Only define memfd_create when not already defined

config.h.meson

@@ -445,3 +445,4 @@
 #mesondefine HAVE_ALARM
 #mesondefine HAVE_DECL_LOCALTIME_R
 #mesondefine HAVE_DECL_STRSIGNAL
+#mesondefine HAVE_MEMFD_CREATE

meson.build

@@ -117,6 +117,10 @@ if cc.has_function('mkstemp', prefix : '#include <stdlib.h>')
   cdata.set('HAVE_MKSTEMP', 1)
 endif
 
+if cc.has_function('memfd_create', prefix : '#include <sys/mman.h>')
+  cdata.set('HAVE_MEMFD_CREATE', 1)
+endif
+
 configure_file(input : 'config.h.meson',
   output : 'config.h',
   configuration : cdata)

src/pipewire/memfd-wrappers.h

@@ -20,6 +20,7 @@
 #include <sys/syscall.h>
 #include <fcntl.h>
 
+#ifndef HAVE_MEMFD_CREATE
 /*
  * No glibc wrappers exist for memfd_create(2), so provide our own.
  *
@@ -32,6 +33,7 @@ static inline int
 memfd_create(const char *name, unsigned int flags) {
 	return syscall(SYS_memfd_create, name, flags);
 }
+#endif
 
 /* memfd_create(2) flags */