N11 gnu-prefix-fieldThe prefix field of a header with GNU magic, which GNU tar uses for times in incremental archives.
Reject(draft) A strict parser must reject this archive.
N11-gnu-prefix-field.tar |
test archive, 2,048 bytes
sha256 ab69942782ab1ef26e364a130c4dfcbc84f9df77ab3890343a4fad81b5b43c99 |
N11-gnu-prefix-field.json | expected result |
N11-gnu-prefix-field.txt | annotated blocks |
N11-gnu-prefix-field.py | generator script |
GNU's format does not have a prefix field: in incremental archives, GNU tar writes the access and change times where ustar has its prefix. This case is ambiguous in practice because the field, taken for ustar's prefix, puts a under a directory 15000000000.
Decision point: whether a header with GNU magic has a prefix.
Seen in: none of the scanned tarballs with times there.
Every block of 512 bytes, to scale, with its offset. Hover over a field for its bytes.
N11-gnu-prefix-field: must reject
The prefix field of a header with GNU magic, which GNU tar uses for times in incremental archives.
GNU's format does not have a prefix field: in incremental archives, GNU tar writes the access and
change times where ustar has its prefix. This case is ambiguous in practice because the field, taken
for ustar's prefix, puts `a` under a directory `15000000000`.
Decision point: whether a header with GNU magic has a prefix.
Seen in: none of the scanned tarballs with times there.
0x000000 header: regular file, GNU magic, with an access and change time where ustar has its prefix
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) "011354\0 " 4844: 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 "
version [263,265) " " + NUL
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) "15000000000\015000000000" + 132 NUL
pad [500,512) 12 NUL
0x000200 data
2 bytes, then 510 NUL to the end of the block
"a\n"
0x000400 2 zero blocks: the end-of-archive marker
0x000800 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 3031 3133 3534 0020 3000 0000 000.011354. 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 2020 0000 0000 0000 0000 .ustar ........ 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 0031 3530 3030 3030 .0000000.1500000 00000160: 3030 3030 0031 3530 3030 3030 3030 3030 0000.15000000000 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: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 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 0000 0000 0000 0000 0000 0000 ................ 00000470: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000480: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 00000490: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 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: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 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 0000 0000 0000 0000 ................ 00000550: 0000 0000 0000 0000 0000 0000 0000 0000 ................ 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 ................
| 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 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| BusyBox tar | BusyBox v1.38.0, defconfig | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| 7-Zip | 7-Zip (z) 26.05 (x64) | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| Python tarfile, filter=data, as in pip | CPython 3.15.2 | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| Python tarfile, filter=tar | CPython 3.15.2 | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| Python tarfile, filter=fully_trusted | CPython 3.15.2 | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| node-tar | tar 7.5.22 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| node-tar, strict | tar 7.5.22 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| tar-fs | tar-fs 3.1.3, on tar-stream 3.2.2 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Java Commons Compress | Commons Compress 1.28.0, Expander, on Java 27.0.1.0.2 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| .NET System.Formats.Tar | System.Formats.Tar of .NET 10.0.14, ExtractToDirectory | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| PHP PharData, as in Composer | PharData of PHP 8.5.12, as Composer's TarDownloader calls it | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| Go containerd archive.Apply | containerd v2.4.2, archive.Apply, of go1.27.3 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Rust tar | tar 0.4.46, unpack | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Rust astral-tokio-tar | astral-tokio-tar 0.7.0, unpack | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| Rust tar-codec, as in uv | tar-codec 0.0.15, with the policies of uv 0.13 | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| RubyGems | RubyGems 4.0.20 of Ruby 4.0.9, extract_tar_gz | ✅ as the verdict says | error: Gem::Package::TarInvalidError: tar is corrupt, name contains null byte |
| R untar, internal | utils::untar of R 4.6.1, tar = "internal" | ⚠️ crashes | embedded nul in string: '15000000000\015000000000' |
| Perl Archive::Tar | Archive::Tar 3.12 of Perl v5.44.0 | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| Haskell tar | tar 0.7.2.0, extract, of GHC 9.14 | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| Julia Tar.jl | Tar 1.10.0 of Julia 1.13.3 | ⚠️ accepts | tree B: 15000000000/, 15000000000/a (2 B, 87428fc5) |
| live-bootstrap untar | mescc-tools-extra a151c245e512, as live-bootstrap pins it, built with cc | ⚠️ accepts | tree A: a (2 B, 87428fc5) |
| 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 gnu.atime-ctime.
| ecosystem | tarballs | with it | share |
|---|---|---|---|
| Spack | 37,553 | 0 | none |
| nixpkgs | 18,990 | 0 | none |
| Guix | 10,168 | 0 | none |
| 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 | 0 | none |