internal/syscall: New package

This package provides wrappers to OS system calls.
Minimal functionality that will be used to implement os and os/signal pacakges.

/reviewed-on nexedi/pygolang!17

MANIFEST.in

@@ -6,6 +6,8 @@ include golang/pyx/runtime.h
 include golang/pyx/runtime.cpp
 include golang/pyx/testprog/golang_dso_user/dsouser/dso.cpp
 include golang/runtime/internal.h
+include golang/runtime/internal/syscall.h
+include golang/runtime/internal/syscall.cpp
 include golang/context.h
 include golang/context.cpp
 include golang/cxx.h

golang/pyx/build.py

@@ -174,6 +174,7 @@ def _with_build_defaults(kw):   # -> (pygo, kw')
     dependv.extend(['%s/golang/%s' % (pygo, _) for _ in [
         'libgolang.h',
         'runtime/internal.h',
+        'runtime/internal/syscall.h',
         'context.h',
         'cxx.h',
         'errors.h',
@@ -207,6 +208,8 @@ def Extension(name, sources, **kw):
     dependv.extend(['%s/golang/%s' % (pygo, _) for _ in [
         '_golang.pxd',
         'runtime/_libgolang.pxd',
+        'runtime/internal/__init__.pxd',
+        'runtime/internal/syscall.pxd',
         '__init__.pxd',
         'context.pxd',
         '_context.pxd',

golang/runtime/internal/syscall.cpp

+// Copyright (C) 2021-2022  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 "golang/runtime/internal/syscall.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <string>
+
+
+// golang::internal::syscall::
+namespace golang {
+namespace internal {
+namespace syscall {
+
+// ---- Errno ----
+
+_Errno::_Errno() {}
+_Errno::~_Errno() {}
+void _Errno::incref() {
+    object::incref();
+}
+void _Errno::decref() {
+    if (__decref())
+        delete this;
+}
+
+error NewErrno(__Errno syserr) {
+    _Errno* _e = new _Errno();
+    _e->syserr = syserr;
+    return adoptref(static_cast<_error*>(_e));
+}
+
+string _Errno::Error() {
+    _Errno& e = *this;
+
+    char ebuf[128];
+#if __APPLE__
+    int x = ::strerror_r(-e.syserr, ebuf, sizeof(ebuf));
+    if (x == 0)
+        return string(ebuf);
+    return "unknown error " + std::to_string(-e.syserr);
+#else
+    char *estr = ::strerror_r(-e.syserr, ebuf, sizeof(ebuf));
+    return string(estr);
+#endif
+}
+
+
+// ---- syscalls ----
+// TODO better call syscalls directly, instead of calling libc wrappers and saving/restoring errno
+
+int Read(int fd, void *buf, size_t count) {
+    int save_errno = errno;
+    int n = ::read(fd, buf, count);
+    if (n < 0)
+        n = -errno;
+    errno = save_errno;
+    return n;
+}
+
+int Write(int fd, const void *buf, size_t count) {
+    int save_errno = errno;
+    int n = ::write(fd, buf, count);
+    if (n < 0)
+        n = -errno;
+    errno = save_errno;
+    return n;
+}
+
+__Errno Close(int fd) {
+    int save_errno = errno;
+    int err = ::close(fd);
+    if (err < 0)
+        err = -errno;
+    errno = save_errno;
+    return err;
+}
+
+__Errno Fcntl(int fd, int cmd, int arg) {
+    int save_errno = errno;
+    int err = ::fcntl(fd, cmd, arg);
+    if (err < 0)
+        err = -errno;
+    errno = save_errno;
+    return err;
+}
+
+__Errno Fstat(int fd, struct ::stat *out_st) {
+    int save_errno = errno;
+    int err = ::fstat(fd, out_st);
+    if (err < 0)
+        err = -errno;
+    errno = save_errno;
+    return err;
+}
+
+int Open(const char *path, int flags, mode_t mode) {
+    int save_errno = errno;
+    int fd = ::open(path, flags, mode);
+    if (fd < 0)
+        fd = -errno;
+    errno = save_errno;
+    return fd;
+}
+
+__Errno Pipe(int vfd[2]) {
+    int save_errno = errno;
+    int err = ::pipe(vfd);
+    if (err == -1)
+        err = -errno;
+    errno = save_errno;
+    return err;
+}
+
+__Errno Sigaction(int signo, const struct ::sigaction *act, struct ::sigaction *oldact) {
+    int save_errno = errno;
+    int err = ::sigaction(signo, act, oldact);
+    if (err < 0)
+        err = -errno;
+    errno = save_errno;
+    return err;
+}
+
+
+}}} // golang::internal::syscall::

golang/runtime/internal/syscall.h

+#ifndef _NXD_LIBGOLANG_RUNTIME_INTERNAL_SYSCALL_H
+#define _NXD_LIBGOLANG_RUNTIME_INTERNAL_SYSCALL_H
+
+// Copyright (C) 2021-2022  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.
+
+// Package syscall provides low-level interface to OS.
+
+#include "golang/libgolang.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <signal.h>
+
+
+// golang::internal::syscall::
+namespace golang {
+namespace internal {
+namespace syscall {
+
+// errors returned by system calls are represented as negative error codes, for example -ENOENT.
+// Those error codes could be converted to error via NewErrno.
+typedef int __Errno;
+struct _Errno final : _error, object {
+    __Errno syserr;
+
+private:
+    _Errno();
+    ~_Errno();
+    friend error NewErrno(__Errno syserr);
+public:
+    void incref();
+    void decref();
+
+public:
+    // Error returns string corresponding to system error syserr.
+    string Error();
+};
+typedef refptr<_Errno> Errno;
+
+error NewErrno(__Errno syserr); // TODO better return Errno directly.
+
+// system calls
+
+int/*n|err*/ Read(int fd, void *buf, size_t count);
+int/*n|err*/ Write(int fd, const void *buf, size_t count);
+
+__Errno Close(int fd);
+__Errno Fcntl(int fd, int cmd, int arg);
+__Errno Fstat(int fd, struct ::stat *out_st);
+int/*fd|err*/ Open(const char *path, int flags, mode_t mode);
+__Errno Pipe(int vfd[2]);
+__Errno Sigaction(int signo, const struct ::sigaction *act, struct ::sigaction *oldact);
+
+
+}}} // golang::internal::syscall::
+
+#endif  // _NXD_LIBGOLANG_RUNTIME_INTERNAL_SYSCALL_H

golang/runtime/internal/syscall.pxd

+# cython: language_level=2
+# Copyright (C) 2021-2022  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.
+
+from posix.fcntl cimport mode_t
+from posix.stat cimport struct_stat
+
+cdef extern from "golang/runtime/internal/syscall.h" namespace "golang::internal::syscall" nogil:
+    int Close(int fd)
+    int Fcntl(int fd, int cmd, int arg)
+    int Fstat(int fd, struct_stat *out_st)
+    int Open(const char *path, int flags, mode_t mode)
+    int Read(int fd, void *buf, size_t count)
+    int Write(int fd, const void *buf, size_t count)

setup.py

@@ -197,6 +197,7 @@ setup(
 
     x_dsos      = [DSO('golang.runtime.libgolang',
                         ['golang/runtime/libgolang.cpp',
+                         'golang/runtime/internal/syscall.cpp',
                          'golang/context.cpp',
                          'golang/errors.cpp',
                          'golang/fmt.cpp',
@@ -207,6 +208,7 @@ setup(
                         depends = [
                             'golang/libgolang.h',
                             'golang/runtime/internal.h',
+                            'golang/runtime/internal/syscall.h',
                             'golang/context.h',
                             'golang/cxx.h',
                             'golang/errors.h',