From faa2d81c6c5733d2eaa28d142f88917ed9c8300b Mon Sep 17 00:00:00 2001
From: Dan Streetman <ddstreet@ieee.org>
Date: Tue, 6 Dec 2022 13:07:34 -0500
Subject: [PATCH] Consolidate various TAKE_* into TAKE_GENERIC(), add
 TAKE_STRUCT()

(cherry picked from commit 40c5cc2b214fd47ebfe85786a2a220bd3e9f275a)

Related: RHEL-16182
---
 src/basic/fd-util.h                 |  8 +-------
 src/basic/process-util.h            | 10 ++--------
 src/fundamental/macro-fundamental.h | 17 +++++++++++------
 src/shared/keyring-util.h           | 10 ++--------
 4 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/src/basic/fd-util.h b/src/basic/fd-util.h
index 29c7d86f27..1fdb8c8fcb 100644
--- a/src/basic/fd-util.h
+++ b/src/basic/fd-util.h
@@ -90,13 +90,7 @@ static inline int make_null_stdio(void) {
 }
 
 /* Like TAKE_PTR() but for file descriptors, resetting them to -1 */
-#define TAKE_FD(fd)                             \
-        ({                                      \
-                int *_fd_ = &(fd);              \
-                int _ret_ = *_fd_;              \
-                *_fd_ = -1;                     \
-                _ret_;                          \
-        })
+#define TAKE_FD(fd) TAKE_GENERIC(fd, int, -1)
 
 /* Like free_and_replace(), but for file descriptors */
 #define close_and_replace(a, b)                 \
diff --git a/src/basic/process-util.h b/src/basic/process-util.h
index ed2f73673e..e49bc47b2c 100644
--- a/src/basic/process-util.h
+++ b/src/basic/process-util.h
@@ -176,14 +176,8 @@ int get_oom_score_adjust(int *ret);
 
 assert_cc(TASKS_MAX <= (unsigned long) PID_T_MAX);
 
-/* Like TAKE_PTR() but for child PIDs, resetting them to 0 */
-#define TAKE_PID(pid)                           \
-        ({                                      \
-                pid_t *_ppid_ = &(pid);         \
-                pid_t _pid_ = *_ppid_;          \
-                *_ppid_ = 0;                    \
-                _pid_;                          \
-        })
+/* Like TAKE_PTR() but for pid_t, resetting them to 0 */
+#define TAKE_PID(pid) TAKE_GENERIC(pid, pid_t, 0)
 
 int pidfd_get_pid(int fd, pid_t *ret);
 
diff --git a/src/fundamental/macro-fundamental.h b/src/fundamental/macro-fundamental.h
index faab16ab31..e0665d9dcb 100644
--- a/src/fundamental/macro-fundamental.h
+++ b/src/fundamental/macro-fundamental.h
@@ -299,13 +299,18 @@
 
 /* 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_;                          \
+#define TAKE_GENERIC(var, type, nullvalue)                       \
+        ({                                                       \
+                type *_pvar_ = &(var);                           \
+                type _var_ = *_pvar_;                            \
+                type _nullvalue_ = nullvalue;                    \
+                *_pvar_ = _nullvalue_;                           \
+                _var_;                                           \
         })
+#define TAKE_PTR_TYPE(ptr, type) TAKE_GENERIC(ptr, type, NULL)
+#define TAKE_PTR(ptr) TAKE_PTR_TYPE(ptr, typeof(ptr))
+#define TAKE_STRUCT_TYPE(s, type) TAKE_GENERIC(s, type, {})
+#define TAKE_STRUCT(s) TAKE_STRUCT_TYPE(s, typeof(s))
 
 /*
  * STRLEN - return the length of a string literal, minus the trailing NUL byte.
diff --git a/src/shared/keyring-util.h b/src/shared/keyring-util.h
index 838e990b80..c8c53f1be1 100644
--- a/src/shared/keyring-util.h
+++ b/src/shared/keyring-util.h
@@ -5,13 +5,7 @@
 
 #include "missing_keyctl.h"
 
-/* TAKE_FD but for key_serial_t instead of fds */
-#define TAKE_KEY_SERIAL(key_serial)                             \
-        ({                                                      \
-                key_serial_t *_key_serialp_ = &(key_serial);    \
-                key_serial_t _key_serial_ = *_key_serialp_;     \
-                *_key_serialp_ = -1;                            \
-                _key_serial_;                                   \
-        })
+/* Like TAKE_PTR() but for key_serial_t, resetting them to -1 */
+#define TAKE_KEY_SERIAL(key_serial) TAKE_GENERIC(key_serial, key_serial_t, -1)
 
 int keyring_read(key_serial_t serial, void **ret, size_t *ret_size);