execute: Open separate handles to /dev/tty (in, out, err)

  # This will no longer cause 'Vim: Warning: Output is not to a terminal'
  fzf --bind 'enter:execute:vim {}' > /tmp/foo

9 files changed, 80 insertions, 66 deletions

diff --git a/src/proxy.go b/src/proxy.go
index adeea213..5ee7317c 100644
--- a/src/proxy.go
+++ b/src/proxy.go
@@ -60,7 +60,7 @@ func runProxy(commandPrefix string, cmdBuilder func(temp string) *exec.Cmd, opts
 
 	var command string
 	commandPrefix += ` --proxy-script "$0"`
-	if opts.Input == nil && util.IsTty() {
+	if opts.Input == nil && util.IsTty(os.Stdin) {
 		command = fmt.Sprintf(`%s > %q`, commandPrefix, output)
 	} else {
 		input, err := fifo("proxy-input")
@@ -131,7 +131,11 @@ func runProxy(commandPrefix string, cmdBuilder func(temp string) *exec.Cmd, opts
 					env = elems[1:]
 				}
 				executor := util.NewExecutor(opts.WithShell)
-				executor.Become(tui.TtyIn(), env, command)
+				ttyin, err := tui.TtyIn()
+				if err != nil {
+					return ExitError, err
+				}
+				executor.Become(ttyin, env, command)
 			}
 			return code, err
 		}
diff --git a/src/reader.go b/src/reader.go
index 99a609e2..83912df5 100644
--- a/src/reader.go
+++ b/src/reader.go
@@ -113,7 +113,7 @@ func (r *Reader) ReadSource(inputChan chan string, root string, opts walkerOpts,
 	var success bool
 	if inputChan != nil {
 		success = r.readChannel(inputChan)
-	} else if util.IsTty() {
+	} else if util.IsTty(os.Stdin) {
 		cmd := os.Getenv("FZF_DEFAULT_COMMAND")
 		if len(cmd) == 0 {
 			success = r.readFiles(root, opts, ignores)
diff --git a/src/terminal.go b/src/terminal.go
index 58073dd7..24c9cdda 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -51,6 +51,7 @@ var whiteSuffix *regexp.Regexp
 var offsetComponentRegex *regexp.Regexp
 var offsetTrimCharsRegex *regexp.Regexp
 var passThroughRegex *regexp.Regexp
+var ttyin *os.File
 
 const clearCode string = "\x1b[2J"
 
@@ -691,11 +692,19 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 	var renderer tui.Renderer
 	fullscreen := !opts.Height.auto && (opts.Height.size == 0 || opts.Height.percent && opts.Height.size == 100)
 	var err error
+	// Reuse ttyin if available to avoid having multiple file descriptors open
+	// when you run fzf multiple times in your Go program. Closing it is known to
+	// cause problems with 'become' action and invalid terminal state after exit.
+	if ttyin == nil {
+		if ttyin, err = tui.TtyIn(); err != nil {
+			return nil, err
+		}
+	}
 	if fullscreen {
 		if tui.HasFullscreenRenderer() {
 			renderer = tui.NewFullscreenRenderer(opts.Theme, opts.Black, opts.Mouse)
 		} else {
-			renderer, err = tui.NewLightRenderer(opts.Theme, opts.Black, opts.Mouse, opts.Tabstop, opts.ClearOnExit,
+			renderer, err = tui.NewLightRenderer(ttyin, opts.Theme, opts.Black, opts.Mouse, opts.Tabstop, opts.ClearOnExit,
 				true, func(h int) int { return h })
 		}
 	} else {
@@ -711,7 +720,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 			effectiveMinHeight += borderLines(opts.BorderShape)
 			return util.Min(termHeight, util.Max(evaluateHeight(opts, termHeight), effectiveMinHeight))
 		}
-		renderer, err = tui.NewLightRenderer(opts.Theme, opts.Black, opts.Mouse, opts.Tabstop, opts.ClearOnExit, false, maxHeightFunc)
+		renderer, err = tui.NewLightRenderer(ttyin, opts.Theme, opts.Black, opts.Mouse, opts.Tabstop, opts.ClearOnExit, false, maxHeightFunc)
 	}
 	if err != nil {
 		return nil, err
@@ -818,7 +827,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		serverOutputChan:   make(chan string),
 		eventChan:          make(chan tui.Event, 6), // (load + result + zero|one) | (focus) | (resize) | (GetChar)
 		tui:                renderer,
-		ttyin:              tui.TtyIn(),
+		ttyin:              ttyin,
 		initFunc:           func() error { return renderer.Init() },
 		executing:          util.NewAtomicBool(false),
 		lastAction:         actStart,
@@ -2874,9 +2883,30 @@ func (t *Terminal) executeCommand(template string, forcePlus bool, background bo
 	cmd.Env = t.environ()
 	t.executing.Set(true)
 	if !background {
-		cmd.Stdin = t.ttyin
+		// Open a separate handle for tty input
+		if in, _ := tui.TtyIn(); in != nil {
+			cmd.Stdin = in
+			if in != os.Stdin {
+				defer in.Close()
+			}
+		}
+
 		cmd.Stdout = os.Stdout
+		if !util.IsTty(os.Stdout) {
+			if out, _ := tui.TtyOut(); out != nil {
+				cmd.Stdout = out
+				defer out.Close()
+			}
+		}
+
 		cmd.Stderr = os.Stderr
+		if !util.IsTty(os.Stderr) {
+			if out, _ := tui.TtyOut(); out != nil {
+				cmd.Stderr = out
+				defer out.Close()
+			}
+		}
+
 		t.tui.Pause(true)
 		cmd.Run()
 		t.tui.Resume(true, false)
diff --git a/src/tui/light.go b/src/tui/light.go
index 1181d167..f202899a 100644
--- a/src/tui/light.go
+++ b/src/tui/light.go
@@ -127,11 +127,7 @@ type LightWindow struct {
 	bg       Color
 }
 
-func NewLightRenderer(theme *ColorTheme, forceBlack bool, mouse bool, tabstop int, clearOnExit bool, fullscreen bool, maxHeightFunc func(int) int) (Renderer, error) {
-	in, err := openTtyIn()
-	if err != nil {
-		return nil, err
-	}
+func NewLightRenderer(ttyin *os.File, theme *ColorTheme, forceBlack bool, mouse bool, tabstop int, clearOnExit bool, fullscreen bool, maxHeightFunc func(int) int) (Renderer, error) {
 	out, err := openTtyOut()
 	if err != nil {
 		out = os.Stderr
@@ -142,7 +138,7 @@ func NewLightRenderer(theme *ColorTheme, forceBlack bool, mouse bool, tabstop in
 		forceBlack:    forceBlack,
 		mouse:         mouse,
 		clearOnExit:   clearOnExit,
-		ttyin:         in,
+		ttyin:         ttyin,
 		ttyout:        out,
 		yoffset:       0,
 		tabstop:       tabstop,
diff --git a/src/tui/light_unix.go b/src/tui/light_unix.go
index 8d5a279b..06099d2f 100644
--- a/src/tui/light_unix.go
+++ b/src/tui/light_unix.go
@@ -7,7 +7,6 @@ import (
 	"os"
 	"os/exec"
 	"strings"
-	"sync"
 	"syscall"
 
 	"github.com/junegunn/fzf/src/util"
@@ -15,13 +14,6 @@ import (
 	"golang.org/x/term"
 )
 
-var (
-	tty    string
-	ttyin  *os.File
-	ttyout *os.File
-	mutex  sync.Mutex
-)
-
 func IsLightRendererSupported() bool {
 	return true
 }
@@ -53,15 +45,13 @@ func (r *LightRenderer) initPlatform() error {
 }
 
 func (r *LightRenderer) closePlatform() {
-	// NOOP
+	r.ttyout.Close()
 }
 
 func openTty(mode int) (*os.File, error) {
 	in, err := os.OpenFile(consoleDevice, mode, 0)
 	if err != nil {
-		if len(tty) == 0 {
-			tty = ttyname()
-		}
+		tty := ttyname()
 		if len(tty) > 0 {
 			if in, err := os.OpenFile(tty, mode, 0); err == nil {
 				return in, nil
@@ -73,31 +63,11 @@ func openTty(mode int) (*os.File, error) {
 }
 
 func openTtyIn() (*os.File, error) {
-	mutex.Lock()
-	defer mutex.Unlock()
-
-	if ttyin != nil {
-		return ttyin, nil
-	}
-	in, err := openTty(syscall.O_RDONLY)
-	if err == nil {
-		ttyin = in
-	}
-	return in, err
+	return openTty(syscall.O_RDONLY)
 }
 
 func openTtyOut() (*os.File, error) {
-	mutex.Lock()
-	defer mutex.Unlock()
-
-	if ttyout != nil {
-		return ttyout, nil
-	}
-	out, err := openTty(syscall.O_WRONLY)
-	if err == nil {
-		ttyout = out
-	}
-	return out, err
+	return openTty(syscall.O_WRONLY)
 }
 
 func (r *LightRenderer) setupTerminal() {
diff --git a/src/tui/tcell_test.go b/src/tui/tcell_test.go
index 54b9c9b3..217ad048 100644
--- a/src/tui/tcell_test.go
+++ b/src/tui/tcell_test.go
@@ -3,6 +3,7 @@
 package tui
 
 import (
+	"os"
 	"testing"
 
 	"github.com/gdamore/tcell/v2"
@@ -20,7 +21,7 @@ func assert(t *testing.T, context string, got interface{}, want interface{}) boo
 
 // Test the handling of the tcell keyboard events.
 func TestGetCharEventKey(t *testing.T) {
-	if util.ToTty() {
+	if util.IsTty(os.Stdout) {
 		// This test is skipped when output goes to terminal, because it causes
 		// some glitches:
 		// - output lines may not start at the beginning of a row which makes
diff --git a/src/tui/ttyname_unix.go b/src/tui/ttyname_unix.go
index 384115fb..d0350a0b 100644
--- a/src/tui/ttyname_unix.go
+++ b/src/tui/ttyname_unix.go
@@ -4,12 +4,19 @@ package tui
 
 import (
 	"os"
+	"sync/atomic"
 	"syscall"
 )
 
 var devPrefixes = [...]string{"/dev/pts/", "/dev/"}
 
+var tty atomic.Value
+
 func ttyname() string {
+	if cached := tty.Load(); cached != nil {
+		return cached.(string)
+	}
+
 	var stderr syscall.Stat_t
 	if syscall.Fstat(2, &stderr) != nil {
 		return ""
@@ -27,17 +34,21 @@ func ttyname() string {
 				continue
 			}
 			if stat, ok := info.Sys().(*syscall.Stat_t); ok && stat.Rdev == stderr.Rdev {
-				return prefix + file.Name()
+				value := prefix + file.Name()
+				tty.Store(value)
+				return value
 			}
 		}
 	}
 	return ""
 }
 
-// TtyIn returns terminal device to be used as STDIN, falls back to os.Stdin
-func TtyIn() *os.File {
-	if in, err := openTtyIn(); err == nil {
-		return in
-	}
-	return os.Stdin
+// TtyIn returns terminal device to read user input
+func TtyIn() (*os.File, error) {
+	return openTtyIn()
+}
+
+// TtyIn returns terminal device to write to
+func TtyOut() (*os.File, error) {
+	return openTtyOut()
 }
diff --git a/src/tui/ttyname_windows.go b/src/tui/ttyname_windows.go
index 39b84f70..0313c608 100644
--- a/src/tui/ttyname_windows.go
+++ b/src/tui/ttyname_windows.go
@@ -2,13 +2,20 @@
 
 package tui
 
-import "os"
+import (
+	"os"
+)
 
 func ttyname() string {
 	return ""
 }
 
 // TtyIn on Windows returns os.Stdin
-func TtyIn() *os.File {
-	return os.Stdin
+func TtyIn() (*os.File, error) {
+	return os.Stdin, nil
+}
+
+// TtyIn on Windows returns nil
+func TtyOut() (*os.File, error) {
+	return nil, nil
 }
diff --git a/src/util/util.go b/src/util/util.go
index 9b926b8d..ec5a1ea0 100644
--- a/src/util/util.go
+++ b/src/util/util.go
@@ -138,17 +138,12 @@ func DurWithin(
 	return val
 }
 
-// IsTty returns true if stdin is a terminal
-func IsTty() bool {
-	fd := os.Stdin.Fd()
+// IsTty returns true if the file is a terminal
+func IsTty(file *os.File) bool {
+	fd := file.Fd()
 	return isatty.IsTerminal(fd) || isatty.IsCygwinTerminal(fd)
 }
 
-// ToTty returns true if stdout is a terminal
-func ToTty() bool {
-	return isatty.IsTerminal(os.Stdout.Fd())
-}
-
 // Once returns a function that returns the specified boolean value only once
 func Once(nextResponse bool) func() bool {
 	state := nextResponse