Add functional options to allow configuring the underlying Cmd

browser.go

@@ -18,18 +18,22 @@ var Stdout io.Writer = os.Stdout
 // Stderr is the io.Writer to which executed commands write standard error.
 var Stderr io.Writer = os.Stderr
 
+type CmdOption func (*exec.Cmd)
+
 // OpenFile opens new browser window for the file path.
-func OpenFile(path string) error {
+// options can be used to configure the underlying exec.Cmd, if any
+func OpenFile(path string, options ...CmdOption) error {
 	path, err := filepath.Abs(path)
 	if err != nil {
 		return err
 	}
-	return OpenURL("file://" + path)
+	return OpenURL("file://" + path, options...)
 }
 
 // OpenReader consumes the contents of r and presents the
 // results in a new browser window.
-func OpenReader(r io.Reader) error {
+// options can be used to configure the underlying exec.Cmd, if any
+func OpenReader(r io.Reader, options ...CmdOption) error {
 	f, err := ioutil.TempFile("", "browser")
 	if err != nil {
 		return fmt.Errorf("browser: could not create temporary file: %v", err)
@@ -46,18 +50,22 @@ func OpenReader(r io.Reader) error {
 	if err := os.Rename(oldname, newname); err != nil {
 		return fmt.Errorf("browser: renaming temporary file failed: %v", err)
 	}
-	return OpenFile(newname)
+	return OpenFile(newname, options...)
 }
 
 // OpenURL opens a new browser window pointing to url.
-func OpenURL(url string) error {
-	return openBrowser(url)
+// options can be used to configure the underlying exec.Cmd, if any
+func OpenURL(url string, options ...CmdOption) error {
+	return openBrowser(url, options)
 }
 
-func runCmd(prog string, args ...string) error {
+func runCmd(prog string, args []string, options []CmdOption) error {
 	cmd := exec.Command(prog, args...)
 	cmd.Stdout = Stdout
 	cmd.Stderr = Stderr
 	setFlags(cmd)
+	for _, o := range options {
+		o(cmd)
+	}
 	return cmd.Run()
 }

browser_darwin.go

@@ -2,8 +2,8 @@ package browser
 
 import "os/exec"
 
-func openBrowser(url string) error {
-	return runCmd("open", url)
+func openBrowser(url string, cmdOptions []CmdOption) error {
+	return runCmd("open", []string{url}, cmdOptions)
 }
 
 func setFlags(cmd *exec.Cmd) {}

browser_freebsd.go

@@ -5,8 +5,8 @@ import (
 	"os/exec"
 )
 
-func openBrowser(url string) error {
-	err := runCmd("xdg-open", url)
+func openBrowser(url string, cmdOptions []CmdOption) error {
+	err := runCmd("xdg-open", []string{url}, cmdOptions)
 	if e, ok := err.(*exec.Error); ok && e.Err == exec.ErrNotFound {
 		return errors.New("xdg-open: command not found - install xdg-utils from ports(8)")
 	}

browser_linux.go

@@ -5,15 +5,15 @@ import (
 	"strings"
 )
 
-func openBrowser(url string) error {
+func openBrowser(url string, cmdOptions []CmdOption) error {
 	providers := []string{"xdg-open", "x-www-browser", "www-browser"}
 
 	// There are multiple possible providers to open a browser on linux
 	// One of them is xdg-open, another is x-www-browser, then there's www-browser, etc.
 	// Look for one that exists and run it
 	for _, provider := range providers {
 		if _, err := exec.LookPath(provider); err == nil {
-			return runCmd(provider, url)
+			return runCmd(provider, []string{url}, cmdOptions)
 		}
 	}
 

browser_openbsd.go

@@ -5,8 +5,8 @@ import (
 	"os/exec"
 )
 
-func openBrowser(url string) error {
-	err := runCmd("xdg-open", url)
+func openBrowser(url string, cmdOptions []CmdOption) error {
+	err := runCmd("xdg-open", []string{url}, cmdOptions)
 	if e, ok := err.(*exec.Error); ok && e.Err == exec.ErrNotFound {
 		return errors.New("xdg-open: command not found - install xdg-utils from ports(8)")
 	}

browser_unsupported.go

@@ -8,7 +8,7 @@ import (
 	"runtime"
 )
 
-func openBrowser(url string) error {
+func openBrowser(url string, cmdOptions []CmdOption) error {
 	return fmt.Errorf("openBrowser: unsupported operating system: %v", runtime.GOOS)
 }
 

browser_windows.go

@@ -5,7 +5,7 @@ package browser
 import "os/exec"
 const SW_SHOWNORMAL = 1
 
-func openBrowser(url string) error {
+func openBrowser(url string, cmdOptions []CmdOption) error {
    return ShellExecute(0, "", url, "", "", SW_SHOWNORMAL)
 }
 

example_test.go

@@ -1,6 +1,11 @@
 package browser
 
-import "strings"
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"strings"
+)
 
 func ExampleOpenFile() {
 	OpenFile("index.html")
@@ -21,3 +26,13 @@ func ExampleOpenURL() {
 	const url = "http://golang.org/"
 	OpenURL(url)
 }
+
+func ExampleOpenURLWithOptions() {
+	out := &bytes.Buffer{}
+	const url = "http://golang.org/"
+	OpenURL(url, func(cmd *exec.Cmd) {
+		cmd.Stdout = out
+		cmd.Stderr = out
+	})
+	fmt.Printf("browser open output: %q\n", out.String())
+}

go.mod

@@ -1,3 +1,5 @@
 module github.com/pkg/browser
 
 go 1.14
+
+require golang.org/x/sys v0.0.0-20210415045647-66c3f260301c

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/sys v0.0.0-20210415045647-66c3f260301c h1:6L+uOeS3OQt/f4eFHXZcTxeZrGCuz+CLElgEBjbcTA4=
+golang.org/x/sys v0.0.0-20210415045647-66c3f260301c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=