F33 size-on-dirA size in the header of a directory, which takes the next header for its data.
Reject(draft) A strict parser must reject this archive.
F33-size-on-dir.tar |
test archive, 2,048 bytes
sha256 f5220b7aa05cee7e28351c06e1ebcbb0038e09af581d161c418b944a0fb4b2b2 |
F33-size-on-dir.json | expected result |
F33-size-on-dir.txt | annotated blocks |
F33-size-on-dir.py | generator script |
The size field in the ustar header of a directory is 512. In POSIX, no data is stored for a directory, whatever its size, so the next block is the header of a file, smuggled. This case is ambiguous in practice because, if the size applies, that block is the directory's data instead, and the tree is a directory alone. The same goes for symlinks and devices, which do not have data either, and implementations need not decide alike for every kind: one that skips the size of a directory may take the size of a symlink for its data.
Decision point: whether a size in the header applies to a member without data.
Seen in: none of the scanned tarballs.
Every block of 512 bytes, to scale, with its offset. Hover over a field for its bytes.
F33-size-on-dir: must reject
A size in the header of a directory, which takes the next header for its data.
The size field in the ustar header of a directory is 512. In POSIX, no data is stored for a
directory, whatever its size, so the next block is the header of a file, `smuggled`. This case is
ambiguous in practice because, if the size applies, that block is the directory's data instead, and
the tree is a directory alone. The same goes for symlinks and devices, which do not have data
either, and implementations need not decide alike for every kind: one that skips the size of a
directory may take the size of a symlink for its data.
Decision point: whether a size in the header applies to a member without data.
Seen in: none of the scanned tarballs.
See also: F15, a pax `size` on a directory, and F34, a size in the header of a hard link, which
are rejected as well.
0x000000 header: directory, no data, but its size field is 512
name [ 0,100) "dir/" + 96 NUL
mode [100,108) "0000755" + NUL 755 (octal)
uid [108,116) "0000000" + NUL 0
gid [116,124) "0000000" + NUL 0
size [124,136) "00000001000" + NUL 512
mtime [136,148) "00000000000" + NUL 0
chksum [148,156) "007764\0 " 4084: the unsigned sum of the header, this field as spaces
typeflag [156,157) "5" directory
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 header: regular file, the block that the size covers
name [ 0,100) "dir/smuggled" + 88 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) "011503\0 " 4931: 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
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: 6469 722f 0000 0000 0000 0000 0000 0000 dir/............ 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 3735 3500 3030 3030 ....0000755.0000 00000070: 3030 3000 3030 3030 3030 3000 3030 3030 000.0000000.0000 00000080: 3030 3031 3030 3000 3030 3030 3030 3030 0001000.00000000 00000090: 3030 3000 3030 3737 3634 0020 3500 0000 000.007764. 5... 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: 6469 722f 736d 7567 676c 6564 0000 0000 dir/smuggled.... 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 3030 3030 3634 3400 3030 3030 ....0000644.0000 00000270: 3030 3000 3030 3030 3030 3000 3030 3030 000.0000000.0000 00000280: 3030 3030 3030 3000 3030 3030 3030 3030 0000000.00000000 00000290: 3030 3000 3031 3135 3033 0020 3000 0000 000.011503. 0... 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: 0075 7374 6172 0030 3000 0000 0000 0000 .ustar.00....... 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 0030 3030 3030 3030 .........0000000 00000350: 0030 3030 3030 3030 0000 0000 0000 0000 .0000000........ 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: dir/, dir/smuggled (0 B, e3b0c442) |
| bsdtar | bsdtar 3.8.10 - libarchive 3.8.10 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| BusyBox tar | BusyBox v1.38.0, defconfig | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| 7-Zip | 7-Zip (z) 26.05 (x64) | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Python tarfile, filter=data, as in pip | CPython 3.15.2 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Python tarfile, filter=tar | CPython 3.15.2 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Python tarfile, filter=fully_trusted | CPython 3.15.2 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| node-tar | tar 7.5.22 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| node-tar, strict | tar 7.5.22 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| tar-fs | tar-fs 3.1.3, on tar-stream 3.2.2 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Java Commons Compress | Commons Compress 1.28.0, Expander, on Java 27.0.1.0.2 | ⚠️ accepts | tree B: dir/ |
| .NET System.Formats.Tar | System.Formats.Tar of .NET 10.0.14, ExtractToDirectory | ✅ as the verdict says | error: InvalidDataException: The value of the size field for the current entry of type 'Directory' is greater than the expected length. |
| PHP PharData, as in Composer | PharData of PHP 8.5.12, as Composer's TarDownloader calls it | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Go containerd archive.Apply | containerd v2.4.2, archive.Apply, of go1.27.3 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Rust tar | tar 0.4.46, unpack | ⚠️ accepts | tree B: dir/ |
| Rust astral-tokio-tar | astral-tokio-tar 0.7.0, unpack | ⚠️ accepts | tree B: dir/ |
| 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 0: member type Directory cannot carry payload size 512 |
| RubyGems | RubyGems 4.0.20 of Ruby 4.0.9, extract_tar_gz | ⚠️ accepts | tree B: dir/ |
| R untar, internal | utils::untar of R 4.6.1, tar = "internal" | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Perl Archive::Tar | Archive::Tar 3.12 of Perl v5.44.0 | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| Haskell tar | tar 0.7.2.0, extract, of GHC 9.14 | ⚠️ accepts | tree B: dir/ |
| Julia Tar.jl | Tar 1.10.0 of Julia 1.13.3 | ✅ as the verdict says | error: directory with non-zero size Tar.Header("dir/", :directory, 0o755, 512, "") |
| live-bootstrap untar | mescc-tools-extra a151c245e512, as live-bootstrap pins it, built with cc | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
| live-bootstrap untar, --non-strict | mescc-tools-extra a151c245e512, as live-bootstrap pins it, built with cc | ⚠️ accepts | tree A: dir/, dir/smuggled (0 B, e3b0c442) |
Release tarballs of Spack, nixpkgs, Guix and live-bootstrap, and samples of PyPI, crates.io and RubyGems with size.on-dir.
| 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 |
F15: a pax size on a directory, and F34, a size in the header of a hard link, which are rejected as well.