Add support for the basic extension done by Schilling's star.

Compute checksums in both ways (unsigned and signed).

R=rsc
APPROVED=rsc
DELTA=188  (145 added, 21 deleted, 22 changed)
OCL=30126
CL=30179

src/pkg/archive/tar/untar.go

@@ -67,6 +67,8 @@ type Header struct {
 	Gname string;
 	Devmajor int64;
 	Devminor int64;
+	Atime int64;
+	Ctime int64;
 }
 
 func (tr *Reader) skipUnread()
@@ -118,7 +120,10 @@ func cString(b []byte) string {
 	return string(b[0:n])
 }
 
-func (tr *Reader) octalNumber(b []byte) int64 {
+func (tr *Reader) octal(b []byte) int64 {
+	if len(b) > 0 && b[len(b)-1] == ' ' {
+		b = b[0:len(b)-1];
+	}
 	x, err := strconv.Btoui64(cString(b), 8);
 	if err != nil {
 		tr.err = err;
@@ -149,23 +154,27 @@ func (tr *Reader) skipUnread() {
 }
 
 func (tr *Reader) verifyChecksum(header []byte) bool {
-	given := tr.octalNumber(header[148:156]);
+	given := tr.octal(header[148:156]);
 	if tr.err != nil {
 		return false
 	}
 
-	var computed int64;
+	// POSIX specifies a sum of the unsigned byte values,
+	// but the Sun tar uses signed byte values.  :-(
+	var unsigned, signed int64;
 	for i := 0; i < len(header); i++ {
 		if i == 148 {
 			// The chksum field is special: it should be treated as space bytes.
-			computed += ' ' * 8;
+			unsigned += ' ' * 8;
+			signed += ' ' * 8;
 			i += 7;
 			continue
 		}
-		computed += int64(header[i]);
+		unsigned += int64(header[i]);
+		signed += int64(int8(header[i]));
 	}
 
-	return given == computed
+	return given == unsigned || given == signed
 }
 
 type slicer []byte
@@ -205,15 +214,52 @@ func (tr *Reader) readHeader() *Header {
 	// so use that value to do the correct parsing below.
 
 	hdr.Name = cString(s.next(100));
-	hdr.Mode = tr.octalNumber(s.next(8));
+	hdr.Mode = tr.octal(s.next(8));
-	hdr.Uid = tr.octalNumber(s.next(8));
+	hdr.Uid = tr.octal(s.next(8));
-	hdr.Gid = tr.octalNumber(s.next(8));
+	hdr.Gid = tr.octal(s.next(8));
-	hdr.Size = tr.octalNumber(s.next(12));
+	hdr.Size = tr.octal(s.next(12));
-	hdr.Mtime = tr.octalNumber(s.next(12));
+	hdr.Mtime = tr.octal(s.next(12));
 	s.next(8);  // chksum
 	hdr.Typeflag = s.next(1)[0];
 	hdr.Linkname = cString(s.next(100));
-	s.next(8);  // magic, version
+
+	// The remainder of the header depends on the value of magic.
+	magic := string(s.next(8));  // contains version field as well.
+	var format string;
+	switch magic {
+	case "ustar\x0000":  // POSIX tar (1003.1-1988)
+		if string(header[508:512]) == "tar\x00" {
+			format = "star";
+		} else {
+			format = "posix";
+		}
+	case "ustar  \x00":  // old GNU tar
+		format = "gnu";
+	}
+
+	switch format {
+	case "posix", "gnu", "star":
+		hdr.Uname = cString(s.next(32));
+		hdr.Gname = cString(s.next(32));
+		devmajor := s.next(8);
+		devminor := s.next(8);
+		if hdr.Typeflag == TypeChar || hdr.Typeflag == TypeBlock {
+			hdr.Devmajor = tr.octal(devmajor);
+			hdr.Devminor = tr.octal(devminor);
+		}
+		var prefix string;
+		switch format {
+		case "posix", "gnu":
+			prefix = cString(s.next(155));
+		case "star":
+			prefix = cString(s.next(131));
+			hdr.Atime = tr.octal(s.next(12));
+			hdr.Ctime = tr.octal(s.next(12));
+		}
+		if len(prefix) > 0 {
+			hdr.Name = prefix + "/" + hdr.Name;
+		}
+	}
 
 	if tr.err != nil {
 		tr.err = HeaderError;

src/pkg/archive/tar/untar_test.go

@@ -10,11 +10,107 @@ import (
 	"fmt";
 	"io";
 	"os";
+	"reflect";
 	"testing";
 )
 
-func TestUntar(t *testing.T) {
+type untarTest struct {
-	f, err := os.Open("testdata/test.tar", os.O_RDONLY, 0444);
+	file string;
+	headers []*Header;
+}
+
+var untarTests = []*untarTest{
+	&untarTest{
+		file: "testdata/gnu.tar",
+		headers: []*Header{
+			&Header{
+				Name: "small.txt",
+				Mode: 0640,
+				Uid: 73025,
+				Gid: 5000,
+				Size: 5,
+				Mtime: 1244428340,
+				Typeflag: '0',
+				Uname: "dsymonds",
+				Gname: "eng",
+			},
+			&Header{
+				Name: "small2.txt",
+				Mode: 0640,
+				Uid: 73025,
+				Gid: 5000,
+				Size: 11,
+				Mtime: 1244436044,
+				Typeflag: '0',
+				Uname: "dsymonds",
+				Gname: "eng",
+			},
+		},
+	},
+	&untarTest{
+		file: "testdata/star.tar",
+		headers: []*Header{
+			&Header{
+				Name: "small.txt",
+				Mode: 0640,
+				Uid: 73025,
+				Gid: 5000,
+				Size: 5,
+				Mtime: 1244592783,
+				Typeflag: '0',
+				Uname: "dsymonds",
+				Gname: "eng",
+				Atime: 1244592783,
+				Ctime: 1244592783,
+			},
+			&Header{
+				Name: "small2.txt",
+				Mode: 0640,
+				Uid: 73025,
+				Gid: 5000,
+				Size: 11,
+				Mtime: 1244592783,
+				Typeflag: '0',
+				Uname: "dsymonds",
+				Gname: "eng",
+				Atime: 1244592783,
+				Ctime: 1244592783,
+			},
+		},
+	},
+};
+
+func TestAll(t *testing.T) {
+testLoop:
+	for i, test := range untarTests {
+		f, err := os.Open(test.file, os.O_RDONLY, 0444);
+		if err != nil {
+			t.Errorf("test %d: Unexpected error: %v", i, err);
+			continue
+		}
+		tr := NewReader(f);
+		for j, header := range test.headers {
+			hdr, err := tr.Next();
+			if err != nil || hdr == nil {
+				t.Errorf("test %d, entry %d: Didn't get entry: %v", i, j, err);
+				f.Close();
+				continue testLoop
+			}
+			if !reflect.DeepEqual(hdr, header) {
+				t.Errorf("test %d, entry %d: Incorrect header:\nhave %+v\nwant %+v",
+					 i, j, *hdr, *header);
+			}
+		}
+		hdr, err := tr.Next();
+		if hdr != nil || err != nil {
+			t.Errorf("test %d: Unexpected entry or error: hdr=%v err=%v", i, err);
+		}
+		f.Close();
+	}
+}
+
+func TestPartialRead(t *testing.T) {
+	f, err := os.Open("testdata/gnu.tar", os.O_RDONLY, 0444);
 	if err != nil {
 		t.Fatalf("Unexpected error: %v", err);
 	}
@@ -22,22 +118,11 @@ func TestUntar(t *testing.T) {
 
 	tr := NewReader(f);
 
-	// First file
+	// Read the first four bytes; Next() should skip the last byte.
 	hdr, err := tr.Next();
 	if err != nil || hdr == nil {
 		t.Fatalf("Didn't get first file: %v", err);
 	}
-	if hdr.Name != "small.txt" {
-		t.Errorf(`hdr.Name = %q, want "small.txt"`, hdr.Name);
-	}
-	if hdr.Mode != 0640 {
-		t.Errorf("hdr.Mode = %v, want 0640", hdr.Mode);
-	}
-	if hdr.Size != 5 {
-		t.Errorf("hdr.Size = %v, want 5", hdr.Size);
-	}
-
-	// Read the first four bytes; Next() should skip the last one.
 	buf := make([]byte, 4);
 	if n, err := io.FullRead(tr, buf); err != nil {
 		t.Fatalf("Unexpected error: %v", err);
@@ -48,22 +133,14 @@ func TestUntar(t *testing.T) {
 
 	// Second file
 	hdr, err = tr.Next();
-	if err != nil {
+	if err != nil || hdr == nil {
 		t.Fatalf("Didn't get second file: %v", err);
 	}
-	if hdr.Name != "small2.txt" {
+	buf = make([]byte, 6);
-		t.Errorf(`hdr.Name = %q, want "small2.txt"`, hdr.Name);
+	if n, err := io.FullRead(tr, buf); err != nil {
+		t.Fatalf("Unexpected error: %v", err);
 	}
-	if hdr.Mode != 0640 {
+	if expected := io.StringBytes("Google"); !bytes.Equal(buf, expected) {
-		t.Errorf("hdr.Mode = %v, want 0640", hdr.Mode);
+		t.Errorf("Contents = %v, want %v", buf, expected);
-	}
-	if hdr.Size != 11 {
-		t.Errorf("hdr.Size = %v, want 11", hdr.Size);
-	}
-
-
-	hdr, err = tr.Next();
-	if hdr != nil || err != nil {
-		t.Fatalf("Unexpected third file or error: %v", err);
 	}
 }