15 files changed, 649 insertions, 0 deletions

diff --git a/misc/cgo/testso/noso_test.go b/misc/cgo/testso/noso_test.go
new file mode 100644
index 0000000..c88aebf
--- /dev/null
+++ b/misc/cgo/testso/noso_test.go
@@ -0,0 +1,9 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !cgo
+
+package so_test
+
+// Nothing to test.
diff --git a/misc/cgo/testso/overlaydir_test.go b/misc/cgo/testso/overlaydir_test.go
new file mode 100644
index 0000000..09a1d51
--- /dev/null
+++ b/misc/cgo/testso/overlaydir_test.go
@@ -0,0 +1,78 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package so_test
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// overlayDir makes a minimal-overhead copy of srcRoot in which new files may be added.
+//
+// TODO: Once we no longer need to support the misc module in GOPATH mode,
+// factor this function out into a package to reduce duplication.
+func overlayDir(dstRoot, srcRoot string) error {
+	dstRoot = filepath.Clean(dstRoot)
+	if err := os.MkdirAll(dstRoot, 0777); err != nil {
+		return err
+	}
+
+	srcRoot, err := filepath.Abs(srcRoot)
+	if err != nil {
+		return err
+	}
+
+	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
+		if err != nil || srcPath == srcRoot {
+			return err
+		}
+
+		suffix := strings.TrimPrefix(srcPath, srcRoot)
+		for len(suffix) > 0 && suffix[0] == filepath.Separator {
+			suffix = suffix[1:]
+		}
+		dstPath := filepath.Join(dstRoot, suffix)
+
+		perm := info.Mode() & os.ModePerm
+		if info.Mode()&os.ModeSymlink != 0 {
+			info, err = os.Stat(srcPath)
+			if err != nil {
+				return err
+			}
+			perm = info.Mode() & os.ModePerm
+		}
+
+		// Always copy directories (don't symlink them).
+		// If we add a file in the overlay, we don't want to add it in the original.
+		if info.IsDir() {
+			return os.MkdirAll(dstPath, perm|0200)
+		}
+
+		// If the OS supports symlinks, use them instead of copying bytes.
+		if err := os.Symlink(srcPath, dstPath); err == nil {
+			return nil
+		}
+
+		// Otherwise, copy the bytes.
+		src, err := os.Open(srcPath)
+		if err != nil {
+			return err
+		}
+		defer src.Close()
+
+		dst, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
+		if err != nil {
+			return err
+		}
+
+		_, err = io.Copy(dst, src)
+		if closeErr := dst.Close(); err == nil {
+			err = closeErr
+		}
+		return err
+	})
+}
diff --git a/misc/cgo/testso/so_test.go b/misc/cgo/testso/so_test.go
new file mode 100644
index 0000000..57f0fd3
--- /dev/null
+++ b/misc/cgo/testso/so_test.go
@@ -0,0 +1,138 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build cgo
+
+package so_test
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func requireTestSOSupported(t *testing.T) {
+	t.Helper()
+	switch runtime.GOARCH {
+	case "arm64":
+		if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
+			t.Skip("No exec facility on iOS.")
+		}
+	case "ppc64":
+		if runtime.GOOS == "linux" {
+			t.Skip("External linking not implemented on linux/ppc64 (issue #8912).")
+		}
+	}
+	if runtime.GOOS == "android" {
+		t.Skip("No exec facility on Android.")
+	}
+}
+
+func TestSO(t *testing.T) {
+	requireTestSOSupported(t)
+
+	GOPATH, err := ioutil.TempDir("", "cgosotest")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(GOPATH)
+
+	modRoot := filepath.Join(GOPATH, "src", "cgosotest")
+	if err := overlayDir(modRoot, "testdata"); err != nil {
+		log.Panic(err)
+	}
+	if err := ioutil.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgosotest\n"), 0666); err != nil {
+		log.Panic(err)
+	}
+
+	cmd := exec.Command("go", "env", "CC", "GOGCCFLAGS")
+	cmd.Dir = modRoot
+	cmd.Stderr = new(strings.Builder)
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	out, err := cmd.Output()
+	if err != nil {
+		t.Fatalf("%s: %v\n%s", strings.Join(cmd.Args, " "), err, cmd.Stderr)
+	}
+	lines := strings.Split(string(out), "\n")
+	if len(lines) != 3 || lines[2] != "" {
+		t.Fatalf("Unexpected output from %s:\n%s", strings.Join(cmd.Args, " "), lines)
+	}
+
+	cc := lines[0]
+	if cc == "" {
+		t.Fatal("CC environment variable (go env CC) cannot be empty")
+	}
+	gogccflags := strings.Split(lines[1], " ")
+
+	// build shared object
+	ext := "so"
+	args := append(gogccflags, "-shared")
+	switch runtime.GOOS {
+	case "darwin", "ios":
+		ext = "dylib"
+		args = append(args, "-undefined", "suppress", "-flat_namespace")
+	case "windows":
+		ext = "dll"
+		args = append(args, "-DEXPORT_DLL")
+	case "aix":
+		ext = "so.1"
+	}
+	sofname := "libcgosotest." + ext
+	args = append(args, "-o", sofname, "cgoso_c.c")
+
+	cmd = exec.Command(cc, args...)
+	cmd.Dir = modRoot
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+	}
+	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
+
+	if runtime.GOOS == "aix" {
+		// Shared object must be wrapped by an archive
+		cmd = exec.Command("ar", "-X64", "-q", "libcgosotest.a", "libcgosotest.so.1")
+		cmd.Dir = modRoot
+		out, err = cmd.CombinedOutput()
+		if err != nil {
+			t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+		}
+	}
+
+	cmd = exec.Command("go", "build", "-o", "main.exe", "main.go")
+	cmd.Dir = modRoot
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+	}
+	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
+
+	cmd = exec.Command("./main.exe")
+	cmd.Dir = modRoot
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	if runtime.GOOS != "windows" {
+		s := "LD_LIBRARY_PATH"
+		if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
+			s = "DYLD_LIBRARY_PATH"
+		}
+		cmd.Env = append(os.Environ(), s+"=.")
+
+		// On FreeBSD 64-bit architectures, the 32-bit linker looks for
+		// different environment variables.
+		if runtime.GOOS == "freebsd" && runtime.GOARCH == "386" {
+			cmd.Env = append(cmd.Env, "LD_32_LIBRARY_PATH=.")
+		}
+	}
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+	}
+	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
+}
diff --git a/misc/cgo/testso/testdata/cgoso.c b/misc/cgo/testso/testdata/cgoso.c
new file mode 100644
index 0000000..612e5d3
--- /dev/null
+++ b/misc/cgo/testso/testdata/cgoso.c
@@ -0,0 +1,14 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "_cgo_export.h"
+
+#if defined(WIN32) || defined(_AIX)
+extern void setCallback(void *);
+void init() {
+	setCallback(goCallback);
+}
+#else
+void init() {}
+#endif
diff --git a/misc/cgo/testso/testdata/cgoso.go b/misc/cgo/testso/testdata/cgoso.go
new file mode 100644
index 0000000..bba5de3
--- /dev/null
+++ b/misc/cgo/testso/testdata/cgoso.go
@@ -0,0 +1,32 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgosotest
+
+/*
+// intentionally write the same LDFLAGS differently
+// to test correct handling of LDFLAGS.
+#cgo linux LDFLAGS: -L. -lcgosotest
+#cgo dragonfly LDFLAGS: -L. -l cgosotest
+#cgo freebsd LDFLAGS: -L. -l cgosotest
+#cgo openbsd LDFLAGS: -L. -l cgosotest
+#cgo solaris LDFLAGS: -L. -lcgosotest
+#cgo netbsd LDFLAGS: -L. libcgosotest.so
+#cgo darwin LDFLAGS: -L. libcgosotest.dylib
+#cgo windows LDFLAGS: -L. libcgosotest.dll
+#cgo aix LDFLAGS: -L. -l cgosotest
+
+void init(void);
+void sofunc(void);
+*/
+import "C"
+
+func Test() {
+	C.init()
+	C.sofunc()
+}
+
+//export goCallback
+func goCallback() {
+}
diff --git a/misc/cgo/testso/testdata/cgoso_c.c b/misc/cgo/testso/testdata/cgoso_c.c
new file mode 100644
index 0000000..e5015ed
--- /dev/null
+++ b/misc/cgo/testso/testdata/cgoso_c.c
@@ -0,0 +1,39 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+#ifdef WIN32
+// A Windows DLL is unable to call an arbitrary function in
+// the main executable. Work around that by making the main
+// executable pass the callback function pointer to us.
+void (*goCallback)(void);
+__declspec(dllexport) void setCallback(void *f)
+{
+	goCallback = (void (*)())f;
+}
+__declspec(dllexport) void sofunc(void);
+#elif defined(_AIX)
+// AIX doesn't allow the creation of a shared object with an
+// undefined symbol. It's possible to bypass this problem by
+// using -Wl,-G and -Wl,-brtl option which allows run-time linking.
+// However, that's not how most of AIX shared object works.
+// Therefore, it's better to consider goCallback as a pointer and
+// to set up during an init function.
+void (*goCallback)(void);
+void setCallback(void *f) { goCallback = f; }
+#else
+extern void goCallback(void);
+void setCallback(void *f) { (void)f; }
+#endif
+
+// OpenBSD and older Darwin lack TLS support
+#if !defined(__OpenBSD__) && !defined(__APPLE__)
+__thread int tlsvar = 12345;
+#endif
+
+void sofunc(void)
+{
+	goCallback();
+}
diff --git a/misc/cgo/testso/testdata/cgoso_unix.go b/misc/cgo/testso/testdata/cgoso_unix.go
new file mode 100644
index 0000000..1860694
--- /dev/null
+++ b/misc/cgo/testso/testdata/cgoso_unix.go
@@ -0,0 +1,20 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build aix dragonfly freebsd linux netbsd solaris
+
+package cgosotest
+
+/*
+extern int __thread tlsvar;
+int *getTLS() { return &tlsvar; }
+*/
+import "C"
+
+func init() {
+	if v := *C.getTLS(); v != 12345 {
+		println("got", v)
+		panic("BAD TLS value")
+	}
+}
diff --git a/misc/cgo/testso/testdata/main.go b/misc/cgo/testso/testdata/main.go
new file mode 100644
index 0000000..963d451
--- /dev/null
+++ b/misc/cgo/testso/testdata/main.go
@@ -0,0 +1,13 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package main
+
+import "cgosotest"
+
+func main() {
+	cgosotest.Test()
+}
diff --git a/misc/cgo/testsovar/noso_test.go b/misc/cgo/testsovar/noso_test.go
new file mode 100644
index 0000000..c88aebf
--- /dev/null
+++ b/misc/cgo/testsovar/noso_test.go
@@ -0,0 +1,9 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !cgo
+
+package so_test
+
+// Nothing to test.
diff --git a/misc/cgo/testsovar/overlaydir_test.go b/misc/cgo/testsovar/overlaydir_test.go
new file mode 100644
index 0000000..09a1d51
--- /dev/null
+++ b/misc/cgo/testsovar/overlaydir_test.go
@@ -0,0 +1,78 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package so_test
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// overlayDir makes a minimal-overhead copy of srcRoot in which new files may be added.
+//
+// TODO: Once we no longer need to support the misc module in GOPATH mode,
+// factor this function out into a package to reduce duplication.
+func overlayDir(dstRoot, srcRoot string) error {
+	dstRoot = filepath.Clean(dstRoot)
+	if err := os.MkdirAll(dstRoot, 0777); err != nil {
+		return err
+	}
+
+	srcRoot, err := filepath.Abs(srcRoot)
+	if err != nil {
+		return err
+	}
+
+	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
+		if err != nil || srcPath == srcRoot {
+			return err
+		}
+
+		suffix := strings.TrimPrefix(srcPath, srcRoot)
+		for len(suffix) > 0 && suffix[0] == filepath.Separator {
+			suffix = suffix[1:]
+		}
+		dstPath := filepath.Join(dstRoot, suffix)
+
+		perm := info.Mode() & os.ModePerm
+		if info.Mode()&os.ModeSymlink != 0 {
+			info, err = os.Stat(srcPath)
+			if err != nil {
+				return err
+			}
+			perm = info.Mode() & os.ModePerm
+		}
+
+		// Always copy directories (don't symlink them).
+		// If we add a file in the overlay, we don't want to add it in the original.
+		if info.IsDir() {
+			return os.MkdirAll(dstPath, perm|0200)
+		}
+
+		// If the OS supports symlinks, use them instead of copying bytes.
+		if err := os.Symlink(srcPath, dstPath); err == nil {
+			return nil
+		}
+
+		// Otherwise, copy the bytes.
+		src, err := os.Open(srcPath)
+		if err != nil {
+			return err
+		}
+		defer src.Close()
+
+		dst, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
+		if err != nil {
+			return err
+		}
+
+		_, err = io.Copy(dst, src)
+		if closeErr := dst.Close(); err == nil {
+			err = closeErr
+		}
+		return err
+	})
+}
diff --git a/misc/cgo/testsovar/so_test.go b/misc/cgo/testsovar/so_test.go
new file mode 100644
index 0000000..57f0fd3
--- /dev/null
+++ b/misc/cgo/testsovar/so_test.go
@@ -0,0 +1,138 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build cgo
+
+package so_test
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func requireTestSOSupported(t *testing.T) {
+	t.Helper()
+	switch runtime.GOARCH {
+	case "arm64":
+		if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
+			t.Skip("No exec facility on iOS.")
+		}
+	case "ppc64":
+		if runtime.GOOS == "linux" {
+			t.Skip("External linking not implemented on linux/ppc64 (issue #8912).")
+		}
+	}
+	if runtime.GOOS == "android" {
+		t.Skip("No exec facility on Android.")
+	}
+}
+
+func TestSO(t *testing.T) {
+	requireTestSOSupported(t)
+
+	GOPATH, err := ioutil.TempDir("", "cgosotest")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(GOPATH)
+
+	modRoot := filepath.Join(GOPATH, "src", "cgosotest")
+	if err := overlayDir(modRoot, "testdata"); err != nil {
+		log.Panic(err)
+	}
+	if err := ioutil.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgosotest\n"), 0666); err != nil {
+		log.Panic(err)
+	}
+
+	cmd := exec.Command("go", "env", "CC", "GOGCCFLAGS")
+	cmd.Dir = modRoot
+	cmd.Stderr = new(strings.Builder)
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	out, err := cmd.Output()
+	if err != nil {
+		t.Fatalf("%s: %v\n%s", strings.Join(cmd.Args, " "), err, cmd.Stderr)
+	}
+	lines := strings.Split(string(out), "\n")
+	if len(lines) != 3 || lines[2] != "" {
+		t.Fatalf("Unexpected output from %s:\n%s", strings.Join(cmd.Args, " "), lines)
+	}
+
+	cc := lines[0]
+	if cc == "" {
+		t.Fatal("CC environment variable (go env CC) cannot be empty")
+	}
+	gogccflags := strings.Split(lines[1], " ")
+
+	// build shared object
+	ext := "so"
+	args := append(gogccflags, "-shared")
+	switch runtime.GOOS {
+	case "darwin", "ios":
+		ext = "dylib"
+		args = append(args, "-undefined", "suppress", "-flat_namespace")
+	case "windows":
+		ext = "dll"
+		args = append(args, "-DEXPORT_DLL")
+	case "aix":
+		ext = "so.1"
+	}
+	sofname := "libcgosotest." + ext
+	args = append(args, "-o", sofname, "cgoso_c.c")
+
+	cmd = exec.Command(cc, args...)
+	cmd.Dir = modRoot
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+	}
+	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
+
+	if runtime.GOOS == "aix" {
+		// Shared object must be wrapped by an archive
+		cmd = exec.Command("ar", "-X64", "-q", "libcgosotest.a", "libcgosotest.so.1")
+		cmd.Dir = modRoot
+		out, err = cmd.CombinedOutput()
+		if err != nil {
+			t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+		}
+	}
+
+	cmd = exec.Command("go", "build", "-o", "main.exe", "main.go")
+	cmd.Dir = modRoot
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+	}
+	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
+
+	cmd = exec.Command("./main.exe")
+	cmd.Dir = modRoot
+	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)
+	if runtime.GOOS != "windows" {
+		s := "LD_LIBRARY_PATH"
+		if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
+			s = "DYLD_LIBRARY_PATH"
+		}
+		cmd.Env = append(os.Environ(), s+"=.")
+
+		// On FreeBSD 64-bit architectures, the 32-bit linker looks for
+		// different environment variables.
+		if runtime.GOOS == "freebsd" && runtime.GOARCH == "386" {
+			cmd.Env = append(cmd.Env, "LD_32_LIBRARY_PATH=.")
+		}
+	}
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+	}
+	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
+}
diff --git a/misc/cgo/testsovar/testdata/cgoso.go b/misc/cgo/testsovar/testdata/cgoso.go
new file mode 100644
index 0000000..9c7f95e
--- /dev/null
+++ b/misc/cgo/testsovar/testdata/cgoso.go
@@ -0,0 +1,44 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgosotest
+
+// This test verifies that Go can access C variables
+// in shared object file via cgo.
+
+/*
+// intentionally write the same LDFLAGS differently
+// to test correct handling of LDFLAGS.
+#cgo windows CFLAGS: -DIMPORT_DLL
+#cgo linux LDFLAGS: -L. -lcgosotest
+#cgo dragonfly LDFLAGS: -L. -l cgosotest
+#cgo freebsd LDFLAGS: -L. -l cgosotest
+#cgo openbsd LDFLAGS: -L. -l cgosotest
+#cgo solaris LDFLAGS: -L. -lcgosotest
+#cgo netbsd LDFLAGS: -L. libcgosotest.so
+#cgo darwin LDFLAGS: -L. libcgosotest.dylib
+#cgo windows LDFLAGS: -L. libcgosotest.dll
+#cgo aix LDFLAGS: -L. -l cgosotest
+
+#include "cgoso_c.h"
+
+const char* getVar() {
+	    return exported_var;
+}
+*/
+import "C"
+
+import "fmt"
+
+func Test() {
+	const want = "Hello world"
+	got := C.GoString(C.getVar())
+	if got != want {
+		panic(fmt.Sprintf("testExportedVar: got %q, but want %q", got, want))
+	}
+	got = C.GoString(C.exported_var)
+	if got != want {
+		panic(fmt.Sprintf("testExportedVar: got %q, but want %q", got, want))
+	}
+}
diff --git a/misc/cgo/testsovar/testdata/cgoso_c.c b/misc/cgo/testsovar/testdata/cgoso_c.c
new file mode 100644
index 0000000..a448c01
--- /dev/null
+++ b/misc/cgo/testsovar/testdata/cgoso_c.c
@@ -0,0 +1,7 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+const char *exported_var = "Hello world";
diff --git a/misc/cgo/testsovar/testdata/cgoso_c.h b/misc/cgo/testsovar/testdata/cgoso_c.h
new file mode 100644
index 0000000..640db7b
--- /dev/null
+++ b/misc/cgo/testsovar/testdata/cgoso_c.h
@@ -0,0 +1,17 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+#ifdef WIN32
+#if defined(EXPORT_DLL)
+#    define VAR __declspec(dllexport)
+#elif defined(IMPORT_DLL)
+#    define VAR __declspec(dllimport)
+#endif
+#else
+#    define VAR extern
+#endif
+
+VAR const char *exported_var;
diff --git a/misc/cgo/testsovar/testdata/main.go b/misc/cgo/testsovar/testdata/main.go
new file mode 100644
index 0000000..87b52ce
--- /dev/null
+++ b/misc/cgo/testsovar/testdata/main.go
@@ -0,0 +1,13 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package main
+
+import "cgosotest"
+
+func main() {
+	cgosotest.Test()
+}