Adding upstream version 0.7.0+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

clipboard_linux.go

@@ -0,0 +1,171 @@
+// Copyright 2021 The golang.design Initiative Authors.
+// All rights reserved. Use of this source code is governed
+// by a MIT license that can be found in the LICENSE file.
+//
+// Written by Changkun Ou <changkun.de>
+
+//go:build linux && !android
+// +build linux,!android
+
+package clipboard
+
+/*
+#cgo LDFLAGS: -ldl
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+int clipboard_test();
+int clipboard_write(
+	char*          typ,
+	unsigned char* buf,
+	size_t         n,
+	uintptr_t      handle
+);
+unsigned long clipboard_read(char* typ, char **out);
+*/
+import "C"
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"runtime"
+	"runtime/cgo"
+	"time"
+	"unsafe"
+)
+
+var helpmsg = `%w: Failed to initialize the X11 display, and the clipboard package
+will not work properly. Install the following dependency may help:
+
+	apt install -y libx11-dev
+
+If the clipboard package is in an environment without a frame buffer,
+such as a cloud server, it may also be necessary to install xvfb:
+
+	apt install -y xvfb
+
+and initialize a virtual frame buffer:
+
+	Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
+	export DISPLAY=:99.0
+
+Then this package should be ready to use.
+`
+
+func initialize() error {
+	ok := C.clipboard_test()
+	if ok != 0 {
+		return fmt.Errorf(helpmsg, errUnavailable)
+	}
+	return nil
+}
+
+func read(t Format) (buf []byte, err error) {
+	switch t {
+	case FmtText:
+		return readc("UTF8_STRING")
+	case FmtImage:
+		return readc("image/png")
+	}
+	return nil, errUnsupported
+}
+
+func readc(t string) ([]byte, error) {
+	ct := C.CString(t)
+	defer C.free(unsafe.Pointer(ct))
+
+	var data *C.char
+	n := C.clipboard_read(ct, &data)
+	if data == nil {
+		return nil, errUnavailable
+	}
+	defer C.free(unsafe.Pointer(data))
+	switch {
+	case n == 0:
+		return nil, nil
+	default:
+		return C.GoBytes(unsafe.Pointer(data), C.int(n)), nil
+	}
+}
+
+// write writes the given data to clipboard and
+// returns true if success or false if failed.
+func write(t Format, buf []byte) (<-chan struct{}, error) {
+	var s string
+	switch t {
+	case FmtText:
+		s = "UTF8_STRING"
+	case FmtImage:
+		s = "image/png"
+	}
+
+	start := make(chan int)
+	done := make(chan struct{}, 1)
+
+	go func() { // serve as a daemon until the ownership is terminated.
+		runtime.LockOSThread()
+		defer runtime.UnlockOSThread()
+
+		cs := C.CString(s)
+		defer C.free(unsafe.Pointer(cs))
+
+		h := cgo.NewHandle(start)
+		var ok C.int
+		if len(buf) == 0 {
+			ok = C.clipboard_write(cs, nil, 0, C.uintptr_t(h))
+		} else {
+			ok = C.clipboard_write(cs, (*C.uchar)(unsafe.Pointer(&(buf[0]))), C.size_t(len(buf)), C.uintptr_t(h))
+		}
+		if ok != C.int(0) {
+			fmt.Fprintf(os.Stderr, "write failed with status: %d\n", int(ok))
+		}
+		done <- struct{}{}
+		close(done)
+	}()
+
+	status := <-start
+	if status < 0 {
+		return nil, errUnavailable
+	}
+	// wait until enter event loop
+	return done, nil
+}
+
+func watch(ctx context.Context, t Format) <-chan []byte {
+	recv := make(chan []byte, 1)
+	ti := time.NewTicker(time.Second)
+	last := Read(t)
+	go func() {
+		for {
+			select {
+			case <-ctx.Done():
+				close(recv)
+				return
+			case <-ti.C:
+				b := Read(t)
+				if b == nil {
+					continue
+				}
+				if !bytes.Equal(last, b) {
+					recv <- b
+					last = b
+				}
+			}
+		}
+	}()
+	return recv
+}
+
+type syncChan struct {
+	c chan int
+}
+
+//export syncStatus
+func syncStatus(h uintptr, val int) {
+	v := cgo.Handle(h).Value().(chan int)
+	v <- val
+	cgo.Handle(h).Delete()
+}