fix execution of external commands with quotes on Windows (#113)

README.md

@@ -119,7 +119,20 @@ paths:
     runOnInitRestart: yes
 ```
 
-After starting the server, the webcam is available on `rtsp://localhost:8554/cam`. The ffmpeg command works only on Linux; for Windows and Mac equivalents, read the [ffmpeg wiki](https://trac.ffmpeg.org/wiki/Capture/Webcam).
+If the platform is Windows:
+```yml
+paths:
+  cam:
+    runOnInit: ffmpeg -f dshow -i video="USB2.0 HD UVC WebCam" -f rtsp rtsp://localhost:$RTSP_PORT/$RTSP_PATH
+    runOnInitRestart: yes
+```
+
+Where `USB2.0 HD UVC WebCam` is the name of your webcam, that can be obtained with:
+```
+ffmpeg -list_devices true -f dshow -i dummy
+```
+
+After starting the server, the webcam can be reached on `rtsp://localhost:8554/cam`.
 
 ### Serve a Raspberry Pi Camera
 

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/aler9/gortsplib v0.0.0-20201108190150-2deddcffab35
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/fsnotify/fsnotify v1.4.9
+	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51
 	github.com/notedit/rtmp v0.0.2
 	github.com/pion/rtp v1.6.1 // indirect
 	github.com/stretchr/testify v1.6.1

go.sum

@@ -10,6 +10,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
+github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNUXsshfwJMBgNA0RU6/i7WVaAegv3PtuIHPMs=
+github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/notedit/rtmp v0.0.2 h1:5+to4yezKATiJgnrcETu9LbV5G/QsWkOV9Ts2M/p33w=
 github.com/notedit/rtmp v0.0.2/go.mod h1:vzuE21rowz+lT1NGsWbreIvYulgBpCGnQyeTyFblUHc=
 github.com/pion/randutil v0.0.0/go.mod h1:XcJrSMMbbMRhASFVOlj/5hQial/Y8oH/HVo7TBZq+j8=

internal/externalcmd/externalcmd.go

@@ -1,10 +1,6 @@
 package externalcmd
 
 import (
-	"os"
-	"os/exec"
-	"runtime"
-	"strings"
 	"time"
 )
 
@@ -81,55 +77,3 @@ func (e *ExternalCmd) run() {
 		}
 	}
 }
-
-func (e *ExternalCmd) runInner() bool {
-	var cmd *exec.Cmd
-	if runtime.GOOS == "windows" {
-		// on Windows the shell is not used and command is started directly
-		// variables are replaced manually in order to guarantee compatibility
-		// with Linux commands
-		tmp := strings.ReplaceAll(e.cmdstr, "$RTSP_PATH", e.env.Path)
-		tmp = strings.ReplaceAll(tmp, "$RTSP_PORT", e.env.Port)
-
-		args := strings.Fields(tmp)
-		cmd = exec.Command(args[0], args[1:]...)
-
-	} else {
-		cmd = exec.Command("/bin/sh", "-c", "exec "+e.cmdstr)
-	}
-
-	cmd.Env = append(os.Environ(),
-		"RTSP_PATH="+e.env.Path,
-		"RTSP_PORT="+e.env.Port,
-	)
-
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-
-	err := cmd.Start()
-	if err != nil {
-		return true
-	}
-
-	cmdDone := make(chan struct{})
-	go func() {
-		defer close(cmdDone)
-		cmd.Wait()
-	}()
-
-	select {
-	case <-e.terminate:
-		// on Windows it's not possible to send os.Interrupt to a process
-		// Kill() is the only supported way
-		if runtime.GOOS == "windows" {
-			cmd.Process.Kill()
-		} else {
-			cmd.Process.Signal(os.Interrupt)
-		}
-		<-cmdDone
-		return false
-
-	case <-cmdDone:
-		return true
-	}
-}

internal/externalcmd/externalcmd_unix.go

@@ -0,0 +1,41 @@
+// +build !windows
+
+package externalcmd
+
+import (
+	"os"
+	"os/exec"
+)
+
+func (e *ExternalCmd) runInner() bool {
+	cmd := exec.Command("/bin/sh", "-c", "exec "+e.cmdstr)
+
+	cmd.Env = append(os.Environ(),
+		"RTSP_PATH="+e.env.Path,
+		"RTSP_PORT="+e.env.Port,
+	)
+
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	err := cmd.Start()
+	if err != nil {
+		return true
+	}
+
+	cmdDone := make(chan struct{})
+	go func() {
+		defer close(cmdDone)
+		cmd.Wait()
+	}()
+
+	select {
+	case <-e.terminate:
+		cmd.Process.Signal(os.Interrupt)
+		<-cmdDone
+		return false
+
+	case <-cmdDone:
+		return true
+	}
+}

internal/externalcmd/externalcmd_win.go

@@ -0,0 +1,57 @@
+// +build windows
+
+package externalcmd
+
+import (
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/kballard/go-shellquote"
+)
+
+func (e *ExternalCmd) runInner() bool {
+	// on Windows the shell is not used and command is started directly
+	// variables are replaced manually in order to guarantee compatibility
+	// with Linux commands
+	tmp := strings.ReplaceAll(e.cmdstr, "$RTSP_PATH", e.env.Path)
+	tmp = strings.ReplaceAll(tmp, "$RTSP_PORT", e.env.Port)
+
+	parts, err := shellquote.Split(tmp)
+	if err != nil {
+		return true
+	}
+
+	cmd := exec.Command(parts[0], parts[1:]...)
+
+	cmd.Env = append(os.Environ(),
+		"RTSP_PATH="+e.env.Path,
+		"RTSP_PORT="+e.env.Port,
+	)
+
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	err := cmd.Start()
+	if err != nil {
+		return true
+	}
+
+	cmdDone := make(chan struct{})
+	go func() {
+		defer close(cmdDone)
+		cmd.Wait()
+	}()
+
+	select {
+	case <-e.terminate:
+		// on Windows it's not possible to send os.Interrupt to a process
+		// Kill() is the only supported way
+		cmd.Process.Kill()
+		<-cmdDone
+		return false
+
+	case <-cmdDone:
+		return true
+	}
+}

internal/syslog/syslog_win.go

@@ -7,20 +7,7 @@ import (
 	"io"
 )
 
-type syslog struct {
-}
-
 // New allocates a io.WriteCloser that writes to the system log.
 func New(prefix string) (io.WriteCloser, error) {
 	return nil, fmt.Errorf("not implemented on windows")
 }
-
-// Close implements io.WriteCloser.
-func (ls *syslog) Close() error {
-	return nil
-}
-
-// Write implements io.WriteCloser.
-func (ls *syslog) Write(p []byte) (int, error) {
-	return 0, nil
-}