S04 hardlink-to-itselfA hardlink to itself.
Reject(draft) A strict parser must reject this archive.
S04-hardlink-to-itself.tar |
test archive, 2,560 bytes
sha256 b165ffbc78a5b4a5974a44848ee420163b194195dc2bf14a2ef1eec5a1ff53b7 |
S04-hardlink-to-itself.json | expected result |
S04-hardlink-to-itself.txt | annotated blocks |
S04-hardlink-to-itself.py | generator script |
The first member is a file a, the second a hardlink a to a. In POSIX, extracting a hardlink to the same directory entry is an error. Read leniently, this case is ambiguous because the link replaces a, which then has nothing to link to, empties it, or leaves it as it is.
Decision point: what a link to itself does to the file.
Seen in: 27 tarballs, 18 of them NVIDIA's cuDNN binaries in Spack, and xscreensaver 6.12 and atari++ 1.85.
Every block of 512 bytes, to scale, with its offset. Hover over a field for its bytes.
S04-hardlink-to-itself: must reject
A hardlink to itself.
The first member is a file `a`, the second a hardlink `a` to `a`. In POSIX, extracting a hardlink
to the same directory entry is an error. Read leniently, this case is ambiguous because the link
replaces `a`, which then has nothing to link to, empties it, or leaves it as it is.
Decision point: what a link to itself does to the file.
Seen in: 27 tarballs, 18 of them NVIDIA's cuDNN binaries in Spack, and xscreensaver 6.12 and
atari++ 1.85.
0x000000 header: regular file
name [ 0,100) "a" + 99 NUL
mode [100,108) "0000644" + NUL 644 (octal)
uid [108,116) "0000000" + NUL 0
gid [116,124) "0000000" + NUL 0
size [124,136) "00000000002" + NUL 2
mtime [136,148) "00000000000" + NUL 0
chksum [148,156) "007340\0 " 3808: the unsigned sum of the header, this field as spaces
typeflag [156,157) "0" regular file
linkname [157,257) 100 NUL
magic [257,263) "ustar" + NUL
version [263,265) "00"
uname [265,297) 32 NUL
gname [297,329) 32 NUL
devmajor [329,337) "0000000" + NUL 0
devminor [337,345) "0000000" + NUL 0
prefix [345,500) 155 NUL
pad [500,512) 12 NUL
0x000200 data
2 bytes, then 510 NUL to the end of the block
"a\n"
0x000400 header: hardlink
name [ 0,100) "a" + 99 NUL
mode [100,108) "0000644" + NUL 644 (octal)
uid [108,116) "0000000" + NUL 0
gid [116,124) "0000000" + NUL 0
size [124,136) "00000000000" + NUL 0
mtime [136,148) "00000000000" + NUL 0
chksum [148,156) "007500\0 " 3904: the unsigned sum of the header, this field as spaces
typeflag [156,157) "1" hardlink
linkname [157,257) "a" + 99 NUL
magic [257,263) "ustar" + NUL
version [263,265) "00"
uname [265,297) 32 NUL
gname [297,329) 32 NUL
devmajor [329,337) "0000000" + NUL 0
devminor [337,345) "0000000" + NUL 0
prefix [345,500) 155 NUL
pad [500,512) 12 NUL
0x000600 2 zero blocks: the end-of-archive marker
0x000a00 end of file
As xxd writes it: xxd -r makes the archive of it.
00000000: 6100 0000 0000 0000 0000 0000 0000 0000 a............... 00000010: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000020: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000030: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000040: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000050: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000060: 0000 0000 3030 3030 3634 3400 3030 3030 ....0000644.0000 00000070: 3030 3000 3030 3030 3030 3000 3030 3030 000.0000000.0000 00000080: 3030 3030 3030 3200 3030 3030 3030 3030 0000002.00000000 00000090: 3030 3000 3030 3733 3430 0020 3000 0000 000.007340. 0... 000000a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000000b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000000c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000000d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000000e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000000f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000100: 0075 7374 6172 0030 3000 0000 0000 0000 .ustar.00....... 00000110: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000120: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000130: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000140: 0000 0000 0000 0000 0030 3030 3030 3030 .........0000000 00000150: 0030 3030 3030 3030 0000 0000 0000 0000 .0000000........ 00000160: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000170: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000180: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000190: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000001a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000001b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000001c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000001d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000001e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000001f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000200: 610a 0000 0000 0000 0000 0000 0000 0000 a............... 00000210: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000220: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000230: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000240: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000250: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000260: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000270: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000280: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000290: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000002a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000002b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000002c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000002d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000002e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000002f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000300: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000310: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000320: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000330: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000340: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000350: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000360: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000370: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000380: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000390: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000003a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000003b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000003c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000003d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000003e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000003f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000400: 6100 0000 0000 0000 0000 0000 0000 0000 a............... 00000410: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000420: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000430: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000440: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000450: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000460: 0000 0000 3030 3030 3634 3400 3030 3030 ....0000644.0000 00000470: 3030 3000 3030 3030 3030 3000 3030 3030 000.0000000.0000 00000480: 3030 3030 3030 3000 3030 3030 3030 3030 0000000.00000000 00000490: 3030 3000 3030 3735 3030 0020 3161 0000 000.007500. 1a.. 000004a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000004b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000004c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000004d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000004e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000004f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000500: 0075 7374 6172 0030 3000 0000 0000 0000 .ustar.00....... 00000510: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000520: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000530: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000540: 0000 0000 0000 0000 0030 3030 3030 3030 .........0000000 00000550: 0030 3030 3030 3030 0000 0000 0000 0000 .0000000........ 00000560: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000570: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000580: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000590: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000005a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000005b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000005c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000005d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000005e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000005f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000600: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000610: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000620: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000630: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000640: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000650: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000660: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000670: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000680: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000690: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000006a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000006b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000006c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000006d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000006e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000006f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000700: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000710: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000720: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000730: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000740: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000750: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000760: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000770: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000780: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000790: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000007a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000007b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000007c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000007d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000007e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000007f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000800: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000810: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000820: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000830: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000840: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000850: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000860: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000870: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000880: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000890: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000008a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000008b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000008c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000008d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000008e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000008f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000900: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000910: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000920: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000930: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000940: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000950: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000960: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000970: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000980: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000990: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000009a0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000009b0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000009c0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000009d0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000009e0: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 000009f0: 0000 0000 0000 0000 0000 0000 0000 0000 ................
| implementation | version | outcome | what it makes of it |
|---|---|---|---|
| GNU tar | tar (GNU tar) 1.35 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| bsdtar | bsdtar 3.8.10 - libarchive 3.8.10 | ✅ as the verdict says | error: a: Skipping hardlink pointing to itself: a: Unknown error -1 bsdtar: Error exit delayed from previous errors |
| BusyBox tar | BusyBox v1.38.0, defconfig | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| 7-Zip | 7-Zip (z) 26.05 (x64) | ✅ as the verdict says | error: ERROR: Cannot create hard link : errno=2 : No such file or directory : DEST/a : DEST/a |
| Python tarfile, filter=data, as in pip | CPython 3.15.2 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Python tarfile, filter=tar | CPython 3.15.2 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Python tarfile, filter=fully_trusted | CPython 3.15.2 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| node-tar | tar 7.5.22 | ⚠️ accepts | tree B: nothing |
| node-tar, strict | tar 7.5.22 | ✅ as the verdict says | error: Error: ENOENT: no such file or directory, link 'DEST/a' -> 'DEST/a' |
| tar-fs | tar-fs 3.1.3, on tar-stream 3.2.2 | ✅ as the verdict says | error: Error: DEST/a is not a valid hardlink |
| Java Commons Compress | Commons Compress 1.28.0, Expander, on Java 27.0.1.0.2 | ⚠️ accepts | tree C: a (0 B, e3b0c442) |
| .NET System.Formats.Tar | System.Formats.Tar of .NET 10.0.14, ExtractToDirectory | ✅ as the verdict says | error: IOException: Cannot create 'DEST/a' because a file or directory with the same name already exists. |
| PHP PharData, as in Composer | PharData of PHP 8.5.12, as Composer's TarDownloader calls it | ⚠️ accepts | tree C: a (0 B, e3b0c442) |
| Go containerd archive.Apply | containerd v2.4.2, archive.Apply, of go1.27.3 | ✅ as the verdict says | error: link DEST/a DEST/a: no such file or directory |
| Rust tar | tar 0.4.46, unpack | ✅ as the verdict says | error: failed to unpack `DEST/a` |
| Rust astral-tokio-tar | astral-tokio-tar 0.7.0, unpack | ✅ as the verdict says | error: failed to unpack `DEST/a` |
| Rust tar-codec, as in uv | tar-codec 0.0.15, with the policies of uv 0.13 | ✅ as the verdict says | error: at byte 1024: invalid link a -> "a": hard-link target is the member path |
| RubyGems | RubyGems 4.0.20 of Ruby 4.0.9, extract_tar_gz | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| R untar, internal | utils::untar of R 4.6.1, tar = "internal" | ⚠️ accepts | tree B: nothing |
| Perl Archive::Tar | Archive::Tar 3.12 of Perl v5.44.0 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Haskell tar | tar 0.7.2.0, extract, of GHC 9.14 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Julia Tar.jl | Tar 1.10.0 of Julia 1.13.3 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| live-bootstrap untar | mescc-tools-extra a151c245e512, as live-bootstrap pins it, built with cc | ✅ as the verdict says | error: unable to create hardlinks |
| live-bootstrap untar, --non-strict | mescc-tools-extra a151c245e512, as live-bootstrap pins it, built with cc | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
Release tarballs of Spack, nixpkgs, Guix and live-bootstrap, and samples of PyPI, crates.io and RubyGems with hardlink.to-itself. The default policy rejects all of them.
| ecosystem | tarballs | with it | share |
|---|---|---|---|
| Spack | 37,553 | 24 | 0.06% |
| nixpkgs | 18,990 | 1 | <0.01% |
| Guix | 10,168 | 2 | 0.02% |
| PyPI | 10,000 | 0 | none |
| crates.io | 5,000 | 0 | none |
| RubyGems | 5,000 | 0 | none |
| live-bootstrap | 171 | 0 | none |
| total (distinct) | 82,586 | 27 | 0.03% |
See the list of these 27 tarballs, with the sha256 of each and an example from it.