1. docker
  2. Commit 9e5b93565c8a10f4b06d2bcf61305fdfb7128628
Browse code

Windows: don't overwrite PID file if process exists

pidfile.New() was opening a file in /proc to determine if the owning
process still exists. Use syscall.OpenProcess() on Windows instead.

Other OSes may also need to be updated here.

Signed-off-by: John Starks <jostarks@microsoft.com>

John Starks authored on 2016/04/19 07:09:55
Showing 4 changed files
pkg/pidfile/pidfile.go
History View file @ 9e5b935
... ... 
@@ -7,7 +7,6 @@ import (
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 	"fmt"
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 	"io/ioutil"
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 	"os"
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-	"path/filepath"
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 	"strconv"
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 	"strings"
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 )
... ... 
@@ -21,7 +20,7 @@ func checkPIDFileAlreadyExists(path string) error {
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 	if pidByte, err := ioutil.ReadFile(path); err == nil {
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 		pidString := strings.TrimSpace(string(pidByte))
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 		if pid, err := strconv.Atoi(pidString); err == nil {
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-			if _, err := os.Stat(filepath.Join("/proc", strconv.Itoa(pid))); err == nil {
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+			if processExists(pid) {
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 				return fmt.Errorf("pid file found, ensure docker is not running or delete %s", path)
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 			}
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 		}
pkg/pidfile/pidfile_test.go
History View file @ 9e5b935
... ... 
@@ -13,11 +13,17 @@ func TestNewAndRemove(t *testing.T) {
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 		t.Fatal("Could not create test directory")
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 	}
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-	file, err := New(filepath.Join(dir, "testfile"))
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+	path := filepath.Join(dir, "testfile")
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+	file, err := New(path)
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 	if err != nil {
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 		t.Fatal("Could not create test file", err)
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 	}
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+	_, err = New(path)
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+	if err == nil {
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+		t.Fatal("Test file creation not blocked")
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+	}
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+
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 	if err := file.Remove(); err != nil {
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 		t.Fatal("Could not delete created test file")
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 	}
pkg/pidfile/pidfile_unix.go
History View file @ 9e5b935
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new file mode 100644
... ... 
@@ -0,0 +1,16 @@
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+// +build !windows
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+
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+package pidfile
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+
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+import (
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+	"os"
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+	"path/filepath"
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+	"strconv"
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+)
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+
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+func processExists(pid int) bool {
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+	if _, err := os.Stat(filepath.Join("/proc", strconv.Itoa(pid))); err == nil {
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+		return true
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+	}
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+	return false
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+}
pkg/pidfile/pidfile_windows.go
History View file @ 9e5b935
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new file mode 100644
... ... 
@@ -0,0 +1,23 @@
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+package pidfile
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+
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+import "syscall"
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+
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+const (
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+	processQueryLimitedInformation = 0x1000
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+
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+	stillActive = 259
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+)
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+
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+func processExists(pid int) bool {
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+	h, err := syscall.OpenProcess(processQueryLimitedInformation, false, uint32(pid))
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+	if err != nil {
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+		return false
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+	}
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+	var c uint32
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+	err = syscall.GetExitCodeProcess(h, &c)
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+	syscall.Close(h)
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+	if err != nil {
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+		return c == stillActive
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+	}
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+	return true
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+}