Refactor the code so that fzf can be used as a library (#3769)

src/util/atexit.go

@@ -1,7 +1,6 @@
 package util
 
 import (
-	"os"
 	"sync"
 )
 
@@ -25,14 +24,5 @@ func RunAtExitFuncs() {
 	for i := len(fns) - 1; i >= 0; i-- {
 		fns[i]()
 	}
-}
-
-// Exit executes any functions registered with AtExit() then exits the program
-// with os.Exit(code).
-//
-// NOTE: It must be used instead of os.Exit() since calling os.Exit() terminates
-// the program before any of the AtExit functions can run.
-func Exit(code int) {
-	defer os.Exit(code)
-	RunAtExitFuncs()
+	atExitFuncs = nil
 }

src/util/util_unix.go

@@ -61,7 +61,7 @@ func (x *Executor) Become(stdin *os.File, environ []string, command string) {
 	shellPath, err := exec.LookPath(x.shell)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "fzf (become): %s\n", err.Error())
-		Exit(127)
+		os.Exit(127)
 	}
 	args := append([]string{shellPath}, append(x.args, command)...)
 	SetStdin(stdin)

src/util/util_windows.go

@@ -97,15 +97,15 @@ func (x *Executor) Become(stdin *os.File, environ []string, command string) {
 	err := cmd.Start()
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "fzf (become): %s\n", err.Error())
-		Exit(127)
+		os.Exit(127)
 	}
 	err = cmd.Wait()
 	if err != nil {
 		if exitError, ok := err.(*exec.ExitError); ok {
-			Exit(exitError.ExitCode())
+			os.Exit(exitError.ExitCode())
 		}
 	}
-	Exit(0)
+	os.Exit(0)
 }
 
 func escapeArg(s string) string {