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archive/tar: fix a case where USTAR-split is not working correctly.

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For some long filenames the USTAR-split code does not work
correctly. It is wrongly assumed that the path would not be too long,
but it is.

The user visible result was that a filename was split, but it still
caused an error.

The cause was a wrongly calculated nlen. In addition I noticed that
at this place it is also seems necessary to check if the prefix will
fit in the 155 chars available for the prefix.

R=dsymonds, rsc
CC=golang-dev
https://golang.org/cl/13300046
This commit is contained in:
Marco Hennings 2013-09-06 16:49:38 -04:00 committed by Russ Cox
parent fb25a61872
commit 4e998d71c9
2 changed files with 41 additions and 2 deletions
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7
src/pkg/archive/tar/writer.go
View File

@ -263,8 +263,11 @@ func (tw *Writer) splitUSTARLongName(name string) (prefix, suffix string, err er
length--
}
i := strings.LastIndex(name[:length], "/")
nlen := length - i - 1
if i <= 0 || nlen > fileNameSize || nlen == 0 {
// nlen contains the resulting length in the name field.
// plen contains the resulting length in the prefix field.
nlen := len(name) - i - 1
plen := i
if i <= 0 || nlen > fileNameSize || nlen == 0 || plen > fileNamePrefixSize {
err = errNameTooLong
return
}

36
src/pkg/archive/tar/writer_test.go
View File

@ -355,3 +355,39 @@ func TestPAXHeader(t *testing.T) {
}
}
}
func TestUSTARLongName(t *testing.T) {
// Create an archive with a path that failed to split with USTAR extension in previous versions.
fileinfo, err := os.Stat("testdata/small.txt")
if err != nil {
t.Fatal(err)
}
hdr, err := FileInfoHeader(fileinfo, "")
hdr.Typeflag = TypeDir
if err != nil {
t.Fatalf("os.Stat:1 %v", err)
}
// Force a PAX long name to be written. The name was taken from a practical example
// that fails and replaced ever char through numbers to anonymize the sample.
longName := "/0000_0000000/00000-000000000/0000_0000000/00000-0000000000000/0000_0000000/00000-0000000-00000000/0000_0000000/00000000/0000_0000000/000/0000_0000000/00000000v00/0000_0000000/000000/0000_0000000/0000000/0000_0000000/00000y-00/0000/0000/00000000/0x000000/"
hdr.Name = longName
hdr.Size = 0
var buf bytes.Buffer
writer := NewWriter(&buf)
if err := writer.WriteHeader(hdr); err != nil {
t.Fatal(err)
}
if err := writer.Close(); err != nil {
t.Fatal(err)
}
// Test that we can get a long name back out of the archive.
reader := NewReader(&buf)
hdr, err = reader.Next()
if err != nil {
t.Fatal(err)
}
if hdr.Name != longName {
t.Fatal("Couldn't recover long name")
}
}