stat-util: add new macros for declaring statx variable

Let's deal with the msan initialization issue once for all cases instead
of over and over again.

src/basic/mountpoint-util.c

@@ -13,6 +13,7 @@
 #include "mountpoint-util.h"
 #include "parse-util.h"
 #include "path-util.h"
+#include "stat-util.h"
 #include "stdio-util.h"
 #include "strv.h"
 
@@ -135,13 +136,8 @@ int fd_is_mount_point(int fd, const char *filename, int flags) {
         _cleanup_free_ struct file_handle *h = NULL, *h_parent = NULL;
         int mount_id = -1, mount_id_parent = -1;
         bool nosupp = false, check_st_dev = true;
+        STRUCT_STATX_DEFINE(sx);
         struct stat a, b;
-        struct statx sx
-#if HAS_FEATURE_MEMORY_SANITIZER
-                = {}
-#  warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
-#endif
-                ;
         int r;
 
         assert(fd >= 0);
@@ -298,15 +294,7 @@ int path_is_mount_point(const char *t, const char *root, int flags) {
 }
 
 int path_get_mnt_id(const char *path, int *ret) {
-        union {
-                struct statx sx;
-                struct new_statx nsx;
-        } buf
-#if HAS_FEATURE_MEMORY_SANITIZER
-                = {}
-#  warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
-#endif
-                ;
+        STRUCT_NEW_STATX_DEFINE(buf);
         int r;
 
         if (statx(AT_FDCWD, path, AT_SYMLINK_NOFOLLOW|AT_NO_AUTOMOUNT, STATX_MNT_ID, &buf.sx) < 0) {

src/basic/stat-util.h

@@ -91,3 +91,22 @@ int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret
 int proc_mounted(void);
 
 bool stat_inode_unmodified(const struct stat *a, const struct stat *b);
+
+#if HAS_FEATURE_MEMORY_SANITIZER
+#  warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
+#  define STRUCT_STATX_DEFINE(var)              \
+        struct statx var = {}
+#  define STRUCT_NEW_STATX_DEFINE(var)          \
+        union {                                 \
+                struct statx sx;                \
+                struct new_statx nsx;           \
+        } var = {}
+#else
+#  define STRUCT_STATX_DEFINE(var)              \
+        struct statx var
+#  define STRUCT_NEW_STATX_DEFINE(var)          \
+        union {                                 \
+                struct statx sx;                \
+                struct new_statx nsx;           \
+        } var
+#endif

src/basic/xattr-util.c

@@ -12,6 +12,7 @@
 #include "macro.h"
 #include "missing_syscall.h"
 #include "sparse-endian.h"
+#include "stat-util.h"
 #include "stdio-util.h"
 #include "string-util.h"
 #include "time-util.h"
@@ -154,12 +155,7 @@ static int parse_crtime(le64_t le, usec_t *usec) {
 }
 
 int fd_getcrtime_at(int dirfd, const char *name, usec_t *ret, int flags) {
-        struct_statx sx
-#if HAS_FEATURE_MEMORY_SANITIZER
-                = {}
-#  warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
-#endif
-                ;
+        STRUCT_STATX_DEFINE(sx);
         usec_t a, b;
         le64_t le;
         size_t n;