Refactoring for support of different platforms

daemon_windows.go → daemon.go

@@ -1,9 +1,22 @@
 package daemon
 
 import (
+	"errors"
 	"os"
+	"syscall"
 )
 
+var errNotSupported = errors.New("daemon: Non-POSIX OS is not supported")
+
+// Mark of daemon process - system environment variable _GO_DAEMON=1
+const (
+	MARK_NAME  = "_GO_DAEMON"
+	MARK_VALUE = "1"
+)
+
+// Default file permissions for log and pid files.
+const FILE_PERM = os.FileMode(0640)
+
 // A Context describes daemon context.
 type Context struct {
 	// If PidFileName is non-empty, parent process will try to create and lock
@@ -34,37 +47,42 @@ type Context struct {
 	Args []string
 
 	// Credential holds user and group identities to be assumed by a daemon-process.
-	Credential *int
+	Credential *syscall.Credential
 	// If Umask is non-zero, the daemon-process call Umask() func with given value.
 	Umask int
 
 	// Struct contains only serializable public fields (!!!)
 	abspath  string
-	pidFile  *int
+	pidFile  *LockFile
 	logFile  *os.File
 	nullFile *os.File
 
 	rpipe, wpipe *os.File
 }
 
+// WasReborn returns true in child process (daemon) and false in parent process.
+func WasReborn() bool {
+	return os.Getenv(MARK_NAME) == MARK_VALUE
+}
+
 // Reborn runs second copy of current process in the given context.
 // function executes separate parts of code in child process and parent process
 // and provides demonization of child process. It look similar as the
 // fork-daemonization, but goroutine-safe.
 // In success returns *os.Process in parent process and nil in child process.
 // Otherwise returns error.
 func (d *Context) Reborn() (child *os.Process, err error) {
-	return
+	return d.reborn()
 }
 
 // Search search daemons process by given in context pid file name.
 // If success returns pointer on daemons os.Process structure,
 // else returns error. Returns nil if filename is empty.
 func (d *Context) Search() (daemon *os.Process, err error) {
-	return
+	return d.search()
 }
 
 // Release provides correct pid-file release in daemon.
 func (d *Context) Release() (err error) {
-	return
+	return d.release()
 }

daemon_stub.go

@@ -0,0 +1,19 @@
+// +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd,!plan9,!solaris
+
+package daemon
+
+import (
+	"os"
+)
+
+func (d *Context) reborn() (child *os.Process, err error) {
+	return nil, errNotSupported
+}
+
+func (d *Context) search() (daemon *os.Process, err error) {
+	return nil, errNotSupported
+}
+
+func (d *Context) release() (err error) {
+	return nil, errNotSupported
+}

daemon_linux.go → daemon_unix.go

@@ -1,3 +1,5 @@
+// +build darwin dragonfly freebsd linux netbsd openbsd plan9 solaris
+
 package daemon
 
 import (
@@ -9,65 +11,7 @@ import (
 	"github.com/kardianos/osext"
 )
 
-// Mark of daemon process - system environment variable _GO_DAEMON=1
-const (
-	MARK_NAME  = "_GO_DAEMON"
-	MARK_VALUE = "1"
-)
-
-// Default file permissions for log and pid files.
-const FILE_PERM = os.FileMode(0640)
-
-// A Context describes daemon context.
-type Context struct {
-	// If PidFileName is non-empty, parent process will try to create and lock
-	// pid file with given name. Child process writes process id to file.
-	PidFileName string
-	// Permissions for new pid file.
-	PidFilePerm os.FileMode
-
-	// If LogFileName is non-empty, parent process will create file with given name
-	// and will link to fd 2 (stderr) for child process.
-	LogFileName string
-	// Permissions for new log file.
-	LogFilePerm os.FileMode
-
-	// If WorkDir is non-empty, the child changes into the directory before
-	// creating the process.
-	WorkDir string
-	// If Chroot is non-empty, the child changes root directory
-	Chroot string
-
-	// If Env is non-nil, it gives the environment variables for the
-	// daemon-process in the form returned by os.Environ.
-	// If it is nil, the result of os.Environ will be used.
-	Env []string
-	// If Args is non-nil, it gives the command-line args for the
-	// daemon-process. If it is nil, the result of os.Args will be used
-	// (without program name).
-	Args []string
-
-	// Credential holds user and group identities to be assumed by a daemon-process.
-	Credential *syscall.Credential
-	// If Umask is non-zero, the daemon-process call Umask() func with given value.
-	Umask int
-
-	// Struct contains only serializable public fields (!!!)
-	abspath  string
-	pidFile  *LockFile
-	logFile  *os.File
-	nullFile *os.File
-
-	rpipe, wpipe *os.File
-}
-
-// Reborn runs second copy of current process in the given context.
-// function executes separate parts of code in child process and parent process
-// and provides demonization of child process. It look similar as the
-// fork-daemonization, but goroutine-safe.
-// In success returns *os.Process in parent process and nil in child process.
-// Otherwise returns error.
-func (d *Context) Reborn() (child *os.Process, err error) {
+func (d *Context) reborn() (child *os.Process, err error) {
 	if !WasReborn() {
 		child, err = d.parent()
 	} else {
@@ -76,10 +20,7 @@ func (d *Context) Reborn() (child *os.Process, err error) {
 	return
 }
 
-// Search search daemons process by given in context pid file name.
-// If success returns pointer on daemons os.Process structure,
-// else returns error. Returns nil if filename is empty.
-func (d *Context) Search() (daemon *os.Process, err error) {
+func (d *Context) search() (daemon *os.Process, err error) {
 	if len(d.PidFileName) > 0 {
 		var pid int
 		if pid, err = ReadPidFile(d.PidFileName); err != nil {
@@ -90,11 +31,6 @@ func (d *Context) Search() (daemon *os.Process, err error) {
 	return
 }
 
-// WasReborn returns true in child process (daemon) and false in parent process.
-func WasReborn() bool {
-	return os.Getenv(MARK_NAME) == MARK_VALUE
-}
-
 func (d *Context) parent() (child *os.Process, err error) {
 	if err = d.prepareEnv(); err != nil {
 		return
@@ -254,8 +190,7 @@ func (d *Context) child() (err error) {
 	return
 }
 
-// Release provides correct pid-file release in daemon.
-func (d *Context) Release() (err error) {
+func (d *Context) release() (err error) {
 	if !initialized {
 		return
 	}

lock_file_linux.go → lock_file.go

@@ -1,14 +1,15 @@
 package daemon
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"syscall"
 )
 
 var (
 	// ErrWoldBlock indicates on locking pid-file by another process.
-	ErrWouldBlock = syscall.EWOULDBLOCK
+	ErrWouldBlock = errors.New("Daemon: Resource temporarily unavailable")
 )
 
 // LockFile wraps *os.File and provide functions for locking of files.
@@ -49,12 +50,12 @@ func OpenLockFile(name string, perm os.FileMode) (lock *LockFile, err error) {
 
 // Lock apply exclusive lock on an open file. If file already locked, returns error.
 func (file *LockFile) Lock() error {
-	return syscall.Flock(int(file.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
+	return lockFile(file.Fd())
 }
 
 // Unlock remove exclusive lock on an open file.
 func (file *LockFile) Unlock() error {
-	return syscall.Flock(int(file.Fd()), syscall.LOCK_UN)
+	return unlockFile(file.Fd())
 }
 
 // ReadPidFile reads process id from file with give name and returns pid.
@@ -105,6 +106,7 @@ func (file *LockFile) Remove() error {
 		return err
 	}
 
+	// TODO(yar): keep filename?
 	name, err := GetFdName(file.Fd())
 	if err != nil {
 		return err
@@ -116,19 +118,5 @@ func (file *LockFile) Remove() error {
 
 // GetFdName returns file name for given descriptor.
 func GetFdName(fd uintptr) (name string, err error) {
-	path := fmt.Sprintf("/proc/self/fd/%d", int(fd))
-
-	var (
-		fi os.FileInfo
-		n  int
-	)
-	if fi, err = os.Lstat(path); err != nil {
-		return
-	}
-	buf := make([]byte, fi.Size()+1)
-
-	if n, err = syscall.Readlink(path, buf); err == nil {
-		name = string(buf[:n])
-	}
-	return
+	return getFdName(fd)
 }

lock_file_stub.go

@@ -0,0 +1,15 @@
+// +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd,!plan9,!solaris
+
+package daemon
+
+func lockFile(fd uintptr) error {
+	return errNotSupported
+}
+
+func unlockFile(fd uintptr) error {
+	return errNotSupported
+}
+
+func getFdName(fd uintptr) (name string, err error) {
+	return "", errNotSupported
+}

lock_file_unix.go

@@ -0,0 +1,44 @@
+// +build darwin dragonfly freebsd linux netbsd openbsd plan9 solaris
+
+package daemon
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+func lockFile(fd uintptr) error {
+	err := syscall.Flock(int(fd), syscall.LOCK_EX|syscall.LOCK_NB)
+	if err == syscall.EWOULDBLOCK {
+		err = ErrWouldBlock
+	}
+	return err
+}
+
+func unlockFile(fd uintptr) error {
+	err := syscall.Flock(int(fd), syscall.LOCK_UN)
+	if err == syscall.EWOULDBLOCK {
+		err = ErrWouldBlock
+	}
+	return err
+}
+
+func getFdName(fd uintptr) (name string, err error) {
+	// TODO(yar): This way does not work on darwin, use fcntl
+	path := fmt.Sprintf("/proc/self/fd/%d", int(fd))
+
+	var (
+		fi os.FileInfo
+		n  int
+	)
+	if fi, err = os.Lstat(path); err != nil {
+		return
+	}
+	buf := make([]byte, fi.Size()+1)
+
+	if n, err = syscall.Readlink(path, buf); err == nil {
+		name = string(buf[:n])
+	}
+	return
+}