From 2c902cc2887340adb6ca7ac6b4b922b52438920f Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 30 Aug 2023 07:16:49 -0700
Subject: [PATCH] maint: rely on Gnulib fdatasync

* m4/jm-macros.m4: Remove fdatasync-related code,
as Gnulib now does this.
* src/dd.c (fdatasync) [!HAVE_FDATASYNC]:
* src/shred.c (dosync) [!HAVE_FDATASYNC]: Rely on Gnulib fdatasync.
---
 m4/jm-macros.m4 | 16 ----------------
 src/dd.c        |  4 ----
 src/shred.c     |  2 --
 3 files changed, 22 deletions(-)

diff --git a/m4/jm-macros.m4 b/m4/jm-macros.m4
index 0da7ae143e..84c1209af9 100644
--- a/m4/jm-macros.m4
+++ b/m4/jm-macros.m4
@@ -94,22 +94,6 @@ AC_DEFUN([coreutils_MACROS],
   dnl This can't use AC_REQUIRE; I'm not quite sure why.
   cu_PREREQ_STAT_PROG
 
-  # for dd.c and shred.c
-  #
-  # Use fdatasync only if declared.  On MacOS X 10.7, fdatasync exists but
-  # is not declared, and is ineffective.
-  LIB_FDATASYNC=
-  AC_SUBST([LIB_FDATASYNC])
-  AC_CHECK_DECLS_ONCE([fdatasync])
-  if test $ac_cv_have_decl_fdatasync = yes; then
-    coreutils_saved_libs=$LIBS
-    AC_SEARCH_LIBS([fdatasync], [rt posix4],
-                   [test "$ac_cv_search_fdatasync" = "none required" ||
-                    LIB_FDATASYNC=$ac_cv_search_fdatasync])
-    AC_CHECK_FUNCS([fdatasync])
-    LIBS=$coreutils_saved_libs
-  fi
-
   # Check whether libcap is usable -- for ls --color support
   LIB_CAP=
   AC_ARG_ENABLE([libcap],
diff --git a/src/dd.c b/src/dd.c
index b50b8411d4..198d4800ca 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -73,10 +73,6 @@
    and would interfere with our use of that name, below.  */
 #undef O_NOCACHE
 
-#if ! HAVE_FDATASYNC
-# define fdatasync(fd) (errno = ENOSYS, -1)
-#endif
-
 #define output_char(c)				\
   do						\
     {						\
diff --git a/src/shred.c b/src/shred.c
index a5da4e038e..b2cf7220e4 100644
--- a/src/shred.c
+++ b/src/shred.c
@@ -300,7 +300,6 @@ dosync (int fd, char const *qname)
 {
   int err;
 
-#if HAVE_FDATASYNC
   if (fdatasync (fd) == 0)
     return 0;
   err = errno;
@@ -310,7 +309,6 @@ dosync (int fd, char const *qname)
       errno = err;
       return -1;
     }
-#endif
 
   if (fsync (fd) == 0)
     return 0;
-- 
2.47.2