Remove possible races (#4070)

Author: junegunn

src/core.go

@@ -172,7 +172,9 @@ func Run(opts *Options) (int, error) {
 			return chunkList.Push(data)
 		}, eventBox, executor, opts.ReadZero, opts.Filter == nil)
 
-		go reader.ReadSource(opts.Input, opts.WalkerRoot, opts.WalkerOpts, opts.WalkerSkip, initialReload, initialEnv)
+		readyChan := make(chan bool)
+		go reader.ReadSource(opts.Input, opts.WalkerRoot, opts.WalkerOpts, opts.WalkerSkip, initialReload, initialEnv, readyChan)
+		<-readyChan
 	}
 
 	// Matcher
@@ -224,7 +226,7 @@ func Run(opts *Options) (int, error) {
 					}
 					return false
 				}, eventBox, executor, opts.ReadZero, false)
-			reader.ReadSource(opts.Input, opts.WalkerRoot, opts.WalkerOpts, opts.WalkerSkip, initialReload, initialEnv)
+			reader.ReadSource(opts.Input, opts.WalkerRoot, opts.WalkerOpts, opts.WalkerSkip, initialReload, initialEnv, nil)
 		} else {
 			eventBox.Unwatch(EvtReadNew)
 			eventBox.WaitFor(EvtReadFin)
@@ -299,7 +301,9 @@ func Run(opts *Options) (int, error) {
 		itemIndex = 0
 		inputRevision.bumpMajor()
 		header = make([]string, 0, opts.HeaderLines)
-		reader.restart(command, environ)
+		readyChan := make(chan bool)
+		go reader.restart(command, environ, readyChan)
+		<-readyChan
 	}
 
 	exitCode := ExitOk

src/reader.go

@@ -6,7 +6,6 @@ import (
 	"io"
 	"io/fs"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"sync"
 	"sync/atomic"
@@ -98,20 +97,14 @@ func (r *Reader) terminate() {
 	r.mutex.Unlock()
 }
 
-func (r *Reader) restart(command commandSpec, environ []string) {
+func (r *Reader) restart(command commandSpec, environ []string, readyChan chan bool) {
 	r.event = int32(EvtReady)
 	r.startEventPoller()
-
-	r.mutex.Lock()
-	defer r.mutex.Unlock()
-
-	if exec, execOut := r.startCommand(command.command, environ); exec != nil {
-		go func() {
-			success := r.feedCommandOutput(exec, execOut)
-			r.fin(success)
-			removeFiles(command.tempFiles)
-		}()
-	}
+	success := r.readFromCommand(command.command, environ, func() {
+		readyChan <- true
+	})
+	r.fin(success)
+	removeFiles(command.tempFiles)
 }
 
 func (r *Reader) readChannel(inputChan chan string) bool {
@@ -128,21 +121,29 @@ func (r *Reader) readChannel(inputChan chan string) bool {
 }
 
 // ReadSource reads data from the default command or from standard input
-func (r *Reader) ReadSource(inputChan chan string, root string, opts walkerOpts, ignores []string, initCmd string, initEnv []string) {
+func (r *Reader) ReadSource(inputChan chan string, root string, opts walkerOpts, ignores []string, initCmd string, initEnv []string, readyChan chan bool) {
 	r.startEventPoller()
 	var success bool
+	signalReady := func() {
+		if readyChan != nil {
+			readyChan <- true
+		}
+	}
 	if inputChan != nil {
+		signalReady()
 		success = r.readChannel(inputChan)
 	} else if len(initCmd) > 0 {
-		success = r.readFromCommand(initCmd, initEnv)
+		success = r.readFromCommand(initCmd, initEnv, signalReady)
 	} else if util.IsTty(os.Stdin) {
 		cmd := os.Getenv("FZF_DEFAULT_COMMAND")
 		if len(cmd) == 0 {
+			signalReady()
 			success = r.readFiles(root, opts, ignores)
 		} else {
-			success = r.readFromCommand(cmd, initEnv)
+			success = r.readFromCommand(cmd, initEnv, signalReady)
 		}
 	} else {
+		signalReady()
 		success = r.readFromStdin()
 	}
 	r.fin(success)
@@ -304,8 +305,9 @@ func (r *Reader) readFiles(root string, opts walkerOpts, ignores []string) bool
 	return fastwalk.Walk(&conf, root, fn) == nil
 }
 
-// Should be called with the mutex held
-func (r *Reader) startCommand(command string, environ []string) (*exec.Cmd, io.ReadCloser) {
+func (r *Reader) readFromCommand(command string, environ []string, signalReady func()) bool {
+	r.mutex.Lock()
+
 	r.termFunc = nil
 	r.command = &command
 	exec := r.executor.ExecCommand(command, true)
@@ -314,7 +316,8 @@ func (r *Reader) startCommand(command string, environ []string) (*exec.Cmd, io.R
 	}
 	execOut, err := exec.StdoutPipe()
 	if err != nil || exec.Start() != nil {
-		return nil, nil
+		r.mutex.Unlock()
+		return false
 	}
 
 	// Function to call to terminate the running command
@@ -323,20 +326,9 @@ func (r *Reader) startCommand(command string, environ []string) (*exec.Cmd, io.R
 		util.KillCommand(exec)
 	}
 
-	return exec, execOut
-}
+	signalReady()
+	r.mutex.Unlock()
 
-func (r *Reader) feedCommandOutput(exec *exec.Cmd, execOut io.ReadCloser) bool {
 	r.feed(execOut)
 	return exec.Wait() == nil
 }
-
-func (r *Reader) readFromCommand(command string, environ []string) bool {
-	r.mutex.Lock()
-	exec, execOut := r.startCommand(command, environ)
-	r.mutex.Unlock()
-	if exec == nil {
-		return false
-	}
-	return r.feedCommandOutput(exec, execOut)
-}

src/reader_test.go

@@ -23,8 +23,12 @@ func TestReadFromCommand(t *testing.T) {
 	}
 
 	// Normal command
-	reader.fin(reader.readFromCommand(`echo abc&&echo def`, nil))
-	if len(strs) != 2 || strs[0] != "abc" || strs[1] != "def" {
+	counter := 0
+	ready := func() {
+		counter++
+	}
+	reader.fin(reader.readFromCommand(`echo abc&&echo def`, nil, ready))
+	if len(strs) != 2 || strs[0] != "abc" || strs[1] != "def" || counter != 1 {
 		t.Errorf("%s", strs)
 	}
 
@@ -48,9 +52,9 @@ func TestReadFromCommand(t *testing.T) {
 	reader.startEventPoller()
 
 	// Failing command
-	reader.fin(reader.readFromCommand(`no-such-command`, nil))
+	reader.fin(reader.readFromCommand(`no-such-command`, nil, ready))
 	strs = []string{}
-	if len(strs) > 0 {
+	if len(strs) > 0 || counter != 2 {
 		t.Errorf("%s", strs)
 	}