archive/tar: remove file type bits from mode field

When writing tar files by using the FileInfoHeader
the type bits was set in the mode field of the header
This is not correct according to the standard (GNU/Posix) and
other implementations.

Fixed #20150

Change-Id: I3be7d946a1923ad5827cf45c696546a5e287ebba
Reviewed-on: https://go-review.googlesource.com/42093Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/archive/tar/common.go

@@ -158,11 +158,15 @@ func (fi headerFileInfo) Mode() (mode os.FileMode) {
 // sysStat, if non-nil, populates h from system-dependent fields of fi.
 var sysStat func(fi os.FileInfo, h *Header) error
 
-// Mode constants from the tar spec.
 const (
+	// Mode constants from the USTAR spec:
+	// See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
 	c_ISUID = 04000 // Set uid
 	c_ISGID = 02000 // Set gid
 	c_ISVTX = 01000 // Save text (sticky bit)
+
+	// Common Unix mode constants; these are not defined in any common tar standard.
+	// Header.FileInfo understands these, but FileInfoHeader will never produce these.
 	c_ISDIR  = 040000  // Directory
 	c_ISFIFO = 010000  // FIFO
 	c_ISREG  = 0100000 // Regular file
@@ -208,30 +212,24 @@ func FileInfoHeader(fi os.FileInfo, link string) (*Header, error) {
 	}
 	switch {
 	case fm.IsRegular():
-		h.Mode |= c_ISREG
 		h.Typeflag = TypeReg
 		h.Size = fi.Size()
 	case fi.IsDir():
 		h.Typeflag = TypeDir
-		h.Mode |= c_ISDIR
 		h.Name += "/"
 	case fm&os.ModeSymlink != 0:
 		h.Typeflag = TypeSymlink
-		h.Mode |= c_ISLNK
 		h.Linkname = link
 	case fm&os.ModeDevice != 0:
 		if fm&os.ModeCharDevice != 0 {
-			h.Mode |= c_ISCHR
 			h.Typeflag = TypeChar
 		} else {
-			h.Mode |= c_ISBLK
 			h.Typeflag = TypeBlock
 		}
 	case fm&os.ModeNamedPipe != 0:
 		h.Typeflag = TypeFifo
-		h.Mode |= c_ISFIFO
 	case fm&os.ModeSocket != 0:
-		h.Mode |= c_ISSOCK
+		return nil, fmt.Errorf("archive/tar: sockets not supported")
 	default:
 		return nil, fmt.Errorf("archive/tar: unknown file mode %v", fm)
 	}

src/archive/tar/tar_test.go

@@ -29,7 +29,7 @@ func TestFileInfoHeader(t *testing.T) {
 	if g, e := h.Name, "small.txt"; g != e {
 		t.Errorf("Name = %q; want %q", g, e)
 	}
-	if g, e := h.Mode, int64(fi.Mode().Perm())|c_ISREG; g != e {
+	if g, e := h.Mode, int64(fi.Mode().Perm()); g != e {
 		t.Errorf("Mode = %#o; want %#o", g, e)
 	}
 	if g, e := h.Size, int64(5); g != e {
@@ -57,7 +57,7 @@ func TestFileInfoHeaderDir(t *testing.T) {
 		t.Errorf("Name = %q; want %q", g, e)
 	}
 	// Ignoring c_ISGID for golang.org/issue/4867
-	if g, e := h.Mode&^c_ISGID, int64(fi.Mode().Perm())|c_ISDIR; g != e {
+	if g, e := h.Mode&^c_ISGID, int64(fi.Mode().Perm()); g != e {
 		t.Errorf("Mode = %#o; want %#o", g, e)
 	}
 	if g, e := h.Size, int64(0); g != e {
@@ -157,7 +157,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// regular file.
 		h: &Header{
 			Name:     "test.txt",
-			Mode:     0644 | c_ISREG,
+			Mode:     0644,
 			Size:     12,
 			ModTime:  time.Unix(1360600916, 0),
 			Typeflag: TypeReg,
@@ -167,7 +167,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// symbolic link.
 		h: &Header{
 			Name:     "link.txt",
-			Mode:     0777 | c_ISLNK,
+			Mode:     0777,
 			Size:     0,
 			ModTime:  time.Unix(1360600852, 0),
 			Typeflag: TypeSymlink,
@@ -177,7 +177,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// character device node.
 		h: &Header{
 			Name:     "dev/null",
-			Mode:     0666 | c_ISCHR,
+			Mode:     0666,
 			Size:     0,
 			ModTime:  time.Unix(1360578951, 0),
 			Typeflag: TypeChar,
@@ -187,7 +187,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// block device node.
 		h: &Header{
 			Name:     "dev/sda",
-			Mode:     0660 | c_ISBLK,
+			Mode:     0660,
 			Size:     0,
 			ModTime:  time.Unix(1360578954, 0),
 			Typeflag: TypeBlock,
@@ -197,7 +197,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// directory.
 		h: &Header{
 			Name:     "dir/",
-			Mode:     0755 | c_ISDIR,
+			Mode:     0755,
 			Size:     0,
 			ModTime:  time.Unix(1360601116, 0),
 			Typeflag: TypeDir,
@@ -207,7 +207,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// fifo node.
 		h: &Header{
 			Name:     "dev/initctl",
-			Mode:     0600 | c_ISFIFO,
+			Mode:     0600,
 			Size:     0,
 			ModTime:  time.Unix(1360578949, 0),
 			Typeflag: TypeFifo,
@@ -217,7 +217,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// setuid.
 		h: &Header{
 			Name:     "bin/su",
-			Mode:     0755 | c_ISREG | c_ISUID,
+			Mode:     0755 | c_ISUID,
 			Size:     23232,
 			ModTime:  time.Unix(1355405093, 0),
 			Typeflag: TypeReg,
@@ -227,7 +227,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// setguid.
 		h: &Header{
 			Name:     "group.txt",
-			Mode:     0750 | c_ISREG | c_ISGID,
+			Mode:     0750 | c_ISGID,
 			Size:     0,
 			ModTime:  time.Unix(1360602346, 0),
 			Typeflag: TypeReg,
@@ -237,7 +237,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// sticky.
 		h: &Header{
 			Name:     "sticky.txt",
-			Mode:     0600 | c_ISREG | c_ISVTX,
+			Mode:     0600 | c_ISVTX,
 			Size:     7,
 			ModTime:  time.Unix(1360602540, 0),
 			Typeflag: TypeReg,
@@ -247,7 +247,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// hard link.
 		h: &Header{
 			Name:     "hard.txt",
-			Mode:     0644 | c_ISREG,
+			Mode:     0644,
 			Size:     0,
 			Linkname: "file.txt",
 			ModTime:  time.Unix(1360600916, 0),
@@ -258,7 +258,7 @@ func TestHeaderRoundTrip(t *testing.T) {
 		// More information.
 		h: &Header{
 			Name:     "info.txt",
-			Mode:     0600 | c_ISREG,
+			Mode:     0600,
 			Size:     0,
 			Uid:      1000,
 			Gid:      1000,