Use FILE_SHARE_DELETE for log files on Windows.

This fixes issues where one goroutine tries to delete or rename a file
while another goroutine has the file open (e.g. a log reader).

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit a5f237c2b5)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/logger/loggerutils/file_unix.go

@@ -0,0 +1,9 @@
+// +build !windows
+
+package loggerutils
+
+import "os"
+
+func openFile(name string, flag int, perm os.FileMode) (*os.File, error) {
+	return os.OpenFile(name, flag, perm)
+}

daemon/logger/loggerutils/file_windows.go

@@ -0,0 +1,224 @@
+package loggerutils
+
+import (
+	"os"
+	"syscall"
+	"unsafe"
+
+	"github.com/pkg/errors"
+)
+
+func openFile(name string, flag int, perm os.FileMode) (*os.File, error) {
+	if name == "" {
+		return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOENT}
+	}
+	h, err := syscallOpen(fixLongPath(name), flag|syscall.O_CLOEXEC, syscallMode(perm))
+	if err != nil {
+		return nil, errors.Wrap(err, "error opening file")
+	}
+	return os.NewFile(uintptr(h), name), nil
+}
+
+// syscallOpen is copied from syscall.Open but is modified to
+// always open a file with FILE_SHARE_DELETE
+func syscallOpen(path string, mode int, perm uint32) (fd syscall.Handle, err error) {
+	if len(path) == 0 {
+		return syscall.InvalidHandle, syscall.ERROR_FILE_NOT_FOUND
+	}
+
+	pathp, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return syscall.InvalidHandle, err
+	}
+	var access uint32
+	switch mode & (syscall.O_RDONLY | syscall.O_WRONLY | syscall.O_RDWR) {
+	case syscall.O_RDONLY:
+		access = syscall.GENERIC_READ
+	case syscall.O_WRONLY:
+		access = syscall.GENERIC_WRITE
+	case syscall.O_RDWR:
+		access = syscall.GENERIC_READ | syscall.GENERIC_WRITE
+	}
+	if mode&syscall.O_CREAT != 0 {
+		access |= syscall.GENERIC_WRITE
+	}
+	if mode&syscall.O_APPEND != 0 {
+		access &^= syscall.GENERIC_WRITE
+		access |= syscall.FILE_APPEND_DATA
+	}
+	sharemode := uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE | syscall.FILE_SHARE_DELETE)
+	var sa *syscall.SecurityAttributes
+	if mode&syscall.O_CLOEXEC == 0 {
+		sa = makeInheritSa()
+	}
+	var createmode uint32
+	switch {
+	case mode&(syscall.O_CREAT|syscall.O_EXCL) == (syscall.O_CREAT | syscall.O_EXCL):
+		createmode = syscall.CREATE_NEW
+	case mode&(syscall.O_CREAT|syscall.O_TRUNC) == (syscall.O_CREAT | syscall.O_TRUNC):
+		createmode = syscall.CREATE_ALWAYS
+	case mode&syscall.O_CREAT == syscall.O_CREAT:
+		createmode = syscall.OPEN_ALWAYS
+	case mode&syscall.O_TRUNC == syscall.O_TRUNC:
+		createmode = syscall.TRUNCATE_EXISTING
+	default:
+		createmode = syscall.OPEN_EXISTING
+	}
+	h, e := syscall.CreateFile(pathp, access, sharemode, sa, createmode, syscall.FILE_ATTRIBUTE_NORMAL, 0)
+	return h, e
+}
+
+func makeInheritSa() *syscall.SecurityAttributes {
+	var sa syscall.SecurityAttributes
+	sa.Length = uint32(unsafe.Sizeof(sa))
+	sa.InheritHandle = 1
+	return &sa
+}
+
+// fixLongPath returns the extended-length (\\?\-prefixed) form of
+// path when needed, in order to avoid the default 260 character file
+// path limit imposed by Windows. If path is not easily converted to
+// the extended-length form (for example, if path is a relative path
+// or contains .. elements), or is short enough, fixLongPath returns
+// path unmodified.
+//
+// See https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath
+//
+// Copied from os.OpenFile
+func fixLongPath(path string) string {
+	// Do nothing (and don't allocate) if the path is "short".
+	// Empirically (at least on the Windows Server 2013 builder),
+	// the kernel is arbitrarily okay with < 248 bytes. That
+	// matches what the docs above say:
+	// "When using an API to create a directory, the specified
+	// path cannot be so long that you cannot append an 8.3 file
+	// name (that is, the directory name cannot exceed MAX_PATH
+	// minus 12)." Since MAX_PATH is 260, 260 - 12 = 248.
+	//
+	// The MSDN docs appear to say that a normal path that is 248 bytes long
+	// will work; empirically the path must be less then 248 bytes long.
+	if len(path) < 248 {
+		// Don't fix. (This is how Go 1.7 and earlier worked,
+		// not automatically generating the \\?\ form)
+		return path
+	}
+
+	// The extended form begins with \\?\, as in
+	// \\?\c:\windows\foo.txt or \\?\UNC\server\share\foo.txt.
+	// The extended form disables evaluation of . and .. path
+	// elements and disables the interpretation of / as equivalent
+	// to \. The conversion here rewrites / to \ and elides
+	// . elements as well as trailing or duplicate separators. For
+	// simplicity it avoids the conversion entirely for relative
+	// paths or paths containing .. elements. For now,
+	// \\server\share paths are not converted to
+	// \\?\UNC\server\share paths because the rules for doing so
+	// are less well-specified.
+	if len(path) >= 2 && path[:2] == `\\` {
+		// Don't canonicalize UNC paths.
+		return path
+	}
+	if !isAbs(path) {
+		// Relative path
+		return path
+	}
+
+	const prefix = `\\?`
+
+	pathbuf := make([]byte, len(prefix)+len(path)+len(`\`))
+	copy(pathbuf, prefix)
+	n := len(path)
+	r, w := 0, len(prefix)
+	for r < n {
+		switch {
+		case os.IsPathSeparator(path[r]):
+			// empty block
+			r++
+		case path[r] == '.' && (r+1 == n || os.IsPathSeparator(path[r+1])):
+			// /./
+			r++
+		case r+1 < n && path[r] == '.' && path[r+1] == '.' && (r+2 == n || os.IsPathSeparator(path[r+2])):
+			// /../ is currently unhandled
+			return path
+		default:
+			pathbuf[w] = '\\'
+			w++
+			for ; r < n && !os.IsPathSeparator(path[r]); r++ {
+				pathbuf[w] = path[r]
+				w++
+			}
+		}
+	}
+	// A drive's root directory needs a trailing \
+	if w == len(`\\?\c:`) {
+		pathbuf[w] = '\\'
+		w++
+	}
+	return string(pathbuf[:w])
+}
+
+// copied from os package for os.OpenFile
+func syscallMode(i os.FileMode) (o uint32) {
+	o |= uint32(i.Perm())
+	if i&os.ModeSetuid != 0 {
+		o |= syscall.S_ISUID
+	}
+	if i&os.ModeSetgid != 0 {
+		o |= syscall.S_ISGID
+	}
+	if i&os.ModeSticky != 0 {
+		o |= syscall.S_ISVTX
+	}
+	// No mapping for Go's ModeTemporary (plan9 only).
+	return
+}
+
+func isAbs(path string) (b bool) {
+	v := volumeName(path)
+	if v == "" {
+		return false
+	}
+	path = path[len(v):]
+	if path == "" {
+		return false
+	}
+	return os.IsPathSeparator(path[0])
+}
+
+func volumeName(path string) (v string) {
+	if len(path) < 2 {
+		return ""
+	}
+	// with drive letter
+	c := path[0]
+	if path[1] == ':' &&
+		('0' <= c && c <= '9' || 'a' <= c && c <= 'z' ||
+			'A' <= c && c <= 'Z') {
+		return path[:2]
+	}
+	// is it UNC
+	if l := len(path); l >= 5 && os.IsPathSeparator(path[0]) && os.IsPathSeparator(path[1]) &&
+		!os.IsPathSeparator(path[2]) && path[2] != '.' {
+		// first, leading `\\` and next shouldn't be `\`. its server name.
+		for n := 3; n < l-1; n++ {
+			// second, next '\' shouldn't be repeated.
+			if os.IsPathSeparator(path[n]) {
+				n++
+				// third, following something characters. its share name.
+				if !os.IsPathSeparator(path[n]) {
+					if path[n] == '.' {
+						break
+					}
+					for ; n < l; n++ {
+						if os.IsPathSeparator(path[n]) {
+							break
+						}
+					}
+					return path[:n]
+				}
+				break
+			}
+		}
+	}
+	return ""
+}

daemon/logger/loggerutils/file_windows_test.go

@@ -0,0 +1,34 @@
+package loggerutils
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"gotest.tools/assert"
+)
+
+func TestOpenFileDelete(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", t.Name())
+	assert.NilError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	f, err := openFile(filepath.Join(tmpDir, "test.txt"), os.O_CREATE|os.O_RDWR, 644)
+	assert.NilError(t, err)
+	defer f.Close()
+
+	assert.NilError(t, os.RemoveAll(f.Name()))
+}
+
+func TestOpenFileRename(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("", t.Name())
+	assert.NilError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	f, err := openFile(filepath.Join(tmpDir, "test.txt"), os.O_CREATE|os.O_RDWR, 0644)
+	assert.NilError(t, err)
+	defer f.Close()
+
+	assert.NilError(t, os.Rename(f.Name(), f.Name()+"renamed"))
+}

daemon/logger/loggerutils/logfile.go

@@ -111,7 +111,7 @@ type GetTailReaderFunc func(ctx context.Context, f SizeReaderAt, nLogLines int)
 
 // NewLogFile creates new LogFile
 func NewLogFile(logPath string, capacity int64, maxFiles int, compress bool, marshaller logger.MarshalFunc, decodeFunc makeDecoderFunc, perms os.FileMode, getTailReader GetTailReaderFunc) (*LogFile, error) {
-	log, err := os.OpenFile(logPath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, perms)
+	log, err := openFile(logPath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, perms)
 	if err != nil {
 		return nil, err
 	}
@@ -182,7 +182,7 @@ func (w *LogFile) checkCapacityAndRotate() error {
 			w.rotateMu.Unlock()
 			return err
 		}
-		file, err := os.OpenFile(fname, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, w.perms)
+		file, err := openFile(fname, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, w.perms)
 		if err != nil {
 			w.rotateMu.Unlock()
 			return err
@@ -250,7 +250,7 @@ func compressFile(fileName string, lastTimestamp time.Time) {
 		}
 	}()
 
-	outFile, err := os.OpenFile(fileName+".gz", os.O_CREATE|os.O_TRUNC|os.O_RDWR, 0640)
+	outFile, err := openFile(fileName+".gz", os.O_CREATE|os.O_TRUNC|os.O_RDWR, 0640)
 	if err != nil {
 		logrus.Errorf("Failed to open or create gzip log file: %v", err)
 		return
@@ -451,7 +451,7 @@ func decompressfile(fileName, destFileName string, since time.Time) (*os.File, e
 		return nil, nil
 	}
 
-	rs, err := os.OpenFile(destFileName, os.O_CREATE|os.O_RDWR, 0640)
+	rs, err := openFile(destFileName, os.O_CREATE|os.O_RDWR, 0640)
 	if err != nil {
 		return nil, errors.Wrap(err, "error creating file for copying decompressed log stream")
 	}