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archive/tar: avoid writing ModTime that is out of range.

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Update #4358
Still to do: support binary numeric format in Reader.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6818101
This commit is contained in:
David Symonds 2012-11-08 08:22:40 +11:00
parent 7c0cbbfa18
commit 0ac317817b
2 changed files with 69 additions and 13 deletions
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43
src/pkg/archive/tar/tar_test.go
View File

@ -5,7 +5,10 @@
package tar
import (
"bytes"
"io/ioutil"
"os"
"reflect"
"testing"
"time"
)
@ -54,3 +57,43 @@ func (symlink) Mode() os.FileMode { return os.ModeSymlink }
func (symlink) ModTime() time.Time { return time.Time{} }
func (symlink) IsDir() bool { return false }
func (symlink) Sys() interface{} { return nil }
func TestRoundTrip(t *testing.T) {
data := []byte("some file contents")
var b bytes.Buffer
tw := NewWriter(&b)
hdr := &Header{
Name: "file.txt",
Size: int64(len(data)),
ModTime: time.Now(),
}
// tar only supports second precision.
hdr.ModTime = hdr.ModTime.Add(-time.Duration(hdr.ModTime.Nanosecond()) * time.Nanosecond)
if err := tw.WriteHeader(hdr); err != nil {
t.Fatalf("tw.WriteHeader: %v", err)
}
if _, err := tw.Write(data); err != nil {
t.Fatalf("tw.Write: %v", err)
}
if err := tw.Close(); err != nil {
t.Fatalf("tw.Close: %v", err)
}
// Read it back.
tr := NewReader(&b)
rHdr, err := tr.Next()
if err != nil {
t.Fatalf("tr.Next: %v", err)
}
if !reflect.DeepEqual(rHdr, hdr) {
t.Errorf("Header mismatch.\n got %+v\nwant %+v", rHdr, hdr)
}
rData, err := ioutil.ReadAll(tr)
if err != nil {
t.Fatalf("Read: %v", err)
}
if !bytes.Equal(rData, data) {
t.Errorf("Data mismatch.\n got %q\nwant %q", rData, data)
}
}

39
src/pkg/archive/tar/writer.go
View File

@ -12,6 +12,7 @@ import (
"fmt"
"io"
"strconv"
"time"
)
var (
@ -110,6 +111,12 @@ func (tw *Writer) numeric(b []byte, x int64) {
b[0] |= 0x80 // highest bit indicates binary format
}
var (
minTime = time.Unix(0, 0)
// There is room for 11 octal digits (33 bits) of mtime.
maxTime = minTime.Add((1<<33 - 1) * time.Second)
)
// WriteHeader writes hdr and prepares to accept the file's contents.
// WriteHeader calls Flush if it is not the first header.
// Calling after a Close will return ErrWriteAfterClose.
@ -133,19 +140,25 @@ func (tw *Writer) WriteHeader(hdr *Header) error {
// TODO(dsymonds): handle names longer than 100 chars
copy(s.next(100), []byte(hdr.Name))
tw.octal(s.next(8), hdr.Mode) // 100:108
tw.numeric(s.next(8), int64(hdr.Uid)) // 108:116
tw.numeric(s.next(8), int64(hdr.Gid)) // 116:124
tw.numeric(s.next(12), hdr.Size) // 124:136
tw.numeric(s.next(12), hdr.ModTime.Unix()) // 136:148
s.next(8) // chksum (148:156)
s.next(1)[0] = hdr.Typeflag // 156:157
tw.cString(s.next(100), hdr.Linkname) // linkname (157:257)
copy(s.next(8), []byte("ustar\x0000")) // 257:265
tw.cString(s.next(32), hdr.Uname) // 265:297
tw.cString(s.next(32), hdr.Gname) // 297:329
tw.numeric(s.next(8), hdr.Devmajor) // 329:337
tw.numeric(s.next(8), hdr.Devminor) // 337:345
// Handle out of range ModTime carefully.
var modTime int64
if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) {
modTime = hdr.ModTime.Unix()
}
tw.octal(s.next(8), hdr.Mode) // 100:108
tw.numeric(s.next(8), int64(hdr.Uid)) // 108:116
tw.numeric(s.next(8), int64(hdr.Gid)) // 116:124
tw.numeric(s.next(12), hdr.Size) // 124:136
tw.numeric(s.next(12), modTime) // 136:148
s.next(8) // chksum (148:156)
s.next(1)[0] = hdr.Typeflag // 156:157
tw.cString(s.next(100), hdr.Linkname) // linkname (157:257)
copy(s.next(8), []byte("ustar\x0000")) // 257:265
tw.cString(s.next(32), hdr.Uname) // 265:297
tw.cString(s.next(32), hdr.Gname) // 297:329
tw.numeric(s.next(8), hdr.Devmajor) // 329:337
tw.numeric(s.next(8), hdr.Devminor) // 337:345
// Use the GNU magic instead of POSIX magic if we used any GNU extensions.
if tw.usedBinary {