Build on Windows

These changes allow go-systemd to build on Windows.

Ideally, on platforms (like Windows) where systemd is not available,
go-systemd should behave similarly to how it does on Linux,
when a service is not started by systemd.

Tipically this is default, no-op, behavior.

Author: ncruces

activation/files.go activation/files_unix.go

@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// +build !windows
+
 // Package activation implements primitives for systemd socket activation.
 package activation
 

activation/files_windows.go

@@ -0,0 +1,21 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package activation
+
+import "os"
+
+func Files(unsetEnv bool) []*os.File {
+	return nil
+}

journal/journal.go

@@ -23,20 +23,7 @@
 package journal
 
 import (
-	"bytes"
-	"encoding/binary"
-	"errors"
 	"fmt"
-	"io"
-	"io/ioutil"
-	"net"
-	"os"
-	"strconv"
-	"strings"
-	"sync"
-	"sync/atomic"
-	"syscall"
-	"unsafe"
 )
 
 // Priority of a journal message
@@ -53,173 +40,7 @@ const (
 	PriDebug
 )
 
-var (
-	// This can be overridden at build-time:
-	// https://github.com/golang/go/wiki/GcToolchainTricks#including-build-information-in-the-executable
-	journalSocket = "/run/systemd/journal/socket"
-
-	// unixConnPtr atomically holds the local unconnected Unix-domain socket.
-	// Concrete safe pointer type: *net.UnixConn
-	unixConnPtr unsafe.Pointer
-	// onceConn ensures that unixConnPtr is initialized exactly once.
-	onceConn sync.Once
-)
-
-func init() {
-	onceConn.Do(initConn)
-}
-
-// Enabled checks whether the local systemd journal is available for logging.
-func Enabled() bool {
-	onceConn.Do(initConn)
-
-	if (*net.UnixConn)(atomic.LoadPointer(&unixConnPtr)) == nil {
-		return false
-	}
-
-	if _, err := net.Dial("unixgram", journalSocket); err != nil {
-		return false
-	}
-
-	return true
-}
-
-// Send a message to the local systemd journal. vars is a map of journald
-// fields to values.  Fields must be composed of uppercase letters, numbers,
-// and underscores, but must not start with an underscore. Within these
-// restrictions, any arbitrary field name may be used.  Some names have special
-// significance: see the journalctl documentation
-// (http://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html)
-// for more details.  vars may be nil.
-func Send(message string, priority Priority, vars map[string]string) error {
-	conn := (*net.UnixConn)(atomic.LoadPointer(&unixConnPtr))
-	if conn == nil {
-		return errors.New("could not initialize socket to journald")
-	}
-
-	socketAddr := &net.UnixAddr{
-		Name: journalSocket,
-		Net:  "unixgram",
-	}
-
-	data := new(bytes.Buffer)
-	appendVariable(data, "PRIORITY", strconv.Itoa(int(priority)))
-	appendVariable(data, "MESSAGE", message)
-	for k, v := range vars {
-		appendVariable(data, k, v)
-	}
-
-	_, _, err := conn.WriteMsgUnix(data.Bytes(), nil, socketAddr)
-	if err == nil {
-		return nil
-	}
-	if !isSocketSpaceError(err) {
-		return err
-	}
-
-	// Large log entry, send it via tempfile and ancillary-fd.
-	file, err := tempFd()
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-	_, err = io.Copy(file, data)
-	if err != nil {
-		return err
-	}
-	rights := syscall.UnixRights(int(file.Fd()))
-	_, _, err = conn.WriteMsgUnix([]byte{}, rights, socketAddr)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
 // Print prints a message to the local systemd journal using Send().
 func Print(priority Priority, format string, a ...interface{}) error {
 	return Send(fmt.Sprintf(format, a...), priority, nil)
 }
-
-func appendVariable(w io.Writer, name, value string) {
-	if err := validVarName(name); err != nil {
-		fmt.Fprintf(os.Stderr, "variable name %s contains invalid character, ignoring\n", name)
-	}
-	if strings.ContainsRune(value, '\n') {
-		/* When the value contains a newline, we write:
-		 * - the variable name, followed by a newline
-		 * - the size (in 64bit little endian format)
-		 * - the data, followed by a newline
-		 */
-		fmt.Fprintln(w, name)
-		binary.Write(w, binary.LittleEndian, uint64(len(value)))
-		fmt.Fprintln(w, value)
-	} else {
-		/* just write the variable and value all on one line */
-		fmt.Fprintf(w, "%s=%s\n", name, value)
-	}
-}
-
-// validVarName validates a variable name to make sure journald will accept it.
-// The variable name must be in uppercase and consist only of characters,
-// numbers and underscores, and may not begin with an underscore:
-// https://www.freedesktop.org/software/systemd/man/sd_journal_print.html
-func validVarName(name string) error {
-	if name == "" {
-		return errors.New("Empty variable name")
-	} else if name[0] == '_' {
-		return errors.New("Variable name begins with an underscore")
-	}
-
-	for _, c := range name {
-		if !(('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || c == '_') {
-			return errors.New("Variable name contains invalid characters")
-		}
-	}
-	return nil
-}
-
-// isSocketSpaceError checks whether the error is signaling
-// an "overlarge message" condition.
-func isSocketSpaceError(err error) bool {
-	opErr, ok := err.(*net.OpError)
-	if !ok || opErr == nil {
-		return false
-	}
-
-	sysErr, ok := opErr.Err.(*os.SyscallError)
-	if !ok || sysErr == nil {
-		return false
-	}
-
-	return sysErr.Err == syscall.EMSGSIZE || sysErr.Err == syscall.ENOBUFS
-}
-
-// tempFd creates a temporary, unlinked file under `/dev/shm`.
-func tempFd() (*os.File, error) {
-	file, err := ioutil.TempFile("/dev/shm/", "journal.XXXXX")
-	if err != nil {
-		return nil, err
-	}
-	err = syscall.Unlink(file.Name())
-	if err != nil {
-		return nil, err
-	}
-	return file, nil
-}
-
-// initConn initializes the global `unixConnPtr` socket.
-// It is meant to be called exactly once, at program startup.
-func initConn() {
-	autobind, err := net.ResolveUnixAddr("unixgram", "")
-	if err != nil {
-		return
-	}
-
-	sock, err := net.ListenUnixgram("unixgram", autobind)
-	if err != nil {
-		return
-	}
-
-	atomic.StorePointer(&unixConnPtr, unsafe.Pointer(sock))
-}