From: Andrew Tridgell <andrew@tridgell.net>
Date: Thu, 4 Jun 2026 04:46:38 +0000 (+1000)
Subject: build: fall back to do_mknod() when mknodat() is unavailable (#896)
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=b3107260a2c34bf41ffa0edfd70101681968641a;p=thirdparty%2Frsync.git

build: fall back to do_mknod() when mknodat() is unavailable (#896)

do_mknod_at() (the symlink-race-safe variant used by a non-chrooted
daemon receiver) calls mknodat()/mkfifoat(), but the at-variant was
gated only on AT_FDCWD.  Older Darwin declares AT_FDCWD without
mknodat(), so the build failed with "mknodat undeclared".

Probe mknodat()/mkfifoat() in configure and require HAVE_MKNODAT for the
at-variant; without it do_mknod_at() falls back to do_mknod(), exactly
as it already does where AT_FDCWD is missing.  Linux keeps the mknodat
path since HAVE_MKNODAT is defined there.

Fixes: #896
---

diff --git a/configure.ac b/configure.ac
index c4166c3c..cfccb37c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -932,7 +932,7 @@ AC_FUNC_UTIME_NULL
 AC_FUNC_ALLOCA
 AC_CHECK_FUNCS(waitpid wait4 getcwd chown chmod lchmod mknod mkfifo \
     fchmod fstat ftruncate strchr readlink link utime utimes lutimes strftime \
-    chflags getattrlist mktime innetgr linkat \
+    chflags getattrlist mktime innetgr linkat mknodat mkfifoat \
     memmove lchown vsnprintf snprintf vasprintf asprintf setsid strpbrk \
     strlcat strlcpy stpcpy strtol mallinfo mallinfo2 getgroups setgroups geteuid getegid \
     setlocale setmode open64 lseek64 mkstemp64 mtrace va_copy __va_copy \
diff --git a/syscall.c b/syscall.c
index 3f023462..243f7f24 100644
--- a/syscall.c
+++ b/syscall.c
@@ -536,7 +536,9 @@ int do_mknod(const char *pathname, mode_t mode, dev_t dev)
 */
 int do_mknod_at(const char *pathname, mode_t mode, dev_t dev)
 {
-#ifdef AT_FDCWD
+	/* HAVE_MKNODAT: older Darwin declares AT_FDCWD but not mknodat(), so
+	 * the at-variant won't build there; fall back to do_mknod() (#896). */
+#if defined(AT_FDCWD) && defined(HAVE_MKNODAT)
 	extern int am_daemon, am_chrooted;
 	char dirpath[MAXPATHLEN];
 	const char *bname;
@@ -598,7 +600,7 @@ int do_mknod_at(const char *pathname, mode_t mode, dev_t dev)
 		return ret;
 	}
 
-#if !defined MKNOD_CREATES_FIFOS && defined HAVE_MKFIFO
+#if !defined MKNOD_CREATES_FIFOS && defined HAVE_MKFIFO && defined HAVE_MKFIFOAT
 	if (S_ISFIFO(mode))
 		ret = mkfifoat(dfd, bname, mode);
 	else