Use winpty to launch fzf in Git bash (mintty)

Close #3806

Known limitation:
* --height cannot be used

12 files changed, 315 insertions, 157 deletions

diff --git a/src/core.go b/src/core.go
index 17b7d1df..9c5ac033 100644
--- a/src/core.go
+++ b/src/core.go
@@ -21,7 +21,11 @@ Matcher  -> EvtHeader         -> Terminal (update header)
 // Run starts fzf
 func Run(opts *Options) (int, error) {
 	if opts.Tmux != nil && len(os.Getenv("TMUX")) > 0 {
-		return runTmux(os.Args[1:], opts)
+		return runTmux(os.Args, opts)
+	}
+
+	if os.Getenv("TERM_PROGRAM") == "mintty" && !opts.NoWinpty {
+		return runWinpty(os.Args, opts)
 	}
 
 	if err := postProcessOptions(opts); err != nil {
diff --git a/src/options.go b/src/options.go
index 669feef4..ac7e76f0 100644
--- a/src/options.go
+++ b/src/options.go
@@ -381,8 +381,9 @@ type walkerOpts struct {
 type Options struct {
 	Input        chan string
 	Output       chan string
+	NoWinpty     bool
 	Tmux         *tmuxOptions
-	TmuxScript   string
+	ProxyScript  string
 	Bash         bool
 	Zsh          bool
 	Fish         bool
@@ -1883,6 +1884,8 @@ func parseOptions(opts *Options, allArgs []string) error {
 		case "--version":
 			clearExitingOpts()
 			opts.Version = true
+		case "--no-winpty":
+			opts.NoWinpty = true
 		case "--tmux":
 			str, err := nextString(allArgs, &i, "tmux options required")
 			if err != nil {
@@ -1893,8 +1896,8 @@ func parseOptions(opts *Options, allArgs []string) error {
 			}
 		case "--no-tmux":
 			opts.Tmux = nil
-		case "--tmux-script":
-			if opts.TmuxScript, err = nextString(allArgs, &i, ""); err != nil {
+		case "--proxy-script":
+			if opts.ProxyScript, err = nextString(allArgs, &i, ""); err != nil {
 				return err
 			}
 		case "-x", "--extended":
diff --git a/src/proxy.go b/src/proxy.go
new file mode 100644
index 00000000..bbac0292
--- /dev/null
+++ b/src/proxy.go
@@ -0,0 +1,132 @@
+package fzf
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/junegunn/fzf/src/tui"
+	"github.com/junegunn/fzf/src/util"
+)
+
+const becomeSuffix = ".become"
+
+func escapeSingleQuote(str string) string {
+	return "'" + strings.ReplaceAll(str, "'", "'\\''") + "'"
+}
+
+func fifo(name string) (string, error) {
+	ns := time.Now().UnixNano()
+	output := filepath.Join(os.TempDir(), fmt.Sprintf("fzf-%s-%d", name, ns))
+	output, err := mkfifo(output, 0600)
+	if err != nil {
+		return output, err
+	}
+	return output, nil
+}
+
+func runProxy(commandPrefix string, cmdBuilder func(temp string) *exec.Cmd, opts *Options, withExports bool) (int, error) {
+	output, err := fifo("proxy-output")
+	if err != nil {
+		return ExitError, err
+	}
+	defer os.Remove(output)
+
+	// Take the output
+	go func() {
+		withOutputPipe(output, func(outputFile io.ReadCloser) {
+			if opts.Output == nil {
+				io.Copy(os.Stdout, outputFile)
+			} else {
+				reader := bufio.NewReader(outputFile)
+				sep := opts.PrintSep[0]
+				for {
+					item, err := reader.ReadString(sep)
+					if err != nil {
+						break
+					}
+					opts.Output <- item
+				}
+			}
+		})
+	}()
+
+	var command string
+	commandPrefix += ` --proxy-script "$0"`
+	if opts.Input == nil && util.IsTty() {
+		command = fmt.Sprintf(`%s > %q`, commandPrefix, output)
+	} else {
+		input, err := fifo("proxy-input")
+		if err != nil {
+			return ExitError, err
+		}
+		defer os.Remove(input)
+
+		go func() {
+			withInputPipe(input, func(inputFile io.WriteCloser) {
+				if opts.Input == nil {
+					io.Copy(inputFile, os.Stdin)
+				} else {
+					for item := range opts.Input {
+						fmt.Fprint(inputFile, item+opts.PrintSep)
+					}
+				}
+			})
+		}()
+
+		if withExports {
+			command = fmt.Sprintf(`%s < %q > %q`, commandPrefix, input, output)
+		} else {
+			// For mintty: cannot directly read named pipe from Go code
+			command = fmt.Sprintf(`command cat %q | %s > %q`, input, commandPrefix, output)
+		}
+	}
+
+	// To ensure that the options are processed by a POSIX-compliant shell,
+	// we need to write the command to a temporary file and execute it with sh.
+	var exports []string
+	if withExports {
+		exports = os.Environ()
+		for idx, pairStr := range exports {
+			pair := strings.SplitN(pairStr, "=", 2)
+			exports[idx] = fmt.Sprintf("export %s=%s", pair[0], escapeSingleQuote(pair[1]))
+		}
+	}
+	temp := writeTemporaryFile(append(exports, command), "\n")
+	defer os.Remove(temp)
+
+	cmd := cmdBuilder(temp)
+	if err := cmd.Run(); err != nil {
+		if exitError, ok := err.(*exec.ExitError); ok {
+			code := exitError.ExitCode()
+			if code == ExitBecome {
+				becomeFile := temp + becomeSuffix
+				data, err := os.ReadFile(becomeFile)
+				os.Remove(becomeFile)
+				if err != nil {
+					return ExitError, err
+				}
+				elems := strings.Split(string(data), "\x00")
+				if len(elems) < 1 {
+					return ExitError, errors.New("invalid become command")
+				}
+				command := elems[0]
+				env := []string{}
+				if len(elems) > 1 {
+					env = elems[1:]
+				}
+				executor := util.NewExecutor(opts.WithShell)
+				executor.Become(tui.TtyIn(), env, command)
+			}
+			return code, err
+		}
+	}
+
+	return ExitOk, nil
+}
diff --git a/src/proxy_unix.go b/src/proxy_unix.go
new file mode 100644
index 00000000..189d0e56
--- /dev/null
+++ b/src/proxy_unix.go
@@ -0,0 +1,38 @@
+//go:build !windows
+
+package fzf
+
+import (
+	"io"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func sh() (string, error) {
+	return "sh", nil
+}
+
+func mkfifo(path string, mode uint32) (string, error) {
+	return path, unix.Mkfifo(path, mode)
+}
+
+func withOutputPipe(output string, task func(io.ReadCloser)) error {
+	outputFile, err := os.OpenFile(output, os.O_RDONLY, 0)
+	if err != nil {
+		return err
+	}
+	task(outputFile)
+	outputFile.Close()
+	return nil
+}
+
+func withInputPipe(input string, task func(io.WriteCloser)) error {
+	inputFile, err := os.OpenFile(input, os.O_WRONLY, 0)
+	if err != nil {
+		return err
+	}
+	task(inputFile)
+	inputFile.Close()
+	return nil
+}
diff --git a/src/proxy_windows.go b/src/proxy_windows.go
new file mode 100644
index 00000000..a957da8a
--- /dev/null
+++ b/src/proxy_windows.go
@@ -0,0 +1,81 @@
+//go:build windows
+
+package fzf
+
+import (
+	"fmt"
+	"io"
+	"os/exec"
+	"strconv"
+	"strings"
+	"sync/atomic"
+)
+
+var shPath atomic.Value
+
+func sh() (string, error) {
+	if cached := shPath.Load(); cached != nil {
+		return cached.(string), nil
+	}
+
+	cmd := exec.Command("cygpath", "-w", "/usr/bin/sh")
+	bytes, err := cmd.Output()
+	if err != nil {
+		return "", err
+	}
+
+	sh := strings.TrimSpace(string(bytes))
+	shPath.Store(sh)
+	return sh, nil
+}
+
+func mkfifo(path string, mode uint32) (string, error) {
+	m := strconv.FormatUint(uint64(mode), 8)
+	sh, err := sh()
+	if err != nil {
+		return path, err
+	}
+	cmd := exec.Command(sh, "-c", fmt.Sprintf(`command mkfifo -m %s %q`, m, path))
+	if err := cmd.Run(); err != nil {
+		return path, err
+	}
+	return path + ".lnk", nil
+}
+
+func withOutputPipe(output string, task func(io.ReadCloser)) error {
+	sh, err := sh()
+	if err != nil {
+		return err
+	}
+	cmd := exec.Command(sh, "-c", fmt.Sprintf(`command cat %q`, output))
+	outputFile, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+
+	task(outputFile)
+	cmd.Wait()
+	return nil
+}
+
+func withInputPipe(input string, task func(io.WriteCloser)) error {
+	sh, err := sh()
+	if err != nil {
+		return err
+	}
+	cmd := exec.Command(sh, "-c", fmt.Sprintf(`command cat - > %q`, input))
+	inputFile, err := cmd.StdinPipe()
+	if err != nil {
+		return err
+	}
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	task(inputFile)
+	inputFile.Close()
+	cmd.Wait()
+	return nil
+}
diff --git a/src/terminal.go b/src/terminal.go
index c396fa20..f50d7698 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -322,7 +322,7 @@ type Terminal struct {
 	forcePreview       bool
 	clickHeaderLine    int
 	clickHeaderColumn  int
-	tmuxScript         string
+	proxyScript        string
 }
 
 type selectedItem struct {
@@ -795,7 +795,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		jumpLabels:         opts.JumpLabels,
 		printer:            opts.Printer,
 		printsep:           opts.PrintSep,
-		tmuxScript:         opts.TmuxScript,
+		proxyScript:        opts.ProxyScript,
 		merger:             EmptyMerger(0),
 		selected:           make(map[int32]selectedItem),
 		reqBox:             util.NewEventBox(),
@@ -3608,9 +3608,9 @@ func (t *Terminal) Loop() error {
 						t.history.append(string(t.input))
 					}
 
-					if len(t.tmuxScript) > 0 {
+					if len(t.proxyScript) > 0 {
 						data := strings.Join(append([]string{command}, t.environ()...), "\x00")
-						os.WriteFile(t.tmuxScript, []byte(data), 0600)
+						os.WriteFile(t.proxyScript+becomeSuffix, []byte(data), 0600)
 						req(reqBecome)
 					} else {
 						t.executor.Become(t.ttyin, t.environ(), command)
diff --git a/src/tmux.go b/src/tmux.go
index 5cc970fa..3be95661 100644
--- a/src/tmux.go
+++ b/src/tmux.go
@@ -1,81 +1,24 @@
 package fzf
 
 import (
-	"bufio"
-	"errors"
-	"fmt"
-	"io"
 	"os"
 	"os/exec"
-	"path/filepath"
-	"strings"
-	"time"
 
 	"github.com/junegunn/fzf/src/tui"
-	"github.com/junegunn/fzf/src/util"
 )
 
-func escapeSingleQuote(str string) string {
-	return "'" + strings.ReplaceAll(str, "'", "'\\''") + "'"
-}
-
 func runTmux(args []string, opts *Options) (int, error) {
-	ns := time.Now().UnixNano()
-
-	output := filepath.Join(os.TempDir(), fmt.Sprintf("fzf-tmux-output-%d", ns))
-	if err := mkfifo(output, 0666); err != nil {
-		return ExitError, err
-	}
-	defer os.Remove(output)
-
-	// Find fzf executable
-	fzf := "fzf"
-	if found, err := os.Executable(); err == nil {
-		fzf = found
-	}
-
 	// Prepare arguments
-	args = append([]string{"--bind=ctrl-z:ignore"}, args...)
+	fzf := args[0]
+	args = append([]string{"--bind=ctrl-z:ignore"}, args[1:]...)
 	if opts.BorderShape == tui.BorderUndefined {
 		args = append(args, "--border")
 	}
-	args = append(args, "--no-height")
-	args = append(args, "--no-tmux")
-	argStr := ""
+	argStr := escapeSingleQuote(fzf)
 	for _, arg := range args {
-		// %q formatting escapes $'foo\nbar' to "foo\nbar"
 		argStr += " " + escapeSingleQuote(arg)
 	}
-	argStr += ` --tmux-script "$0"`
-
-	// Build command
-	var command string
-	if opts.Input == nil && util.IsTty() {
-		command = fmt.Sprintf(`%q%s > %q`, fzf, argStr, output)
-	} else {
-		input := filepath.Join(os.TempDir(), fmt.Sprintf("fzf-tmux-input-%d", ns))
-		if err := mkfifo(input, 0644); err != nil {
-			return ExitError, err
-		}
-		defer os.Remove(input)
-
-		go func() {
-			inputFile, err := os.OpenFile(input, os.O_WRONLY, 0)
-			if err != nil {
-				return
-			}
-			if opts.Input == nil {
-				io.Copy(inputFile, os.Stdin)
-			} else {
-				for item := range opts.Input {
-					fmt.Fprint(inputFile, item+opts.PrintSep)
-				}
-			}
-			inputFile.Close()
-		}()
-
-		command = fmt.Sprintf(`%q%s < %q > %q`, fzf, argStr, input, output)
-	}
+	argStr += ` --no-tmux --no-height`
 
 	// Get current directory
 	dir, err := os.Getwd()
@@ -106,65 +49,9 @@ func runTmux(args []string, opts *Options) (int, error) {
 	tmuxArgs = append(tmuxArgs, "-w"+opts.Tmux.width.String())
 	tmuxArgs = append(tmuxArgs, "-h"+opts.Tmux.height.String())
 
-	// To ensure that the options are processed by a POSIX-compliant shell,
-	// we need to write the command to a temporary file and execute it with sh.
-	exports := os.Environ()
-	for idx, pairStr := range exports {
-		pair := strings.SplitN(pairStr, "=", 2)
-		exports[idx] = fmt.Sprintf("export %s=%s", pair[0], escapeSingleQuote(pair[1]))
-	}
-	temp := writeTemporaryFile(append(exports, command), "\n")
-	defer os.Remove(temp)
-	tmuxArgs = append(tmuxArgs, "sh", temp)
-
-	// Take the output
-	go func() {
-		outputFile, err := os.OpenFile(output, os.O_RDONLY, 0)
-		if err != nil {
-			return
-		}
-		if opts.Output == nil {
-			io.Copy(os.Stdout, outputFile)
-		} else {
-			reader := bufio.NewReader(outputFile)
-			sep := opts.PrintSep[0]
-			for {
-				item, err := reader.ReadString(sep)
-				if err != nil {
-					break
-				}
-				opts.Output <- item
-			}
-		}
-
-		outputFile.Close()
-	}()
-
-	cmd := exec.Command("tmux", tmuxArgs...)
-	if err := cmd.Run(); err != nil {
-		if exitError, ok := err.(*exec.ExitError); ok {
-			code := exitError.ExitCode()
-			if code == ExitBecome {
-				data, err := os.ReadFile(temp)
-				if err != nil {
-					return ExitError, err
-				}
-				elems := strings.Split(string(data), "\x00")
-				if len(elems) < 1 {
-					return ExitError, errors.New("invalid become command")
-				}
-				command := elems[0]
-				env := []string{}
-				if len(elems) > 1 {
-					env = elems[1:]
-				}
-				os.Remove(temp)
-				executor := util.NewExecutor(opts.WithShell)
-				executor.Become(tui.TtyIn(), env, command)
-			}
-			return code, err
-		}
-	}
-
-	return ExitOk, nil
+	return runProxy(argStr, func(temp string) *exec.Cmd {
+		sh, _ := sh()
+		tmuxArgs = append(tmuxArgs, sh, temp)
+		return exec.Command("tmux", tmuxArgs...)
+	}, opts, true)
 }
diff --git a/src/tmux_unix.go b/src/tmux_unix.go
deleted file mode 100644
index f6ddd58b..00000000
--- a/src/tmux_unix.go
+++ /dev/null
@@ -1,9 +0,0 @@
-//go:build !windows
-
-package fzf
-
-import "golang.org/x/sys/unix"
-
-func mkfifo(path string, mode uint32) error {
-	return unix.Mkfifo(path, mode)
-}
diff --git a/src/tmux_windows.go b/src/tmux_windows.go
deleted file mode 100644
index bd356364..00000000
--- a/src/tmux_windows.go
+++ /dev/null
@@ -1,17 +0,0 @@
-//go:build windows
-
-package fzf
-
-import (
-	"os/exec"
-	"strconv"
-)
-
-func mkfifo(path string, mode uint32) error {
-	m := strconv.FormatUint(uint64(mode), 8)
-	cmd := exec.Command("mkfifo", "-m", m, path)
-	if err := cmd.Run(); err != nil {
-		return err
-	}
-	return nil
-}
diff --git a/src/util/util.go b/src/util/util.go
index f6e00e9c..b5b27f28 100644
--- a/src/util/util.go
+++ b/src/util/util.go
@@ -139,7 +139,8 @@ func DurWithin(
 
 // IsTty returns true if stdin is a terminal
 func IsTty() bool {
-	return isatty.IsTerminal(os.Stdin.Fd())
+	fd := os.Stdin.Fd()
+	return isatty.IsTerminal(fd) || isatty.IsCygwinTerminal(fd)
 }
 
 // ToTty returns true if stdout is a terminal
diff --git a/src/winpty.go b/src/winpty.go
new file mode 100644
index 00000000..46f9400f
--- /dev/null
+++ b/src/winpty.go
@@ -0,0 +1,9 @@
+//go:build !windows
+
+package fzf
+
+import "errors"
+
+func runWinpty(_ []string, _ *Options) (int, error) {
+	return ExitError, errors.New("Not supported")
+}
diff --git a/src/winpty_windows.go b/src/winpty_windows.go
new file mode 100644
index 00000000..83802a2b
--- /dev/null
+++ b/src/winpty_windows.go
@@ -0,0 +1,29 @@
+//go:build windows
+
+package fzf
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+)
+
+func runWinpty(args []string, opts *Options) (int, error) {
+	sh, err := sh()
+	if err != nil {
+		return ExitError, err
+	}
+
+	argStr := escapeSingleQuote(args[0])
+	for _, arg := range args[1:] {
+		argStr += " " + escapeSingleQuote(arg)
+	}
+	argStr += ` --no-winpty --no-height`
+
+	return runProxy(argStr, func(temp string) *exec.Cmd {
+		cmd := exec.Command(sh, "-c", fmt.Sprintf(`winpty < /dev/tty > /dev/tty -- sh %q`, temp))
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		return cmd
+	}, opts, false)
+}