patch 8.1.0915: fsync() may not work properly on Mac

Problem:    fsync() may not work properly on Mac.
Solution:   Use fcntl() with F_FULLFSYNC. (suggested by Justin M. Keyes)

src/evalfunc.c

@@ -14791,7 +14791,7 @@ f_writefile(typval_T *argvars, typval_T *rettv)
 	else if (do_fsync)
 	    // Ignore the error, the user wouldn't know what to do about it.
 	    // May happen for a device.
-	    vim_ignored = fsync(fileno(fd));
+	    vim_ignored = vim_fsync(fileno(fd));
 #endif
 	fclose(fd);
     }
@@ -14803,7 +14803,7 @@ f_writefile(typval_T *argvars, typval_T *rettv)
 	else if (do_fsync)
 	    /* Ignore the error, the user wouldn't know what to do about it.
 	     * May happen for a device. */
-	    vim_ignored = fsync(fileno(fd));
+	    vim_ignored = vim_fsync(fileno(fd));
 #endif
 	fclose(fd);
     }

src/fileio.c

@@ -4661,7 +4661,7 @@ restore_backup:
 	 * work (could be a pipe).
 	 * If the 'fsync' option is FALSE, don't fsync().  Useful for laptops.
 	 */
-	if (p_fs && fsync(fd) != 0 && !device)
+	if (p_fs && vim_fsync(fd) != 0 && !device)
 	{
 	    errmsg = (char_u *)_(e_fsync);
 	    end = 0;
@@ -5123,6 +5123,25 @@ nofail:
     return retval;
 }
 
+#if defined(HAVE_FSYNC) || defined(PROTO)
+/*
+ * Call fsync() with Mac-specific exception.
+ * Return fsync() result: zero for success.
+ */
+    int
+vim_fsync(int fd)
+{
+    int r;
+
+# ifdef MACOS_X
+    r = fcntl(fd, F_FULLFSYNC);
+    if (r != 0 && errno == ENOTTY)
+# endif
+	r = fsync(fd);
+    return r;
+}
+#endif
+
 /*
  * Set the name of the current buffer.  Use when the buffer doesn't have a
  * name and a ":r" or ":w" command with a file name is used.

src/memfile.c

@@ -600,7 +600,7 @@ mf_sync(memfile_T *mfp, int flags)
 	 */
 	if (STRCMP(p_sws, "fsync") == 0)
 	{
-	    if (fsync(mfp->mf_fd))
+	    if (vim_fsync(mfp->mf_fd))
 		status = FAIL;
 	}
 	else
@@ -617,7 +617,7 @@ mf_sync(memfile_T *mfp, int flags)
 #ifdef VMS
 	if (STRCMP(p_sws, "fsync") == 0)
 	{
-	    if (fsync(mfp->mf_fd))
+	    if (vim_fsync(mfp->mf_fd))
 		status = FAIL;
 	}
 #endif
@@ -627,7 +627,7 @@ mf_sync(memfile_T *mfp, int flags)
 #endif
 #ifdef AMIGA
 # if defined(__AROS__) || defined(__amigaos4__)
-	if (fsync(mfp->mf_fd) != 0)
+	if (vim_fsync(mfp->mf_fd) != 0)
 	    status = FAIL;
 # else
 	/*

src/proto/fileio.pro

@@ -7,6 +7,7 @@ void set_file_options(int set_options, exarg_T *eap);
 void set_forced_fenc(exarg_T *eap);
 int check_file_readonly(char_u *fname, int perm);
 int buf_write(buf_T *buf, char_u *fname, char_u *sfname, linenr_T start, linenr_T end, exarg_T *eap, int append, int forceit, int reset_changed, int filtering);
+int vim_fsync(int fd);
 void msg_add_fname(buf_T *buf, char_u *fname);
 void msg_add_lines(int insert_space, long lnum, off_T nchars);
 char_u *shorten_fname1(char_u *full_path);

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    915,
 /**/
     914,
 /**/