simple stdin implementation

cmd.go

@@ -195,7 +195,12 @@ func (c *Cmd) Clone() *Cmd {
 // Exactly one Status is sent on the channel when the command ends. The channel
 // is not closed. Any Go error is set to Status.Error. Start is idempotent; it
 // always returns the same channel.
+
 func (c *Cmd) Start() <-chan Status {
+	return c.StartWithStdin(nil)
+}
+
+func (c *Cmd) StartWithStdin(in io.Reader) <-chan Status {
 	c.Lock()
 	defer c.Unlock()
 
@@ -204,7 +209,7 @@ func (c *Cmd) Start() <-chan Status {
 	}
 
 	c.statusChan = make(chan Status, 1)
-	go c.run()
+	go c.run(in)
 	return c.statusChan
 }
 
@@ -290,7 +295,7 @@ func (c *Cmd) Done() <-chan struct{} {
 
 // --------------------------------------------------------------------------
 
-func (c *Cmd) run() {
+func (c *Cmd) run(in io.Reader) {
 	defer func() {
 		c.statusChan <- c.Status() // unblocks Start if caller is waiting
 		close(c.doneChan)
@@ -300,6 +305,9 @@ func (c *Cmd) run() {
 	// Setup command
 	// //////////////////////////////////////////////////////////////////////
 	cmd := exec.Command(c.Name, c.Args...)
+	if in != nil {
+		cmd.Stdin = in
+	}
 
 	// Platform-specific SysProcAttr management
 	setProcessGroupID(cmd)

cmd_test.go

@@ -3,6 +3,7 @@
 package cmd_test
 
 import (
+	"bytes"
 	"errors"
 	"io/ioutil"
 	"os"
@@ -1028,3 +1029,52 @@ func TestCmdNoOutput(t *testing.T) {
 		t.Errorf("got stderr, expected no output: %v", s.Stderr)
 	}
 }
+
+func TestStdinOk(t *testing.T) {
+
+	tests := []struct {
+		in []byte
+	}{
+		{
+			in: []byte("1"),
+		},
+		{
+			in: []byte("hello"),
+		},
+		{
+			in: []byte{65, 66, 67, 226, 130, 172}, // ABC€
+		},
+	}
+	for _, tt := range tests {
+		now := time.Now().Unix()
+		p := cmd.NewCmd("test/stdin")
+		gotStatus := <-p.StartWithStdin(bytes.NewReader(tt.in))
+		expectStatus := cmd.Status{
+			Cmd:      "test/stdin",
+			PID:      gotStatus.PID, // nondeterministic
+			Complete: true,
+			Exit:     0,
+			Error:    nil,
+			Runtime:  gotStatus.Runtime, // nondeterministic
+			Stdout:   []string{"stdin: " + string(tt.in)},
+			Stderr:   []string{},
+		}
+		if gotStatus.StartTs < now {
+			t.Error("StartTs < now")
+		}
+		if gotStatus.StopTs < gotStatus.StartTs {
+			t.Error("StopTs < StartTs")
+		}
+		gotStatus.StartTs = 0
+		gotStatus.StopTs = 0
+		if diffs := deep.Equal(gotStatus, expectStatus); diffs != nil {
+			t.Error(diffs)
+		}
+		if gotStatus.PID < 0 {
+			t.Errorf("got PID %d, expected non-zero", gotStatus.PID)
+		}
+		if gotStatus.Runtime < 0 {
+			t.Errorf("got runtime %f, expected non-zero", gotStatus.Runtime)
+		}
+	}
+}

test/stdin

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+IN=$(< /dev/stdin)
+
+echo "stdin: $IN"