libgolang: Provide custom bzero, mode_t and unistd.h on MSVC

We need unistd.h because e.g. `cimport posix.stat` forces inclusion of unistd.h
even if we use part of posix.stat that is available everywhere.

We use bzero in libgolang.cpp - provide it in similar way via compat
strings.h because on windows there is only string.h (no "s" in the end).

We also use mode_t in several places - provide it via typedef in
libgolang.h directly, because fcntl.h is present on MSVC.

MANIFEST.in

@@ -34,6 +34,8 @@ include golang/sync_test.cpp
 include golang/time.h
 include golang/time.cpp
 include golang/_testing.h
+include golang/_compat/windows/strings.h
+include golang/_compat/windows/unistd.h
 recursive-include golang    *.py *.pxd *.pyx *.toml *.txt*
 recursive-include gpython   *.py
 recursive-include 3rdparty  *.h

golang/_compat/windows/strings.h

+#ifndef _NXD_LIBGOLANG_COMPAT_WIN_STRINGS_H
+#define _NXD_LIBGOLANG_COMPAT_WIN_STRINGS_H
+//
+// Copyright (C) 2023  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+#include <string.h>
+
+static inline void bzero(void *p, size_t n) {
+    memset(p, '\0', n);
+}
+
+#endif  // _NXD_LIBGOLANG_COMPAT_WIN_STRINGS_H
+

golang/_compat/windows/unistd.h

+#ifndef _NXD_LIBGOLANG_COMPAT_WIN_UNISTD_H
+#define _NXD_LIBGOLANG_COMPAT_WIN_UNISTD_H
+//
+// Copyright (C) 2023  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+// stub unistd.h to be used on Windows where it is absent.
+// we need this because e.g. `cimport posix.stat` forces inclusion of unistd.h
+// even if we use part of posix.stat that is available everywhere.
+
+#include <io.h>
+
+#endif  // _NXD_LIBGOLANG_COMPAT_WIN_UNISTD_H

golang/libgolang.h

@@ -176,6 +176,12 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
+#include <fcntl.h>
+#ifdef _MSC_VER // no mode_t on msvc
+typedef int mode_t;
+#endif
+
+
 // DSO symbols visibility (based on https://gcc.gnu.org/wiki/Visibility)
 #if defined _WIN32 || defined __CYGWIN__
   #define LIBGOLANG_DSO_EXPORT __declspec(dllexport)

golang/pyx/build.py

@@ -169,9 +169,11 @@ def _with_build_defaults(name, kw):   # -> (pygo, kw')
     win  = (sysname == 'windows')
     msvc = win  # TODO also support mingw ?
 
-    # prepend -I<pygolang> so that e.g. golang/libgolang.h is found
+    # prepend   -I<pygolang> so that e.g. golang/libgolang.h is found
+    # same with -I<pygolang>/golang/_compat/<os>
     incv = kw.get('include_dirs', [])[:]
     incv.insert(0, pygo)
+    incv.insert(1, join(pygo, 'golang', '_compat', sysname))
     kw['include_dirs'] = incv
 
     # link with libgolang.so  if it is not libgolang itself
@@ -225,6 +227,8 @@ def _with_build_defaults(name, kw):   # -> (pygo, kw')
         'os/signal.h',
         'pyx/runtime.h',
         '_testing.h',
+        '_compat/windows/strings.h',
+        '_compat/windows/unistd.h',
     ]])
     kw['depends'] = dependv
 

golang/runtime/libgolang.cpp

-// Copyright (C) 2018-2022  Nexedi SA and Contributors.
+// Copyright (C) 2018-2023  Nexedi SA and Contributors.
 //                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
@@ -43,6 +43,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 
 // linux/list.h needs ARRAY_SIZE    XXX -> better use c.h or ccan/array_size.h ?
 #ifndef ARRAY_SIZE