -865,8 +864,7 @@ int rearrange_stdio(int original_input_fd, int original_output_fd, int original_
                                 goto finish;
                         }
 
-                        safe_close(null_fd);
-                        null_fd = copy;
+                        CLOSE_AND_REPLACE(null_fd, copy);
                 }
         }
 

src/basic/fd-util.h

@@ -93,6 +93,16 @@ static inline int make_null_stdio(void) {
                 _fd_;                           \
         })
 
+/* Like free_and_replace(), but for file descriptors */
+#define CLOSE_AND_REPLACE(a, b)                 \
+        ({                                      \
+                int *_fdp_ = &(a);              \
+                safe_close(*_fdp_);             \
+                *_fdp_ = TAKE_FD(b);            \
+                0;                              \
+        })
+
+
 int fd_reopen(int fd, int flags);
 
 int read_nr_open(void);

src/core/execute.c

@@ -4217,8 +4217,7 @@ static int exec_child(
                                 return log_unit_error_errno(unit, errno, "Couldn't move exec fd up: %m");
                         }
 
-                        safe_close(exec_fd);
-                        exec_fd = moved_fd;
+                        CLOSE_AND_REPLACE(exec_fd, moved_fd);
                 } else {
                         /* This fd should be FD_CLOEXEC already, but let's make sure. */
                         r = fd_cloexec(exec_fd, true);

src/import/import-raw.c

@@ -185,9 +185,7 @@ static int raw_import_maybe_convert_qcow2(RawImport *i) {
 
         (void) unlink(i->temp_path);
         free_and_replace(i->temp_path, t);
-
-        safe_close(i->output_fd);
-        i->output_fd = TAKE_FD(converted_fd);
+        CLOSE_AND_REPLACE(i->output_fd, converted_fd);
 
         return 1;
 }

src/import/pull-raw.c

@@ -253,9 +253,7 @@ static int raw_pull_maybe_convert_qcow2(RawPull *i) {
 
         (void) unlink(i->temp_path);
         free_and_replace(i->temp_path, t);
-
-        safe_close(i->raw_job->disk_fd);
-        i->raw_job->disk_fd = TAKE_FD(converted_fd);
+        CLOSE_AND_REPLACE(i->raw_job->disk_fd, converted_fd);
 
         return 1;
 }

src/libsystemd-network/sd-ipv4acd.c

@@ -471,8 +471,7 @@ int sd_ipv4acd_start(sd_ipv4acd *acd, bool reset_conflicts) {
         if (r < 0)
                 return r;
 
-        safe_close(acd->fd);
-        acd->fd = r;
+        CLOSE_AND_REPLACE(acd->fd, r);
         acd->defend_window = 0;
 
         if (reset_conflicts)

src/login/logind-session-device.c

@@ -195,8 +195,7 @@ static int session_device_start(SessionDevice *sd) {
 
                 /* For evdev devices, the file descriptor might be left uninitialized. This might happen while resuming
                  * into a session and logind has been restarted right before. */
-                safe_close(sd->fd);
-                sd->fd = r;
+                CLOSE_AND_REPLACE(sd->fd, r);
                 break;
 
         case DEVICE_TYPE_UNKNOWN: