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Richard W.M. Jones

2020-Mar-17 21:20 UTC

[Libguestfs] [PATCH libnbd v2 0/3] Unfinished golang bindings.

These bindings get as far as running very simple connections.
However there are many missing parts still:

* No callbacks.

* No functions which handle buffers (pread/pwrite!)

This is posted just for general early interest, not even for review.

Rich.

Richard W.M. Jones

2020-Mar-17 21:20 UTC

head link

[Libguestfs] [PATCH libnbd v2 1/3] generator: Modify C.print_* with optional parens flag.

Controls whether or not we print the parentheses around the function
parameters.
---
 generator/C.ml  | 26 ++++++++++++++------------
 generator/C.mli |  5 +++--
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/generator/C.ml b/generator/C.ml
index e79ac42..568e3f1 100644
--- a/generator/C.ml
+++ b/generator/C.ml
@@ -96,16 +96,17 @@ let rec name_of_arg = function
 | UInt32 n -> [n]
 | UInt64 n -> [n]
 
-let rec print_arg_list ?(wrap = false) ?maxcol ?handle ?types args optargs - 
pr "(";
+let rec print_arg_list ?(wrap = false) ?maxcol ?handle ?types ?(parens = true)
+          args optargs +  if parens then pr "(";
   if wrap then
     pr_wrap ?maxcol ','
-      (fun () -> print_arg_list_no_parens ?handle ?types args optargs)
+      (fun () -> print_arg_list' ?handle ?types args optargs)
   else
-    print_arg_list_no_parens ?handle ?types args optargs;
-  pr ")"
+    print_arg_list' ?handle ?types args optargs;
+  if parens then pr ")"
 
-and print_arg_list_no_parens ?(handle = false) ?(types = true) args optargs
+and print_arg_list' ?(handle = false) ?(types = true) args optargs    let
comma = ref false in
   if handle then (
     comma := true;
@@ -191,16 +192,17 @@ let print_extern ?wrap name args optargs ret    print_call
?wrap name args optargs ret;
   pr ";\n"
 
-let rec print_cbarg_list ?(wrap = false) ?maxcol ?types cbargs -  pr
"(";
+let rec print_cbarg_list ?(wrap = false) ?maxcol ?types ?(parens = true)
+          cbargs +  if parens then pr "(";
   if wrap then
     pr_wrap ?maxcol ','
-      (fun () -> print_cbarg_list_no_parens ?types cbargs)
+      (fun () -> print_cbarg_list' ?types cbargs)
   else
-    print_cbarg_list_no_parens ?types cbargs;
-  pr ")"
+    print_cbarg_list' ?types cbargs;
+  if parens then pr ")"
 
-and print_cbarg_list_no_parens ?(types = true) cbargs +and
print_cbarg_list' ?(types = true) cbargs    if types then pr "void
*";
   pr "user_data";
 
diff --git a/generator/C.mli b/generator/C.mli
index 7748bc7..c8268c1 100644
--- a/generator/C.mli
+++ b/generator/C.mli
@@ -25,9 +25,10 @@ val generate_docs_api_links_pod : unit -> unit
 val generate_docs_api_flag_links_pod : unit -> unit
 val generate_docs_nbd_pod : string -> API.call -> unit -> unit
 val print_arg_list : ?wrap:bool -> ?maxcol:int ->
-                     ?handle:bool -> ?types:bool ->
+                     ?handle:bool -> ?types:bool -> ?parens:bool ->
                      API.arg list -> API.optarg list -> unit
-val print_cbarg_list : ?wrap:bool -> ?maxcol:int -> ?types:bool ->
+val print_cbarg_list : ?wrap:bool -> ?maxcol:int ->
+                       ?types:bool -> ?parens:bool ->
                        API.cbarg list -> unit
 val errcode_of_ret : API.ret -> string option
 val type_of_ret : API.ret -> string
-- 
2.25.0

Richard W.M. Jones

2020-Mar-17 21:20 UTC

head link

[Libguestfs] [PATCH libnbd v2 2/3] Add outline framework for Go language bindings (golang).

This simply compiles, passes tests, but is only able open a handle.
This commit does not contain the full bindings.
---
 Makefile.am                                   |   2 +
 configure.ac                                  |  32 ++++
 generator/GoLang.ml                           | 150 ++++++++++++++++++
 generator/GoLang.mli                          |  19 +++
 generator/Makefile.am                         |   2 +
 generator/generator.ml                        |   3 +
 golang/Makefile.am                            |  58 +++++++
 golang/config-test.go                         |  34 ++++
 golang/examples/LICENSE-FOR-EXAMPLES          |  38 +++++
 golang/examples/Makefile.am                   |  21 +++
 golang/run-tests.sh                           |  24 +++
 golang/src/libguestfs.org/libnbd/.gitignore   |   1 +
 .../libnbd/libnbd_010_load_test.go            |  25 +++
 .../libnbd/libnbd_100_handle_test.go          |  29 ++++
 run.in                                        |  17 ++
 15 files changed, 455 insertions(+)

diff --git a/Makefile.am b/Makefile.am
index bf2db68..a9f13ca 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -43,6 +43,8 @@ SUBDIRS = \
 	ocaml \
 	ocaml/examples \
 	ocaml/tests \
+	golang \
+	golang/examples \
 	interop \
 	fuzzing \
 	bash \
diff --git a/configure.ac b/configure.ac
index 9fd284b..36617fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -403,6 +403,34 @@ AS_IF([test "x$enable_python" !=
"xno"],[
 AM_CONDITIONAL([HAVE_PYTHON],
     [test "x$PYTHON" != "xno" && test
"x$have_python_module" = "x1" ])
 
+dnl Golang.
+AC_ARG_ENABLE([golang],
+    AS_HELP_STRING([--disable-golang], [disable Go language bindings]),
+        [],
+        [enable_golang=yes])
+AS_IF([test "x$enable_golang" != "xno"],[
+    AC_CHECK_PROG([GOLANG],[go],[go],[no])
+    AS_IF([test "x$GOLANG" != "xno"],[
+        AC_MSG_CHECKING([if $GOLANG is usable])
+        AS_IF([$GOLANG run $srcdir/golang/config-test.go
2>&AS_MESSAGE_LOG_FD],[
+            AC_MSG_RESULT([yes])
+
+            # Substitute some golang environment.
+            GOOS=`$GOLANG env GOOS`
+            GOARCH=`$GOLANG env GOARCH`
+            GOROOT=`$GOLANG env GOROOT`
+            AC_SUBST([GOOS])
+            AC_SUBST([GOARCH])
+            AC_SUBST([GOROOT])
+        ],[
+            AC_MSG_RESULT([no])
+            AC_MSG_WARN([golang ($GOLANG) is installed but not usable])
+            GOLANG=no
+        ])
+    ])
+],[GOLANG=no])
+AM_CONDITIONAL([HAVE_GOLANG],[test "x$GOLANG" != "xno"])
+
 dnl Produce output files.
 AC_CONFIG_HEADERS([config.h])
 
@@ -423,6 +451,8 @@ AC_CONFIG_FILES([Makefile
                  fuse/Makefile
                  fuzzing/Makefile
                  generator/Makefile
+                 golang/Makefile
+                 golang/examples/Makefile
                  include/Makefile
                  interop/Makefile
                  lib/Makefile
@@ -472,6 +502,8 @@ feature "Bash tab completion ....................
" \
 echo
 echo "Language bindings:"
 echo
+feature "Go ..................................... " \
+        test "x$HAVE_GOLANG_TRUE" = "x"
 feature "OCaml .................................. " \
         test "x$HAVE_OCAML_TRUE" = "x"
 feature "Python ................................. " \
diff --git a/generator/GoLang.ml b/generator/GoLang.ml
new file mode 100644
index 0000000..1b8f20b
--- /dev/null
+++ b/generator/GoLang.ml
@@ -0,0 +1,150 @@
+(* nbd client library in userspace: generator
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *)
+
+(* Go language bindings. *)
+
+open Printf
+
+open API
+open Utils
+
+let generate_golang_libnbd_go () +  generate_header CStyle;
+
+  pr "\
+package libnbd
+
+/*
+#cgo CFLAGS:
+#cgo LDFLAGS: -lnbd
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include \"libnbd.h\"
+
+struct error {
+  char *error;
+  int errnum;
+};
+
+static void
+save_error (struct error *err)
+{
+  err->error = strdup (nbd_get_error ());
+  err->errnum = nbd_get_errno ();
+}
+
+static void
+free_error (struct error *err)
+{
+  free (err->error);
+}
+
+static struct nbd_handle *
+_nbd_create_wrapper (struct error *err)
+{
+  struct nbd_handle *r;
+
+  r = nbd_create ();
+  if (r == NULL)
+    save_error (err);
+  return r;
+}
+
+// There must be no blank line between end comment and import!
+// https://github.com/golang/go/issues/9733
+*/
+import \"C\"
+
+import (
+    \"fmt\"
+    \"runtime\"
+    \"syscall\"
+)
+
+/* Handle. */
+type Libnbd struct {
+    h *C.struct_nbd_handle
+}
+
+/* Convert handle to string (just for debugging). */
+func (h *Libnbd) String () string {
+    return \"&Libnbd{}\"
+}
+
+/* All functions (except Close) return ([result,] LibnbdError). */
+type LibnbdError struct {
+    Op string                // operation which failed
+    Errmsg string            // string (nbd_get_error)
+    Errno syscall.Errno      // errno (nbd_get_errno)
+}
+
+func (e *LibnbdError) String() string {
+    if e.Errno != 0 {
+        return fmt.Sprintf (\"%%s: %%s\", e.Op, e.Errmsg);
+    } else {
+        return fmt.Sprintf (\"%%s: %%s: %%s\", e.Op, e.Errmsg,
e.Errno);
+    }
+}
+
+/* Implement the error interface */
+func (e *LibnbdError) Error() string {
+     return e.String()
+}
+
+func get_error (op string, c_err C.struct_error) *LibnbdError {
+    errmsg := C.GoString (c_err.error)
+    errno := syscall.Errno (c_err.errnum)
+    return &LibnbdError{ Op : op, Errmsg : errmsg, Errno : errno }
+}
+
+func closed_handle_error (op string) *LibnbdError {
+    return &LibnbdError{ Op : op, Errmsg : \"handle is closed\",
+                         Errno : syscall.Errno (0) }
+}
+
+/* Create a new handle. */
+func Create () (*Libnbd, error) {
+    c_err := C.struct_error{}
+    c_h := C._nbd_create_wrapper (&c_err)
+    if c_h == nil {
+        err := get_error (\"create\", c_err)
+        C.free_error (&c_err)
+        return nil, err
+    }
+    h := &Libnbd{h : c_h}
+    // Finalizers aren't guaranteed to run, but try having one anyway ...
+    runtime.SetFinalizer (h, (*Libnbd).Close)
+    return h, nil
+}
+
+/* Close the handle. */
+func (h *Libnbd) Close () *LibnbdError {
+    if h.h == nil {
+        return closed_handle_error (\"close\")
+    }
+    C.nbd_close (h.h)
+    h.h = nil
+    return nil
+}
+
+";
diff --git a/generator/GoLang.mli b/generator/GoLang.mli
new file mode 100644
index 0000000..b8ec1b5
--- /dev/null
+++ b/generator/GoLang.mli
@@ -0,0 +1,19 @@
+(* nbd client library in userspace: generator
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *)
+
+val generate_golang_libnbd_go : unit -> unit
diff --git a/generator/Makefile.am b/generator/Makefile.am
index e499ca8..0389d70 100644
--- a/generator/Makefile.am
+++ b/generator/Makefile.am
@@ -57,6 +57,8 @@ sources = \
 	Python.ml \
 	OCaml.mli \
 	OCaml.ml \
+	GoLang.mli \
+	GoLang.ml \
 	generator.ml \
 	$(NULL)
 
diff --git a/generator/generator.ml b/generator/generator.ml
index 1c97492..817c032 100755
--- a/generator/generator.ml
+++ b/generator/generator.ml
@@ -55,3 +55,6 @@ let ()    output_to "ocaml/NBD.mli"
OCaml.generate_ocaml_nbd_mli;
   output_to "ocaml/NBD.ml" OCaml.generate_ocaml_nbd_ml;
   output_to "ocaml/nbd-c.c" OCaml.generate_ocaml_nbd_c;
+
+  output_to "golang/src/libguestfs.org/libnbd/libnbd.go"
+    GoLang.generate_golang_libnbd_go;
diff --git a/golang/Makefile.am b/golang/Makefile.am
new file mode 100644
index 0000000..47234ff
--- /dev/null
+++ b/golang/Makefile.am
@@ -0,0 +1,58 @@
+# nbd client library in userspace
+# Copyright (C) 2013-2020 Red Hat Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+include $(top_srcdir)/subdir-rules.mk
+
+# http://golang.org/doc/code.html#Organization
+pkg = libguestfs.org/libnbd
+
+source_files = \
+	src/$(pkg)/libnbd.go \
+	src/$(pkg)/libnbd_*_test.go
+
+generator_built = \
+	$(source_files)
+
+EXTRA_DIST = \
+	src/$(pkg)/.gitignore \
+	$(generator_built) \
+	config-test.go \
+	run-tests.sh
+
+if HAVE_GOLANG
+
+golangpkgdir = $(GOROOT)/pkg/$(GOOS)_$(GOARCH)/$(pkg)
+golangsrcdir = $(GOROOT)/src/pkg/$(pkg)
+
+golangpkg_DATA = \
+	pkg/$(GOOS)_$(GOARCH)/$(pkg).a
+
+pkg/$(GOOS)_$(GOARCH)/$(pkg).a: src/$(pkg)/libnbd.go
+	$(top_builddir)/run $(GOLANG) install $(pkg)
+
+golangsrc_DATA = $(source_files)
+
+TESTS_ENVIRONMENT = pkg=$(pkg) LIBNBD_DEBUG=1
+LOG_COMPILER = $(top_builddir)/run
+TESTS = run-tests.sh
+
+endif
+
+CLEANFILES += src/$(pkg)/*~
+
+clean-local:
+	rm -rf pkg
diff --git a/golang/config-test.go b/golang/config-test.go
new file mode 100644
index 0000000..e104c71
--- /dev/null
+++ b/golang/config-test.go
@@ -0,0 +1,34 @@
+/* libnbd Go configuration test
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/* This is called from ./configure to check that golang works
+ * and is above the minimum required version.
+ */
+
+package main
+
+func main() {
+	/* XXX Check for minimum runtime.Version() >= "go1.1.1"
+         * Unfortunately go version numbers are not easy to parse.
+         * They have the 3 formats "goX.Y.Z", "release.rN"
or
+         * "weekly.YYYY-MM-DD".  The latter two formats are mostly
+         * useless, and the first one is hard to parse.  See also
+         * cmpGoVersion in
+         *
http://web.archive.org/web/20130402235148/http://golang.org/src/cmd/go/get.go?m=text
+         */
+}
diff --git a/golang/examples/LICENSE-FOR-EXAMPLES
b/golang/examples/LICENSE-FOR-EXAMPLES
new file mode 100644
index 0000000..4986466
--- /dev/null
+++ b/golang/examples/LICENSE-FOR-EXAMPLES
@@ -0,0 +1,38 @@
+The files in the golang/examples/ directory are licensed under this
+very permissive BSD license.  This means that you can copy, use, adapt
+and modify them without any significant restrictions.  You can also
+combine them with proprietary code or include them in code that is
+distributed under other open source licenses.
+
+----------------------------------------------------------------------
+
+libnbd examples
+Copyright (C) 2013-2020 Red Hat Inc.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+* Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+* Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS''
AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/golang/examples/Makefile.am b/golang/examples/Makefile.am
new file mode 100644
index 0000000..90498ab
--- /dev/null
+++ b/golang/examples/Makefile.am
@@ -0,0 +1,21 @@
+# nbd client library in userspace
+# Copyright (C) 2013-2020 Red Hat Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+include $(top_srcdir)/subdir-rules.mk
+
+EXTRA_DIST = \
+	LICENSE-FOR-EXAMPLES
diff --git a/golang/run-tests.sh b/golang/run-tests.sh
new file mode 100755
index 0000000..a155819
--- /dev/null
+++ b/golang/run-tests.sh
@@ -0,0 +1,24 @@
+#!/bin/sh -
+# nbd client library in userspace
+# Copyright (C) 2013-2020 Red Hat Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+set -e
+
+# The -count=1 parameter is the "idiomatic way to bypass test
caching".
+# https://golang.org/doc/go1.10#test
+# The -v option enables verbose output.
+$GOLANG test -count=1 -v $pkg
diff --git a/golang/src/libguestfs.org/libnbd/.gitignore
b/golang/src/libguestfs.org/libnbd/.gitignore
new file mode 100644
index 0000000..a2ce7eb
--- /dev/null
+++ b/golang/src/libguestfs.org/libnbd/.gitignore
@@ -0,0 +1 @@
+/libnbd.go
diff --git a/golang/src/libguestfs.org/libnbd/libnbd_010_load_test.go
b/golang/src/libguestfs.org/libnbd/libnbd_010_load_test.go
new file mode 100644
index 0000000..24cfe66
--- /dev/null
+++ b/golang/src/libguestfs.org/libnbd/libnbd_010_load_test.go
@@ -0,0 +1,25 @@
+/* libnbd golang tests
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
USA.
+ */
+
+package libnbd
+
+import "testing"
+
+func Test010Load (t *testing.T) {
+	/* Nothing - just test that the library can be linked to. */
+}
diff --git a/golang/src/libguestfs.org/libnbd/libnbd_100_handle_test.go
b/golang/src/libguestfs.org/libnbd/libnbd_100_handle_test.go
new file mode 100644
index 0000000..a3d933d
--- /dev/null
+++ b/golang/src/libguestfs.org/libnbd/libnbd_100_handle_test.go
@@ -0,0 +1,29 @@
+/* libnbd golang tests
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
USA.
+ */
+
+package libnbd
+
+import "testing"
+
+func Test100Handle (t *testing.T) {
+	h, err := Create ()
+	if err != nil {
+		t.Errorf ("could not create handle: %s", err)
+	}
+	h.Close ()
+}
diff --git a/run.in b/run.in
index 0411c85..9ffece5 100755
--- a/run.in
+++ b/run.in
@@ -78,6 +78,23 @@ export PYTHONPATH
 prepend CAML_LD_LIBRARY_PATH "$b/ocaml"
 export CAML_LD_LIBRARY_PATH
 
+# For golang.
+export GOLANG="@GOLANG@"
+prepend GOPATH "$b/golang"
+export GOPATH
+if [ -z "$CGO_CFLAGS" ]; then
+    CGO_CFLAGS="-I$s/include -I$b"
+else
+    CGO_CFLAGS="$CGO_CFLAGS -I$s/include -I$b"
+fi
+export CGO_CFLAGS
+if [ -z "$CGO_LDFLAGS" ]; then
+    CGO_LDFLAGS="-L$b/lib/.libs"
+else
+    CGO_LDFLAGS="$CGO_LDFLAGS -L$b/lib/.libs"
+fi
+export CGO_LDFLAGS
+
 # This is a cheap way to find some use-after-free and uninitialized
 # read problems when using glibc.
 export MALLOC_CHECK_=1
-- 
2.25.0

Richard W.M. Jones

2020-Mar-17 21:20 UTC

head link

[Libguestfs] [PATCH libnbd v2 3/3] golang: Add straightforward bindings, without callbacks.

---
 generator/GoLang.ml                           | 336 +++++++++++++++++-
 .../libnbd/libnbd_200_connect_command_test.go |  35 ++
 2 files changed, 367 insertions(+), 4 deletions(-)

diff --git a/generator/GoLang.ml b/generator/GoLang.ml
index 1b8f20b..e5fb97c 100644
--- a/generator/GoLang.ml
+++ b/generator/GoLang.ml
@@ -23,6 +23,304 @@ open Printf
 open API
 open Utils
 
+let go_name_of_arg = function
+  | Bool n -> n
+  | BytesIn (n, len) -> n
+  | BytesOut (n, len) -> n
+  | BytesPersistIn (n, len) -> n
+  | BytesPersistOut (n, len) -> n
+  | Closure { cbname } -> cbname
+  | Enum (n, _) -> n
+  | Fd n -> n
+  | Flags (n, _) -> n
+  | Int n -> n
+  | Int64 n -> n
+  | Path n -> n
+  | SockAddrAndLen (n, len) -> n
+  | String n -> n
+  | StringList n -> n
+  | UInt n -> n
+  | UInt32 n -> n
+  | UInt64 n -> n
+
+let go_arg_type_to_string = function
+  | Bool _ -> "bool"
+  | BytesIn _ -> "*string/*XXX*/"
+  | BytesPersistIn _ -> "*string/*XXX*/"
+  | BytesOut _ -> "*string/*XXX*/"
+  | BytesPersistOut _ -> "*string/*XXX*/"
+  | Closure { cbargs } -> "func (/*XXX*/)"
+  | Enum _ -> "uint32"
+  | Fd _ -> "int/*XXX*/"
+  | Flags _ -> "uint32"
+  | Int _ -> "int"
+  | Int64 _ -> "int64"
+  | Path _ -> "string"
+  | SockAddrAndLen _ -> "string"
+  | String _ -> "string"
+  | StringList _ -> "[]string"
+  | UInt _ -> "uint"
+  | UInt32 _ -> "uint32"
+  | UInt64 _ -> "uint64"
+
+let go_name_of_optarg = function
+  | OClosure { cbname } -> String.capitalize_ascii cbname
+  | OFlags (n, _) -> String.capitalize_ascii n
+
+(* For consistency every method will return (type, error) where
+ * type is defined by this function.  However some functions
+ * never really have a type (RErr) and others never really have
+ * an error (RUInt).
+ *)
+let go_ret_type = function
+  | RBool -> "bool"
+  | RStaticString -> "*string"
+  | RErr -> "int" (* always 0 *)
+  | RFd -> "int/*XXX*/"
+  | RInt -> "int"
+  | RInt64 -> "int64"
+  | RCookie -> "int64"
+  | RString -> "*string"
+  | RUInt -> "uint"
+
+let go_ret_error = function
+  | RBool -> "false"
+  | RStaticString -> "nil"
+  | RErr -> "0"
+  | RFd -> "0/*XXX*/"
+  | RInt -> "0"
+  | RInt64 -> "0"
+  | RCookie -> "0"
+  | RString -> "nil"
+  | RUInt -> "0"
+
+let go_ret_c_errcode = function
+  | RBool -> Some "-1"
+  | RStaticString -> Some "nil"
+  | RErr -> Some "-1"
+  | RFd -> Some "-1/*XXX*/"
+  | RInt -> Some "-1"
+  | RInt64 -> Some "-1"
+  | RCookie -> Some "-1"
+  | RString -> Some "nil"
+  | RUInt -> None
+
+(* We need a wrapper around every function (except Close) to
+ * handle errors because cgo calls are sequence points and
+ * could result in us being rescheduled on another thread,
+ * but libnbd error handling means we must call nbd_get_error
+ * etc from the same thread.
+ *)
+let print_wrapper (name, { args; optargs; ret }) +  let ret_c_type =
C.type_of_ret ret and errcode = C.errcode_of_ret ret in
+  pr "static %s\n" ret_c_type;
+  pr "_nbd_%s_wrapper (struct error *err,\n" name;
+  pr "        ";
+  C.print_arg_list ~wrap:true ~handle:true ~parens:false args optargs;
+  pr ")\n";
+  pr "{\n";
+  pr "  %s ret;\n" ret_c_type;
+  pr "\n";
+  pr "  ret = nbd_%s " name;
+  C.print_arg_list ~wrap:true ~handle:true ~types:false args optargs;
+  pr ";\n";
+  (match errcode with
+   | None -> ()
+   | Some errcode ->
+      pr "  if (ret == %s)\n" errcode;
+      pr "    save_error (err);\n";
+  );
+  pr "  return ret;\n";
+  pr "}\n";
+  pr "\n"
+
+let print_binding (name, { args; optargs; ret; shortdesc }) +  let uname =
String.capitalize_ascii name in
+
+  (* Tedious method of passing optional arguments in golang. *)
+  if optargs <> [] then (
+    pr "/* Struct carrying optional arguments for %s. */\n" uname;
+    pr "type Optargs_%s struct {\n" uname;
+    List.iter (
+      fun optarg ->
+        let fname = go_name_of_optarg optarg in
+        pr "  /* %s field is ignored unless %s_is_set == true. */\n"
+          fname fname;
+        pr "  %s_is_set bool\n" fname;
+        pr "  %s " fname;
+        (match optarg with
+         | OClosure { cbargs } -> pr "func (/*XXX*/)"
+         | OFlags _ -> pr "uint32"
+        );
+        pr "\n"
+    ) optargs;
+    pr "}\n";
+    pr "\n";
+  );
+
+  (* Define the golang function which calls the C wrapper. *)
+  pr "/* %s: %s */\n" uname shortdesc;
+  pr "func (h *Libnbd) %s (" uname;
+  let comma = ref false in
+  List.iter (
+    fun arg ->
+      if !comma then pr ", ";
+      comma := true;
+      pr "%s %s" (go_name_of_arg arg) (go_arg_type_to_string arg)
+  ) args;
+  if optargs <> [] then (
+    if !comma then pr ", ";
+    comma := true;
+    pr "optargs *Optargs_%s" uname
+  );
+  pr ") (%s, error)" (go_ret_type ret);
+  pr " {\n";
+  pr "    if h.h == nil {\n";
+  pr "        return %s, closed_handle_error (\"%s\")\n"
+    (go_ret_error ret) name;
+  pr "    }\n";
+  pr "\n";
+  pr "    c_err := C.struct_error{}\n";
+  List.iter (
+    function
+    | Bool n ->
+       pr "    c_%s := C.bool (%s)\n" n n
+    | BytesIn (n, len) ->
+       pr "    var c_%s unsafe.Pointer /* XXX */\n" n;
+       pr "    var c_%s C.size_t /* XXX */\n" len;
+    | BytesOut (n, len) ->
+       pr "    var c_%s unsafe.Pointer /* XXX */\n" n;
+       pr "    var c_%s C.size_t /* XXX */\n" len;
+    | BytesPersistIn (n, len) ->
+       pr "    var c_%s unsafe.Pointer /* XXX */\n" n;
+       pr "    var c_%s C.size_t /* XXX */\n" len;
+    | BytesPersistOut (n, len) ->
+       pr "    var c_%s unsafe.Pointer /* XXX */\n" n;
+       pr "    var c_%s C.size_t /* XXX */\n" len;
+    | Closure { cbname } ->
+       pr "    c_%s := C.nbd_%s_callback{} /* XXX */\n" cbname cbname
+    | Enum (n, _) ->
+       pr "    c_%s := C.int (%s)\n" n n
+    | Fd n ->
+       pr "    c_%s := C.int (%s) /* XXX */\n" n n
+    | Flags (n, _) ->
+       pr "    c_%s := C.uint32_t (%s)\n" n n
+    | Int n ->
+       pr "    c_%s := C.int (%s)\n" n n
+    | Int64 n ->
+       pr "    c_%s := C.int64_t (%s)\n" n n
+    | Path n ->
+       pr "    c_%s := C.CString (%s)\n" n n;
+       pr "    defer C.free (unsafe.Pointer (c_%s))\n" n
+    | SockAddrAndLen (n, len) ->
+       pr "    panic (\"SockAddrAndLen not supported\")\n";
+       pr "    var c_%s *C.struct_sockaddr\n" n;
+       pr "    var c_%s C.uint\n" len
+    | String n ->
+       pr "    c_%s := C.CString (%s)\n" n n;
+       pr "    defer C.free (unsafe.Pointer (c_%s))\n" n
+    | StringList n ->
+       pr "    c_%s := arg_string_list (%s)\n" n n;
+       pr "    defer free_string_list (c_%s)\n" n
+    | UInt n ->
+       pr "    c_%s := C.uint (%s)\n" n n
+    | UInt32 n ->
+       pr "    c_%s := C.uint32_t (%s)\n" n n
+    | UInt64 n ->
+       pr "    c_%s := C.uint64_t (%s)\n" n n
+  ) args;
+  if optargs <> [] then (
+    List.iter (
+      function
+      | OClosure { cbname } ->
+         pr "    c_%s := C.nbd_%s_callback{} /* XXX */\n" cbname
cbname
+      | OFlags (n, _) ->
+         pr "    var c_%s C.uint32_t\n" n
+    ) optargs;
+    pr "    if optargs != nil {\n";
+    List.iter (
+      fun optarg ->
+         pr "        if optargs.%s_is_set {\n" (go_name_of_optarg
optarg);
+         (match optarg with
+          | OClosure { cbname } -> () (* XXX *)
+          | OFlags (n, _) ->
+             pr "            c_%s = C.uint32_t (optargs.%s)\n"
+               n (go_name_of_optarg optarg);
+         );
+         pr "        }\n";
+    ) optargs;
+    pr "    }\n";
+  );
+  pr "\n";
+  pr "    ret := C._nbd_%s_wrapper (&c_err, h.h" name;
+  List.iter (
+    function
+    | Bool n -> pr ", c_%s" n
+    | BytesIn (n, len) -> pr ", c_%s, c_%s" n len
+    | BytesOut (n, len) ->  pr ", c_%s, c_%s" n len
+    | BytesPersistIn (n, len) ->  pr ", c_%s, c_%s" n len
+    | BytesPersistOut (n, len) ->  pr ", c_%s, c_%s" n len
+    | Closure { cbname } ->  pr ", c_%s" cbname
+    | Enum (n, _) -> pr ", c_%s" n
+    | Fd n -> pr ", c_%s" n
+    | Flags (n, _) -> pr ", c_%s" n
+    | Int n -> pr ", c_%s" n
+    | Int64 n -> pr ", c_%s" n
+    | Path n -> pr ", c_%s" n
+    | SockAddrAndLen (n, len) -> pr ", c_%s, c_%s" n len
+    | String n -> pr ", c_%s" n
+    | StringList n -> pr ", c_%s" n
+    | UInt n -> pr ", c_%s" n
+    | UInt32 n -> pr ", c_%s" n
+    | UInt64 n -> pr ", c_%s" n
+  ) args;
+  List.iter (
+    function
+    | OClosure { cbname} -> pr ", c_%s" cbname
+    | OFlags (n, _) -> pr ", c_%s" n
+  ) optargs;
+  pr ")\n";
+  let errcode = go_ret_c_errcode ret in
+  (match errcode with
+   | None -> ()
+   | Some errcode ->
+      pr "    if ret == %s {\n" errcode;
+      pr "        err := get_error (\"%s\", c_err)\n" name;
+      pr "        C.free_error (&c_err)\n";
+      pr "        return %s, err\n" (go_ret_error ret);
+      pr "    }\n";
+  );
+  (match ret with
+   | RBool ->
+      pr "    r := int (ret)\n";
+      pr "    if r != 0 { return true, nil } else { return false, nil
}\n"
+   | RStaticString ->
+      pr "    /* ret is statically allocated, do not free it. */\n";
+      pr "    r := C.GoString (ret);\n";
+      pr "    return &r, nil\n"
+   | RErr ->
+      pr "    /* Note that the return value 0 has no meaning
here.\n";
+      pr "     * It is only returned for consistency.\n";
+      pr "     */\n";
+      pr "    return 0, nil\n"
+   | RFd ->
+      pr "    return int/*XXX*/ (ret), nil\n"
+   | RInt ->
+      pr "    return int (ret), nil\n"
+   | RInt64 ->
+      pr "    return int64 (ret), nil\n"
+   | RCookie ->
+      pr "    return int64 (ret), nil\n"
+   | RString ->
+      pr "    r := C.GoString (ret)\n";
+      pr "    C.free (unsafe.Pointer (ret))\n";
+      pr "    return &r, nil\n"
+   | RUInt ->
+      pr "    return uint (ret), nil\n"
+  );
+  pr "}\n";
+  pr "\n"
+
 let generate_golang_libnbd_go ()    generate_header CStyle;
 
@@ -62,14 +360,20 @@ free_error (struct error *err)
 static struct nbd_handle *
 _nbd_create_wrapper (struct error *err)
 {
-  struct nbd_handle *r;
+  struct nbd_handle *ret;
 
-  r = nbd_create ();
-  if (r == NULL)
+  ret = nbd_create ();
+  if (ret == NULL)
     save_error (err);
-  return r;
+  return ret;
 }
 
+";
+
+  (* Wrappers. *)
+  List.iter print_wrapper handle_calls;
+
+  pr "\
 // There must be no blank line between end comment and import!
 // https://github.com/golang/go/issues/9733
 */
@@ -79,6 +383,7 @@ import (
     \"fmt\"
     \"runtime\"
     \"syscall\"
+    \"unsafe\"
 )
 
 /* Handle. */
@@ -147,4 +452,27 @@ func (h *Libnbd) Close () *LibnbdError {
     return nil
 }
 
+/* Functions for translating between NULL-terminated lists of
+ * C strings and golang []string.
+ */
+func arg_string_list (xs []string) **C.char {
+    r := make ([]*C.char, 1 + len (xs))
+    for i, x := range xs {
+        r[i] = C.CString (x)
+    }
+    r[len (xs)] = nil
+    return &r[0]
+}
+
+func free_string_list (argv **C.char) {
+    for *argv != nil {
+        //C.free (*argv)
+        argv = (**C.char) (unsafe.Pointer (uintptr (unsafe.Pointer (argv)) +
+                                           unsafe.Sizeof (*argv)))
+    }
+}
+
 ";
+
+  (* Bindings. *)
+  List.iter print_binding handle_calls;
diff --git a/golang/src/libguestfs.org/libnbd/libnbd_200_connect_command_test.go
b/golang/src/libguestfs.org/libnbd/libnbd_200_connect_command_test.go
new file mode 100644
index 0000000..9faf244
--- /dev/null
+++ b/golang/src/libguestfs.org/libnbd/libnbd_200_connect_command_test.go
@@ -0,0 +1,35 @@
+/* libnbd golang tests
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
USA.
+ */
+
+package libnbd
+
+import "testing"
+
+func Test200ConnectCommand (t *testing.T) {
+	h, err := Create ()
+	if err != nil {
+		t.Errorf ("could not create handle: %s", err)
+	}
+        _, err = h.Connect_command ([]string{
+            "nbdkit", "-s", "--exit-with-parent",
"-v", "null",
+        })
+        if err != nil {
+		t.Errorf ("could not connect: %s", err)
+        }
+	h.Close ()
+}
-- 
2.25.0

Daniel P. Berrangé

2020-Mar-18 09:32 UTC

head link

Re: [Libguestfs] [PATCH libnbd v2 2/3] Add outline framework for Go language bindings (golang).

On Tue, Mar 17, 2020 at 09:20:12PM +0000, Richard W.M. Jones
wrote:> +
> +/*
> +#cgo CFLAGS:
> +#cgo LDFLAGS: -lnbd
I assume you support pkg-config for libnbd, and thus you
should just do

#cgo pkg-config: libnbd

> +
> +#include <config.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +
> +#include \"libnbd.h\"
> +
> +struct error {
> +  char *error;
> +  int errnum;
> +};
> +
> +static void
> +save_error (struct error *err)
> +{
> +  err->error = strdup (nbd_get_error ());
> +  err->errnum = nbd_get_errno ();
> +}
> +
> +static void
> +free_error (struct error *err)
> +{
> +  free (err->error);
> +}
> +
> +static struct nbd_handle *
> +_nbd_create_wrapper (struct error *err)
> +{
> +  struct nbd_handle *r;
> +
> +  r = nbd_create ();
> +  if (r == NULL)
> +    save_error (err);
> +  return r;
> +}
> +
> +// There must be no blank line between end comment and import!
> +// https://github.com/golang/go/issues/9733
> +*/
> +import \"C\"
> +
> +import (
> +    \"fmt\"
> +    \"runtime\"
> +    \"syscall\"
> +)
> +
> +/* Handle. */
> +type Libnbd struct {
> +    h *C.struct_nbd_handle
> +}
> +
> +/* Convert handle to string (just for debugging). */
> +func (h *Libnbd) String () string {
> +    return \"&Libnbd{}\"
> +}
> +
> +/* All functions (except Close) return ([result,] LibnbdError). */
> +type LibnbdError struct {
> +    Op string                // operation which failed
> +    Errmsg string            // string (nbd_get_error)
> +    Errno syscall.Errno      // errno (nbd_get_errno)
> +}
> +
> +func (e *LibnbdError) String() string {
> +    if e.Errno != 0 {
> +        return fmt.Sprintf (\"%%s: %%s\", e.Op, e.Errmsg);
> +    } else {
> +        return fmt.Sprintf (\"%%s: %%s: %%s\", e.Op, e.Errmsg,
e.Errno);
> +    }
> +}
> +
> +/* Implement the error interface */
> +func (e *LibnbdError) Error() string {
> +     return e.String()
> +}
> +
> +func get_error (op string, c_err C.struct_error) *LibnbdError {
> +    errmsg := C.GoString (c_err.error)
> +    errno := syscall.Errno (c_err.errnum)
> +    return &LibnbdError{ Op : op, Errmsg : errmsg, Errno : errno }
> +}
> +
> +func closed_handle_error (op string) *LibnbdError {
> +    return &LibnbdError{ Op : op, Errmsg : \"handle is
closed\",
> +                         Errno : syscall.Errno (0) }
> +}
> +
> +/* Create a new handle. */
> +func Create () (*Libnbd, error) {
> +    c_err := C.struct_error{}
> +    c_h := C._nbd_create_wrapper (&c_err)
> +    if c_h == nil {
> +        err := get_error (\"create\", c_err)
> +        C.free_error (&c_err)
> +        return nil, err
> +    }
> +    h := &Libnbd{h : c_h}
> +    // Finalizers aren't guaranteed to run, but try having one anyway
...
> +    runtime.SetFinalizer (h, (*Libnbd).Close)
> +    return h, nil
> +}
> +
> +/* Close the handle. */
> +func (h *Libnbd) Close () *LibnbdError {
> +    if h.h == nil {
> +        return closed_handle_error (\"close\")
> +    }
> +    C.nbd_close (h.h)
> +    h.h = nil
> +    return nil
> +}
> +
> +";
> diff --git a/generator/GoLang.mli b/generator/GoLang.mli
> new file mode 100644
> index 0000000..b8ec1b5
> --- /dev/null
> +++ b/generator/GoLang.mli
> @@ -0,0 +1,19 @@
> +(* nbd client library in userspace: generator
> + * Copyright (C) 2013-2020 Red Hat Inc.
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
> + *)
> +
> +val generate_golang_libnbd_go : unit -> unit
> diff --git a/generator/Makefile.am b/generator/Makefile.am
> index e499ca8..0389d70 100644
> --- a/generator/Makefile.am
> +++ b/generator/Makefile.am
> @@ -57,6 +57,8 @@ sources = \
>  	Python.ml \
>  	OCaml.mli \
>  	OCaml.ml \
> +	GoLang.mli \
> +	GoLang.ml \
>  	generator.ml \
>  	$(NULL)
>  
> diff --git a/generator/generator.ml b/generator/generator.ml
> index 1c97492..817c032 100755
> --- a/generator/generator.ml
> +++ b/generator/generator.ml
> @@ -55,3 +55,6 @@ let () >    output_to "ocaml/NBD.mli"
OCaml.generate_ocaml_nbd_mli;
>    output_to "ocaml/NBD.ml" OCaml.generate_ocaml_nbd_ml;
>    output_to "ocaml/nbd-c.c" OCaml.generate_ocaml_nbd_c;
> +
> +  output_to "golang/src/libguestfs.org/libnbd/libnbd.go"
> +    GoLang.generate_golang_libnbd_go;
> diff --git a/golang/Makefile.am b/golang/Makefile.am
> new file mode 100644
> index 0000000..47234ff
> --- /dev/null
> +++ b/golang/Makefile.am
> @@ -0,0 +1,58 @@
> +# nbd client library in userspace
> +# Copyright (C) 2013-2020 Red Hat Inc.
> +#
> +# This library is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU Lesser General Public
> +# License as published by the Free Software Foundation; either
> +# version 2 of the License, or (at your option) any later version.
> +#
> +# This library is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +# Lesser General Public License for more details.
> +#
> +# You should have received a copy of the GNU Lesser General Public
> +# License along with this library; if not, write to the Free Software
> +# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
USA
> +
> +include $(top_srcdir)/subdir-rules.mk
> +
> +# http://golang.org/doc/code.html#Organization
> +pkg = libguestfs.org/libnbd
> +
> +source_files = \
> +	src/$(pkg)/libnbd.go \
> +	src/$(pkg)/libnbd_*_test.go
> +
> +generator_built = \
> +	$(source_files)
> +
> +EXTRA_DIST = \
> +	src/$(pkg)/.gitignore \
> +	$(generator_built) \
> +	config-test.go \
> +	run-tests.sh
> +
> +if HAVE_GOLANG
> +
> +golangpkgdir = $(GOROOT)/pkg/$(GOOS)_$(GOARCH)/$(pkg)
> +golangsrcdir = $(GOROOT)/src/pkg/$(pkg)
> +
> +golangpkg_DATA = \
> +	pkg/$(GOOS)_$(GOARCH)/$(pkg).a
> +
> +pkg/$(GOOS)_$(GOARCH)/$(pkg).a: src/$(pkg)/libnbd.go
> +	$(top_builddir)/run $(GOLANG) install $(pkg)
> +
> +golangsrc_DATA = $(source_files)
> +
> +TESTS_ENVIRONMENT = pkg=$(pkg) LIBNBD_DEBUG=1
> +LOG_COMPILER = $(top_builddir)/run
> +TESTS = run-tests.sh
> +
> +endif
> +
> +CLEANFILES += src/$(pkg)/*~
> +
> +clean-local:
> +	rm -rf pkg
> diff --git a/golang/config-test.go b/golang/config-test.go
> new file mode 100644
> index 0000000..e104c71
> --- /dev/null
> +++ b/golang/config-test.go
> @@ -0,0 +1,34 @@
> +/* libnbd Go configuration test
> + * Copyright (C) 2013-2020 Red Hat Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
> + */
> +
> +/* This is called from ./configure to check that golang works
> + * and is above the minimum required version.
> + */
> +
> +package main
> +
> +func main() {
> +	/* XXX Check for minimum runtime.Version() >= "go1.1.1"
> +         * Unfortunately go version numbers are not easy to parse.
> +         * They have the 3 formats "goX.Y.Z",
"release.rN" or
> +         * "weekly.YYYY-MM-DD".  The latter two formats are
mostly
> +         * useless, and the first one is hard to parse.  See also
> +         * cmpGoVersion in
> +         *
http://web.archive.org/web/20130402235148/http://golang.org/src/cmd/go/get.go?m=text
> +         */
I believe you can just achieve the version check using a build tag
comment at the top of the source file

eg to mandate go 1.10 or later:

 // +build go1.10

See build constraints here:

  https://golang.org/pkg/go/build/

Regards,
Daniel
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Daniel P. Berrangé

2020-Mar-18 09:37 UTC

head link

Re: [Libguestfs] [PATCH libnbd v2 3/3] golang: Add straightforward bindings, without callbacks.

On Tue, Mar 17, 2020 at 09:20:13PM +0000, Richard W.M. Jones
wrote:> +  | Fd _ -> "int/*XXX*/"
snip.
> +  | RFd -> "int/*XXX*/"
snip.
> +  | RFd -> "0/*XXX*/"
snip.
> +  | RFd -> Some "-1/*XXX*/"
snip.

For passing file descriptors in or out of Go APIs you'll want to use
the os.File object.

To pass it from Go to C use a param 'file os.File' and call
'C.int(file.Fd())'
to get the POSIX file descriptor to pass to C. libvirt-go OpenGraphics API
gives an illustration of this.

For the reverse direction from C to Go use

   os.NewFile(uintptr(fd), "name")

where 'name' is any sensibiel identifying short name. libvirt-go
OpenGraphicsFD gives an illustration of this direction.

Regards,
Daniel
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