From 4b5b1a2409784590456f14d501b484000a6f9a52 Mon Sep 17 00:00:00 2001
From: Valentin Rothberg <rothberg@redhat.com>
Date: Fri, 20 Sep 2019 09:30:49 +0200
Subject: [PATCH] get dnsmasq process: lookup in proc FS
Golang`s `os.FindProcess()` always returns success on UNIX machines -
even when the PID doesn't exist. Hence, add a lookup in the proc FS
to check if the given exists or not. That's okay since dnsmane is
targetting Linux only.
Also rename the method to `getProcess()` and add some comments.
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>
---
plugins/meta/dnsname/dnsname_test.go | 4 ++--
plugins/meta/dnsname/main.go | 2 +-
plugins/meta/dnsname/service.go | 16 +++++++++++-----
3 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/plugins/meta/dnsname/dnsname_test.go b/plugins/meta/dnsname/dnsname_test.go
index 9646d8b..5bc4032 100644
--- a/plugins/meta/dnsname/dnsname_test.go
+++ b/plugins/meta/dnsname/dnsname_test.go
@@ -127,7 +127,7 @@ var _ = Describe("dnsname tests", func() {
Expect(err).To(BeNil())
// Check that the dns masq instance is running
- pid, err := d.getPidProcess()
+ pid, err := d.getProcess()
Expect(err).To(BeNil())
// Send it a signal 0; if alive, error will be nil
err = pid.Signal(syscall.Signal(0))
@@ -166,7 +166,7 @@ var _ = Describe("dnsname tests", func() {
d, err := newDNSMasqFile("foobar.io", "dummy0", "test")
Expect(err).To(BeNil())
- pid, err := d.getPidProcess()
+ pid, err := d.getProcess()
Expect(err).To(BeNil())
err = pid.Signal(syscall.Signal(0))
Expect(err).To(BeNil())
diff --git a/plugins/meta/dnsname/main.go b/plugins/meta/dnsname/main.go
index 8630480..4b49f13 100644
--- a/plugins/meta/dnsname/main.go
+++ b/plugins/meta/dnsname/main.go
@@ -186,7 +186,7 @@ func cmdCheck(args *skel.CmdArgs) error {
}
}()
- pid, err := dnsNameConf.getPidProcess()
+ pid, err := dnsNameConf.getProcess()
if err != nil {
return err
}
diff --git a/plugins/meta/dnsname/service.go b/plugins/meta/dnsname/service.go
index 93c4ee3..6922ad4 100644
--- a/plugins/meta/dnsname/service.go
+++ b/plugins/meta/dnsname/service.go
@@ -10,6 +10,7 @@ import (
"strings"
"syscall"
+ "github.com/pkg/errors"
"golang.org/x/sys/unix"
)
@@ -38,7 +39,7 @@ func (d dnsNameFile) hup() error {
if _, err := os.Stat(d.PidFile); os.IsNotExist(err) {
return d.start()
}
- pid, err := d.getPidProcess()
+ pid, err := d.getProcess()
if err != nil {
return err
}
@@ -57,6 +58,7 @@ func isRunning(pid *os.Process) bool {
return true
}
+// start starts the dnsmasq instance.
func (d dnsNameFile) start() error {
args := []string{
"-u",
@@ -67,17 +69,18 @@ func (d dnsNameFile) start() error {
return cmd.Run()
}
+// stop stops the dnsmasq instance.
func (d dnsNameFile) stop() error {
- pid, err := d.getPidProcess()
+ pid, err := d.getProcess()
if err != nil {
return err
}
return pid.Kill()
}
-// getPidProcess reads the PID for the dnsmasq instance and returns it in the
-// form of an int
-func (d dnsNameFile) getPidProcess() (*os.Process, error) {
+// getProcess reads the PID for the dnsmasq instance and returns an
+// *os.Process. Returns an error if the PID does not exist.
+func (d dnsNameFile) getProcess() (*os.Process, error) {
pidFileContents, err := ioutil.ReadFile(d.PidFile)
if err != nil {
return nil, err
@@ -86,6 +89,9 @@ func (d dnsNameFile) getPidProcess() (*os.Process, error) {
if err != nil {
return nil, err
}
+ if _, err := os.Stat(fmt.Sprintf("/proc/%d/", pid)); os.IsNotExist(err) {
+ return nil, errors.Wrapf(err, "dnsmasq process with PID %d does not exist", pid)
+ }
return os.FindProcess(pid)
}
--
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