Unix fsync (#1839)

* added otherlibs/unix/fsync.c and otherlibs/unix/unix.ml

* add Unix.fsync

* added otherlibs/win32unix/fsync.c

* Unix.fsync for windows

* big typo

* Rewrite Unix.fsync stub for Windows

* belts and braces: fail in the case of named pipe

* Add missing include

* corrected header

* better ocamldoc for fsync

* rm fsync.c from the UNIX_FILES list

* updated Changes for Unix.fsync

* Use _commit instead of FlushFileBuffers

* Include <io.h>

7 files changed, 43 insertions, 3 deletions

diff --git a/otherlibs/threads/unix.ml b/otherlibs/threads/unix.ml
index 605b732f0b..4cf44916db 100644
--- a/otherlibs/threads/unix.ml
+++ b/otherlibs/threads/unix.ml
@@ -212,6 +212,7 @@ external openfile : string -> open_flag list -> file_perm -> file_descr
            = "unix_open"
 
 external close : file_descr -> unit = "unix_close"
+external fsync : file_descr -> unit = "unix_fsync"
 external unsafe_read : file_descr -> bytes -> int -> int -> int = "unix_read"
 external unsafe_write : file_descr -> bytes -> int -> int -> int
     = "unix_write"
diff --git a/otherlibs/unix/Makefile b/otherlibs/unix/Makefile
index 5638191f78..cbd398e4b7 100644
--- a/otherlibs/unix/Makefile
+++ b/otherlibs/unix/Makefile
@@ -23,7 +23,7 @@ EXTRACAMLFLAGS=-nolabels
 LDOPTS=$(NATIVECCLIBS)
 
 COBJS=accept.o access.o addrofstr.o alarm.o bind.o channels.o chdir.o \
-  chmod.o chown.o chroot.o close.o closedir.o connect.o cst2constr.o \
+  chmod.o chown.o chroot.o close.o fsync.o closedir.o connect.o cst2constr.o \
   cstringv.o dup.o dup2.o envir.o errmsg.o execv.o execve.o execvp.o exit.o \
   fchmod.o fchown.o fcntl.o fork.o ftruncate.o \
   getaddrinfo.o getcwd.o getegid.o geteuid.o getgid.o \
diff --git a/otherlibs/unix/fsync.c b/otherlibs/unix/fsync.c
new file mode 100644
index 0000000000..48e9f19665
--- /dev/null
+++ b/otherlibs/unix/fsync.c
@@ -0,0 +1,35 @@
+/**************************************************************************/
+/*                                                                        */
+/*                                 OCaml                                  */
+/*                                                                        */
+/*             Francois Berenger, Kyushu Institute of Technology          */
+/*                                                                        */
+/*   Copyright 2018 Institut National de Recherche en Informatique et     */
+/*     en Automatique.                                                    */
+/*                                                                        */
+/*   All rights reserved.  This file is distributed under the terms of    */
+/*   the GNU Lesser General Public License version 2.1, with the          */
+/*   special exception on linking described in the file LICENSE.          */
+/*                                                                        */
+/**************************************************************************/
+
+#include <caml/mlvalues.h>
+#include <caml/signals.h>
+#include "unixsupport.h"
+
+#ifdef _WIN32
+#include <io.h>
+#define fsync(fd) _commit(win_CRT_fd_of_filedescr(fd))
+#else
+#define fsync(fd) fsync(Int_val(fd))
+#endif
+
+CAMLprim value unix_fsync(value fd)
+{
+  int ret;
+  caml_enter_blocking_section();
+  ret = fsync(fd);
+  caml_leave_blocking_section();
+  if (ret == -1) uerror("fsync", Nothing);
+  return Val_unit;
+}
diff --git a/otherlibs/unix/unix.ml b/otherlibs/unix/unix.ml
index 42110cce5c..dd1d770ff2 100644
--- a/otherlibs/unix/unix.ml
+++ b/otherlibs/unix/unix.ml
@@ -303,8 +303,8 @@ type file_perm = int
 
 external openfile : string -> open_flag list -> file_perm -> file_descr
            = "unix_open"
-
 external close : file_descr -> unit = "unix_close"
+external fsync : file_descr -> unit = "unix_fsync"
 external unsafe_read : file_descr -> bytes -> int -> int -> int
    = "unix_read"
 external unsafe_write : file_descr -> bytes -> int -> int -> int = "unix_write"
diff --git a/otherlibs/unix/unix.mli b/otherlibs/unix/unix.mli
index 6ef823f00a..78d60df704 100644
--- a/otherlibs/unix/unix.mli
+++ b/otherlibs/unix/unix.mli
@@ -307,6 +307,9 @@ val openfile : string -> open_flag list -> file_perm -> file_descr
 val close : file_descr -> unit
 (** Close a file descriptor. *)
 
+val fsync : file_descr -> unit
+(** Flush file buffers to disk. *)
+
 val read : file_descr -> bytes -> int -> int -> int
 (** [read fd buff ofs len] reads [len] bytes from descriptor [fd],
     storing them in byte sequence [buff], starting at position [ofs] in
diff --git a/otherlibs/win32unix/Makefile b/otherlibs/win32unix/Makefile
index 05732c60e9..53c9a3917b 100644
--- a/otherlibs/win32unix/Makefile
+++ b/otherlibs/win32unix/Makefile
@@ -34,7 +34,7 @@ UNIX_FILES = access.c addrofstr.c chdir.c chmod.c cst2constr.c \
   exit.c getaddrinfo.c getcwd.c gethost.c gethostname.c \
   getnameinfo.c getproto.c \
   getserv.c gmtime.c mmap_ba.c putenv.c rmdir.c \
-  socketaddr.c strofaddr.c time.c unlink.c
+  socketaddr.c strofaddr.c time.c unlink.c fsync.c
 
 UNIX_CAML_FILES = unix.mli unixLabels.mli unixLabels.ml
 
diff --git a/otherlibs/win32unix/unix.ml b/otherlibs/win32unix/unix.ml
index f51f52d433..a2d8dde199 100644
--- a/otherlibs/win32unix/unix.ml
+++ b/otherlibs/win32unix/unix.ml
@@ -182,6 +182,7 @@ type file_perm = int
 external openfile : string -> open_flag list -> file_perm -> file_descr
            = "unix_open"
 external close : file_descr -> unit = "unix_close"
+external fsync : file_descr -> unit = "unix_fsync"
 external unsafe_read : file_descr -> bytes -> int -> int -> int
                      = "unix_read"
 external unsafe_write : file_descr -> bytes -> int -> int -> int