Issue-70: Add timeout to zfs/zpool commands, except zfs send/receive commands

Author: avnish30jn

.travis.yml

@@ -26,8 +26,8 @@ before_install:
   - sudo apt-get update -y && sudo apt-get install -y libattr1-dev libblkid-dev linux-headers-$(uname -r) tree uuid-dev
   - mkdir -p $HOME/zfs
   - cd $HOME/zfs
-  - [[ -d spl-$rel.tar.gz ]] || curl -L https://github.com/zfsonlinux/zfs/releases/download/zfs-$rel/spl-$rel.tar.gz | tar xz
-  - [[ -d zfs-$rel.tar.gz ]] || curl -L https://github.com/zfsonlinux/zfs/releases/download/zfs-$rel/zfs-$rel.tar.gz | tar xz
+  - "[[ -d spl-$rel.tar.gz ]] || curl -L https://github.com/zfsonlinux/zfs/releases/download/zfs-$rel/spl-$rel.tar.gz | tar xz"
+  - "[[ -d zfs-$rel.tar.gz ]] || curl -L https://github.com/zfsonlinux/zfs/releases/download/zfs-$rel/zfs-$rel.tar.gz | tar xz"
   - (cd spl-$rel && ./configure --prefix=/usr && make && sudo make install)
   - (cd zfs-$rel && ./configure --prefix=/usr && make && sudo make install)
   - sudo modprobe zfs

utils.go

@@ -2,28 +2,50 @@ package zfs
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"io"
+	"os"
 	"os/exec"
 	"regexp"
 	"runtime"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/pborman/uuid"
 )
 
+const (
+	cmdtimeoutEnv = "COMMAND_TIMEOUT"
+)
+
 type command struct {
 	Command string
 	Stdin   io.Reader
 	Stdout  io.Writer
+	timeout *time.Duration
 }
 
-func (c *command) Run(arg ...string) ([][]string, error) {
+func getCommandTimeout() *time.Duration {
+	value := os.Getenv(cmdtimeoutEnv)
+	if timeout, err := time.ParseDuration(value); value != "" && err == nil {
+		return &timeout
+	}
+	return nil
+}
 
-	cmd := exec.Command(c.Command, arg...)
+func (c *command) Run(arg ...string) ([][]string, error) {
+	var cmd *exec.Cmd
 
+	if c.timeout == nil {
+		cmd = exec.Command(c.Command, arg...)
+	} else {
+		ctx, cancel := context.WithTimeout(context.TODO(), *c.timeout)
+		defer cancel()
+		cmd = exec.CommandContext(ctx, c.Command, arg...)
+	}
 	var stdout, stderr bytes.Buffer
 
 	if c.Stdout == nil {

zfs.go

@@ -111,7 +111,7 @@ func SetLogger(l Logger) {
 
 // zfs is a helper function to wrap typical calls to zfs.
 func zfs(arg ...string) ([][]string, error) {
-	c := command{Command: "zfs"}
+	c := command{Command: "zfs", timeout: getCommandTimeout()}
 	return c.Run(arg...)
 }
 

zpool.go

@@ -29,7 +29,7 @@ type Zpool struct {
 
 // zpool is a helper function to wrap typical calls to zpool.
 func zpool(arg ...string) ([][]string, error) {
-	c := command{Command: "zpool"}
+	c := command{Command: "zpool", timeout: getCommandTimeout()}
 	return c.Run(arg...)
 }